JPH0878398A - Microwave plasma processing apparatus - Google Patents

Abstract

PURPOSE: To obtain a micro wave plasma processing apparatus wherein microwaves can be uniformly applied to the entire surface of a substrate by placing a means for uniformizing the intensity distribution of micro wave along a waveguide adjacent to the entrance of a process chamber in a direction crossing the entry direction of the microwave to the process chamber. CONSTITUTION: A uniformizing means 32 absorbs or blocks microwaves 111 an area with comparatively high microwave intensity and allows those in an area with comparatively low microwave intensity to transmit, uniformizing the intensity distribution of microwaves. The means 32 consists of a quartz disc as a microwave transmitting disc that has the same diameter as that of the circular section of a waveguide 16 and an aluminum metallic powder that is distributed in such a way that its distribution density will be gradually decreased from the center of the disc to the periphery thereof. The means 32 is placed in the waveguide 16 just before a bell-jar 13 in a manner that the disc will be placed along the direction crossing at a right angle the entry direction of micro,waves and be also concentric to the section of the waveguide 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave plasma processing apparatus for processing a substrate in a process chamber while introducing microwave into a process chamber into which a reaction gas is fed to generate plasma. More specifically, the present invention relates to a microwave plasma processing apparatus capable of uniformly processing the entire surface of a large-sized substrate such as a large-diameter wafer.

[0002]

2. Description of the Related Art Various microwave plasma processing apparatuses are used in the manufacturing process of semiconductor devices. For example, a microwave plasma etching apparatus is used to perform an etching process on a wafer, or a microwave plasma CVD is used to perform a CVD process on a wafer to form a thin film.
Each device is being used. A conventional microwave plasma processing apparatus will be described below by taking a microwave plasma etching apparatus as an example. FIG. 5 is a schematic diagram showing the configuration of a conventional microwave plasma etching apparatus (hereinafter simply referred to as an etching apparatus). As shown in FIG. 5, the conventional etching apparatus basically has a magnetron 1 for generating a microwave having a frequency of 2.45 GHz.
2, an etching chamber 14 partitioned by a quartz bell jar 13 and adjusted to a constant pressure, and a magnetron 12
A waveguide 16 having a circular cross section for introducing microwaves into the etching chamber 14 and a solenoid coil 18 for generating a magnetic field in the etching chamber 14 are provided.

An electrode 20 on which a wafer W to be etched is placed is installed in the etching chamber 14, and etching gas is introduced into the etching chamber 14 through an inlet 22 and sucked and exhausted through an exhaust port 24. It Electrode 20
A high-frequency bias is applied by the high-frequency power source 26 to the bias potential. The etching gas generates plasma by the action of the introduced microwave and collides with the wafer W to etch the wafer surface.

[0004]

By the way, the microwave introduced into the etching chamber 14 has not a uniform intensity but a strong and weak distribution in a cross section orthogonal to its traveling direction.
Usually, the strength is high in the central portion of the cross section orthogonal to the traveling direction and low in the peripheral portion. As a result, plasma having a density distribution corresponding to the intensity distribution of microwaves is generated in the etching chamber, and as a result, the etching process performed on the wafer becomes nonuniform between the central portion and the peripheral portion of the wafer. There's a problem. That is, the etching rate is large in the central portion of the wafer and low in the peripheral portion, so that the central portion is strongly etched and the peripheral portion is weakly etched.

In the above description, the etching process is taken as an example, but the problem of process non-uniformity on the wafer surface is the same when performing other processes. For example, in a microwave plasma CVD apparatus. If so, the deposit rate is large in the central part of the wafer and low in the peripheral part, so that the film thickness of the formed thin film is large in the central part and thin in the peripheral part. The non-uniformity of the plasma processing by such microwaves is particularly remarkable when processing a wafer having a large diameter in recent years, and if the predetermined processing is performed on the central portion of the wafer, the peripheral processing is rejected, On the contrary, when the peripheral portion was subjected to the predetermined treatment, the treatment in the central portion failed. Therefore, it is difficult to improve the yield of semiconductor products, and it has been demanded to provide an apparatus capable of uniform processing.

Therefore, an object of the present invention is to provide a microwave plasma processing apparatus capable of uniformly processing the entire surface of the substrate.

[0007]

In order to achieve the above object, a microwave plasma processing apparatus according to the present invention introduces microwaves into a process chamber into which a reaction gas is fed to generate plasma. In a microwave plasma processing apparatus for processing a substrate in a process chamber, a microwave in a region having a relatively high microwave intensity is absorbed or shielded, and a microwave in a region having a relatively low microwave intensity is transmitted to cause a microwave. A uniformizing means for uniformizing the intensity distribution of the above is extended to the waveguide near the entrance of the process chamber in a direction intersecting with the direction of entrance of microwaves into the process chamber.

In a preferred embodiment of the present invention, the homogenizing means is distributed on the microwave transmitting plate and the microwave transmitting plate such that the distribution density gradually decreases from the center of the microwave transmitting plate toward the periphery. It is characterized in that the microwave transmitting plate is made of metal powder and extends in a direction orthogonal to the microwave intrusion direction, and the center of the microwave transmitting plate is concentric with the center of the waveguide. Quartz or other ceramic plates can be used as the microwave transmitting plate, and aluminum powder, silver powder, copper powder or the like can be used as the metal powder.

In another preferred embodiment of the present invention, the homogenizing means comprises a lens-like upper curved surface which is convex upward, and a lower curved surface which is substantially symmetrical to the upper curved surface with respect to a symmetrical plane orthogonal to the convex direction of the upper curved surface. A microwave transmissive body block having a hollow portion having therein, and a microwave absorbing liquid housed in the hollow portion, the plane of symmetry of the hollow portion extends in a direction orthogonal to the microwave entering direction, and It is characterized in that the center of the hollow portion is arranged so as to be concentric with the center of the waveguide.
As an example, the microwave transmissive body block may be formed of quartz, and a liquid such as water or oil may be used as the microwave absorbing liquid. A ceramic block other than quartz can also be used as the microwave transparent body block.

As long as the present invention is a microwave plasma processing apparatus for processing a substrate in a process chamber while introducing a microwave into a process chamber into which a reaction gas is fed to generate plasma, the type of the substrate can be changed. There is no limitation in the above, and it can be applied to a microwave plasma etching apparatus, a microwave plasma ashing apparatus, a microwave plasma CVD apparatus, and the like.

[0011]

According to the present invention, the microwaves in the region having a relatively high microwave intensity are absorbed or shielded, and the microwaves in the region having a relatively low microwave intensity are transmitted to make the intensity distribution of the microwaves uniform. The uniformizing means is extended to the waveguide near the entrance of the process chamber in a direction intersecting with the direction of microwaves entering the process chamber. As a result, microwaves in a high intensity region are absorbed or shielded, and microwaves in a low intensity region are transmitted, so that the intensity of microwaves that enter the process chamber through the homogenizing means has a cross section that is orthogonal to the intrusion direction. Is homogenized at. Therefore, the plasma density is also made uniform, so that even a large-sized substrate, for example, a large-diameter wafer, can be uniformly processed over the entire surface thereof.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the accompanying drawings. As an embodiment of the microwave plasma processing apparatus according to the present invention, a microwave plasma etching apparatus (hereinafter simply referred to as an etching apparatus) will be taken up. FIG. 1 is a schematic diagram showing the configuration of the main part of the etching apparatus of this embodiment, and FIGS.
2A is a plan view showing the configuration of an example of the uniformizing means and FIG. 2A is a sectional view of the uniformizing means taken along line XX. Of the parts shown in FIG. 1, the same parts as those in FIG. 5 are designated by the same reference numerals, and the description thereof will be omitted. As shown in FIG. 1, in addition to the configuration of FIG. 3, the etching apparatus 30 of the present embodiment absorbs or shields microwaves in a region having a relatively high microwave intensity and protects a region having a relatively low microwave intensity. The waveguide 16 immediately before the bell jar 13 is provided with a homogenizing means 32 that transmits microwaves and homogenizes the intensity distribution of the microwaves.

In explaining the homogenizing means 32, it is assumed that the microwave intensity in the etching device 30 is high in the central portion and low in the peripheral portion with respect to the cross section of the waveguide 16. In the case of such intensity distribution, the uniformizing means 32
In the present embodiment, as shown in FIGS. 2A and 2B, a quartz disk 34 having a diameter equal to the circular cross section of the waveguide 16 is used as a microwave transmission plate, and the periphery of the disk 34 from the center thereof. And an aluminum metal powder 36 distributed so that the distribution density gradually decreases toward the. The present homogenizing means 32 includes the waveguide immediately before the bell jar 13 so that the circular plate 34 extends in the direction orthogonal to the microwave entering direction and the center thereof is concentric with the cross-sectional center of the waveguide 16. 16 are arranged. The aluminum powder 36 is processed to be self-adhesive and thereby adheres to the quartz disk 34. As an alternative to the self-adhesive aluminum powder, a similarly distributed aluminum powder may be sandwiched between two quartz disks.

With the above structure, the distribution density of the aluminum powder 36 that absorbs microwaves is high in the center and low in the periphery. With the aluminum powder layer 36 having such a distribution, the microwave is absorbed relatively strongly in the central portion of the disk 34 and relatively weakly absorbed in the peripheral portion. After that, the quartz disk 34 holding the aluminum powder is freely transmitted. Therefore, the microwave transmitted through the homogenizing means 32 becomes a microwave having uniform intensity. Since the microwave has a uniform intensity in the plane orthogonal to the entrance direction, the density of the plasma is also made uniform, and thus a large substrate,
For example, even in the case of a large-diameter wafer, the entire surface of the wafer can be uniformly etched. The aluminum powder may be dispersed on the wall itself of the bell jar 13 to form the homogenizing means 32.

As another example of the uniformizing means 32, FIG.
As shown in (a) and (b), the homogenizing means 32 includes a quartz circular block 40 having a diameter equal to the circular cross section of the waveguide 16 and a hollow portion 42 formed inside the circular block 40. May be configured. 3A is a plan view of the uniformizing means 32, and FIG. 3B is a line YY of FIG. 3A.
FIG. 4 is a sectional view of the homogenizing means 32 in FIG. The hollow portion 42 has an upward curved surface with respect to a lens-shaped upward curved surface 44 that is convex upward and a symmetry plane 45 (indicated by a virtual line in FIG. 3B) that extends in a direction orthogonal to the convex direction of the upward curved surface 44. Lower curved surface 4 symmetrical to 44
6, and the hollow portion 42 is filled with a microwave absorbing liquid, for example, water. Further, in consideration of the temperature rise of water, water is always made to flow from the inlet 48 and the outlet 50 is supplied.
You may make it flow out more. The plane of symmetry 45 of the hollow portion 42 extends in a direction orthogonal to the microwave entering direction,
The homogenizing means 32 is arranged in the waveguide 16 immediately before the bell jar 13 so that the center of the hollow portion 42 is concentric with the center of the cross section of the waveguide 16.

With the above structure, since the microwave absorbing water layer is deep in the center and shallow in the periphery, the microwave is absorbed relatively strongly in the central portion of the hollow portion 42 and relatively weakly absorbed in the peripheral portion. . Therefore, the microwave transmitted through the homogenizing means 32 becomes a microwave having a uniform intensity distribution.

As another example of the homogenizing means 32, FIG.
A circular block 52 of quartz having a diameter approximately equal to the circular cross section of the waveguide 16, as shown in FIGS.
The homogenizing means 32 may be composed of a plurality of concentric annular flow paths 54 formed inside the circular block 52. FIG.
4A is a plan view of the uniformizing means 32, and FIG.
It is sectional drawing of the equalization means 32 in the line ZZ of (a).
The annular flow path 42 is a tubular flow path provided in the circular block 52, and is concentrically and annularly formed around the center of the circular block 52, and is densely dispersed in the central portion of the circular block 52 and in the peripheral portion. Are formed in a disposition. In the annular flow path 54,
A microwave absorbing liquid, such as water, flows in through the inlet header 56 and flows out through the outlet header 58. Circular block 5
So that the center of 2 is concentric with the cross-sectional center of the waveguide 16,
The homogenizing means 32 is arranged in the waveguide 16 immediately in front of the bell jar 13 so that the annular flow path 54 is orthogonal to the microwave entering direction.

With the above structure, the distribution of the water flow that absorbs microwaves is dense in the center and coarse in the periphery, so that the microwaves are absorbed relatively strongly in the center of the circular block 52 and in the periphery. It is absorbed relatively weakly. Therefore, the microwave transmitted through the homogenizing means 32 becomes a microwave having uniform intensity. Incidentally, instead of the concentric annular flow path,
A spiral channel may be used.

In the above description, the waveguide 16 having a circular cross section has been described as an example, but when the waveguide 16 is rectangular, the rectangular uniforming means 32 may be similarly formed.

[0020]

According to the present invention, a microwave plasma processing apparatus for processing a substrate in a process chamber while introducing a microwave into a process chamber into which a reaction gas is fed to generate plasma A homogenizing means that absorbs or shields microwaves in a region having a relatively high wave intensity and transmits microwaves in a region having a relatively low microwave intensity to homogenize the intensity distribution of microwaves to the process chamber. The microwave transmitted through the homogenizing means has a uniform intensity in a cross section in a direction orthogonal to the traveling direction by extending the microwave near the entrance of the process chamber in a direction that intersects with the entering direction of the microwave. As a result, even a large-sized substrate, for example, a large-diameter wafer can be uniformly processed over the entire surface of the wafer. Moreover, since the structure of the homogenizing means is extremely simple, the existing microwave plasma processing apparatus can be easily modified.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of a main part of a microwave plasma etching apparatus according to the present invention.

FIG. 2 (a) is a plan view showing the configuration of an example of a uniformizing means, and FIG. 2 (b) is a sectional view of the uniformizing means taken along line XX of FIG. 2 (a).

3 (a) is a plan view of another example of the uniformizing means, and FIG. 3 (b) is a sectional view of the uniformizing means taken along line YY of FIG. 3 (a).

FIG. 4 (a) is a plan view of still another example of the uniformizing means, and FIG. 4 (b) is a cross-sectional view of the uniformizing means taken along line ZZ in FIG. 4 (a).

FIG. 5 is a schematic view showing a main part of a conventional microwave plasma etching apparatus.

[Explanation of symbols]

12 magnetron 13 bell jar 14 etching chamber 16 waveguide 18 solenoid coil 20 electrode 22 inlet port 24 exhaust port 26 high frequency power source 30 embodiment of microwave plasma etching apparatus according to the present invention 32 uniformizing means 34 disk 36 aluminum powder 40 circular Block 42 Hollow part 44 Upper curved surface 45 Symmetrical surface 46 Lower curved surface 48 Inlet 50 Outlet 52 Circular block 54 Annular flow path 56 Inlet header 58 Outlet header

Claims (5)

[Claims] 1. A microwave plasma processing apparatus for processing a substrate in a process chamber while introducing a microwave into a process chamber into which a reaction gas is fed to generate plasma, and the microwave intensity is relatively high. A uniformizing means that absorbs or blocks microwaves in a region and transmits microwaves in a region having a relatively low microwave intensity to make the intensity distribution of microwaves uniform is directed in the direction in which the microwave enters the process chamber. A microwave plasma processing apparatus, characterized in that the microwave plasma processing apparatus extends in a waveguide near a process chamber inlet in a direction intersecting with. 2. The homogenizing means comprises a microwave transmitting plate and a metal powder distributed on the microwave transmitting plate so that the distribution density gradually decreases from the center of the microwave transmitting plate toward the periphery. 2. The microwave transmitting plate according to claim 1, wherein the microwave transmitting plate extends in a direction orthogonal to a microwave entering direction, and is arranged so that its center is concentric with the cross-sectional center of the waveguide. Microwave plasma processing equipment. 3. The microwave plasma processing apparatus according to claim 2, wherein the microwave transmitting plate is a quartz plate and the metal powder is aluminum powder. 4. The uniformizing means internally includes a hollow portion having a lens-shaped upper curved surface that is convex upward and a lower curved surface that is substantially symmetrical to the upper curved surface with respect to a symmetric plane orthogonal to the convex direction of the upper curved surface. The microwave transmissive body block and the microwave absorbing liquid housed in the hollow portion, the plane of symmetry of the hollow portion extends in the direction orthogonal to the microwave entrance direction, and the center of the hollow portion is the waveguide. The microwave plasma processing apparatus according to claim 1, wherein the microwave plasma processing apparatus is arranged so as to be concentric with the center of the cross section. 5. The microwave plasma processing apparatus according to claim 4, wherein the microwave transparent body block is made of quartz, and the microwave absorbing liquid is water.