Optics symmetrization for metrology

0001This application relates to and claims the earliest possible filing date benefits from the applications listed below (related applications) (eg, claims or claims the earliest possible priority date other than a provisional patent application). Claim the benefits of 35 USC 119 (e) for any and all related patent applications, parent applications, grandfather applications, and other provisional patent applications). [Related application] Due to non-statutory requirements of the United States Patent and Trademark Office, this application is a US provisional patent application with application serial number 61 / 370,347 filed on August 3, 2010, inventor Amnon Manassen, Daniel Kandel, Moshe Baruch, Consists of a formal (non-provisional) patent application for "OPTICS SYMMETRIZATION FOR METROLOGY" by Joel Seligson, Alexander Svizher, Guy Cohen, Efraim Rotem, Ohad Bachar, Daria Negri and Noam Sapiens.

0002The present invention generally relates to Tool Induced Shift (TIS) measurements in optical measurement systems.

0003As the dimensions of semiconductor devices and components continue to decrease, the need for increased alignment control between various layers, or the functionality within a single layer of a sample continues to increase. In a semiconductor processing environment, semiconductor-based equipment may be produced by processing a series of layers on a substrate, some or all of which have various structures. The relative position of both these structures in relation to the structures within a single layer and within the other layers is important to the performance of the device.

0004Measurement processes are used to monitor and control one or more semiconductor layer processes at various steps between semiconductor manufacturing processes. For example, a measurement process is used to measure one or more characteristics of a wafer, such as the dimensions of the characteristics formed on the wafer during the processing step (eg, line width, thickness, etc.), where the process The quality of the steps can be measured by measuring one or more characteristics. One such property includes overlay errors.

0005Overlay measurements generally show how exactly the first pattern layer is aligned with or below the second pattern layer, or the first pattern is placed on the same layer. It specifies how accurately it aligns with the second pattern. Overlay errors are typically measured on overlay targets with structures formed on one or more layers of work pieces (eg, semiconductor wafers). If the layers or patterns of a semiconductor device are not properly formed, then the structure of one layer or pattern tends to be biased (offset) or offset from the structure of the other layer or pattern. .. The deviation between any of the patterns used at different stages of semiconductor integrated circuit manufacturing is known as "overlay error".

0006In general detection, the application of measurements such as overlay measurements requires high quality optics to meet the requirements of advanced lithography processes. In the case of overlay measurements, optical imperfections (eg, aberrations) in the optical components of the execution system may result in tool-induced shifts (TIS). In this way, optical imperfections in the optical system may cause the measured overlay shift with respect to the actual overlay. For example, the optical aberrations present in the measurement optical column may lead to TIS. Standard TIS measurements include measuring the overlay in a first position and then rotating the wafer 180 degrees to repeat the overlay measurement. As such, TIS is defined as:<maths num="1"><img id="000002" he="17" wi="132" file="JP6000247B2_D0001.tif" img-format="tif" img-content="drawing" /></maths>

0007Here, OVL (0 °) indicates the overlay measured at the first position, and OVL (180 °) indicates the overlay measured after rotating the sample 180 degrees with respect to the first position.

0008Traditionally, there are two ways to eliminate or limit the existence of TIS. First, expensive high-end optical components may be used to run measurement systems to help avoid optical imperfections leading to TIS. Second, when measuring TIS within a system, that system may be calibrated to correct the observed TIS level. Due to the need for calibration, the presence of TIS leads to a reduction in the throughput of a given semiconductor processing process. Also, the need for high-end optics to avoid or limit TIS leads to increased costs for semiconductor processing and measurement. Therefore, it may be desirable to provide a more efficient TIS measurement process, as well as a method and / or system that provides an improved optical system that reduces the amount of TIS in a given system.

<p num="0009"><patcit num="1"><text>U.S. Patent Application Publication No. 2005/0200856</text></patcit><patcit num="2"><text>U.S. Pat. No. 7,511,826</text></patcit><patcit num="3"><text>U.S. Patent Application Publication No. 2009/0086184</text></patcit></p>

<p num="0010"> Equipment suitable for irradiation symmetry is disclosed. In one embodiment, the instrument is a source, at least one irradiation symmetry module (ISM) configured to symmetry at least a portion of the light emitted from the source, and a first of the light processed by the ISM. A first beam configured to orient the portion of the light along the object path to the surface of one or more samples and to orient the second portion of the ISM-treated light along the reference path. It may have a splitter and a detector arranged along the primary optical axis and configured to collect a portion of light reflected from the surface of one or more samples, but is not limited thereto.</p><p num="0011"> In another aspect, suitable instruments for measuring tool-induced shifts are disclosed. The instrument comprises a source, a direct channel configured to transmit a first portion of the light emitted from the source to the surface of one or more samples, and a second portion of the light emitted from the source. A rotation channel having an optical rotation module configured to rotate a second portion of light 180 degrees, and a rotation channel configured to transmit light to the surface of one or more samples. A first shutter configured to selectively block the optical path and a second shutter configured to selectively block the optical path of the direct channel, reflected from the surface of one or more samples. The light portion is configured to collect the light portion, which may have an arranged detector containing at least one of the light from the direct channel or the light from the rotating channel, but limited to them. Not done.</p><p num="0012"> In another aspect, suitable instruments for measuring tool-induced shifts are disclosed. The instrument comprises a source, a direct channel configured to transmit a first portion of the light emitted from the source to the surface of one or more samples, and a second portion of the light emitted from the source. A rotation channel configured to transmit light to the surface of one or more samples, and a rotation channel having an optical reflection module configured to rotate a second portion of light 180 degrees. A first shutter configured to selectively block the optical path and a second shutter configured to selectively block the optical path of the direct channel, reflected from the surface of one or more samples. It is configured to collect a portion of light, which portion of light may have, but is not limited to, a detector that includes at least one of light from a direct channel or light from a rotating channel.</p><p num="0013"> It should be understood that both the general description above and the detailed description below are illustrations and explanations only and do not necessarily limit the invention as claimed. The accompanying figures included in the specification and constituting a part show the embodiments of the present invention, and explain the principle of the present invention together with general descriptions.</p><p num="0014"> One of ordinary skill in the art may better understand the many advantages of this disclosure with reference to the accompanying figures below.</p>

0015<figref num="1A">A block diagram of a device suitable for irradiation symmetry according to the present invention is shown.</figref><figref num="1B">A block diagram of the type of irradiation symmetrization module suitable for implementation according to the present invention is shown.</figref><figref num="2A">The block diagram of the 180 degree rotation irradiation symmetry module according to this invention is shown.</figref><figref num="2B">The block diagram of the 180 degree rotation irradiation symmetry module according to this invention is shown.</figref><figref num="3A">The block diagram of the Y reflection irradiation symmetry module according to this invention is shown.</figref><figref num="3B">The block diagram of the Y reflection angle rotation irradiation symmetry module according to this invention is shown.</figref><figref num="4A">The block diagram of the combination of the Y reflection angle rotation irradiation symmetry module and the 180 degree rotation irradiation symmetry module according to the present invention is shown.</figref><figref num="4B">The block diagram of the combination of the Y reflection angle rotation irradiation symmetry module and the 180 degree rotation irradiation symmetry module according to the present invention is shown.</figref><figref num="5A">A block diagram of a device suitable for tool-induced shift measurement according to the present invention is shown.</figref><figref num="5B">A block diagram of a device suitable for tool-induced shift measurement according to the present invention is shown.</figref><figref num="6">A block diagram of a device suitable for tool-induced shift measurement according to the present invention is shown.</figref><figref num="7A">A block diagram of an instrument suitable for tool-induced shift measurements performed in conjunction with an irradiation symmetry module according to the present invention is shown.</figref><figref num="7B">A block diagram of an instrument suitable for tool-induced shift measurements performed in conjunction with an irradiation symmetry module according to the present invention is shown.</figref>

0016The subject to be disclosed shown in the attached figure will be described in detail.

0017A system 100 suitable for providing irradiation symmetry, broadly through FIGS. 1A-4B, is described by the present invention. In one aspect, the invention is directed to irradiation symmetry using an irradiation symmetry module. Irradiation symmetry of the measurement system works to eliminate or limit tool-induced shifts (TIS) within a given system 100.

0018As used herein, the present invention is considered to consist of (but do not require) adaptation or reconstruction of an existing microscopic examination system. For example, the present invention may consist of conformance with the KLA-Tencor Archer 100 overlay control system. For example, the ISM may be inserted into a conventional system (eg, Archer100 system) so that the ISM and associated adapted optics direct light along the source and the reference and object paths of the system. It is installed between the beam splitter and the beam splitter used for transmission. It should be recognized that the present invention is not limited to the suitability of the Archer 100 system, but rather the above should be construed as merely exemplary. It is expected that the present invention may be extended to a wide range of microscopic and overlay measurement systems.

0019With reference to FIG. 1A, the appropriate system 100 for irradiation symmetry is the irradiation source 102, the irradiation symmetry module 104, the first beam splitter 108, and one or more samples 114 (eg, one of the wafer lots). Alternatively, it may have a detector 110 configured and arranged to receive light reflected from a plurality of wafers).

0020In one embodiment of the invention, the irradiation symmetry module 104 is configured to symmetry the light emitted from the irradiation source 102. For example, the light emitted from the light source 102 is processed (ie, symmetric) by the irradiation symmetry module 104 and additional optical components of the system 100 (eg, objective lens 109 in object path 112, reference mirror in reference path 113, etc. And the irradiation symmetry module 104 may be placed along the irradiation path 115 so that it is oriented towards the detector 110). In normal detection, one of ordinary skill in the art should be aware that the irradiation symmetry module 104 may be performed within an overlay measurement system to improve the symmetry of light incident on a given sample 114. A particular type of symmetry operation performed on the light emitted from the source 102 is of a particular irradiation symmetry of a given measurement application (eg overlay measurement, differential signal scattering measurement overlay measurement, optical limit dimension measurement). It may be necessary. For example, improving irradiation symmetry to 180 ° rotation may reduce the measurement of tool-induced shift (TIS) in overlay measurement measurements caused by optical imperfections. In other cases, improved reflection symmetry for a given axis (eg, X-axis or Y-axis) helps achieve the desired level of reflection symmetry required for certain differential signal scattering measurement overlay measurements. May do.

0021Referring here to FIG. 1B, the irradiation symmetry module 104 of the system 100 is a 180 ° rotational symmetry module 200, a Y reflection symmetry module 300, an X reflection symmetry module (not shown), or one or more. There may be, but are not limited to, a linear combination of 400 of the individual irradiation symmetry modules of. The arrangement of the specific optics of these embodiments of the irradiation symmetry module 104, which is required to achieve a particular desired irradiation symmetry operation, is described in further detail herein.

0022In one embodiment of the invention, sample 114 may be placed on sample stage 118. In one embodiment, the sample stage 118 is a convertible stage (eg, XY convertible stage) and / or a rotatable stage (eg, theta) that can be controlled by a communicably connected computer system (not shown). It may have a rotatable stage). The sample 114 and the stage 118 may be arranged so that the sample 114 is substantially perpendicular to the primary optical axis 107 of the system 100.

0023The irradiation source 102 of the system 100 may have any irradiation source known in the art. In one embodiment, the irradiation source 102 may have a broadband light source (eg, a white light source). For example, the irradiation source 102 may have a halogen light source (HLS), but is not limited to this. For example, the halogen light source may include, but is not limited to, a tungsten-based halogen light source. For example, the irradiation source 102 may have a xenon arc lamp. In another embodiment, the irradiation source 102 may have a narrowband light source. For example, the irradiation source 102 may have a laser light source, but is not limited thereto.

0024In another aspect of the invention, the first beam splitter 108 of the system 100 splits the light beam radiating from the source 102 after passing through the ISM 104 to two paths, the object path 112 and the reference path 113. You may. With this detection, the object path 112 and reference path 113 of system 100 may form part of a two-beam interferometric optical system. For example, the first beam splitter 108 directs the first portion of the beam of light from the irradiation path 115 along the object path 112, while the second portion of the beam of light from the irradiation path 115 is the reference path 113. It may be possible to allow transmission along the line. More specifically, the first beam splitter 108 passes a portion of the light emitted from the irradiation source 102 through the irradiation symmetry module 104 to the surface of the sample 114 placed on the sample stage 118 ( It may be oriented (eg via object path 112). The first beam splitter 108 may also transmit a second portion of light emitted from the irradiation source 102 to a component of reference path 113. For example, the beam splitter 108 may transmit a portion of light from the irradiation path 115 along the reference path 113 to a reference mirror (not shown). Those skilled in the art should recognize that any beam splitter known in the art is suitable for implementation as the first beam splitter 108 of the present invention.

0025It should be apparent to those skilled in the art that the reference path 113 may have a reference mirror, a reference objective lens, and a shutter configured to selectively block the reference path 113, but is not limited thereto. Is. For normal detection, the two-beam interferometric optical system may be configured as a Linnik interferometer. Linnik interference measurements are generally described in US Pat. No. 4,818,110, issued April 4, 1989, and US Pat. No. 6,172,349, issued January 9, 2001, which are incorporated herein by reference. Be incorporated.

0026In another embodiment, the system 100 may have a primary objective lens 109. The primary objective lens 109 may assist in directing light along the object path 112 to the surface of the sample 114 located on the sample stage 118. For example, the beam splitter 108 may direct a portion of the light beam 115 radiating from the irradiation source 102 along the object path 112 after passing through the ISM 104. Following the splitting process by the first beam splitter 108, the primary objective lens 109 may focus the light from the object path 112 on the same straight line as the primary optical axis 107 onto the surface of the sample 114. With normal detection, any objective lens known in the art may be suitable for implementation as the primary objective lens 109 of the present invention.

0027Further, the portion of light corresponding to the surface of the sample 114 may be reflected by the sample 114 and directed to the detector 110 along the primary optical axis 107 via the objective lens 109 and the beam splitter 108. Intermediate lenses, intermediate optics such as additional beam splitters (eg beam splitters configured to split the light portion into a focusing system), and imaging lenses on the imaging surface of the objective lens 109 and detector 110. It should be further recognized that it may be installed between and.

0028In another aspect of the invention, the detector 110 of the system 100 may be placed along the primary optical axis 107 of the system 100. In this regard, the camera 110 may be arranged to collect image data from the surface of the sample 114. For example, in normal detection, after being reflected from the surface of sample 114, light may travel along the primary optical axis 107 to the image plane of detector 110 via the primary objective lens 109 and the first beam splitter 108. .. It should be recognized that any detector system known in the art is suitable for the practice of the present invention. For example, the detector 110 may have a camera system based charge-coupled device (CCD). For other exemplary purposes, the detector 110 may have a time-delayed integral (TDI) -CCD based camera system. In a further aspect, the detector 110 may be communicatively connected to a computer system (not shown). In this regard, digitized image data may be transmitted from the detector 110 to the computer system via a signal such as a wired signal (eg, copper wire, fiber optic cable, etc.) or a wireless signal (eg, wireless RF signal). Good.

0029Although the detector 110 has been described above as being positioned along the primary optical axis 107 of the system 100, this property should not be construed as a requirement. As used herein, it is believed that the detector 110 may be along the additional optical axis of system 100. For example, with normal detection, one or more additional beam splitters are used to divert the portion of light that is reflected from the surface of sample 114 and travels along the additional optical axis along the object path 112. It is also good. The camera 110 may be arranged so that the light traveling along the additional optical axis hits the image plane of the camera 110.

00302A and 2B show embodiments of the irradiation symmetry module 200 suitable for performing a 180 ° rotational symmetry operation of light emitted from the irradiation source 102. The 180 ° rotation symmetry module 200 shown in FIGS. 2A and 2B may operate to improve the symmetry of the processed light to 180 ° rotation. In other words, the 180 ° rotational symmetry module 200 may operate to convert the light emitted from the irradiation source 102 into an irradiation with improved 180 ° rotational symmetry characteristics.

0031Here, with reference to FIG. 2A, an embodiment of the 180 ° irradiation symmetrization module 200 is shown. The 180 ° irradiation symmetry module 200 of the present invention was formed by a first beam splitter 202, a first mirror 204, a one-to-one imaging module 206, a second mirror 208, and a second beam splitter 210. It may have a rotating channel 203 defined by a path and a direct channel 205 defined by a path formed by a first beam splitter 202 and a second beam splitter 210.

0032In one embodiment, the first beam splitter 202 directs the first portion of light from the irradiation path 115 (ie, emitted from the irradiation source 102) to the first mirror 204 along a 180 ° ISM rotation path 203. It is arranged to be deflected (bypassed). The first beam splitter 202 is further configured to transmit a second portion of light along the direct path 205 to the second beam splitter 210, which is substantially identical to the irradiation path 115 of system 100. It is on the line. Further, the first mirror 204 is arranged to direct a portion of light emerging from the first beam splitter 202 to the second mirror 208 through the one-to-one imaging module 206. The one-to-one imaging module 206 is configured to rotate the image 180 ° with respect to the first image while at the same time avoiding image enlargement. The one-to-one imaging module 206 may have any set of optics known in the art, optic placement and / or spacing suitable for achieving 180 ° rotation and one-to-one imaging. ..

0033Further, the second mirror 208 is arranged to direct the light transmitted through the one-to-one rotation module 206 to the second beam splitter 210. The 180 ° rotating ISM200 second beam splitter 210 then combines (combines) the light from the direct path 205 with the light from the rotating path 203.

0034Those skilled in the art should recognize that the light from the direct path 205 is composed of non-rotated irradiation, while the light from the rotating channel 203 is composed of light rotated by 180 °. Combining (combining) the unrotated light of direct channel 205 with the 180 ° rotated irradiation of rotating channel 203 exits the second beam splitter 210 (and is transmitted to the first beam splitter 108 of system 100). It should be further recognized that the light may have improved rotational symmetry compared to the irradiation input to the first beam splitter 202 of the 180 ° rotating ISM200. With conventional detection, Applicants point out that optical components such as the 180 ° rotating ISM200 mirror and beam splitter described above may have any suitable optical component known in the art.

0035Here, with reference to FIG. 2B, an alternative embodiment of the 180 ° rotated ISM200 is shown. The 180 ° rotation ISM200 of FIG. 2B has a rotation channel 213 defined by a path formed by a first beam splitter 212, a one-to-one imaging module 214, a second mirror 218, and a second beam splitter 220. , A first beam splitter 212, a second mirror 216, and a direct channel 215 defined by a second beam splitter 220.

0036In a manner similar to that of the 180 ° rotated ISM200 shown in FIG. 2A, the ISM200 in FIG. 2B also uses a second beam splitter 220 to illuminate the unrotated light of the direct channel 215 and the rotated irradiation of the rotating channel 213. Acts to synthesize (combine) and provide improved rotational symmetry compared to the irradiation input to the first beam splitter 212 of the 180 ° rotating ISM200. It should be further recognized that the alternative design shown in FIG. 2B facilitates equalization of the optical path lengths of the rotating channel 213 and the direct channel 215.

0037Here, with reference to FIG. 3A, one embodiment of the Y reflection module 300 of the system 100 is shown. The Y reflection module 300 includes a first beam splitter 302, a first mirror 304, a pair of inversion mirrors 306, 307, a reflection channel 303 defined by a path formed by the second beam splitter 308, and a first beam splitter. It may have a direct channel 305 defined by a path formed by 302 and a second beam splitter 308.

0038In one aspect, the first beam splitter 302 is arranged to divert the first portion of light from the irradiation path 115 to the first mirror 304 along the reflection channel 303 of the Y-reflection ISM300. To. The first beam splitter 302 is further configured to transmit a second portion of light along the direct channel 305 to the second beam splitter 308, which is substantially identical to the irradiation path 115 of system 100. It is on a straight line. Further, the first mirror 304 is arranged so as to direct a portion of light emerging from the first beam splitter 302 to the pair of reversing mirrors 306,307. The pair of reversing mirrors 306 and 307 are configured to flip the image with respect to the first image on the Y axis and direct the light reflected from the surface of the reversing mirror 307 to the second beam splitter 308. The pair of reversing mirrors 306 and 307 may have any set of optics known in the art, optical device placement and / or optical device spacing suitable for image reflection on the Y-axis of the image plane.

0039Further, the second mirror 208 is arranged to direct the light transmitted through the one-to-one rotation module 206 to the second beam splitter 210. The 180 ° rotating ISM200 second beam splitter 210 then combines (combines) the light from the direct path 205 with the light from the rotating path 203.

0040Those skilled in the art should recognize that the light from the direct path 305 is composed of non-inverted irradiation, while the light emerging from the reflection channel 303 is composed of the irradiation reflected about the Y axis. When the second beam splitter 308 is used to combine (combine) the uninverted light of the direct channel 305 with the inverted irradiation of the reflected channel 303, it exits the second beam splitter 308 (and the first of System 100). The light (transmitted to the beam splitter 108) may have improved reflection symmetry about the Y axis compared to the irradiation input to the first beam splitter 302 of the Y-reflecting ISM300. Further recognition should be made. With conventional detection, Applicants point out that optical components such as the mirror and beam splitter of the Y-Reflective ISM300 described above may have any suitable optical component known in the art.

0041Here, with reference to FIG. 3B, an alternative embodiment of the Y-reflection ISM300 is shown. The Y reflection module 300 in FIG. 3B includes a first beam splitter 310, a pair of inversion mirrors 312, 314, a reflection channel 313 defined by a path formed by the second beam splitter 318, and a first beam splitter 310, first. It may have one mirror 316 and a direct channel 315 defined by a path formed by a second beam splitter 318.

0042In a manner similar to that of the Y-reflected ISM300 shown in FIG. 3A, the ISM300 of FIG. 3B also uses a second beam splitter 318 to split the uninverted light of the direct channel 315 and the Y-inverted irradiation of the reflected channel 313. Acting to combine (combine), it provides improved reflection symmetry about the Y-axis compared to the irradiation input to the first beam splitter 310 of the Y-reflection ISM300. It should be further recognized that the alternative design shown in FIG. 3B allows for easy equalization of the optical path lengths of the reflective channel 313 and the direct channel 315.

0043The design of the ISM modules 200 and 300 shown in FIGS. 2A, 2B, 3A and 3B recognizes that approximately 50% of system 100 irradiation deviates from the system and does not reach system 100's common beam splitter 108. Should be. This irradiation loss may be substantially avoided by replacing the ISM 200 or 300 second beam splitter (eg 210, 220, 308 and 318) with a moving mirror (flip-in mirror) (not shown). You should be aware of that. In this way, the irradiation of the conversion channel (eg, 180 ° rotation channel 203,213 or reflection channel 303,313) and the direct channel (eg 205,215,305,315) may be measured sequentially, and the images collected from each measurement are added together. , May form a composite image with significantly improved symmetry properties (eg, 180 ° rotational symmetry, Y reflection symmetry or X reflection symmetry (not shown)). Applicants point out that any moving mirror (flip-in mirror) system known in the art is suitable for the practice of the present invention.

0044Instead, the aforementioned light loss is split with a given ISM (eg 200 or 300) first beam splitter (eg 202,212,302,310) and second beam splitter (eg 210,220,308,318) with two synchronized choppers. It may be avoided by replacing it. In this way, the synchronized choppers operate to allow light to pass through each channel for 50% of the time. For example, at a given time 1, light is transmitted through the first chopper while being blocked by the second chopper. Then, at time 2, the light is blocked by the first chopper and transmitted by the second chopper. The resulting waveform passed through the system 100's combined beam splitter 108 is then an alternative pulse of irradiation from a conversion channel (eg, 180 ° rotation channel 203,213 or reflection channel 303,313) and a direct channel (eg 205,215,305,315). It is composed. Applicants point out that any chopper system known in the art is suitable for the practice of the present invention.

00454A and 4B show embodiments of the linearly combined irradiation symmetrization modules. A linear combination of ISMs may be used to improve the level of symmetry of a given image, or when more than one symmetry process is required. For example, as shown in FIGS. 4A and 4B, Y-reflecting ISMs (eg, 404a or 419a) are optically coupled to a 180 ° rotating ISM (eg, 404b or 419b) (via a beam splitter 410). You may connect. For example, the light emitted from the source 102 may first undergo a Y-reflection symmetry process with the Y-reflection ISM404a. Upon exiting the Y-reflecting ISM404a, light may be transmitted from the common beam splitter 410 into the 180 ° rotating ISM404b. The light emanating from the 180 ° rotation ISM404b is recognized as having improved 180 ° rotation and Y reflection symmetry.

0046It is further considered that the same ISMs may be combined in series (not shown). For example, a first 180 ° rotating ISM may be optically connected in series with a second 180 ° rotating ISM using a common beam splitter. It is further predicted that any number and type of ISM may be combined in series. Applicants point out that the use of the same serially connected ISMs increases the level of symmetry up to 100 times depending on the number and type of ISMs performed.

0047It is further conceivable that two or more modules of the same type may be combined to improve irradiation symmetry. Applicants point out that using two series of combined ISMs of the same symmetry type, a 100-fold increase in irradiation symmetry may be obtained.

0048It should be noted that the aforementioned description of the various ISMs of FIGS. 2A-4B does not represent a series of limitations, but rather should be construed as an example of a feature. Various additional irradiation modules may be configured herein, and the particular choice of irradiation symmetry module component may depend on the particular type of symmetry required for a given application. it is conceivable that.

0049In general, referring to FIGS. 5A-7, systems 500, 501, 600 and 700 suitable for tool-induced shift measurements are described by the present invention. In one aspect, the invention is a system that provides an improved (tool-induced shift) TIS measurement rate. The use of faster TIS measurements may reduce the overall time required for TIS calibration and increase the throughput of a given semiconductor processing step.

00505A and 5B show embodiments of systems 500 and 501 suitable for tool-induced shift measurements according to the present invention.

0051Now referring to FIG. 5A, in one embodiment, the system 500 may have an irradiation source 102, a detector 110, a rotating channel 506, a direct channel 507, a first shutter 504, and a second shutter 505. Good, but not limited to these. It is acknowledged herein that the aforementioned description of source 102 and detector 110 with respect to FIG. 1A should be construed as applying in whole to the rest of the disclosure.

0052In one embodiment, the system 500 direct channel 507 is formed by a path defined by a first beam splitter 502 and a second beam splitter 508. It is recognized that irradiation emitted from the source 102 may pass between the first beam splitter 502 and the second beam splitter 508 via either the rotating channel 506 or the direct channel 507. ..

0053In one embodiment, the first beam splitter 502 is arranged to direct the first portion of light from the irradiation path 115 to the second beam splitter 508 via the direct channel 507. It is stated in this embodiment that the direct channel 507 is substantially aligned with the object path 112 (and primary optical axis 107) of the system 500. The first beam splitter 502 is further configured to transmit a second portion of light from the irradiation source 102 through the rotation module to the optical return module 511 via the rotation channel 506. Light traveling along the rotation channel 506 may be applied to the return module 511 of the rotation channel 506 and reflected to the second beam splitter 508.

0054In one embodiment, the rotation module of the system 500 may have one or more one-to-one 180 ° rotation modules 210 as shown in FIG. 5A, but is not limited to this. The one-to-one imaging module 210 may be configured to rotate the image 180 ° with respect to the first image while at the same time avoiding image enlargement. The one-to-one imaging module 210 may have any set, arrangement and / or optical device spacing known in the art suitable for 180 ° rotation and one-to-one imaging. After passing through the 1: 1 180 ° rotation module 210, the light in the rotation channel 506 may travel through the set of return optics of the optical return module 511, which is the light from the upper arm of the rotation channel 506. Acts to redirect to the second beam splitter 508 via the lower arm of rotation channel 506.

0055In one embodiment, the return optics of the optical return module 511 may include, but are not limited to, a first mirror 510 and a second mirror 512. The first mirror 510 may be configured to reflect light transmitted through the 1: 1 180 ° rotation module 210 to the second mirror 512. The second mirror 512 may be configured to reflect the light received from the first mirror 510 to the second beam splitter 508. In a further embodiment, the first mirror 510 and the second mirror 512 of the return optical module 511 may constitute a substantially planar mirror, as shown in FIG. 5A.

0056In another aspect, the first shutter 504 may be configured to selectively block the optical path of the rotation channel 506. In this way, the system 500 may operate to selectively block light from the source 102 as it is transmitted through the rotating channel 506. In the same way, the second shutter 505 may be configured to selectively block the optical path of the direct channel 507. In this way, the system 500 may operate to selectively block light from being transmitted from the source 102 through the direct channel 507.

0057In one embodiment, in this regard, it is conceivable that the first shutter 504 and the second shutter 505 may have a shutter that can be opened and closed within 10 ms. It is further recognized herein that any suitable shutter system known in the art may be used as the first shutter 504 and / or the second shutter 505 of the present invention.

0058It is the present invention that the optical path used between the first beam splitter 502 and the second beam splitter 508 may be selected by the coupling control of the first shutter 504 and the second shutter 505. This is one aspect. In the first configuration, when the second shutter 505 is open (ie the direct channel is open) and the first shutter 504 is closed (ie the rotating channel is closed), the system 500 is standard. Acts as an imaging microscope. In this way, the light from the irradiation path 115 is directed to the surface of the sample 114 along the direct channel 507 via the first beam splitter 502. Upon leaving the first beam splitter 502, light from the source 102 then passes through the second beam splitter 508 and the primary objective lens 109 to the surface of sample 114 and the object path 112 on the same line as the direct channel 507. Is transmitted along. The shining light is then reflected from the surface of the sample 114 and directed towards the imaging surface of the detector 110.

0059In the second configuration, when the second shutter 505 is closed (ie the direct channel 507 is closed) and the first shutter 504 is open (ie the rotating channel 506 is open), the system 500 Acts as an imaging microscope that rotates both the illuminated pupil and the image on the wafer by 180 °. In this way, light from the source 102 may travel through the rotation channel 506 to the second beam splitter 508. The second beam splitter 508 then directs the light from the output of the rotation channel 506 to the surface of the sample 114 through the objective lens 109. Upon hitting the surface of sample 114, the rotated and converted light may then be reflected off the imaging surface of the detector 110. It is further recognized that various additional optical components, such as intermediate lenses and imaging lenses generally known to it, may, but are not limited to, be present within the system 500.

0060In the third configuration, both the shutter 505 and the shutter 504 may be opened to allow light from the irradiation path 115 to be transmitted along both the rotating channel 506 and the direct channel 507. This configuration allows the light from the reference path 113 to interfere with the light from the object path 112 and creates interference fringes on the image plane of the focusing system (not shown) so that the two-beam interference-based focusing process Allows it to be executed. Details of the two-beam interference-based automatic focusing system can be found in U.S. Pat. No. 4,818,110, issued April 4, 1989, and U.S. Pat. No. 6,172,349, issued January 9, 2001, which are referenced. Is incorporated herein by.

0061The aforementioned system 500 may be used to perform rapid TIS measurements. In this way, the system 500 may perform two continuous measurements. The first measurement may be performed on the direct channel 507, while the second measurement may be performed via the rotating channel 506. First, the system 500 measures the TIS of the source 102 and the contribution of any optical component positioned between the first beam splitter 502 and the detector 110 and corrects the remaining TIS to give the user TIS. Allows calibration of measurements. Applicants point out that the system 500 is not measuring the TIS contribution due to the TIS contribution from the aberration effect of the objective lens 109 or the optical component of the rotating channel . As a result, this rapid TIS measurement system is most useful when the optical components of the objective lens 109 and the rotating channel 506 are of high quality.

0062System 500 may measure TIS by sequentially measuring overlays at 0 ° and 180 °. In this way, the system uses light from direct channel 507 to measure the overlay at 0 ° (ie, OVL (0) in Equation 1), and then uses irradiation from rotating channel 506 to rotate at 180 °. Overlays (ie, OVL (180) of Equation 1) may be measured. In that way, the TIS measured using Equation 1 above may be calculated.

0063However, if the part of the objective lens closest to the sample 114 has a module that can move in and out of the optical path in a short time and can be actuated to rotate the image 180 degrees, then the TIS contribution of the part of the objective lens 109 It is further conceivable that may be measured. In this way, the modified portion of the objective acts to replace the rotation module 210 positioned along the rotation channel 506. TIS measurements are performed with and without a rotating module using two continuous measurements. Such an optical design relaxes the objective lens requirements, leaving high requirements only for the desired rotating module.

0064It is further conceivable herein that the optical component of rotation channel 506 may be replaced with an optical component that performs a transformation other than 180 ° rotation. For example, suitable optical components to perform xy inversion on irradiation may be used to replace the optics shown in rotating channel 506 of FIG. 5A. The possibility of applying different types of conversion operations of light from the source 102 is useful when TIS measurements relate to symmetric behavior.

0065Here, with reference to FIG. 5B, an alternative embodiment of the system for tool-induced shift measurements is shown. As shown in FIG. 5A, the system 501 of FIG. 5B may have an irradiation source 102, a detector 110, a rotating channel 506, a direct channel 507, a first shutter 518, and a second shutter 520. Not limited to.

0066In one aspect, the direct channel 507 of the system 501 is formed by a path defined by a first beam splitter 513, a first mirror 514, and a second beam splitter 517. In another aspect, the rotation channel 506 of the system 501 is formed by a path defined by a first beam splitter 513, a rotation module 210, a second mirror 516, and a second beam splitter 517. As in system 500 described above, irradiation emitted from the source 102 passes between the first beam splitter 513 and the second beam splitter 517 via either the rotating channel 506 or the direct channel 507. It should be recognized that it may be. The way light passes along the direct channel 507 and / or the rotating channel may be controlled by controlling shutters 518 and 520, respectively. The above statements relating to the operation of the TIS measurement system 500 should be construed as applying to system 501.

0067Here, with reference to FIG. 6, an alternative embodiment of the system for tool-induced shift measurements is shown. The system 600 may include, but is not limited to, an irradiation source 102, a detector 110, a rotating channel 606, a direct channel 607, a first shutter 604, and a second shutter 605. Unlike the system 500 of the present invention, the rotation channel 606 of the system 600 lacks the rotation module 506. Conversely, system 600 has a reflection module 603 configured to perform a 180 ° rotation of the incident image. In one embodiment, the reflection module 603 may have a pair of convex mirrors, a mirror 602 and a mirror 604. Concave mirror mirrors 602 and 604 may be arranged so that when they emerge from the mirror 604, the irradiation incident of the mirror 602 is reflected across both the X and Y axes of the image, resulting in an image with features rotated 180 °. As mentioned above for System 500, this 180 ° rotated irradiation may be used for rapid TIS measurements. Therefore, the above statements relating to the operation of the TIS measurement system 500 should be construed as applying to the system 600.

0068With reference to FIGS. 7A and 7B, it is further conceivable herein that the irradiation symmetry module 104 as described above may be performed in connection with the TIS measurement system 500, 501 or 600.

0069All systems and methods described herein may include storage of the results of one or more steps of an embodiment of the method on a storage medium. The results may have any of the results described herein and may be stored in any manner known in the art. The storage medium may be any storage medium described herein, or any other suitable storage medium known in the art. After the results have been stored, the results are stored by any method or system embodiment described herein used by other software modules, methods, or systems, formatted for display to the user. Can be accessed and used. In addition, the results may be stored "permanently," "semi-permanently," "temporarily," or for a period of time. For example, the storage medium may be random access memory (RAM), and the results may not necessarily last indefinitely within the storage medium.

0070One of ordinary skill in the art has various means by which the processes and / or systems and / or other techniques described herein can be affected (eg, hardware, software, and / or firmware), and the preferred means are processes and / or firmware. You will understand that / or the system and / or other technologies change in relation to their placement. For example, if a developer decides that speed and accuracy are paramount, he may primarily choose hardware and / or firmware means. Instead, if flexibility is paramount, developers may primarily choose software implementations. Alternatively, the developer may instead choose some combination of hardware, software, and / or firmware. Thus, there are several possible means by which the processes and / or devices and / or other techniques described herein may be affected, and any used means is associated with the means being placed. None of them are inherently superior to other means, in that they are choices based on the particular interests of the developer (eg, speed, flexibility, or predictability), and all may change. One of ordinary skill in the art will recognize that the optical aspects of practice usually employ optical-oriented hardware, software, and / or firmware.

0071Those skilled in the art will integrate the equipment and / or process described herein in the form described herein, and subsequently use technical techniques to integrate such described equipment and / or process into a data processing system. You will recognize that it is common to do. That is, at least a portion of the equipment and / or process described herein can be integrated into a data processing system after a sufficient amount of experimentation. For those skilled in the art, common data processing systems typically include one or more system unit housings, video display devices, memories such as volatile and non-volatile memory, processors such as microprocessors and digital signal processors, operating. Computational entities such as systems, drivers, graphical user interfaces, and application programs, one or more interacting devices such as touchpads or screens, and / or feedback loops and control motors (eg, detection position and / or speed). You will recognize that you usually have a control system that includes feedback, components and / or control motors that move and / or adjust the amount. Common data processing systems may be run using any suitable commercially available component, such as those commonly found in data computing / communication and / or network computing / communication systems.

0072The subject matter described herein refers to different components that are sometimes included or connected to different other components. It should be understood that such presented basic design concepts are merely exemplary and that many other basic design concepts that achieve the same function are practically feasible. Conceptually, any arrangement of components that achieve the same function is effectively "related" to achieve the desired function. Thus, any two components of the specification combined to achieve a particular function are viewed as "related" to each other to achieve the desired function, regardless of the basic design concept or intermediate components. be able to. Similarly, any two components so related can be seen as "connected" or "connected" to each other to achieve the desired function, and any that can be so related. The two components can be seen as "connectable" to each other to achieve the desired function. Certain connectable examples are physically matchable and / or physically interacting components, and / or wirelessly interactable and / or wirelessly interacting components, and /. Or include, but is not limited to, logically interacting and / or logically interactable components.

0073Although specific aspects of the subject matter described herein have been described and described, based on the teachings of this specification, modifications and improvements have been made without departing from the subject matter described herein and its broader aspects. Accordingly, the appended claims should include all such changes and improvements within their scope as being within the true intent and scope of the subject matter described herein. It will be clear to those skilled in the art.

0074Although the specific embodiments of the present invention have been described, it will be apparent to those skilled in the art that various improvements and embodiments of the present invention may be made without departing from the scope and gist of the above disclosure. Therefore, the scope of the present invention should be limited only by the claims attached herein.

0075The present disclosure and many of its concomitant benefits are believed to be understood by the description above, and various changes may be made without departing from the disclosed subject matter or at the expense of all the benefits of the device. It will become clear that the form, structure and arrangement of the components may be changed. The described form is merely explanatory and it is the intent of the claims described below to include and include such modifications.

0076Furthermore, it should be understood that the present invention is defined by the appended claims.