WO1996019096A1

WO1996019096A1 - Method and device for plasma processing

Info

Publication number: WO1996019096A1
Application number: PCT/JP1995/000506
Authority: WO
Inventors: Muneo Furuse; Seiichi Watanabe; Tadamitsu Kanekiyo; Yoshiaki Sato
Original assignee: Hitachi, Ltd.
Priority date: 1994-12-16
Filing date: 1995-03-20
Publication date: 1996-06-20
Also published as: JPH08171998A

Abstract

A method for plasma processing, e.g., etching and film formation, using a microwave plasma. Microwaves of a specific mode are locally generated. The diffusion distance of the microwaves is so determined that the microwaves are diffused and propagated in a specific mode. The cross-sectional area of the propagating space of the microwaves is gradually changed over the distance. After propagated through the distance, the microwaves are introduced into a plasma discharging area. In the plasma discharging area, a plasma whose plasma density distribution at the central part of the plasma is higher than that at the peripheral part is generated, so that a sample in the processing chamber is processed uniformly.

Description

Specification

Plasma processing method and apparatus

The present invention relates to a plasma processing method and apparatus, and more particularly to a plasma processing method and apparatus suitable for performing high-speed and uniform plasma processing such as etching and film formation on a wafer. Background art

Conventionally, as a plasma processing apparatus using microwaves, for example, as described in Japanese Patent Application Laid-Open No. 6-104977, the upper part of the vacuum chamber is opposed to a sample table provided in the vacuum chamber. A circular magnifying tube is provided at the opening via a quartz plate, a circular waveguide, a circular rectangular waveguide, and a rectangular waveguide are connected to the circular magnifying tube in order, and a magnetron is connected to the end of the rectangular waveguide. It is known that a coil is wound around a discharge part of a vacuum chamber and an outer peripheral part of a circular magnifying tube.

In such a conventional plasma processing apparatus, the microwave oscillated from the magnetron passes through a microwave waveguide comprising a circular magnifying tube, a circular waveguide, a circular rectangular waveguide, and a rectangular waveguide to form a vacuum chamber. The microwave energy introduced into the discharge section is efficiently supplied to the plasma mainly in the electron cyclotron resonance (ECR) region, and a high-density plasma is generated in the discharge section. In addition, since the plasma generated in the discharge part is transported to the wafer side along the magnetic field lines formed in the discharge part, the plasma density on the wafer must be as wide as possible to uniformly process the wafer. It is necessary to make it uniform. However, the plasma density distribution on the sample table in such an apparatus has a medium-high (convex) distribution with a high density at the center, and high-density, uniform plasma can be obtained on the sample table. Nanatsu Was.

Therefore, in the conventional apparatus having such a configuration, in order to process the wafer as quickly and uniformly as possible, the vicinity of the center of the sample stage having a relatively high plasma density and relatively uniform was used. The uniformity of the etching rate and the like in the outer peripheral portion was insufficient. Furthermore, in the case of processing a large-diameter wafer of 8 inches or more, the plasma density in the peripheral portion of the wafer is further reduced, so that the etching rate is slower than that in the central portion of the wafer, and the entire wafer is uniform. Was difficult to etch. There is also a method of increasing the inner diameter of the discharge part and widening the area where the plasma density is high in the central part in order to uniformly etch the entire wafer, but there is a problem that the etching equipment becomes large. . As a technique related to solving the above problems, there is a plasma processing apparatus of a type that resonates a microwave using a cavity resonator and radiates a microwave from the cavity resonator through a slit. For example, as disclosed in Japanese Patent Application Laid-Open No. 63-108388 (corresponding US Pat. No. U.S.P. 4, 776, 918), one type of cavity resonator is disclosed. In which a slit is provided, and the slit is directed toward the plasma generation chamber, and Japanese Patent Application Laid-Open No. HEI 2-138735 (corresponding to U.S. Pat. The first cavity resonance chamber is provided in the plasma chamber via the first slot plate, and the second cavity plate is provided in the first cavity resonance chamber via the second slot plate, as described in JP-A-9-965. A device provided with a second cavity resonance chamber is known. Note that the slits or slots described in these sections are part of the processing chamber that can be depressurized, maintain the inside of the processing chamber in a vacuum, and make contact with the microphone mouth wave transmitting window that introduces the microphone mouth wave into the processing chamber. It was located very near.

The above technology is a point of propagation of the microwave radiated from the slot antenna. Was not considered. In other words, since a slot antenna was provided in contact with or very close to the microphone aperture wave transmission window that forms the plasma region, microwaves radiated from the slot antenna were locally localized directly below the slot antenna. As soon as a specific mouth opening mode is formed, it is absorbed by the plasma just below the microwave transmission window. For this reason, the plasma density becomes large just below the microwave transmission window corresponding to the slot antenna, and there is a problem that it is difficult to generate uniform plasma in the processing chamber.

A first object of the present invention is to provide a plasma processing method and apparatus capable of uniformly processing a sample in a processing chamber.

Further, a second object of the present invention is to provide a plasma processing method and apparatus capable of forming an optimum plasma state and uniformly processing a sample.

Further, a third object of the present invention is to provide a plasma processing method and apparatus capable of processing a sample uniformly and at high speed. Disclosure of the invention

The first object is to uniformly process the sample in the processing chamber by performing plasma processing on the sample while evacuating from the periphery of the sample and increasing the plasma density distribution at the outer peripheral portion from the central portion.

The second object is to introduce a specific mode of microwave into the plasma processing chamber using a waveguide whose opening cross-sectional area changes gradually, so that the high-density distribution region of plasma can be moved to the optimal position. The optimum plasma state can be created when plasma processing the sample, and the sample can be uniformly processed.

Further, the third object is to provide a TE 01 mode microwave and an ECR The sample can be processed uniformly and at high speed by bringing the ECR plane formed by the magnetic field strength under the condition that is parallel to the sample with the magnetic field having a strength parallel to the sample.

In the case where the etching process is performed on the wafer by the plasma generated in the plasma processing chamber, the distribution of the etching rate on the wafer is largely influenced by the distribution of ions and radicals in the plasma on the wafer. In addition, when performing an etching process with a plasma processing apparatus, the plasma processing chamber is constantly evacuated, and the electrically neutral radicals generated in the plasma processing chamber are etched without being drawn into the electrodes. With the etching gas introduced into the room, it is evacuated along with the gas flow. Therefore, even if the plasma density is uniform on the electrode, the distribution of radicals contributing to etching on the wafer will be high at the center, and the etching rate of the wafer will be low at the periphery. I understood. Therefore, by increasing the plasma density at the outer peripheral portion of the wafer and increasing the etching speed due to the ions at the outer peripheral portion of the wafer, it is possible to supplement the etching speed at the portion where the radical density at the outer peripheral portion of the wafer is low, and processing the wafer. Therefore, processing can be performed with an optimum plasma distribution, and wafers can be processed at high speed and uniformly. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a longitudinal sectional view showing a plasma processing apparatus according to one embodiment of the present invention, FIG. 2 is a view showing details of a slit plate in the apparatus shown in FIG. 1, and FIG. Fig. 4 shows the relationship between the presence / absence of a microwave resonator and a reduced waveguide and the ion current density distribution. Fig. 4 shows the relationship between the presence / absence of a microwave resonator and a reduced waveguide and the etching rate distribution. FIG. 5 is a diagram illustrating the relationship between the microwaves of the plasma processing apparatus according to the second embodiment of the present invention. FIG. 6 is a longitudinal sectional view showing a propagation means, FIG. 6 is a longitudinal sectional view showing a microwave propagation means of a plasma processing apparatus according to a third embodiment of the present invention, and FIG. FIG. 13 is a longitudinal sectional view showing a microphone mouth wave propagation means of the plasma processing apparatus according to the fourth embodiment. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a longitudinal sectional view showing a plasma processing apparatus of the present invention. Reference numeral 1 denotes a magnetron which is a microwave oscillator, which can oscillate a microwave of 2.45 GHz, for example. Reference numeral 2 denotes microphone mouth wave propagation means for propagating the microwave oscillated from the magnetron 1. In this case, the rectangular waveguide 21, circular-to-rectangular conversion waveguide 22, and circular waveguide 2 are used. 3. It is composed of a resonator 24 and a reduced waveguide 26, and is connected to the magnetron 1 sequentially. In this case, the rectangular waveguide 21 is set to have a size capable of transmitting a microwave in a rectangular TE 11 mode, and has a matching unit 27 for achieving microwave impedance matching on the way. are doing. In this case, the circular waveguide 23 is set to have such a size as to transmit the microwave of the circular TE 11 mode. The resonator 24 has a slit plate 25 located between the reduced waveguide 26 and the slit plate 25. In this case, the slit plate 25 has a plurality of radially arranged slit plates as shown in FIG. A slit hole is formed. The resonator 24 is set to a mode in which the electric field strength of the microwave increases in the outer peripheral portion inside the resonator 24, in this case, the size for resonating the microwave in the circular TE01 mode. Similarly, the slit plate 25 may be in a mode in which the microwave electric field strength is high in the outer peripheral portion (in this case, the same as the resonance mode in the resonator 24, that is, a circular TE01 mode). The slit holes are set radially so that waves are emitted. δ

I have. The reduced waveguide 26 has a tapered inner surface whose opening cross-sectional area gradually decreases in the direction of microwave propagation. In this case, the tapered shape of the reduced waveguide 26 is such that the microwave entrance aperture is substantially the same as the inside diameter of the resonator 24, and the exit diameter of the microwave resonator is the microwave diameter of the plasma processing chamber 4 (described later). The diameter of the incident aperture on the wave introduction side is made substantially the same.

Reference numeral 4 denotes a chamber connected to the reduced waveguide 26 to form a plasma generation space. In this case, a plasma processing chamber also serves as a plasma processing. The plasma processing chamber 4 is a conductor, and is made of, for example, high-purity aluminum or the like. The inner surface of the plasma processing chamber 4 is subjected to hard alumite processing or the like, and also serves as a microwave waveguide. The plasma processing chamber 4 is formed by providing a quartz plate 3 between the reduced waveguide 26 and the quartz plate 3 to separate the space on the reduced waveguide 26 side from the processing chamber space. Reference numeral 5 denotes a vacuum chamber having an opening on the upper surface, and the plasma processing chamber 4 is connected to the opening. At the bottom of the vacuum chamber 5, a sample table 8 is supported via an electrical insulating material. The sample table 8 holds a wafer 10 on which processing such as etching or film formation is performed in a space formed by the plasma processing chamber 4 and the vacuum chamber 5. The sample stage 8 is provided so that the surface on which the wafer 10 is arranged faces the quartz plate 3 in parallel.

In this case, the vacuum chamber 5 is provided with a gas supply means capable of uniformly supplying a processing gas for processing such as etching or film formation to the wafer 10 on the sample stage 8 from around the inner surface of the upper part of the plasma processing chamber 4. A vacuum evacuation means 11 capable of depressurizing and evacuating the inside of the vacuum chamber 5 to a predetermined pressure is connected. The vacuum exhaust means 11 is connected to an exhaust port provided at the bottom of the vacuum chamber 5, and supplies processing gas supplied to the wafer 10 from the upper part of the plasma chamber 4 from the periphery of the sample table 8 to the vacuum chamber 5. An exhaust path is formed so that it is guided to the lower part of the chamber and exhausted. A high frequency power supply 9 which is a power supply for applying a bias voltage to the sample table 8 is connected to the sample table 8. Reference numeral 28 partitions the vacuum chamber 5, and the bra This is a gate valve that is connected to the Zuma processing chamber 4 to form a processing chamber.

Outside the resonator 24, the reduced waveguide 26 and the plasma processing chamber 4, solenoid coils 6 and 7 for forming a magnetic field in the plasma generating chamber 4 are wound. In the apparatus of the present embodiment, the solenoid coil 6 can generate a stronger magnetic field than the solenoid coil 7, and can combine with the magnetic field of the solenoid coil 7 to form a flat ECR surface in the plasma processing chamber 4. Is set. Furthermore, the height of the ECR surface from the sample stage 8 can be adjusted by adjusting the power supplied to each of the solenoid coils 6 and 7.

In the plasma processing apparatus configured as described above, the microwave emitted from the magnetron 1 is converted into a rectangular waveguide 21, a matching device 27, a circular-rectangular conversion waveguide 22, and a circular waveguide 23. , And guided to the microwave resonator 24. The microphone mouth wave guided to the resonator 24 is internally resonated in a specific microphone mouth wave mode (in this case, a circular TE 01 mode is set), and the microwave that can be in the specific mode is used. Is guided to the reduced waveguide 26 through the slit plate 25 for emitting the light. The microwave passing through the reduced waveguide 26 is locally emitted from the slit plate 25, in other words, gradually spreads after being partially emitted to form a specific mode, and is formed through the quartz plate 3 through the plasma processing chamber. Guided to within 4. The microwave guided into the plasma processing chamber 4 in the specific mode changes the processing gas in the plasma processing chamber 4 into plasma by the action of the magnetic field formed in the plasma processing chamber by the solenoid coils 6 and 7. At this time, the microphone mouth wave emitted from the magnetron 1 is introduced into the plasma processing chamber 4 through the resonator 24 and the reduced waveguide 26, thereby being generated in the plasma processing chamber 4. The density and distribution of the plasma resembles the electric field mode of the microwave introduced into the plasma processing chamber 4, and in this case, the density around the sample stage 8 resembles the TE01 mode with a strong electric field in a ring shape. An experimental result was obtained that a high-density ring-shaped high-density plasma distribution was obtained.

Fig. 3 shows the results of measurement of the ion current density in the plasma incident on the wafer (actually with a plurality of probes provided on the sample stage) under actual plasma etching conditions using this apparatus. Etching conditions in this case, it is the same as the conditions when performing etching using a mixed treatment gas of A 1 film e Bok resist as a mask BC 1 ₃ ZC. Etching by the apparatus, process pressure: 5 to 5 OMT orr, process gas flow rate: 50 to 300 sc cm, the process gas mixing ratio: 0.5 to 1.5 (8_Rei _{_{1 3) 1 (C 1 2}} ), High-frequency power output: 25 to 250 W, microwave output: 200 W to 1.5 KW.

In FIG. 3, a curve A shows an ion current density distribution in the case of the present device provided with the resonator 24 and the reduced waveguide 26. Curve B shows the ion current density distribution when a simple cylindrical waveguide is provided instead of the resonator 24 and the reduced waveguide 26. Curve C shows an enlarged waveguide (without the slit plate 25 of the resonator 24) through the quartz plate 3 directly from the waveguide 2 without providing the resonator 24 and the reduced waveguide 26. Fig. 3 shows the ion current density distribution when the (wave tube) is connected to the plasma processing chamber 4.

In the ion current density shown in Fig. 3, the curve A when the resonator 24 and the reduced waveguide 26 are used shows the ion current density distribution at the outer periphery on the sample stage (electrode). Curve B with a resonator 24 and a cylindrical tube shows a somewhat high but nearly uniform ion current density distribution near the outer circumference on the sample stage (electrode). Curve C when the enlarged waveguide is simply connected shows the ion current density distribution at the center height on the sample stage (electrode).

Fig. 4 shows the etch in the wafer when the aluminum wiring (A1 film) was actually etched under the plasma etching conditions described above. Indicate the speed. In Fig. 4, curves a and b are obtained by etching with this device provided with a resonator 24 and a reduced waveguide 26, and the difference is the distance of the ECR surface from the sample stage. Curve a is for the case where the ECR surface is close to the sample stage 8, and curve b is for the case where the ECR surface is far from the sample stage 8. Curve c shows an enlarged waveguide (without slit plate 25 of resonator 24) through quartz plate 3 directly from waveguide 2 without providing resonator 24 and reduced waveguide 26. The waveguide was re-etched by an apparatus connected to the plasma processing chamber 4, and was etched by plasma having an ion current density shown by a curve C in FIG.

At the etching rate shown in Fig. 4, the curve a when the ECR surface is brought close to the wafer 10 using the resonator 24 and the reduced waveguide 26 shows a substantially uniform etching rate distribution in the wafer, and the etching rate It can be seen that they are excellent in uniformity. The curve b when the ECR surface is moved away from the wafer 10 using the resonator 24 and the reduced waveguide 26 has improved uniformity, but the etching rate is low. It can be seen that the curve c when the enlarged waveguide is simply connected is a state in which the etching rate at the center of the wafer is high and the periphery is low and the uniformity is low.

As can be seen from FIGS. 3 and 4, the etching rate distribution of the wafer and the ion current density distribution on the wafer do not always coincide with each other. It is necessary to consider the ion current density distribution and other factors, that is, the distribution of radicals and reaction products, and to make them uniform. Here, since radicals and reaction products are evacuated around the sample table 8 by the vacuum exhaust means 11, that is, through the outer periphery of the wafer 10, even if plasma is uniform on the wafer surface, Actually, however, the plasma density decreases at the outer peripheral portion of the wafer 10. To compensate, the distribution of ion current density on the wafer must be high at the outer periphery of the wafer.

As shown in Fig. 3C, when the ion current density at the center of the sample stage is high and small at the periphery of the sample stage, the plasma density distribution on the wafer is not uniform. When the etching process is performed under such plasma conditions, the selectivity to resist at the center of the wafer is particularly low, and when the A1 film having the step structure is etched, the resist film at the step is thinner at the center of the wafer. There is a problem that the chip portion is etched away faster than the chip portion at the peripheral portion of the wafer, and the etched shape of the A1 film at the step portion cannot be maintained. When the resonator 24 is provided and a cylindrical waveguide is provided, the ion current density at the center of the sample stage slightly decreases as shown by the curve B in FIG. However, the ion current density at the periphery of the sample stage increases, and the uniformity of the ion current density over the entire sample stage is improved as compared with the curve C. That is, it is understood that the plasma density on the sample stage 8 has a high distribution in the peripheral portion, and the uniformity is also improved. This is because the resonator 26 having the slit plate 25 has a ring-like strong electric field intensity distribution mode. In this case, the outer peripheral microphone mouth wave electric field intensity is high as in the TE01 mode. Since the microwave is guided to the plasma processing chamber 4 through the cylindrical waveguide portion, a strong ring-shaped plasma density distribution is formed on the ECR surface, and the plasma is directed to the wafer. It is considered that the diffusion is performed while maintaining the plasma distribution in accordance with the following equation. When processing such as etching is performed under such plasma conditions, the difference in resist selectivity between the central part and the peripheral part of the wafer is improved, the uniformity of resist selectivity is improved, and the above-described problem is solved. Could be improved. The etching uniformity of the A1 film at this time was not affected.

Further, in the case of the present embodiment in which the resonator 24 and the reduced waveguide 26 are provided, As shown in the curve A in FIG. 3, the ion current density is improved over the entire surface of the sample table while maintaining the uniformity of the curve B, that is, the uniformity of the low-density plasma with the increased plasma density is improved on the sample table 8. It can be seen that it was generated with improvement. When the etching process is performed under such plasma conditions, the processing uniformity and the processing speed of the wafer can be respectively improved. As described above, the resonator 24 is attached to a part of the waveguide of the microwave propagation means 2 to specify the mode in which the electric field intensity of the microphone mouth wave is ring-shaped, and the cylindrical waveguide is introduced to the plasma processing chamber 4. By providing the resonator 24 via the waveguide, the ion current density distribution at the periphery of the sample table is high, and the uniformity is improved. Further, by replacing the cylindrical waveguide part with the reduced waveguide 26 and providing the reduced waveguide 26 between the resonator 24 and the quartz plate 3, the distribution state of the ion current density on the sample stage is improved. The value of the ion current density can be increased as a whole while maintaining a ring shape, that is, the plasma on the sample stage can be made denser and the uniformity can be improved. Thus, when performing processing such as etching or film formation, the processing speed can be improved and the wafer 10 can be uniformly processed.

Next, a second embodiment of the plasma processing apparatus of the present invention will be described with reference to FIG.

FIG. 5 shows the microphone mouth wave propagation means and the plasma processing chamber of the apparatus shown in FIG. 1, and is the same as the member shown in FIG. Omitted. This figure is different from FIG. 1 in that a reduced waveguide provided after the resonator 24 (in the direction in which the microwave travels) to guide the microwave to the plasma processing chamber 4 is the same as the waveguide in FIG. The point is that a reduced waveguide 26a in which the diameter reaching the plasma processing chamber 4 side is gradually reduced is used. In this case, the degree of decrease in the aperture of the microwave reduced waveguide 26a is ignored with respect to the wavelength of the microwave passing through the reduced waveguide 26a. The gradual decline as much as possible. With this configuration, it is possible to obtain the same effects as those of the above-described embodiment. In addition, if a reduced waveguide whose diameter is gradually reduced is used in this way, it is possible to easily configure the reduced waveguide 26a by stacking cylindrical plates having different diameters. Thus, the shape of the reduced waveguide 26a can be easily changed.

Next, a third embodiment of the plasma processing apparatus of the present invention will be described with reference to FIG.

FIG. 6 shows the microwave propagation means and the plasma processing chamber of the apparatus shown in FIG. 1, and is the same as the member shown in FIG. 1 except for the members denoted by the same reference numerals and the illustration in FIG. Omitted. This figure is different from Fig. 1 in that the diameter of the reduced waveguide on the plasma processing chamber 4 side is smaller than the diameter of the microphone mouth wave introduction part of the plasma processing chamber 4 26b. It is. By doing so, the ion current density could be further increased especially in the outer peripheral portion of the wafer 10 as compared with the apparatus shown in FIG. This is because, of the microwave once introduced into the plasma processing chamber 4 through the reduced waveguide 26 b and the quartz plate 3, part of the microphone mouth wave is reflected at the interface with the plasma, and the reduced waveguide It is considered that when returning to the direction of the tube 26 b, the microwave introduction portion is restricted, so that it is difficult for the microwave to be emitted to the outside of the plasma processing chamber 4.

Note that the above-mentioned curve shape in FIG. 3 changes depending on the processing gas used, that is, the ion current density changes depending on the processing gas, but the distribution tendency of the ion current density depends on the resonator and the reduced waveguide. The relationship between the presence or absence and the size of the diameter of the reduced waveguide on the plasma processing chamber side is similar to the tendency shown in FIG. Therefore, as described above, by providing a resonator and a reduced waveguide in the microwave propagation means and adjusting the diameter of the reduced waveguide on the plasma processing chamber 4 side, the high-density region of the plasma on the wafer can be obtained. To Since it can be generated at a desired position, it is possible to generate plasma conditions that are optimal for processing such as etching or film formation. For example, it is advantageous when the plasma density at the upper part of the wafer is higher at the periphery than at the center in order to make the selectivity with respect to the resist uniform within the wafer plane.

Next, a fourth embodiment of the plasma processing apparatus of the present invention will be described with reference to FIG.

FIG. 7 shows the microphone mouth wave propagating means and the plasma processing chamber of the apparatus shown in FIG. 1, and is the same as the member shown in FIG. Omitted. The difference between this figure and Fig. 1 is that the diameter of the cross-section of the opening in the waveguide is gradually changed toward the plasma processing chamber 4, that is, with respect to the traveling direction of the microwave, instead of the reduced waveguide 26. This is an expanded waveguide 29 that has been expanded to the point shown in FIG. By doing so, it is also possible to change the high-density region of the plasma generated in the plasma processing chamber 4, and to optimize the plasma state for wafer processing according to the conditions of the material to be etched and the processing gas. Can be obtained.

As described above, according to these embodiments, in the plasma processing exhausted from the periphery of the sample, the sample in the processing chamber can be uniformly processed by increasing the plasma density distribution in the outer peripheral part from the central part. In this case, it is preferable that the processing gas flow from above the wafer surface in order to improve the uniformity.

In addition, the microwave of a specific mode set by the resonator is introduced into the plasma processing chamber by gradually changing the cross-sectional area of the opening using the reduced waveguide or the expanded waveguide, and the high density of plasma is obtained. The distribution area can be changed from the state of the central high state to the ring-shaped optimum position in the peripheral direction, and the optimum plasma state can be created when performing plasma processing on the wafer. As a result, the wafer can be processed uniformly and at a high speed. In addition, in the case of the etching process, by optimizing the plasma density in the plasma processing chamber as described above, the uniformity of the etching speed in the wafer surface and the improvement of the etching speed can be achieved. Quality and quality.

In addition, by performing plasma processing with a higher plasma density at the outer peripheral portion than at the central portion of the wafer to be etched, the resist selectivity can be made uniform on the wafer.

When the diameters of the reduced waveguide and the enlarged waveguide in these embodiments described above on the side of the plasma processing chamber 4 are appropriately adjusted, for example, a portion corresponding to the inner surface of the reduced waveguide is made of a conductor. The plasma density distribution can be adjusted during processing such as etching by adopting a reduced or enlarged waveguide whose diameter can be automatically varied, such as by rounding the plate into a conical shape and overlapping the ends to allow sliding. Can be adjusted. In the case of etching, the reduced waveguide shape is changed during etching and during overetching, and the plasma distribution is changed so as to improve the selectivity with respect to the resist or the base, thereby further increasing the yield. Good etching treatment can be performed. In addition, the plasma distribution control during the processing can be applied during the film formation processing as needed.

These techniques for adjusting the plasma distribution can also be applied to etching of metals, gates, and oxide films other than the A1 film, and can be applied to processing using plasma such as film formation other than etching.

The apparatus shown in Fig. 1 employs a plasma generation method using ECR resonance by microwaves to generate a magnetic field by solenoids 6, 7, but etching gas and reaction products are generated from the outer periphery of the wafer. In a configuration in which matter is exhausted, the behavior of the plasma changes even in an apparatus that does not use a microwave or a magnetic field, such as an inductively coupled plasma generation method. Instead, the concept of the plasma processing apparatus of the present invention, that is, a plasma processing method in which a wafer is uniformly processed by plasma having a ring-shaped density distribution with a peripheral height on the wafer can be applied. Electron density of the plasma generated in the plasma processing chamber, if the field-free, 7 X 1 0 '° pieces Roh cm ³ or more on (in the case of a magnetic field, ¹ X 1 0 1 1 / cm ³ or higher) becomes a However, the plasma has a reflecting boundary surface of the microwave and reflects a part of the incident microwave. At this time, by making the space large enough to resonate the microwave between the boundary surface and the slit plate, the energy of the microwave is efficiently transmitted to the plasma, and the plasma density is improved. Alternatively, it is preferable that the dimensions of the enlarged waveguide be set in consideration of this point. Further, in the apparatus shown in FIG. 1, the processing gas is supplied to the wafer from the periphery of the inner surface above the processing chamber 4, but it is supplied from the surface of the quartz window 3 facing the wafer. The details of the apparatus can be changed as appropriate. Industrial applicability

ADVANTAGE OF THE INVENTION According to the present invention, in plasma processing evacuated from the periphery of a sample, the plasma density distribution is made higher at the outer periphery than at the center, whereby the sample in the processing chamber can be uniformly treated. is there.

In addition, by introducing a microwave of a specific mode into the plasma processing chamber using a waveguide whose opening cross-sectional area changes gradually, the high-density distribution region of the plasma can be set to the optimal position. Since an optimum plasma state can be created when the sample is subjected to plasma processing, there is an effect that the sample can be uniformly processed.

Furthermore, an ECR formed by a TE 01 mode microwave and a magnetic field having a magnetic field intensity parallel to the sample under ECR conditions. By bringing the surface close to the sample, there is an effect that the sample can be processed uniformly and at high speed.

Claims

The scope of the claims

1. A plasma processing method, wherein a plasma density distribution on a sample table holding a sample to be subjected to replasma processing in a plasma processing chamber is higher at a peripheral portion than at a central portion, and the sample is subjected to plasma processing.

2. The plasma processing method according to claim 1, wherein a plasma treatment E Tsuchingu process, the material to be etched in said sample a A 1-based material, a gas for generating the plasma is C 1 ₂ alone or C A plasma processing method using a mixed gas of ₁₂ and BC 1 and ₃ .

3. The plasma processing method according to claim 2, wherein the sample is an A1-based material having a step structure.

4. While propagating the microphone mouth wave in a specific mode, the propagation area is gradually changed in the traveling direction of the microphone mouth wave, and the microwave is introduced into the plasma generation region. A plasma processing method characterized by processing.

5. The plasma processing method according to claim 4, wherein the plasma generated using the microwave with a magnetic field is a plasma having an electron density of 1 × 10 ″ cm ³ or more.

6. The plasma processing method according to claim 4, wherein the plasma generated using the microwave without a magnetic field is a plasma having an electron density of 7 × 10 ″ ″ Z cm ³ or more. .

7. A step of guiding microwaves into the resonator, a step of resonating microwaves of a specific mode in the resonator, and a step of causing the microwaves emitted from the resonator to form the specific mode. Radiating the microwave from the resonator; propagating a predetermined distance so that the microwave radiated from the resonator forms the specific mode; A step of gradually changing the propagation area with respect to the traveling direction of the tip wave; a step of introducing a microwave of a specific mode formed by the propagation into the plasma generation region; and a step of generating the microwave in the plasma generation region by the microwave. And a step of processing the sample with the generated plasma.

8. Means for locally radiating a microwave that can be in a specific mode, means for providing a distance for the emitted microwave to spread to the microwave in the specific mode, A plasma processing apparatus, comprising: a plasma generation chamber that generates a plasma having a higher plasma density in the outer periphery than in a central portion by a wave.

9. The plasma processing apparatus according to claim 8, wherein the specific mode is set as a circular TE01 mode.

10. Resonant means for resonating the microwave from the microphone mouth wave generating means in the TE01 mode, radiation means for partially radiating the TE01 mode microwave from the resonance means, and radiation Restoring means for restoring microwaves radiated from the means to TE 01 mode microwaves, and introducing means for introducing the TE 01 mode microphone mouth wave restored by the restoring means into a discharge region; An arrangement means for arranging a sample for processing using plasma generated in the discharge region.

11. The plasma processing apparatus according to claim 10, wherein a microphone mouth wave introduction part of the introduction means is smaller than an inner diameter of the discharge region.

12. The plasma processing apparatus according to claim 10, wherein a magic mouth wave introduction part of the introduction means is substantially equal to an inner diameter of the discharge region.

13. The plasma processing apparatus according to claim 10, wherein the micro mouth wave introduction part of the introduction means is larger than an inner diameter of the discharge region.

1. Plasma processing in which microwaves oscillated from a microwave oscillator are guided to a plasma generation space via microwave propagation means, and a sample is processed using plasma generated in the plasma generation space using the microwaves. In the apparatus, the microwave propagation means resonates a microwave propagating through the means into a specific mode and partially radiates a microphone mouth wave of the mode, and the plasma generation space from the resonator. And a microwave introducing means for introducing the microwave propagating through the waveguide into the plasma generation space. A plasma processing apparatus characterized in that:

15. The plasma processing apparatus according to claim 14, wherein the waveguide side of the resonator is a slit plate.

16. The plasma processing apparatus according to claim 14, wherein an opening cross-sectional area of the waveguide gradually decreases and changes in a propagation direction of the microwave.

17. The plasma processing apparatus according to claim 14, wherein an opening cross-sectional area of the waveguide gradually expands and changes in a propagation direction of the microwave.

18. The plasma processing apparatus according to claim 16, wherein an opening cross-sectional area of the waveguide is changed stepwise.

19. The plasma processing apparatus according to claim 14 or 16, wherein an opening of the waveguide in the plasma generation space side is substantially the same as an inner diameter of the waveguide in the chamber forming the plasma generation space. Plasma processing equipment.

20. The plasma processing apparatus according to claim 14 or 16, wherein an opening of the waveguide in the plasma generation space is smaller than an inner diameter of the waveguide in a chamber forming the plasma generation space. Plasma processing equipment.