Dual mode gas field ion source

FIELD OF THE INVENTION

p-0002The invention relates to a charged particle beam device and a method of operating a charged particle beam device. Particularly, it relates to a focused ion beam device having a gas field ion source, in particular for imaging, inspecting and structuring a specimen. Further, it relates to a gas field ion source column for dual mode operation and a method of operating a gas field ion source with different modes of operation. More specifically, it relates to a focused ion beam device and a method of operating a focused ion beam device.

BACKGROUND OF THE INVENTION

p-0003Technologies such as microelectronics, micromechanics and biotechnology have created a high demand for structuring and probing specimens within the nanometer scale. Micrometer and nanometer scale process control, inspection or structuring, is often done with charged particle beams. Probing or structuring is often performed with charged particle beams which are generated and focused in charged particle beam devices. Examples of charged particle beam devices are electron microscopes, electron beam pattern generators, ion microscopes as well as ion beam pattern generators. Charged particle beams, in particular ion beams, offer superior spatial resolution compared to photon beams, due to their short wave lengths at comparable particle energy.

p-0004During manufacturing of semiconductor devices or the like, a plurality of observation steps and sample modification steps are usually conducted. Common systems include an electron beam column for observation, imaging, testing or inspecting of a specimen and an ion beam column for patterning of a specimen or material modification. These “dual beam” systems have a high complexity and are, thus, expensive.

SUMMARY

p-0005In light of the above, the present invention provides a focused ion beam device according to independent claim <b>1</b>, a method of operating a focused ion beam device according to independent claim <b>10</b>, a method of operating a focused ion beam device according to independent claim <b>15</b>, and a focused ion beam device according to independent claim <b>17</b>.

p-0006According to one embodiment, a focused ion beam device is provided. The focused ion beam device includes an ion beam column adapted to house a gas field ion source emitter with an emitter tip and an emitter area for generating ions; a heating means adapted to heat the emitter tip; one or more gas inlets adapted to introduce a first gas and at least one second gas to the emitter area; and a controller adapted to switch between a first emitter tip temperature and at least a second emitter tip temperature for generating an ion beam of ions of the first gas or an ion beam of ions of the at least one second gas.

p-0007According to another embodiment, a method of operating a focused ion beam device is provided, the method including: biasing an emitter with an emitter tip within an emitter area wherein ions are generated to a potential for providing an extraction voltage for emitting an ion beam of at least one gas of a first gas and at least one second gas; heating to a first emitter tip temperature to emit an ion beam of the first gas; and heating to at least one second emitter tip temperature to emit at least one ion beam of the at least one second gas.

p-0008According to a further embodiment, a focused ion beam device is provided, including: an ion beam column housing an emitter with an emitter tip and an emitter area for generating ions of a first gas and at least one second gas; and means for switching between a first emitter tip temperature and at least one second emitter tip temperature, wherein the first gas is selected from the group consisting of hydrogen and helium and the at least one second gas has an atomic mass of 10 g/mol or higher.

p-0009According to a yet further embodiment, a method of operating a focused ion beam device is provided, wherein at least two different ion beams of a first gas and at least one second gas are consecutively generated by switching between at least two different emitter tip temperatures, the emitter tip temperatures each providing ionization of at least one of the gases.

p-0010Further advantages, features, aspects and details that can be combined with embodiments described herein are evident from the depending claims, the description and the drawings.

p-0011Embodiments are also directed to apparatuses for carrying out the disclosed methods and including apparatus parts for performing each described method step. These method steps may be performed by way of hardware components, a computer programmed by appropriate software, by any combination of the two or in any other manner. Furthermore, embodiments according to the invention are also directed to methods by which the described apparatus operates. It includes method steps for carrying out every function of the apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

p-0012So that the manner in which the above-recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments. The accompanying drawings relate to embodiments of the invention and are described in the following:

p-0013<figref idrefs="DRAWINGS">FIG. 1A</figref> shows a schematic view of parts of a charged particle beam device in the form of a focused ion beam device with a first gas inlet, a second gas inlet and a heater according to embodiments described herein;

p-0014<figref idrefs="DRAWINGS">FIG. 1B</figref> shows a schematic view of parts of a charged particle beam device in the form of a focused ion beam device with a first gas inlet, a second gas inlet and a heater according to embodiments described herein;

p-0015<figref idrefs="DRAWINGS">FIG. 2</figref> shows a schematic view of an emitter tip in a gas field ion source and the principle of operation of the emitter tip according to embodiments described herein;

p-0016<figref idrefs="DRAWINGS">FIG. 3A</figref> shows a schematic view of parts of a charged particle beam device in the form of a focused ion beam device with a first gas inlet and a second gas inlet according to embodiments described herein;

p-0017<figref idrefs="DRAWINGS">FIG. 3B</figref> shows a schematic view of parts of a charged particle beam device in the form of a focused ion beam device with a first gas inlet, a second gas inlet, and a common gas inlet according to embodiments described herein;

p-0018<figref idrefs="DRAWINGS">FIG. 4</figref> shows a schematic view of an emitter tip in a gas field ion source and the principle of operation of the emitter tip in a first mode of operation according to embodiments described herein;

p-0019<figref idrefs="DRAWINGS">FIG. 5</figref> shows a schematic view of an emitter tip in a gas field ion source and the principle of operation of the emitter tip in a second mode of operation according to embodiments described herein;

p-0020<figref idrefs="DRAWINGS">FIG. 6</figref> shows a schematic view of parts of a charged particle beam device in the form of a focused ion beam device with a first gas inlet, a second gas inlet and a third gas inlet according to embodiments described herein;

p-0021<figref idrefs="DRAWINGS">FIG. 7A</figref> shows a schematic view of parts of a charged particle beam device in the form of a focused ion beam device with gas inlets and valves according to embodiments described herein;

p-0022<figref idrefs="DRAWINGS">FIG. 7B</figref> shows a schematic view of parts of a charged particle beam device in the form of a focused ion beam device with gas inlets and valves according to embodiments described herein;

p-0023<figref idrefs="DRAWINGS">FIG. 8</figref> shows a schematic view of parts of a charged particle beam device in the form of a focused ion beam device with gas inlets, valves and a vacuum recipient according to embodiments described herein; and

p-0024<figref idrefs="DRAWINGS">FIG. 9</figref> shows a schematic view of parts of a charged particle beam device in the form of a focused ion beam device with gas inlets, valves and vacuum recipients according to embodiments described herein.

DETAILED DESCRIPTION OF THE INVENTION

p-0025Reference will now be made in detail to the various embodiments of the invention, one or more examples of which are illustrated in the figures. Each example is provided by way of explanation of the invention and is not meant as a limitation of the invention. For example, features illustrated or described as part of one embodiment can be used on or in conjunction with other embodiments to yield yet a further embodiment. It is intended that the present invention includes such modifications and variations.

p-0026Without limiting the scope of protection of the present application, in the following the charged particle beam device or components thereof will exemplarily be referred to as a charged particle beam device including the detection of secondary electrons. The present invention can still be applied for apparatuses and components detecting corpuscles such as secondary and/or backscattered charged particles in the form of electrons or ions, photons, X-rays or other signals in order to obtain a specimen image.

p-0027Generally, when referring to corpuscles it is to be understood as a light signal, in which the corpuscles are photons, as well as particles, in which the corpuscles are ions, atoms, electrons or other particles.

p-0028Within the following description of the drawings, the same reference numbers refer to the same components. Generally, only the differences with respect to the individual embodiments are described.

p-0029A “specimen” as referred to herein, includes, but is not limited to, semiconductor wafers, semiconductor workpieces, and other workpieces such as memory disks and the like. Embodiments of the invention may be applied to any workpiece on which material is deposited or which is structured. A specimen includes a surface to be structured or on which layers are deposited, an edge, and typically a bevel.

p-0030According to embodiments described herein, a single column charged particle beam device is provided, which allows for a high-resolution imaging and sample modification. Thereby, a simplified single column operation can be provided. Further, in light of the fact that one column can be omitted, a reduction of costs can be achieved.

p-0031Generally, focused ion beam devices can, for example, be based on liquid-metal ion sources or gas ion sources. Ions in gas ion sources can be produced by bombardment of electrons, atoms or ions with gas atoms or molecules or by exposing gas atoms or molecules to high electric fields or irradiation. Thereby, noble gas ion sources have been found to be potential candidates for focused ion beam (FIB) applications. Sources based on the field ionization process are known as gas field ion sources (GFIS). An ionization process takes place at high electric fields or extraction voltages, respectively, larger than 10¹⁰V/m. The field may, for example, be applied between an emitter tip and a biased extraction aperture, which are for instance provided in a gun chamber which may in one example include an enclosure in which the emitter tip is provided.

p-0032The emitter tip is biased to a positive potential with respect to a downstream extraction aperture, whereby an electric field strong enough to ionize the gas atoms in the vicinity of the tip of the emitter unit is generated. The area in the vicinity of the emitter, wherein the desired electric field is provided or, more generally, wherein the generation of ions is conducted, may be referred to as an emitter area. Gas pressures of 10⁻⁶mbar to 10⁻²mbar are desirable near the tip of the emitter unit. Thereby, as explained in more detail below, a gas gradient is typically used in order to, on the one hand, provide a sufficient amount of gas atoms or molecules in the emitter area and, on the other hand, to not disturb emitted ions by gas molecules provided in the gun chamber.

p-0033<figref idrefs="DRAWINGS">FIGS. 1A and 1B</figref> show a first gas inlet <b>110</b> and a second gas inlet <b>112</b>. According to embodiments described herein, different modes of operation can be provided. According to one operational mode, a light gas, e.g., a gas having an atomic mass of less than 10 g/mol, such as hydrogen or helium, is introduced into the chamber/enclosure <b>14</b> through one of the first and the second gas inlets, and an ion beam of the ionized light gas can be generated. The light gas ions can be used for an observation or imaging without damaging the specimen.

p-0034According to another operational mode, a different gas, which is a heavier gas as, for example, argon, neon, xenon or krypton is introduced into the chamber/enclosure <b>14</b> through one of the first or second gas inlets <b>110</b> or <b>112</b>. The ion beam of the ionized heavy gas, which is generated within the gun chamber, that is the enclosure <b>14</b>, is similar to an ion beam of a standard focused ion beam column for sputtering material. The heavy gas beam can, thus, be used for material modification, or to produce cuts or trenches within a specimen, or to get depth information.

p-0035Within the embodiments described herein, the enclosure <b>14</b>, in which the emitter <b>12</b> including the emitter tip <b>14</b> is provided, may be a part of the ion beam column. Alternatively, it may be a separate chamber included in the ion beam column. Moreover, the enclosure <b>14</b> may correspond to the emitter area. Further, it is possible that the ion beam column itself provides the enclosure, wherein the emitter is located and wherein the gases are introduced.

p-0036The light gas ions do not sputter the sample material and can be used for imaging, testing, observation, or the like. Thereby, a light gas ion may have an even better resolution than an electron beam because of the shorter wavelengths of the ion beam as compared to an electron beam

p-0037Generally, as shown in <figref idrefs="DRAWINGS">FIGS. 1A and 1B</figref>, a focused ion beam device <b>100</b> can schematically be illustrated as follows. An enclosure <b>14</b> with a biased gas field ion source emitter tip <b>13</b> is provided. Further, a first (light) gas inlet <b>110</b> and a second (heavy) gas inlet <b>112</b> is provided. Thereby, the first gas and the second gas are provided into the enclosure <b>14</b> towards the emitter tip <b>13</b> and to the emitter area in the vicinity of the emitter. In the vicinity of the emitter, tip the desired excitation conditions are provided. According to different embodiments, which can be combined with other embodiments described herein, the two gas inlets can be provided in the form of two nozzles, gas channels, or other gas inlet means. According to other embodiments, the two gas inlets provide the two gases in a common nozzle, gas channel, or other gas inlet means.

p-0038As shown in <figref idrefs="DRAWINGS">FIGS. 1A and 1B</figref>, a gas outlet <b>120</b> is provided. The gas outlet <b>120</b> can be connected to a vacuum pump, a further vacuum chamber, or other means to support the evacuation and/or the control of the pressure in the enclosure <b>14</b>. Thereby, the process parameters for ion beam generation can be controlled.

p-0039Typically, a gas pressure gradient within the gun chamber can be provided. Thereby, the gas pressure is higher in the vicinity of the emitter, and the emitter tip and is reduced towards an extraction electrode. Thereby, a sufficient amount of gas can be provided to the emitter tip, and the amount of gas that may disturb the ion emission is reduced. According to different examples, which can be combined with any of the embodiments described herein, the gas pressure gradient may reach from 10⁻⁵mbar to 10⁻³mbar, typically from 10⁻⁴mbar to 5×10⁻³mbar. Behind the extractor, the gas pressure decreases further.

p-0040As shown in <figref idrefs="DRAWINGS">FIGS. 1A and 1B</figref>, according to some embodiments described herein, a controller <b>130</b> can be provided. The controller <b>130</b> controls the supply of light gas into the enclosure <b>14</b> and the supply of heavy gas in the enclosure <b>14</b>. Further, for embodiments including a separate gas outlet <b>120</b>, the controller may control the gas outlet, a vacuum system, vacuum pumps or valves corresponding therewith. According to further embodiments, controllers <b>111</b>, <b>113</b> and <b>121</b> can be provided. These controllers are controllers for the individual inlets, outlets, valves, pumps and the like. As indicated by the dashed lines, these controllers may be omitted as they are redundant in cases where the controller <b>130</b> is able to control the components directly.

p-0041The ion beam is focused by the lens <b>20</b> on the specimen <b>24</b>. According to one embodiment, lens <b>20</b> is an electrostatic lens. Depending on the application, one or more optical elements like lenses, deflectors, Wien filters, condensers, alignment units, collimators, acceleration or deceleration units, apertures etc. could be additionally arranged in the focused ion beam device.

p-0042Generally, the ion beam is deflected with a scan deflector <b>26</b> to raster scan the ion beam over the specimen <b>24</b> or position the ion beam at the position of the specimen. Secondary and/or backscatter particles, for example secondary and/or secondary electrons, are detected with detector <b>22</b>, particularly when the focused ion beam device is operated in an observation mode.

p-0043According to further embodiments, as shown in <figref idrefs="DRAWINGS">FIGS. 1A and 1B</figref>, a controller <b>140</b> can be provided. Controller <b>140</b> controls the scan deflector <b>26</b> and the detector <b>22</b>. During the observation mode of the focused ion beam device <b>100</b>, the device works similar to a scanning electron microscope. The ion beam with a diameter of a few nanometers or less (e.g., 1 nm or less) is scanned over the specimen <b>24</b>, e.g., raster scanned in a pattern over the specimen <b>24</b>, vector-scanned, or interlaced scanned. Secondary and/or backscattered electrons or other corpuscles can be detected with a detector. A time resolved signal is generated, and the controller <b>140</b> allows for correlating a signal at a given instance of time with a corresponding deflection value. Thereby, the raster pattern can be assembled to an image by correlating the signals with respect to the position on the specimen <b>24</b>.

p-0044A dual mode gas ion column could, on the one hand, be provided by supplying different gases, that is, for example a light gas and a heavy gas, in the enclosure <b>14</b> and switching between the two modes of operation by supplying different gases for each of the operational modes. According to embodiments described herein, which can individually be combined with details of the individual examples, instead of supplying the different species of gas by switching between the different gas supplies, the gas field ion gun may contain a mixture of the required gases. According to examples of embodiments, the selection of different ion species can be conducted based on different tip temperatures. According to some examples of embodiments, the selection of different ion species can further be conducted based on different ionization energies.

p-0045In light of the above, according to embodiments, which may be combined with any other embodiment disclosed herein, as a heating means a heater <b>15</b> is provided for heating the emitter tip <b>13</b>.

p-0046As illustrated in <figref idrefs="DRAWINGS">FIG. 1A</figref>, the heater <b>15</b> may be connected to the emitter tip <b>13</b> for heating. In one example of embodiments, which can be combined with any other example or embodiment disclosed herein, the emitter tip <b>13</b> is provided at a filament of a support including the filament and a filament base. In this case, the heater <b>15</b> may be adapted to heat at least one element selected from the group consisting of the emitter tip, the filament and the filament base. For instance, the heater <b>15</b> may be a resistance heater. In one example, the heater <b>15</b> may include a heating current supply, e.g., of about <b>10</b> V, having one port connected to one end of the filament and a second port connected to the other end of the filament. In another example, the heater <b>15</b> may be connected to the filament base and may heat the emitter tip via the filament base and the filament. As a result, a front part of the emitter tip support, i.e., the part adjacent to the emitter tip, is heated, thereby heating the emitter tip, while cooling of a rear part of the emitter tip support, i.e., the part between the front part and a cooling unit (not shown), is continued. The cooling unit will be described below.

p-0047In another example of embodiments, which can be combined with any other example or embodiment disclosed herein, the heater <b>15</b> is positioned adjacent to the emitter tip. In this case, the heater <b>15</b> may not be connected to the emitter tip. For instance, the heater <b>15</b> may be positioned in an emitter tip region, e.g., in the enclosure <b>14</b>, adjacent to the emitter tip, as shown in <figref idrefs="DRAWINGS">FIG. 1B</figref>. In such a case, the heater <b>15</b> may e.g., be at least one element selected from the group consisting of an electromagnetic heater, an induction heater, a radiant heater, an IR heater, a particle source (e.g., an electron source), and a laser. As a result, the emitter tip may be heated while cooling of the front part and/or the rear part of the emitter tip support is continued.

p-0048Hence, according to embodiments described herein, a rapid switching between an operation of cooling the emitter tip and an operation of heating the emitter tip may be achieved.

p-0049Further, according to some embodiments described herein, an adjustable power supply <b>72</b> is provided for supplying an extraction voltage between the emitter tip <b>13</b> and the electrode <b>18</b>. The extraction voltage can be controlled by a controller <b>172</b> as will be described in more detail below. Further, the controller may optionally also control the controller <b>130</b> for controlling the partial pressures of the gases.

p-0050<figref idrefs="DRAWINGS">FIG. 2</figref> shows an emitter tip <b>13</b> and an extraction electrode <b>18</b>. Between the emitter tip and the extraction electrode, a voltage supply <b>72</b> is provided for generating a high electric field. Typically, the emitter tip <b>13</b> includes a shank <b>210</b> and a tip <b>212</b>, which may include in one example a supertip. According to different embodiments, the tip <b>212</b>, which is provided at the shank <b>210</b> can be a tip including one, two, three, four, five atoms or more. The operation principle of the ion generation of a gas field ion source is explained with respect to one species. As shown in <figref idrefs="DRAWINGS">FIG. 2</figref>, for example helium atoms <b>52</b> which are ionized to generate helium ions <b>53</b> are provided.

p-0051The emitter tip <b>13</b> can typically be in communication with a cooling unit (not shown). According to different embodiments, which can be combined with any of the embodiments described herein, the cooling unit can include any of the following systems: the cooling unit may be a cryocooler, EG, open or closed cycle-coolers, open or closed cycle helium coolers, open or closed cycle nitro tin coolers, a combination thereof or another cooler. Particular examples can be a pulse tube cooler or GM cooler (Gifford McMahon cooler).

p-0052If helium gas is provided to the emitter tip along a direction in <figref idrefs="DRAWINGS">FIG. 2</figref> from top to bottom, the helium atoms <b>52</b> condense at the shank <b>210</b> of the emitter <b>13</b>. Thereby, it is typically desired to have a shank <b>210</b> which provides a sufficiently large surface for condensation of the helium atoms. The surface can be in a range typically from 0.2 μm²to 5 μm².

p-0053As indicated by arrows <b>62</b> the atoms diffuse towards the tip <b>212</b>. Thereby, movement based on diffusion due to different helium concentration at the shank <b>212</b> with respect to the tip <b>212</b> and based on drifts due to the electric field can result in a movement of the helium atoms <b>52</b> towards the tip <b>212</b>. As an example, helium typically requires an electrical field of approximately 44 V/nm for ionization. The voltage between the emitter tip <b>13</b> and the extraction electrode <b>18</b> is chosen such that the electric field at the tip <b>212</b> provides at least the ionization energy for the species to be ionized. Thereby, it has to be considered that the electric field at the tip with its small dimensions is higher than at any other point of the emitter. Helium atoms <b>52</b> are thus ionized at the tip <b>212</b> and are emitted as helium ions <b>53</b>.

p-0054<figref idrefs="DRAWINGS">FIGS. 3A and 3B</figref> illustrate further embodiments of a portion of focused ion beam columns <b>300</b><i>a </i>and <b>300</b><i>b, </i>respectively. Therein, a gun chamber <b>17</b> is provided on top of the column <b>16</b>. The emitter <b>12</b> is mounted to an emitter holder <b>10</b>. A cooling unit <b>30</b> is provided to have thermal conductivity between the cooling unit <b>30</b> and the emitter tip <b>13</b> via the emitter holder <b>10</b>. An extraction electrode <b>18</b> is provided for the voltage between the emitter tip <b>13</b> and the extraction electrode. Connections from the emitter to the extraction electrode are connected via a voltage supply <b>72</b>, which is able to provide different voltages. Further, as shown in <figref idrefs="DRAWINGS">FIG. 3A</figref> a first gas inlet <b>110</b> and a second gas inlet <b>112</b> provide a first and a second gas, respectively, to the enclosure such that a gas mixture is provided to the emitter. According to some embodiments described herein, the emitter <b>12</b> including the emitter tip <b>13</b> may be provided within an enclosure <b>14</b>, and the enclosure <b>14</b> may be shaped such that the gas is provided to the emitter <b>13</b> from top to bottom in order to provide a sufficiently large condensation surface at the shank of the emitter tip. A gas outlet <b>120</b> can be included in order to evacuate and/or control the pressure in the enclosure <b>14</b>. The ions generated in the vicinity of the emitter tip <b>13</b> are accelerated towards the extraction electrode and are guided along optical access <b>102</b>.

p-0055As shown in <figref idrefs="DRAWINGS">FIG. 3B</figref>, according to some embodiments it is possible that the first gas inlet and the second gas inlet provide the gas to a common gas inlet <b>310</b>, which supplies the gas mixture into the emitter area. According to embodiments described herein, the gas mixture can be either provided to the vicinity of the emitter tip by having two separate gas inlets, having two separate gas inlets feeding the respective gases into a common gas inlet, or by supplying a gas mixture through a single gas inlet.

p-0056According to yet further embodiments, more than two gases and, thus, more than two gas inlets can be provided for feeding gases or a common gas inlet. Further, it is possible, that a mixture of more than two gases, for example three or four gases, can be directly fed into the emitter area.

p-0057The dual or multiple modes of operation, which are provided according to embodiments described herein, can be better understood with respect to <figref idrefs="DRAWINGS">FIGS. 4 and 5</figref>. As an example, reference is made to helium as a light (first) gas and argon as a second (heavy) gas. It is to be understood that according to other embodiments any combination of gases described herein can be used.

p-0058As mentioned above, according to some examples of embodiments, the selection of different ion species can be conducted based on different ionization energies. Hence, one possibility to switch between gases is to switch the extraction voltage of the emitter tip <b>13</b>.

p-0059Within <figref idrefs="DRAWINGS">FIG. 4</figref>, a voltage is provided by the voltage source <b>72</b> between the emitter <b>13</b> and the extraction electrode <b>18</b>. The voltage source can be controlled by controller <b>172</b>. According to some embodiments, the controller <b>172</b> can be in communication with controller <b>130</b> (not shown in <figref idrefs="DRAWINGS">FIG. 4</figref>) for the supply of the first and the second gas inlet. The emitter includes a shank <b>210</b> and a tip <b>212</b>. For the example illustrated in <figref idrefs="DRAWINGS">FIG. 4</figref>, a mixture of helium atoms <b>52</b> and argon atoms <b>54</b>, which are indicated by different shapes, is provided to be able to condensate or be deposited at the shank <b>210</b> of the emitter tip <b>13</b>. Typically, helium requires an electrical field of approximately 44 V/nm for ionization, while argon requires an electrical field of approximately 22 V/nm for ionization. If, for example, a helium ion beam of helium ions <b>53</b> is to be formed, the voltage supply <b>72</b> is adjusted such that an extraction voltage, which provides at at least a part of the tip surface an electrical field of approximately 44 V/nm or slightly higher, is applied at the position of the tip <b>212</b>. As shown in <figref idrefs="DRAWINGS">FIG. 4</figref>, helium atoms <b>52</b> condensate or are deposited at the shank <b>210</b> and move by diffusion or drift towards the tip <b>212</b> where the helium atoms are ionized. For the voltage provided between the emitter tip and the extractor electrode as indicated in <figref idrefs="DRAWINGS">FIG. 4</figref> the helium atoms <b>52</b> are ionized at the vicinity of the tip in light of the higher electric field due to the small radius of the tip. Since the ionization energy of argon is significantly lower as compared to the ionization energy of helium, the argon atoms <b>54</b> are ionized to argon ions <b>55</b> before they reach the tip <b>212</b>. Accordingly, argon ions are generated at the shank <b>210</b> and do not reach the emitter tip because they are ionized earlier while they diffuse along the emitter shank. In light of the positive potential of the shank <b>210</b> the argon ions are repelled by the shank and do not form a collimated beam at the tip. Since the argon ions are emitted from a much larger region as compared to the helium ions, argon does not form a collimated beam under the voltage supply conditions indicated in <figref idrefs="DRAWINGS">FIG. 4</figref>.

p-0060According to some embodiments, which can be combined with other embodiments described herein, it would be possible to provide a mass separator <b>742</b> (see, e.g., <figref idrefs="DRAWINGS">FIGS. 1A and 1B</figref>) such as a magnetic deflector, a Wien-filter or the like in the event a significant number of argon ions would travel along the optical access and would reach the sample.

p-0061For a second mode of operation, which is illustrated in <figref idrefs="DRAWINGS">FIG. 5</figref> the voltage supply <b>72</b> is adjusted to apply a voltage such that the extraction voltage provides at at least a part of the tip surface an electrical field of approximately 22 V/nm or slightly above this value. Thereby, the maximum electric field is significantly below the value required for ionization of helium. Accordingly, only argon is ionized, and argon ions <b>55</b> are generated in the vicinity of the tip <b>212</b>. As described above, the argon atoms condense at the shank <b>210</b> of the emitter <b>13</b> and diffuse and/or drift towards the tip by a concentration gradient and/or an electric field along the shank <b>210</b>. Since the field strengths illustrated in <figref idrefs="DRAWINGS">FIG. 5</figref> are too low for helium ionization, an argon beam is formed and guided through extraction electrode <b>18</b> along the optical access towards the specimen.

p-0062As shown in <figref idrefs="DRAWINGS">FIG. 5</figref>, helium atoms <b>52</b> condensate, or are deposited at the shank <b>210</b> of the emitter <b>13</b>. Since helium is not emitted from the emitter tip, it might accumulate on the tip. Depending on the operation conditions, the accumulated helium may reduce the argon supply along the shank <b>210</b>. If the argon supply along the shank towards the tip <b>212</b> is reduced to an unacceptable amount, a short pulse with a high field strength can be applied to emit the helium atoms and reduce the amount of helium atoms that are condensed on the emitter tip <b>13</b>. According to additional or alternative embodiments, the emitter tip can be heated by, for example, a short current pulse through the supporting wire to evaporate the absorbed gases. Thereby a similar or additional effect can be generated.

p-0063According to some embodiments, which can yield by a combination with other embodiments described herein, the ratio between the “light” gas and the heavy gas can be adjusted according to requirements. Since heavy species are used for etching etc., which should be done fast, concentration of heavy species can be larger than concentration of He.

p-0064By switching the potential difference between the emitter tip <b>13</b> and the extraction electrode <b>18</b>, or by other adjustments to change the electrical field at the tip <b>212</b>, different modes of operation for emitting different ion beams can be generated.

p-0065According to embodiments described herein, a gas mixture can be provided in a range of 10⁻⁴mbar to 10⁻²mbar.

p-0066According to embodiments described herein, which can be combined with other embodiments described herein, at least two different voltages are provided by the power supply <b>72</b>. According to a first operational mode a voltage is provided that corresponds to a high electric field at the position of the tip of the emitter tip <b>13</b> where the highest electric field is provided. Thereby the emitter tip provides three different regions with respect to a first, lower electric field and a second, higher electric field. At the very top of the shank <b>210</b>, the electric field is below the first and the second electric field. At an intermediate portion of the shank <b>210</b>, an electric field is equal to the first, lower electric field such, that the first species can be ionized. Further, in the vicinity of the tip with the smallest curvature an electric field equal to or at least having the second, higher electric field is provided. Thereby according to this mode of operation, two species get ionized. However, only one of them forms an accumulated beam at the tip of the emitter tip <b>13</b>.

p-0067For the second mode of operation, the electric field is below the first, lower electric field along the majority of the emitter tip <b>13</b>. The first, lower electric field is reached only at the portion of the emitter tip with the smallest curvature or in the vicinity of this position. Accordingly, only one species is ionized.

p-0068As mentioned above, the selection of different ion species can be conducted by the selection of the emitter tip temperature. Hence, another possibility to switch between gases is to switch the temperature of the emitter tip <b>13</b>.

p-0069According to one example of embodiments, while providing a constant electric field by establishing a constant extraction voltage, the ion current of a first gas may be at maximum at a first tip temperature, while the ion current of a second gas may be at maximum at a second tip temperature. The constant extraction voltage may for instance be an extraction voltage chosen from a range between an extraction voltage, at which one of the gases has a sufficient emission current at commonly used cooling temperatures, and an extraction voltage, at which another one of the gases has a sufficient emission current at commonly used cooling temperatures. For instance, when applying an extraction voltage providing at at least a part of the tip surface an electrical field in the range of about 20 V/nm to about 50 V/nm at the emitter tip <b>13</b>, an argon ion current may be at a maximum at tip temperatures of about 80 K, while He has an emission maximum at about 20 K. The gas to be emitted preferentially is thus chosen by switching the temperature of the tip.

p-0070If, for instance, a closed cycle He cryocooler is used for cooling the emitter tip, e.g., a pulse tube cooler, a Gifford-Mc-Mahon cooler, a Stirling cooler, a fast switching between temperatures can be attained by having the cooler constantly operating at the lower temperature required for helium. If the higher temperature for e.g., argon emission is needed, the heater <b>15</b>, e.g., a resistive heater, located close to the emitter tip is switched on, so that the temperature rises. In this way, fast switching of temperatures is achieved, because the temperature of the tip changes, while the cooler itself with its high heat capacitance stays at the same temperature.

p-0071Within an example illustrated referring to <figref idrefs="DRAWINGS">FIG. 4</figref>, a constant voltage may be provided by the voltage source <b>72</b> between the emitter <b>13</b> and the extraction electrode <b>18</b>. The heater <b>15</b> connected to the emitter tip <b>212</b> is controlled by controller <b>172</b>, which may also control the voltage source <b>72</b>. For controlling the tip temperature, a temperature sensor (not shown) connected to the controller <b>172</b> may be provided e.g., at the emitter tip support. As a cooling unit, e.g., a closed cycle He cryocooler (not shown) is connected to the emitter tip support and used for cooling the emitter tip <b>13</b>. According to some embodiments, the controller <b>172</b> can be in communication with controller <b>130</b> for the supply of the first and the second gas inlet. The emitter includes a shank <b>210</b> and a tip <b>212</b>, for instance an ultra sharp tip or a tip including a supertip. For the example illustrated in <figref idrefs="DRAWINGS">FIG. 4</figref>, a mixture of helium atoms <b>52</b> and argon atoms <b>54</b>, which are indicated by different shapes, is provided to be able to condensate or be deposited at the shank <b>210</b> of the emitter tip <b>13</b>. Helium requires an electrical field of approximately 44 V/nm for ionization, while argon requires an electrical field of approximately 22 V/nm for ionization. For example, the voltage supply <b>72</b> is adjusted such that an extraction voltage, which provides at at least a part of the tip surface an electrical field of e.g., approximately 44 V/nm or slightly higher, is applied at the position of the tip <b>212</b>. Moreover, the heater <b>15</b> is not operated, such that at the emitter tip <b>13</b> a temperature of e.g., about 20 K is provided. As shown in <figref idrefs="DRAWINGS">FIG. 4</figref>, helium atoms <b>52</b> and argon atoms <b>54</b> condensate, or are deposited, at the shank <b>210</b>, and move by diffusion or drift towards the tip <b>212</b>. Since the tip temperature corresponds to the temperature at which helium has its emission maximum, also referred to herein as emission maximum temperature, the helium atoms are ionized. For the voltage provided between the emitter tip and the extractor electrode as indicated in <figref idrefs="DRAWINGS">FIG. 4</figref>, the helium atoms <b>52</b> are ionized at the vicinity of the tip. Since the emission, maximum temperature of argon is significantly higher (80 K) as compared to the emission maximum temperature of helium (20 K), a substantial amount of the helium atoms <b>52</b> are ionized, while the argon atoms <b>54</b> predominantly are not ionized. Hence, a collimated beam of helium ions <b>53</b> is generated under the voltage and temperature conditions described with respect to <figref idrefs="DRAWINGS">FIG. 4</figref>. Accordingly, for ionizing a substantial amount of the argon atoms <b>54</b>, the heater <b>15</b> is switched on. This situation is illustrated in <figref idrefs="DRAWINGS">FIG. 5</figref>. Thereby, the ionization efficiency for the argon atoms <b>54</b> is maximized while the helium atoms <b>52</b> predominantly are not ionized. Hence, a collimated beam of argon ions <b>55</b> is generated at the tip <b>212</b> under the temperature and voltage supply conditions provided in the situation illustrated in <figref idrefs="DRAWINGS">FIG. 5</figref>.

p-0072Of course, this principle can be applied for other combinations of a plurality of gases with different optimum emission temperatures.

p-0073Moreover, for providing a constant electric field in the present example of embodiments, other suitable extraction voltages may be applied. For instance, an extraction voltage may be chosen at or in the vicinity of an extraction voltage providing an electric field at which one of the gases has a maximum emission current at commonly used cooling temperatures. In another example, an extraction voltage may be chosen from a range between an extraction voltage, at which one of the gases has a sufficient emission current at commonly used cooling temperatures, and an extraction voltage, at which another one of the gases has a sufficient emission current at commonly used cooling temperatures. Typically, an extraction voltage may be chosen, which provides the electric field for ionizing the one of e.g., two gases, which has the higher ionization energy, while cooling at commonly used cooling temperatures. In another typical example, an extraction voltage may be chosen, which provides the electric field for ionizing the one of e.g., two gases, which has the smaller ionization energy, while cooling at commonly used cooling temperatures. In any case, ionization of the other of the e.g., two gases may then be initiated by heating the emitter tip.

p-0074In further embodiments, the principle of switching the tip temperature and of switching the extraction voltage can be combined to attain maximum efficiency. In some embodiments, more than two gases may be provided, and the gas to be emitted preferentially is chosen by providing more than two temperatures of the tip, and optionally more than two extraction voltages and/or optionally adapting the partial pressure of the gas. Correspondingly, in some embodiments, more than two different ion beams may be generated by switching between more than two different emitter tip temperatures, and optionally switching between more than two different extraction voltages and/or optionally switching between more than two different gases.

p-0075Hence, in one embodiment, a method of operating a focused ion beam device is provided, wherein at least two different ion beams of a first gas and at least one second gas are consecutively generated by switching between at least two different emitter tip temperatures, and optionally by switching between at least two different extraction voltages and/or between at least two of the first gas and the at least second gas, the emitter tip temperatures and the extraction voltages each providing ionization of at least one of the gases. In some embodiments, the emitter tip temperatures and/or the extraction voltages each provide an optimum, e.g., maximum, ionization efficiency of at least one of the gases.

p-0076For instance, according to one example of embodiments, referring to <figref idrefs="DRAWINGS">FIG. 4</figref>, a voltage may be provided by the voltage source <b>72</b> between the emitter <b>13</b> and the extraction electrode <b>18</b>. The heater <b>15</b> adjacent to the emitter tip <b>212</b> is controlled by controller <b>172</b>, which may also control the voltage source <b>72</b>. For controlling the tip temperature, a temperature sensor (not shown) connected to the controller <b>172</b> may be provided e.g., at the emitter tip support. As a cooling unit, e.g., a closed cycle He cryocooler (not shown) is connected to the emitter tip support and used for cooling the emitter tip <b>13</b>. According to some embodiments, the controller <b>172</b> can be in communication with controller <b>130</b> for the supply of the first and the second gas inlet. The emitter includes the shank <b>210</b> and the tip <b>212</b>. For the example illustrated in <figref idrefs="DRAWINGS">FIG. 4</figref>, a mixture of helium atoms <b>52</b> and argon atoms <b>54</b>, which are indicated by different shapes, is provided and may adsorb or be deposited at the shank <b>210</b> of the emitter tip <b>13</b>. As mentioned above, typically, helium requires an electrical field of approximately 44 V/nm for ionization, while argon requires an electrical field of approximately 22 V/nm for ionization. If, for example, a helium ion beam of helium ions <b>53</b> is to be formed, the voltage supply <b>72</b> is adjusted such that e.g., an extraction voltage, which provides at at least a part of the tip surface an electrical field of e.g., approximately 44 V/nm or slightly higher, is applied at the position of the tip <b>212</b>. Moreover, the heater <b>15</b> is not operated, such that at the emitter tip <b>13</b>, a temperature of e.g., about 20 K is provided. As shown in <figref idrefs="DRAWINGS">FIG. 4</figref>, helium atoms <b>52</b> and argon atoms <b>54</b> condensate, or are deposited at the shank <b>210</b>, and move by diffusion or drift towards the tip <b>212</b>. Since the tip temperature corresponds to the temperature and the electric field at the emitter tip <b>13</b> corresponds to the electric field, at which helium has its emission maximum, the helium atoms are ionized, while the argon atoms <b>54</b> predominantly are not ionized. Hence, a collimated beam of helium ions <b>53</b> is generated under the voltage and temperature conditions described with respect to <figref idrefs="DRAWINGS">FIG. 4</figref>. If a substantial amount of the argon atoms <b>54</b> is to be ionized, the heater <b>15</b> is switched on, in order to heat the emitter tip to e.g., about 80 K. Further, the voltage supply <b>72</b> is adjusted such that an extraction voltage, which provides at at least a part of the tip surface an electrical field of e.g., approximately 22 V/nm or slightly higher is applied at the position of the tip <b>212</b>. The switching of the emitter tip temperature and the extraction voltage at the emitter tip can be performed substantially simultaneously. In the present example, when both the emitter tip temperature and the extraction voltage at the emitter tip have been switched, the ionization efficiency for the argon atoms <b>54</b> is maximized while the helium atoms <b>52</b> predominantly are not ionized. This situation is depicted in <figref idrefs="DRAWINGS">FIG. 5</figref>. Hence, a collimated beam of argon ions <b>55</b> is generated at the tip <b>212</b> under the temperature and voltage supply conditions provided in the situation described referring to <figref idrefs="DRAWINGS">FIG. 5</figref>.

p-0077<figref idrefs="DRAWINGS">FIG. 6</figref> illustrates embodiments of further focused ion beam devices <b>600</b>, which may be combined with any other embodiment disclosed herein. The charged particle beam device includes an emitter <b>12</b> having an emitter area, optionally an enclosure/gun chamber <b>14</b>, and an ion beam column <b>16</b>. An electric field is provided between the emitter tip of the emitter <b>12</b> and the extraction electrode <b>18</b>. Ions of gases, which are present in the enclosure <b>14</b>, are generated by the high electric field in the vicinity of the small curvature of the tip portion of the emitter tip, e.g., a tip being an ultra sharp tip or having a supertip.

p-0078According to one embodiment, a first gas inlet <b>110</b>, a second gas inlet <b>112</b> and a third gas inlet <b>613</b> are provided. Thereby, three different gases and/or a mixture thereof can be provided in the enclosure. For example, a light gas like hydrogen or helium may be introduced through the first gas inlet <b>110</b> for observation of a specimen without damaging the specimen. For a different mode of operation, a second gas like argon, neon, xenon or krypton may be introduced through the second gas inlet <b>112</b> for sputtering of a specimen. For an even further mode of operation, a third gas having different properties with respect to sputtering or sample modification can be used.

p-0079According to further embodiments, hydrogen may be used with regard to the even further mode of operation in the event materials like a photo resist are etched. The reducing property of hydrogen may be used for an etching of oxygen-containing materials. Nevertheless, hydrogen may be used in an imaging mode for a plurality of materials, like silicon, metals, and the like.

p-0080According to an even further embodiment, a fourth gas inlet could be provided. Thereby, a fourth mode of operation can be conducted by introducing a conditioning gas (e.g., oxygen) in the enclosure around the emitter tip. According to this embodiment, oxygen can be used for conditioning the tip. This further conditioning mode of operation, wherein the tip of the emitter is shaped or re-shaped, may be supported by the introduction of oxygen. According to yet further embodiments, a fourth or fifth gas may also be used for imaging and/or sample modification modes of operation.

p-0081Generally, within the embodiments described herein, at least two different gases for generating an ion beam or ion beams, the gases also referred to herein as ion beam generating gases, can be introduced in the enclosure. According to embodiments described herein, the at least two different ion beam generating gases are introduced as a gas mixture in the enclosure, and the ion beam, which is generated to be guided through the column of the focused ion beam device, can be selected by changing the emitter tip temperature and optionally the voltage between the emitter tip <b>13</b> and an extraction electrode or another electrode provided to adjust the electric field at the tip portion of the emitter tip.

p-0082As explained above, a light gas and a heavy gas can be used as ion generating gases. According to further embodiments, at least one further ion generating gas can be introduced in the enclosure. Thereby, an ion generation gas for etching or an ion generation gas for a second sputtering option (e.g., first sputtering option with argon and second sputtering option with neon or xenon) can be introduced. According to some embodiments, at least a third gas inlet or a mixture of three gases is provided. In the event more than one ion beam generating gas for sputtering or more than one ion beam generating gas for etching is used, also a fourth, fifth, etc. gas inlet or a mixture of four, five etc. gases can be provided.

p-0083Yet according to further embodiments, processing gases in the form of the above-mentioned emitter tip conditioning gas (oxygen), carrier gases, purge gases, or the like may be introduced. Processing gases are to be understood as gases, which are not used for ion beam generating, but for process support instead.

p-0084According to another embodiment, which is described with respect to <figref idrefs="DRAWINGS">FIG. 6</figref> and may be combined with any other embodiment disclosed herein, additionally a gas outlet <b>620</b> can be provided. The gas outlet <b>620</b> may be connected to a vacuum system including a vacuum pump and/or a vacuum recipient. An evacuation of the enclosure <b>14</b> can be used to control the pressure in the enclosure and, thereby, control a process parameter for the ion generation. Typically, a partial pressure of the gas to be ionized is controlled to be in the range of 10⁻⁶to 10⁻²mbar in the area of the emitter. According to another embodiment, the evacuation of the enclosure <b>14</b> can be used during a switching between a first operational mode and a further (second or third) operational mode. Thus, a gas used for the first operational mode can be removed faster from the area of ion generation. As a consequence, a switching between one mode of operation and another mode of operation can be conducted faster, for example, in 5 s or less.

p-0085For some embodiments, which can be combined with other implementations, a gas pressure gradient in the gun chamber can be provided. Thereby, the gas pressure is higher in the vicinity of the emitter and the emitter tip and is reduced towards an extraction electrode. Thereby, a sufficient amount of gas can be provided to the emitter tip, and the amount of gas that may disturb the ion emission is reduced. According to different examples, which can be combined with any of the embodiments described herein, the gas pressure gradient may reach from 10⁻⁵mbar to 10⁻³mbar, typically from 10⁻⁴mbar to 5×10⁻³mbar.

p-0086Within <figref idrefs="DRAWINGS">FIG. 7A</figref>, a charged particle beam device <b>700</b> is shown. The charged particle beam device includes an emitter <b>12</b>, an enclosure/gun chamber <b>14</b>, and an ion beam column <b>16</b>. Ions of gases, which are present in the enclosure <b>14</b>, are generated by the high electric field of the biased emitter <b>12</b>.

p-0087According to one embodiment, a first gas inlet <b>110</b> and a second gas inlet <b>112</b> are provided. Additionally, valve <b>718</b> is provided within the first gas inlet <b>110</b>. Further, valve <b>719</b> is provided within the second gas inlet <b>112</b>. The valves are controlled by a controller adapted for switching between introducing the first gas in the enclosure <b>14</b> and introducing the second gas in the enclosure.

p-0088According to one embodiment, valves <b>718</b> and <b>719</b> are positioned close to the outlet opening of the gas inlets. Thereby, the amount of gas remaining from a previous operational mode, which has to be removed for a second or third operational mode, is reduced. When one of the valves is closed, the volume, in which the gas of the previous operational mode is still present, is minimized if the valve is positioned close to the outlet opening of the gas inlet. The dead volume of the gas inlet may for example be in the range of 1 cm³or less. Typically, micro-valves may be used to realize a small dead volume. Herein, a dead volume may be defined as a part of a passage, where a portion could retain materials or gases to contaminate subsequent flow media. During switching, the previous gas may contaminate the subsequent gas.

p-0089According to other embodiments referred to with respect to <figref idrefs="DRAWINGS">FIG. 7A</figref>, a gas outlet <b>620</b> can also be provided. The gas outlet <b>620</b> may be connected to a vacuum system including a vacuum pump or a vacuum recipient. As described above, an evacuation of the enclosure <b>14</b> can be used to control the pressure in the enclosure. The evacuation of the enclosure <b>14</b> can also be used to evacuate the enclosure during a switching between a first operational mode and a further (second or third) operational mode. Thus, a gas used for the first operational mode can be removed faster from the area of ion generation.

p-0090Within <figref idrefs="DRAWINGS">FIG. 7B</figref>, the charged particle beam device includes an emitter <b>12</b>, an enclosure/gun chamber <b>14</b>, and an ion beam column <b>16</b>. Ions of gases, which are present in the enclosure <b>14</b>, are generated by the high electric field of the biased emitter <b>12</b>. The gases can be introduced in the enclosure according to any of the embodiments described herein.

p-0091According to another embodiment, as, for example, described with respect to <figref idrefs="DRAWINGS">FIG. 7B</figref>, a valve <b>728</b> is provided within the gas outlet <b>620</b>. The valve <b>428</b> within the gas outlet may be closed in order to provide a low pressure on the side of the valve opposing the enclosure <b>14</b>. Thereby, it is possible during a switching between the first operational mode and a further operational mode to open the valve and use the low-pressure on the opposing side for a faster removal of the gas in the enclosure, which has to be removed for switching between the operational modes.

p-0092This aspect may, according to an even further embodiment, be combined with a vacuum recipient <b>822</b> as shown in the focused ion beam device <b>800</b> of <figref idrefs="DRAWINGS">FIG. 8</figref>. Within <figref idrefs="DRAWINGS">FIG. 8</figref>, a charged particle beam device <b>800</b> is shown. The charged particle beam device includes an emitter <b>12</b>, an enclosure/gun chamber <b>14</b>, and an ion beam column <b>16</b>. Ions of gases, which are present in the enclosure <b>14</b>, are generated by the high electric field of the biased emitter <b>12</b>. Additionally, valve <b>718</b> is provided within the first gas inlet <b>110</b>. Further, valve <b>719</b> is provided within the second gas inlet <b>112</b>. The valves are controlled by a controller adapted for switching between introducing the first gas in the enclosure <b>14</b> and the second gas in the enclosure. When one of the valves is closed, the volume-in which the gas of the previous operational mode is still present and which needs to be removed for switching to another operational mode-is minimized if the valve is positioned close to the outlet opening of the gas inlet.

p-0093Within <figref idrefs="DRAWINGS">FIG. 8</figref>, the conduit of the gas outlet <b>620</b> is connected to a vacuum pump. The vacuum pump evacuates the vacuum recipient <b>822</b>. Thus, an enlarged volume with low pressure is provided. During opening of valve <b>728</b>, the volume of the enclosure <b>14</b> can be evacuated faster as a consequence of the additional volume of recipient <b>822</b>. The shorter time for evacuation of the enclosure allows for a faster switching between the two operational modes.

p-0094<figref idrefs="DRAWINGS">FIG. 9</figref> shows the focused ion beam device <b>900</b>. The charged particle beam device <b>900</b> includes an emitter <b>12</b>, an enclosure/gun chamber <b>14</b>, and an ion beam column <b>16</b>. Ions of gases, which are present in the enclosure <b>14</b>, are generated by the high electric field of the biased emitter <b>12</b>.

p-0095According to one embodiment, a first gas inlet <b>110</b> with a conduit and a second gas inlet <b>112</b> with a conduit are provided. Additionally, valve <b>818</b> is provided within the first gas inlet <b>110</b>. Further, valve <b>819</b> is provided within the second gas inlet <b>112</b>. The valves are controlled by a controller adapted for switching between introducing the first gas in the enclosure <b>14</b> and the second gas in the enclosure. According to one embodiment, valves <b>818</b> and <b>819</b> are positioned close to the outlet opening of the gas inlets. Thereby, the amount of gas remaining from a previous operational mode, which has to be removed for a second or third operational mode, is reduced.

p-0096Within <figref idrefs="DRAWINGS">FIG. 9</figref>, valves <b>818</b> and <b>819</b> are <b>2</b>-way valves. The further connections of the valves are connected to vacuum recipients <b>822</b> and <b>823</b>, respectively. The vacuum recipients <b>822</b> and <b>823</b> are evacuated by a vacuum pump or the like. Thereby, an improved switching behavior between a first mode of operation and a further mode of operation may be provided. When for example valve <b>818</b> is closed, on the one hand, the supply of the first gas, which has been introduced by the first gas inlet <b>110</b>, is stopped. On the other hand, the vacuum recipient <b>822</b> is connected to the outlet opening portion of the gas inlet. Thereby, the gas remaining in the outlet opening portion of the gas inlet is removed therefrom, and the enclosure <b>14</b> is evacuated. Currently or thereafter, the valve <b>819</b> within the second gas inlet <b>112</b> is opened, such that the gas introduced through the second gas inlet can be supplied in the enclosure <b>14</b>.

p-0097According to another embodiment, valves <b>818</b> and <b>819</b> may be connected with respective conduits to a common vacuum recipient.

p-0098According to one embodiment, as shown in <figref idrefs="DRAWINGS">FIG. 9</figref>, a further gas outlet <b>620</b> including valve <b>728</b> is provided. The valve <b>728</b> within the gas outlet may be closed in order to provide a low pressure on the side of the valve opposing the enclosure <b>14</b>. Thereby, it is possible during a switching between the first operational mode and a further operational mode to open the valve and use the low-pressure for a faster removing of the gas in the enclosure, which has to be removed for switching between the operational modes.

p-0099According to another embodiment, the gas outlet <b>620</b> may be omitted. The enclosure <b>14</b> may then be evacuated through one of the valves <b>818</b> and <b>819</b>, respectively. Thereby, when one of the valves is in a position to introduce a gas in the area of the emitter <b>12</b>, the other valve is in a position to evacuate the enclosure <b>14</b> via the vacuum recipient connected to the corresponding valve. Generally, by using a 2-way valve, in order to shut off the gas flow, the connection between the gas and the emitter chamber, that is the enclosure, is closed, and the connection between the emitter chamber and the vacuum recipient or vacuum pump is opened. This results in an immediate drop of the gas pressure in the emitter.

p-0100In addition to the modes of operation, which have been described above, the heavy gas ion beam can be used for material analysis. Thereby, a detector suitable for secondary ion mass spectrometry SIMS <b>722</b> (see, e.g., <figref idrefs="DRAWINGS">FIGS. 1A and 1B</figref>) is provided. The detector detects and analyzes the ions of a specimen, which are created by sputtering. On sputtering, the specimen emits particles, some of which are themselves ions. These secondary ions are measured with a mass spectrometer to determine the quantitative elemental or isotopic composition of the surface.

p-0101According to one embodiment, the sputtering is realized by the ion beam emitted by emitter <b>12</b> as shown in the previous figures. According to another embodiment, an additional flood electron source <b>732</b> (see, e.g., <figref idrefs="DRAWINGS">FIGS. 1A and 1B</figref>) may be provided. Thereby the number of ionized secondary particles, which are released from the specimen on impingement of the ion beam from emitter <b>12</b>, can be increased. The increased amount of ionized secondary particles improves the detection sensitivity of the detector.

p-0102As described above, a single column charged particle beam device in the form of a focused ion beam device can be provided which allows for a high-resolution imaging and sample modification. Thereby, in light of the fact that only one column is used, a reduction of costs can be achieved.

p-0103According to one embodiment, which may be combined with any other embodiment disclosed herein, a focused ion beam device is provided, including: an ion beam column adapted to house a gas field ion source emitter with an emitter tip and an emitter area for generating ions; a heating means adapted to heat the emitter tip; one or more gas inlets adapted to introduce a first gas and at least a second gas to the emitter area; and a controller adapted to switch between a first emitter tip temperature and at least a second emitter tip temperature for generating an ion beam of ions of the first gas or an ion beam of ions of the at least second gas.

p-0104According to one embodiment which may be combined with any other embodiment disclosed herein, the heating means is at least one element selected from the group consisting of a resistance heater, an electromagnetic heater, an induction heater, a radiant heater, an IR heater, a particle source and a laser.

p-0105According to one embodiment which may be combined with any other embodiment disclosed herein, the heating means is positioned adjacent to the emitter tip.

p-0106According to one embodiment which may be combined with any other embodiment disclosed herein, the emitter tip is provided at a support including filaments and a filament base, wherein the heating means is adapted to heat at least one element selected from the group consisting of the emitter tip, the filaments and the filament base.

p-0107One embodiment, which may be combined with any other embodiment disclosed herein, includes an electrode adapted to extract ions from the gas field ion source emitter and a voltage supply adapted to provide a voltage between the electrode and the gas field ion source emitter.

p-0108According to one embodiment which may be combined with any other embodiment disclosed herein, the controller is further adapted to switch between a first voltage and at least one second voltage of the voltage supply for generating an ion beam of ions of the first gas or an ion beam of ions of the at least one second gas.

p-0109According to one embodiment which may be combined with any other embodiment disclosed herein, the first gas is a light gas which is at least one gas selected from the group consisting of a gas having an atomic mass of less than 10 g/mol, hydrogen and helium, and the at least one second gas is at least one gas selected from the group consisting a heavy gas which has an atomic mass of 10 g/mol or higher, and a reactive gas.

p-0110According to one embodiment which may be combined with any other embodiment disclosed herein, the heavy gas is at least one gas selected from the group consisting of a physical sputtering gas, argon, neon, and krypton, and the reactive gas is at least one gas selected from the group consisting of oxygen, hydrogen and CO₂.

p-0111One embodiment, which may be combined with any other embodiment disclosed herein, further includes a gas outlet connected to a vacuum system adapted to evacuate at least the emitter area.

p-0112One embodiment, which may be combined with any other embodiment disclosed herein, further includes: a first valve provided within a first gas inlet of the gas inlets and at least one second valve provided within at least one second gas inlet of the gas inlets, wherein the first valve and the at least one second valve are controlled for adapting the partial pressures of the first gas and the at least one second gas.

p-0113In one embodiment, which may be combined with any other embodiment disclosed herein, a method of operating a focused ion beam device is provided, including biasing an emitter with an emitter tip within an emitter area wherein ions are generated to a potential for providing an extraction voltage for emitting an ion beam of at least one gas of a first gas and at least one second gas; heating to a first emitter tip temperature to emit an ion beam of the first gas, and heating to at least one second emitter tip temperature to emit at least one ion beam of the at least one second gas.

p-0114According to one embodiment, which may be combined with any other embodiment disclosed herein, the emitter is biased to a potential for providing an extraction voltage for emitting an ion beam of the first gas.

p-0115One embodiment, which may be combined with any other embodiment disclosed herein, includes, in the step of heating to a first emitter tip temperature, biasing to a first potential providing an extraction voltage of the first gas.

p-0116One embodiment, which may be combined with any other embodiment disclosed herein, includes, in the step of heating to a first emitter tip temperature, biasing to a first potential providing an extraction voltage of the first gas and, in the step of heating to at least one second emitter tip temperature, biasing to at least one second potential providing an extraction voltage of the at least one second gas.

p-0117One embodiment, which may be combined with any other embodiment disclosed herein, includes, in the step of heating to at least one second emitter tip temperature, biasing to at least one second potential providing an extraction voltage of the at least one second gas.

p-0118In one embodiment, which may be combined with any other embodiment disclosed herein, the first gas is a light gas, and the at least one second gas is at least one gas selected from the group consisting of a heavy inert gas and a reactive gas, wherein the ion beam of the first gas is generated for an observation mode, an ion beam of the heavy inert gas is generated for a sputtering mode, and an ion beam of the reactive gas is generated for a reaction mode.

p-0119One embodiment which may be combined with any other embodiment disclosed herein includes scanning the ion beam generated from the first gas over a specimen for an observation mode and detecting corpuscles released from the specimen on impingement of the ion beam generated from the first gas for observation of the specimen.

p-0120One embodiment which may be combined with any other embodiment disclosed herein includes modifying the specimen during a modification mode, during a time when the at least one second gas is introduced in the emitter area.

p-0121According to one embodiment which may be combined with any other embodiment disclosed herein, the modifying includes at least a step selected from the group consisting of sputtering and etching.

p-0122According to one embodiment which may be combined with any other embodiment disclosed herein, the first gas is at least one gas selected from the group consisting of a light gas, a gas having an atomic mass of less than 10 g/mol, hydrogen and helium.

p-0123According to one embodiment which may be combined with any other embodiment disclosed herein, the at least one second gas is at least one gas selected from the group consisting of a heavy gas, a physical sputtering gas, a gas having an atomic mass of 10 g/mol or higher, argon, neon, krypton, a reactive gas, a processing gas, oxygen, hydrogen and CO₂.

p-0124One embodiment, which may be combined with any other embodiment disclosed herein, further includes at least one step selected from the group consisting of introducing a processing gas in the emitter area and optionally heating to a further tip temperature, wherein the processing gas optionally is oxygen; introducing a further heavy gas into the emitter area, wherein the further heavy gas has an atomic mass of 10 g/mol or higher, and optionally heating to a further tip temperature; and introducing hydrogen into the emitter area for an etching operation mode and optionally heating to a further tip temperature, and separating ions of the first gas from ions of the at least one second gas.

p-0125According to a further embodiment, which may be combined with any other embodiment disclosed herein, the processing gas is oxygen.

p-0126According to a further embodiment, which may be combined with any other embodiment disclosed herein, a focused ion beam device is provided, including an ion beam column including an enclosure for housing an emitter with an emitter tip and an emitter area for generating ions of a first gas and at least one second gas and means for switching between a first emitter tip temperature and at least one second emitter tip temperature, wherein the first gas is selected from the group consisting of hydrogen and helium and the at least one second gas has an atomic mass of 10 g/mol or higher.

p-0127According to one embodiment which may be combined with any other embodiment disclosed herein, the first valve has a first gas supply conduit to a gas supply for the first gas, a first gas inlet conduit for introducing the first gas in the chamber and a first evacuation conduit for connection to at least one vacuum recipient, and wherein the second valve has a second gas supply conduit to a gas supply for the second gas, a second gas inlet conduit for introducing the second gas in the chamber and a second evacuation conduit for connection to the at least one vacuum recipient.

p-0128According to one embodiment which may be combined with any other embodiment disclosed herein, the first gas inlet and the second gas inlet provide the gas into a common gas inlet for supply in the enclosure.

p-0129According to one embodiment which may be combined with any other embodiment disclosed herein, the vacuum system includes a vacuum recipient.

p-0130One embodiment, which may be combined with any other embodiment disclosed herein, further includes a scan deflector provided in the ion beam column and adapted for scanning an ion beam over a specimen, a detector provided in the ion beam column and adapted for time resolved detection of corpuscles released from the specimen on impingement of the ion beam, and a controller connected to the scan deflector and the detector.

p-0131According to one embodiment which may be combined with any other embodiment disclosed herein, the time resolved measurement is adapted for a time resolution of 2 μs or below 2 μs.

p-0132According to one embodiment, which may be combined with any other embodiment disclosed herein, the enclosure is provided in a gun chamber of the ion beam column.

p-0133According to one embodiment, which may be combined with any other embodiment disclosed herein, the enclosure has a volume of 5 cm³or less.

p-0134One embodiment, which may be combined with any other embodiment disclosed herein, further includes a mass spectrometer for identification of ions or ionized particles released from the specimen.

p-0135One embodiment, which may be combined with any other embodiment disclosed herein, further includes a flood electron gun provided in an area adjacent to a specimen area.

p-0136One embodiment, which may be combined with any other embodiment disclosed herein, further includes at least a third gas inlet for introducing at least a third gas into the enclosure.

p-0137One embodiment, which may be combined with any other embodiment disclosed herein, further includes at least a third valve provided within the at least third gas inlet being controlled by the controller.

p-0138According to one embodiment, which may be combined with any other embodiment disclosed herein, the first gas is a light gas selected from the group consisting of hydrogen and helium, wherein the second gas is a heavy gas selected from the group consisting of argon, neon, krypton, and combinations thereof.

p-0139One embodiment, which may be combined with any other embodiment disclosed herein, further includes a mass separator for separating ions from the first gas from ions from the second gas.

p-0140One embodiment, which may be combined with any other embodiment disclosed herein, further includes biasing the emitter within the emitter area wherein ions are generated to a first potential for providing a first extraction voltage for emitting an ion beam of a light gas and biasing the emitter within the emitter area wherein ions are generated to a second potential for providing a second extraction voltage for emitting an ion beam of a heavy gas, wherein the light gas is selected from the group consisting of hydrogen and helium and the heavy gas has an atomic mass of 10 g/mol or higher.

p-0141One embodiment, which may be combined with any other embodiment disclosed herein, further includes evacuating an enclosure surrounding the emitter area.

p-0142According to one embodiment, which may be combined with any other embodiment disclosed herein, the switching includes controlling a power supply for an extraction voltage.

p-0143One embodiment, which may be combined with any other embodiment disclosed herein, further includes scanning the ion beam generated from the light ion beam generating gas over a specimen for an observation mode, detecting corpuscles released from the specimen on impingement of the ion beam from the light ion beam generating gas for observation of the specimen, and modifying the specimen during a modification mode, during a time when the heavy ion beam generating gas is introduced in the emitter area.

p-0144One embodiment, which may be combined with any other embodiment disclosed herein, further includes mass detecting of ionized particles released from the specimen during a time when the heavy ion beam generating gas is introduced in the emitter area.

p-0145One embodiment, which may be combined with any other embodiment disclosed herein, further includes ionizing particles released from the specimen during a time when the heavy ion beam generating gas is introduced in the emitter area.

p-0146In one embodiment, which may be combined with any other embodiment disclosed herein, a method of operating a focused ion beam device is provided, wherein at least two different ion beams of a first gas and at least one second gas are consecutively generated by switching between at least two different emitter tip temperatures, and optionally by switching between at least two different extraction voltages and/or between at least two of the first gas and the at least second gas, the emitter tip temperatures and the extraction voltages each providing ionization of at least one of the gases.

p-0147In a further embodiment, which may be combined with any other embodiment disclosed herein, a method of operating a focused ion beam device is provided, wherein at least two different ion beams of a first gas and at least one second gas are consecutively generated by switching between at least two different emitter tip temperatures, the emitter tip temperatures each providing ionization of at least one of the gases.

p-0148In one embodiment, which may be combined with any other embodiment disclosed herein, the at least two different ion beams of the first gas and the at least one second gas are consecutively generated by additionally switching between at least two different extraction voltages and/or between at least two of the first gas and the at least second gas, the emitter tip temperatures and the extraction voltages each providing ionization of at least one of the gases.

p-0149The written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modifications within the spirit and scope of the claims. Especially, mutually non-exclusive features of the embodiments described above may be combined with each other. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims.

p-0150While the foregoing is directed to embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.