System for generating a high density plasma

Technological background of the invention

1. Field of the invention

The present invention relates to a plasma deposition method and various devices for depositing a thin film on a substrate and removing (etching) a film from a substrate, respectively.

Second Description of related technologies

etching

Plasma etching relies on the use of chemically active atoms or high energy ions to remove material from a substrate. It is a key technology in the manufacture of semiconductor integrated circuits. However, prior to the advent of microwave plasmas using electron cyclotron resonance (ECR), it has been difficult for conventional plasma etching techniques to meet the requirements imposed by the increase in device storage density. Specifically, the need for fine structure sets without undercut (anisotropic etching) and the demands for low damage and high selectivity could hardly be met simultaneously.

secrete

In many applications, plasma enhanced chemical vapor deposition is a widely used technique for depositing materials on substrates. In normal CVD, the chemical reaction is driven by the temperature of the substrate and is high in most reactions (> 800 ° C). The high substrate temperature required precludes the use of this method in a variety of applications, particularly in microelectronics, displays, and optical coatings. The role of the plasma is to dissociate and activate the chemical gas so that the substrate temperature can be reduced. Dissociation, activation and ionization rates are proportional to the density of the plasma. It is therefore important to make the plasma as dense as possible.

sputtering

In a wide variety of applications, such as sputtering is also a widely used method for depositing materials on substrates. Generally, a plasma is produced at the sputtering target material and the sputtering target is generated to a negative strain of about 700 V biased plasma ions, generally argon, strike the surface and sputter the material, which then transitions to a substrate as neutral atoms. Reaction gases may be introduced to chemically react with the sputtered atoms on the support substrate in a process called reactive sputter deposition. Often the speed is important and so it is important to make the plasma as dense as possible. Ionization of the reaction gases is also important and helps to have a plasma near the substrate material. Sputtering is also performed by accelerating ions in an ion or plasma source and then causing them to bombard the sputtering target. In this case, a bias on the target is not necessary. For sputtering of insulating materials, an RF bias can be applied to the sputtering target.

Existing procedures

There are currently two widely used plasma deposition and etching processes, the parallel plate reactor and the ECR plasma separation system.

Parallel plate reactor (diode)

The RF diode has been widely used for both deposition and etching. It is described in detail in the book by Chapman ("Glow Discharge Processes" John Wiley & Sons 1980). It uses high frequency (RF) at 13.56 MHz, which is capacitively coupled to one electrode while the other electrode is grounded. The pressure in the system is typically 1.33 x 10 & supmin; & sup5; to 1.33 x 10 & supmin; ² Pa (1 mtorr to 1 torr) and the plasma density is typically 10¹ & sup0; Electrons per cm³ (cc). The rate at which both deposition and etching occur depends on the density of the plasma and the density (pressure) of the reaction gas used for etching or in CVD deposition processes.

During etching, the high pressure necessary to assist the discharge causes collisions between the ions and the background gas. This causes the paths of the etching ions or atoms to become random or undirected, resulting in undercutting of the mask. This is called an anisotropic etching. It is desirable that the etching atoms or ions be bundled so that straight anisotropic etching can be achieved. With the high pressure used in RF diode discharges, it is necessary for the ions to have a high energy (greater than several hundred eV) to achieve anisotropic etching. However, the high energy of the ions can cause damage to the substrate, the film materials or the photoresist.

The plasma is assisted by secondary electrons emitted by ions impinging on the cathode. These electrons are accelerated by the voltage drop across the space charge layer, which is typically 400 to 1000 volts. These fast electrons may bombard the substrate, causing it to have a high voltage space charge layer loss. This high voltage can accelerate the ions, resulting in damage to the substrate or film material. The presence of high energy electrons leading to high voltage space charge layer losses is undesirable.

Electron cyclotron resonance plasmas

The beginning of using 2.45 GHz microwave and a magnetic field of 875 Gauss (0.0875 Tesla) using electron cyclotron resonance allowed high density plasmas to be generated at a low pressure. The advantages of this technique for plasma etching are described by Suzuki in an article entitled "Microwave Plasma Etching" published in Vacuum 34 No. 10/11 1894, described. Due to a low gas pressure (0.04 to 0.4 Pa) and a high plasma density (1.7 to 7 x 10¹¹ electrons / cm³) anisotropic etching with high etching speeds is achievable.

Suzuki, in U.S. Patent 4,101,411, describes a plasma etching apparatus using ECR; Matsuo, in U.S. Patent 4,401,054, describes a plasma separation apparatus using ECR.

While this technique is desirable over the parallel plate reactor in several aspects, it has several limitations. The required magnetic field is very high (1 to 2 kG) (0.1 to 0.2 Tesla), which means that heavy, energy-consuming electromagnets must be used. The maximum density is limited to the value of 1 x 10¹² electron / cm³ either by a cutoff frequency in certain configurations or by refraction in other configurations. The expenses for the power supply and the necessary hardware for generating and transmitting the microwaves are high. The uniformity (or width of the plasma profile) is not very good.

EP-A-0 403 418, issued on February 5, 1991 as US Pat. No. 4,990,229, describes a plasma etching apparatus which uses a dual ring antenna configuration to deposit or etch substances onto a substrate. The physical shape of the antenna used will be that shown in FIG Determine the type of excitation of the ions in the plasma generator.

Summary of the invention

The present invention utilizes low frequency RF whistler waves to produce high density plasmas for plasma etching, deposition and sputtering equipment. In conjunction with a source tube, in which a gas is fed and along the central axis of a magnetic field is constructed, a single-ring antenna is arranged in a plane transverse to the central axis. The angle of the antenna plane is 90 ° if only the M = 0 vibration mode is to be excited, or less than 90 ° if both the M = 0 and M = 1 vibration modes are to be excited. The gas is a noble gas or reaction gas and has a pressure of 1.33 x 10 & supmin; & sup6; to 2.66 x 10 &³ Pa) (0.1 mtorr to 200 mtorr). The magnetic field strength is in the range of 0.001 to 0.1 Tesla (10 to 1000 Gauss) and the antenna is operated with an RF energy of 100 W to 5 kW in a frequency range of 2 MHz to 50 MHz. With the antenna placed along the tube source a sufficient distance along the axis from the gas feed side, with the other end forming an open exit zone leading to a process chamber, the single ring antenna surprisingly provides high efficiency wave coupling for building a high density, high current plasma ,

In accordance with further features of the invention, the plasma generated by this plasma source is provided to a process chamber including a magnetic bucket system for keeping the plasma away from the process chamber walls. The assembly in combination provides a uniform plasma density over a large circular area so that a large substrate can be etched or otherwise processed. Another feature is that a magnetic crescent zone can be built up on the material surface to be processed in order to homogenize and uniformize the plasma at the site. One aspect of this is that the magnetic acuity position relative to the substrate can be time modulated to enhance uniformity and reduce sensitivity to the substrate location.

In addition, the magnetic field can be extended to allow deposition or etching over a large area, and power flows can be smoothed by serially operating antennas in systems with more than one antenna. Further features exist in configurations utilizing one or more multi-geometrical regions for coating or etching square or rectangular substrates or a linear juxtaposition for coating or etching large substrates.

Brief description of the drawings

FIG. 1 is a schematic diagram illustrating the operation principle and RF current flow in a plasma source constructed in accordance with the present invention; FIG.

Fig. 2 is a schematic diagram of the basic configuration of a plasma deposition or etching apparatus in combination with a plasma source as shown in Fig. 1;

Fig. 3 is a schematic diagram of a second example of a system according to the present invention in which the plasma source region is connected to a magnetic bucket region in which requirements for uniformity are important;

Fig. 3A is a plan view of the arrangement of Fig. 3 along the line 3A-3A in Fig. 3;

Fig. 4 is a perspective view of a third example of a system according to the present invention for depositing or etching over a large rectangular area where uniformity is important;

Fig. 4A is a plan view of the arrangement of Fig. 4 taken along line 4A-4A in Fig. 4;

Fig. 5 is a schematic diagram of another example of a system according to the present invention in which a lower magnet is added behind the plane of the substrate holder to provide a magnetic squirrel field with the plane of the sickle approximately the same as the plane of the substrate holder ;

FIG. 5A is a plan view of the assembly of FIG. 5 taken along line 5A-5A in FIG. 5; FIG.

Fig. 6 is a schematic diagram of an example of a system according to the invention for sputter deposition;

Fig. 7 is a graph showing the plasma current density at the substrate location according to the example of Fig. 3 using the in

Fig. 1 illustrates a plasma source as a function of the magnetic field in the source region;

Fig. 8 is a graph of the same data as in Fig. 7 but on a linear scale for the magnetic field to show the plasma current density at the substrate location where the magnetic field is low and varies from 0 to 0.016 Tesla (0 to 160 Gauss) ;

Fig. 9 is a graph showing the total plasma current (or total flux) at the substrate location according to the invention shown in Fig. 3 using the plasma source shown in Fig. 1 as a function of RF energy for the source at a gas pressure of 2.66 x 10 & supmin; & sup5; Pa (2 mtorr) represents;

Fig. 10 is a graph illustrating the plasma current density at the substrate location according to the invention shown in Fig. 3 using the antenna shown in Fig. 1 as a function of gas pressure; and

Fig. 11 is a graph illustrating the plasma current density at the substrate location according to the invention shown in Fig. 3 and the plasma source of Fig. 1 as a function of position to show the excellent uniformity over a substantial width.

Detailed description of the invention

A simplified view of the principal elements and arrangements to each other in a device according to the invention is shown by the illustration of FIG. 1 in which a high density plasma is to be generated in a source tube 10 having a generally cylindrical shape about a central axis (here vertical). At an end (upper end), an injector 11 feeds gas to be ionized into the inner volume of the source tube, where the gas is excited by an outer loop antenna 12 comprising an intermediate region of the source tube 10. The antenna ring 12 in this example comprises a non-perfectly circular element which lies in a plane which is less than 90 ° or less in each direction relative to the central axis. The propagation direction of the plasma here runs downwards in the direction of an outlet opening 13. The opposite ends of the antenna ring 12 are coupled to the outer conductor 14 and middle conductor 15 of a coaxial drive line 16, which is powered by an RF power source 19 via a matching box 18. A pair of variable vacuum capacitors 20, 21 in the matching box 18 are adjustable to tune the circuit so that the antenna resistance plus the reactive load of the matching box 18 is approximately 50 ohms to minimize the reflected energy.

The antenna tuning and the wave spectrum are adjusted to match the conditions in the plasma field and also relative to an inner axial magnetic field generated by the source tube 10 from at least one magnetic field coil 22. The fit condition is determined in theory by the dispersion relationship:

[c) / ω / -ωp / 2 / C²kz²] ² = 1 + (3,83 / kza) 2.

In order to effect a wave coupling and to establish a high plasma current density, measured in mA / cm³, the antenna ring 12 will be at 13.56 MHz and with an RF energy of the order of 2.0 kW (in the range of 100 W to 5 kW ) is driven by the RF power source 19. The magnetic field built up by the coil 22 is in the range of 0.001 to 0.1 Tesla (10 to 1000 Gauss) for various useful applications. The gas is argon and, in this example, is pressurized to about 1.33 x 10 & supmin; & sup5; Pa (1 mtorr) held. In addition to a noble gas, such as Argon, however, are reaction gases, such as SF6, chlorine, oxygen and mixtures with oxygen have been used with comparatively useful results. There may be a pressure range of 1.33 x 10 & supmin; & sup6; to 2.66 x 10 &³ Pa (0.1 mtorr to 200 mtorr), if other variables are properly considered. With a 5kW power supply, depending on the application, less than the maximum available energy may be used, up to a much lower value by several hundred watts. Although the 13.56 MHz frequency is available in many industrial sources, the range from 2 MHz to 50 MHz can be used to advantage.

In Fig. 1 the antenna ring 12 is shown at 90 ° to the longitudinal axis of the source tube 10. This orientation produces the M = 0 vibration mode, while a 90 degree angle reduction introduces components of the M = 1 vibration mode as well as components of the M = 0 vibration mode in both directions. Angles of less than 90 ° to the longitudinal axis require correspondingly longer antenna rings 12, so that there is a practical limit of about 45 ° for the useable angle. Most orientations are preferably in the range of 60 to 90 degrees. It should be noted that the ring 12 is disposed within a flat plane that is directly perpendicular or tilted to the longitudinal axis. In the prior art designs with double rings and other configurations, it has usually been theorized that the looped parts must describe a helical path to provide a spiral wave property, but this is by the results given below regarding the effectiveness of the present invention Refuted invention. However, it is important that the antenna ring 12 be sufficiently spaced from the closed (gas inlet) end of the source tube 10 to allow the necessary interactions between the plasma and RF energy to occur and fulfill the dispersion relationship so that proper energization is realized high density can be achieved. However, too long a length can also preclude the construction of suitable wavenumbers. In practice, source tubes 10 having a diameter of 2.5 cm to 10 cm (1 inch to 4 inches) and a length of 20 cm to 23 cm (8 inches to 9 inches) were used, with the antenna ring being one third or more the distance from the closed end.

This arrangement produces low frequency Whistler waves, but the mechanism of wave energy-plasma interaction is not fully understood. A simple analysis according to the dispersion relationship is not feasible. The presence of the plasma resistance in the RF field appears to produce selective interactions under appropriate conditions where the gas density and dielectric properties determine the wavenumbers that occur. In a sense, therefore, the plasma itself seems to determine the wavelengths for an interaction, and thus the value of kz, from the spectrum of radiation from the antenna that excites the plasma.

The physics of the propagation of Whistler waves in plasmas has been studied in other contexts. For cylindrical geometries, these waves are commonly referred to as helicon waves. The classical helicon wave was first studied by Lehame and Thonemann and follows the following equations:

the electric field, the magnetic field, j the current density, & sub0; the vacuum magnetic field, e the charge on an electron, n & sub0; the density of the plasma and η is the specific electrical resistance of the plasma.

Following the derivation of Chen one can easily find distortions of the form B exp (i (m θ + kz - ω, t)), and in the transition to the limit θ = 0 the above equations result:

² + α²B = 0, where α = (ω / k) (μ & en & / B),

where = (α / μ &) B

and ω, the angular frequency of the wave, μ & sub0; the dielectric constant, k is the wavenumber, 2π / λ, where λ is the wavelength. These equations can be solved in cylindrical coordinates to provide the dispersion relation:

m α Jm (T a) + Tka Jm '(T a) = 0,

where Jm is a Bessel function of the first kind, Jm 'is a derivative of Jm according to its argument, a is the plasma radius and T is a transversal wave number defined by

T² = α² - k².

It is important to remember that m is the mode number describing the θ dependence on perturbations of the form B exp (i (m θ + kz - ω)).

The two lowest fads meet

J1 (T a) = 0 (m = 0)

J1 (T a) = T ka / 2 α (J 2 - J 0) (m = 1)

This leads to the simple relationship

[(ω / ωc) (ωp² / C²kz²)] ² = 1 + (3,83 / kza) ²,

in which

ωc = cyclotron angular frequency

ωp = plasma frequency

for the m = 0 mode. The above derivation is important for understanding the excitation of the desired mode by the antenna.

Another important mechanism to understand is the attenuation of the wave by the plasma. In Boswell's papers, wave collimation by electron collisions could not explain the experimentally observed results. Chen, however, found that Landau attenuation was responsible for the experimentally observed large attenuation. Landau attenuation is a collisionless attenuation of waves in a plasma due to particles in the plasma having a velocity nearly equal to the phase velocity of the wave. These particles travel with the wave, do not see a rapidly fluctuating electric field and thus can effectively exchange energy with the wave. In a plasma, there are electrons that are both faster and slower than the wave. In a Maxwell distribution, however, there are more slow electrons than fast ones, so more particles absorb energy from the wave than vice versa.

The damping rate due to Landau damping has been calculated by Chen for helicon waves and can be expressed as:

damping speed

Jm (kz) / Re (kz) 2 π c² (3.8 / a) ² ³ e + ²,

where = ω / kz Vth

and Vth is the thermal velocity of the plasma electrons. It is interesting to demonstrate how sensitive the damping rate is to the value of k, since it is a steep function of. Take, for example a plasma with a density of 1012 electrons / cm³, an electron temperature of 3 eV and a control frequency of 8 MHz. The collision damping rate would be 0.065 and the Landau damping rate would be 0.6 for kz = 0.25 cm -1 and 0.0005 for kz = 0.125 cm -1. It is clear that the Landau attenuation is the important damping mechanism and depends very much on the wavenumber kz.

There are a number of important factors in designing an antenna structure that stimulates Whistler waves to generate plasmas, including a) excitation frequency, b) wave mode, and c) efficiency of coupling RF energy into the plasma. The frequency of the waves should be such as to satisfy Ωc <ω <ωc, where Ωc is the ion cyclotron frequency, e B o / Mi. and ωc is the electron cyclotron frequency e B 0 / M. These waves are low frequency waves far below the electron cyclotron frequency.

The mode structure of the wave of electric and magnetic fields should be understood so that the antenna assembly effectively couples the RF energy into the wave excitation. As shown above, the two lowest modes are the m = 0 and m = 1 modes. The mode structure of the electric field wave for a m = 0 mode includes radial and circular electric field vectors spatially arranged in different transverse planes along the direction of wave propagation, z. Within one wavelength of a wave, the electric field varies between purely radial and purely azimuthal. The azimuthal electric field varies in a counterclockwise direction in a plane while running half a wavelength away in a clockwise direction. With this understanding, it has been found that the wave in this mode can be effectively excited with an antenna having a single ring located in a plane perpendicular to the magnetic field, thereby producing a spectrum of wavenumbers, so that one part of the generated spectrum 2ir / kz, where kz is given by the given dispersion relationship. The mode structure of the electric field wave for a m = 1 mode exerts a natural spiral slope on the electric and magnetic field vectors as the wave propagates along the z direction. The vector of the electric field rotates in a right-handed sense, that is, it rotates clockwise as it travels along B & sub0 ;. runs, which lies in the z-direction. This mode can be excited with the present invention, when the ring is skewed at an angle to the magnetic field, so that the generated wave spectrum contains a significant portion around 2π / kz, where kz is given by the dispersion relationships.

The efficiency of plasma generation depends on the coupling of RF energy into the plasma. As discussed above, it is believed that the important mechanism for attenuating RF energy is Landau attenuation. The phase velocity of the Whistler wave is given by ω / kz, where kz is given by the dispersion relationship and depends on the plasma density and the magnetic field strength without plasma. Ideally, the phase velocity of the wave should be close to the maximum of the ionization potential of the gas that is to ionize. Based on the above dispersion relationship for the m = 0 mode, the following applies:

n = α B & sub0; kz (T 2 + kz 2) 1/2

where α = B & sub0; kz² for T <kz.

In other words, the higher the value of kz, the higher the density. However, the phase velocity of the wave is ω / kz, and thus an increasing kz lowers the energy of the electrons accelerated by the wave. If kz is too high, then the energy of the electrons can fall below the ionization potential. It is thus important to control kz in order to increase the density and to control the electron temperature.

The present invention utilizes low frequency Whistler waves to produce plasmas of high density exceeding 10¹³ per cm³. The first use of Whistler waves to create dense plasmas has been described by Boswell, who used an antenna array with current flows along the axis of the cylinder. This antenna arrangement is used and previously described by Ovchinnikov, and excites the m = 1 mode due to current flow in conductors parallel to the direction of the magnetic field B & sub0; run. The excitation frequency was 8 mHz, and the density profile of the 10 cm plasma had peaks especially at higher magnetic field strengths needed for higher densities. In these publications, the mechanism for effectively coupling the RF energy to the plasma could not be explained. Chen explained the mechanism in a Australian National University report as Landau damping.

Chen described in a paper presented in August 1988 a system using whistler waves to produce dense plasmas for advanced particle accelerators. The type of antenna used in this arrangement was similar to that used by Boswell, by exciting the m = 1 mode, and corresponded to a type known as Nagoya Art III antenna having circular axial rings in spaced-apart states coupled with signals opposite phase are stimulated.

A variety of variables can be used once it is recognized that the single-ring antenna of the present invention effectively builds a high density plasma. The z-axis wavenumber, kz, varies as the ratio n / B, and vice versa with the wavenumber λ, which requires a longer source tube. Conversely, if B is decreased, the plasma density is relatively higher, since the shorter wavelengths will cause needed wavenumbers regardless of the tube size.

The results of the present solution are best understood by examining various process units as described below.

The basic configuration of a plasma deposition or etching apparatus according to the present invention is shown in FIG. 2 shown. The plasma generating chamber 10 'has a cylindrical shape and is made of a non-conductive material, such as Quartz or Pyrex, made. The antenna 12 'is mounted with an inclination to the longitudinal axis 10', as described in connection with FIG. 1 is described. An axial magnetic field is determined by the in Fig. 2 provided magnetic field coils 24 and 25, but the plasma can also work using only one of the coils.

The plasma is transferred from the magnetic field to a separate process chamber 27. The shape of the plasma entering the process chamber 27 may be controlled by changing the magnitude and direction of the current flowing through a coil 28 around the exit of the chamber 27. A substrate 30 to be coated or etched is mounted on a substrate holder 31 which is electrically insulated. The plasma bombarding the substrate 30 causes the substrate 30 to reach a negative self-bias of between 0 to 10V. For certain films to be formed, it is advantageous for the film to be bombarded with ions that have greater energy than would be obtained due to self-bias. In this case, it is desirable to apply RF energy from a second RF source 33 via a second matching circuit 34. The substrate holder 31 is a copper block, which is cooled by a heating / cooling circuit 35 or is heated. A gas is fed via a stainless steel feed pipe 11 'which is connected to the source for the plasma generation chamber 10'. A stainless steel ring 36 has a diameter which is large in comparison with the size of the holes 37 evenly distributed around the ring 36. This arrangement is such that a uniform gas flow is directed to the substrate. The RF voltage is applied by means of a matching circuit 18 and an RF source 19, as described in connection with FIG. 1 are shown, placed on the antenna 12 '. Tuning is performed in the matching circuit 18 to maximize the energy that is coupled into the plasma and to minimize the energy reflected back to the RF power supply 19 along a 50 ohm cable 38.

FIG. 3 shows an arrangement in which a high uniformity over a large area is required. The plasma generating chamber 10 'has a cylindrical shape and is made of a non-conductive material, such as Quartz or pyrex, herge presents. The antenna 12 is mounted at an angle smaller than a right angle, but otherwise corresponds to the one shown in FIG. 1 described configuration. An axial magnetic field is provided by the magnetic field coils 24 and 25. The plasma is transferred from the magnetic field to a process volume comprising a portion of a magnetic chamber 40.

In a paper by Limpaecher and MacKenzie (R. Limpaecher and KR MacKenzie, Rev. Sci. Instrum. 44, 726 (1973)), it is disclosed that the use of magnets in an external multiple-axis array can provide very uniform plasma parameters in a central region of the volume confined by the magnets. The arrangement of the magnets around the circumference of a cylinder is a common arrangement used for ion sources and is referred to as a magnetic bucket. It is important to design the magnetic field such that there is a good match between the axial field provided by the lower magnetic field coil 25 and the field in the magnetic bucket 40. The plasma from the generator 10 'disperses along the magnetic field lines and expands to fill the bucket 40. The wall 41 for the magnetic bucket 40 is made of stainless steel and can, for example have a circular or rectangular cross-section. In any case, the internal dimensions of the magnet bucket 40 are such that they are larger than the inside diameter of the plasma generator 10 '. The magnetic field within the bucket is provided by a plurality of permanent magnets 43 arranged with their poles perpendicular to the wall 41 of the bucket chamber and with alternating north N and south S poles.

In this arrangement, the magnetic field lines 44 follow a multiple-axis pattern, with the field pattern provided by the magnets in FIG. 3A is shown. Referring again to FIG. 3 For example, a substrate 45 to be coated or etched is mounted on a substrate holder 46 in the lower area of ​​the plasma field in the magnetic bucket. The substrate holder is a copper block, which is cooled by a heating / cooling circuit 47 or is heated. As in the system of FIG. 2 gas is supplied via a stainless steel pipe 11 'connected to the gas source for the plasma generating chamber 10' and into the magnetic bucket 40 via a stainless steel ring 36 connected to the gas supply and enclosing small diameter holes 37, which are evenly distributed around the ring 36. A uniform plasma flow is directed to the substrate 45 when an RF voltage from a power supply 19 is provided by means of a matching circuit 18 consisting of two vacuum capacitors as shown in FIG. 1 are applied to the antenna 12 'is applied.

FIG. 4 shows an arrangement in which a high uniformity over a large rectangular shaped area is required, such as is needed when coating large flat screens. The plasma generating units are of the type described above, but in this arrangement, multiple generators may be used depending on the size and shape of the required plasma. In Fig. 4 For example, three plasma generators 49, 50, and 51 are shown arranged along the central axis of the top of a process chamber. Each plasma generating chamber has a cylindrical shape and is made of a non-conductive material, such as Quartz or pyrex, made and includes a separate single ring antenna 52, 53 or 54 of the type shown in FIG. 1 a kind described. However, to ensure the generation of uniform plasmas, the antennas 52, 53, 54 are coupled in electrical series with the matching box 18 and the RF power supply so as to ensure equal RF current flows. Magnetic field coils 55, 56, 57, 58, 59 and 60 provide an axial magnetic field for each generator. The plasmas generated separately in this way are transferred by the magnetic field into a conventional rectangular magnet chamber 61. The plasmas scatter along the field lines and expand to fill the bucket 61. The magnetic field within the bucket chamber 61 is provided by permanent magnets 62 arranged with their poles perpendicular to the surface of the bucket chamber and with alternating N and S poles. The magnetic field pattern provided by the magnets is shown in FIG. 4A. The substrate 63 to be coated or etched is mounted on a substrate holder 64 which is electrically insulated. The plasma bombarding the substrate causes the substrate to reach a negative self-bias of between 0 and 10V. For certain films to be formed or for certain etching applications, it is advantageous for the substrate 63 to be bombarded with high-energy ions. In this case, it is desirable to apply RF power from a second RF power supply (not shown) to the substrate holder 64 via a matching circuit, which may again be a copper block that is cooled or heated by a heating / cooling circuit 65 ,

FIG. 5 is another example of a device according to the invention for providing further control of plasma uniformity over a large area. The plasma generation chamber 10 'has a cylindrical shape, is made of a non-conductive material, such as Quartz or pyrex, and is surrounded by an antenna 12 'at an angle of less than 90 °. An axial magnetic field is provided in the source region by the magnetic field coils 69 and 70 or by only one such coil. The plasma is transferred by the magnetic field from the source 67 to a magnetic chamber 71, which has substantially the same shape as shown in FIG. 3 is described. To enhance uniformity and facilitate the passage of the plasma into the bucket chamber 71, there is an additional magnetic field coil 72 concentric with the central axis of the plasma generating chamber 10 'below the substrate holder 74 received from a heating / cooling circuit 75 cooled or heated. The permanent magnets 76 around the bucket chamber 71 are in the in Fig. 2 arranged form and create a magnetic squirrel field 77, as shown in FIG. 5A can be seen. The current in the additional magnetic field coil 72 is generated to carry a current in the opposite direction to that of the currents flowing in the coils 69 and 70. The effect is to provide another magnetic sickle, now a ringing sickle, which is approximately in the plane of the substrate 78, the plane being substantially perpendicular to the line sickle created by the north-south permanent magnets 76.

As described above, gas is fed through a feed port 11 into the plasma generator 10 'and through another feed pipe 11' into a stainless steel ring 36 in the bucket chamber 71. The ring 36 has a large diameter compared to the size of the holes 37 which direct a uniform gas flow to the substrate 78. The ring 36 may also be the gas supply to the source when the main supply is not used. Small amplitude changes over time in the current flowing in coil 72 are generated by a modulation driver 73 to oscillate the annulus plane about the plane of substrate 78, thereby averaging the plasma profile incident across the substrate, and also the time Uniformity is enhanced. This solution of using the temporal change of a lower coil can also be used to enhance uniformity when a magnetic bucket is not used by using the ones shown in FIG. 2 as shown, and the current in coil 28 therein is allowed to pass in the exit region opposite to that in coils 24 and 25 at the plasma generating chamber 10 ', thereby creating the annulus in the plane of the substrate as just described.

FIG. 6 Another example according to the present invention is suitable for use with the RF generation system in conjunction with a sputtering target. The plasma generating chamber 10 "has a cylindrical shape, is made of a non-conductive material and is surrounded by an antenna 12 ', which, as in the example of FIG. 1, is mounted in a plane perpendicular to the longitudinal axis. An axial magnetic field is provided by the magnetic field coils 80 and 81 around the chamber 10 "and 82 and 83 around a process chamber 91. The plasma 90 is transferred from the plasma generator 10 "into the process chamber 91 and flows along the magnetic field to a lowermost sputtering target 93 which is biased to a large negative voltage (approximately -700 V) from a power supply 94. A direct current (DC) current source is used to maintain charge when the substrate holder is conductive, but when the substrate holder is nonconductive, an alternating current (AC) current source is used instead. The plasma diameter is adjusted by controlling the magnetic field to match that of the target. The material sputtered from the target 93 is placed on the adjacent substrates 96. A horizontal baffle 97 in a plane above the target 93 may be used to control the gas pressure in the vicinity of the substrate, and other gases may be introduced near the substrate through an outlet 98. The substrates 96 are mounted on a substrate holder 101 and positioned over the sputtering target. The substrate holder 101 can rotate about the vertical axis to enhance the uniformity of the deposition of sputtered material. The substrate holder 101 has a central opening for allowing plasma to pass along the magnetic field from the plasma generator 10 "to the sputtering target 93.

In Fig. 7 For example, data are shown in terms of plasma current density measured in mA / cm 2, which in accordance with the present invention is shown in FIG. 3 shown arrangement using the in Fig. 1 and measured using a high-speed Langmuir probe at a location just above the plane of the substrate. The RF frequency was 13.56 MHz and was supplied using a conventional RF power supply which generates 2.0 kW, which is indicated by a signal in FIG. 1 passes through the matching box shown. The data were obtained for the plasma current density as a function of the magnetic field in the source chamber 10 'from 0 to 0.1 Tesla (0 to 1000 Gauss). The data for a field varying from 0 to 0.016 Tesla (0 to 160 Gauss) is shown in FIG. 8th shown. The gas pressure is about 1.33 x 10 & supmin; & sup5; Pa (1 mtorr). A substantial current density approaching 40 mA / cm² was noted at a low field value of 0.02 Tesla (20 Gauss). An increase in the magnetic field to 0.01 Tesla (100 gauss) and above also produces high values ​​for the plasma current density reaching values ​​of 140 mA / cm 2. These data prove that resonances exist at low field values ​​to result in surprisingly high and new plasma current densities. Resonances in turn occur monotonically increasing with the field strength after an intermediate region in which the current densities are lower.

In Figure 9, data for the total plasma flux measured in amperes reaching the substrate plane as a function of RF energy for a gas pressure of 2.66 x 10 & supmin; & sup5; Pa (2 mtorr) and a magnetic field in the source chamber of 0.025 Tesla (250 gauss). The entire flow reaches a diameter of 8 inches (20 cm). The total flux entering the substrate reaches 15 amps from a source having a chamber diameter of about 4 inches (10 cm).

Fig. 10 illustrates the operation of the plasma source in the arrangement described in Fig. 3 and with the antenna described in Fig. 1 as a function of the gas pressure in the chamber, showing that the source is at low pressures (below 1.33 x 10 'Pa (1 mtorr)) works up to higher pressures. The source has been successfully operated at pressures greater than 1.33 x 10 &³ Pa (100 mtorr).

The uniformity of the plasma is shown in FIG. 11 with uniformity at a distance of 15 cm (6 inches) below the exit of the source chamber 10 'in the bucket chamber 40 with a substrate 45 in place, using the method shown in FIG. 3 shown arrangement and the in Fig. 1 antenna was measured. The magnetic field in the source chamber 10 'is 0.015 Tesla (150 gauss) and the pressure is about 2.66 x 10 & supmin; & sup5; Pa (2 mtorr). The plasma is most uniform over an 8 inch (20 cm) width. A similar degree of uniformity is achieved using the techniques described in FIG. 5 Sickle magnet arrangement achieved, wherein the magnetic coil 72 is used, which carries a current in a direction opposite to the current flowing in the magnetic field coils 69 and 70 current direction.

Accordingly, it will be apparent that the systems and devices according to the invention provide uniform plasmas using low frequency whistler wave excitations using a single channel antenna with a source chamber. By interacting with the plasma resistance under a suitable magnetic field condition and with a selected RF energy, an extended plasma in a process chamber can cover a wide area of ​​designed area property with a high plasma current density and a high total plasma current. Both low and high magnetic field strength modes are to be maintained, and etching, deposition and sputtering processes may be used.

While the invention has been described in terms of a number of forms and variations, it will be understood that the invention is not limited thereto but includes all modifications within the scope of the appended claims.