JP4558975B2 - Plasma processing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a plasma processing apparatus using microwaves.
[0002]
[Prior art]
Conventionally, a plasma processing apparatus having a planar antenna as shown in FIG. 3 is known.
[0003]
The plasma processing apparatus 71 includes a processing container 73 that is formed into a bottomed cylindrical shape as a whole, and a quartz plate 75 that is airtightly provided on the ceiling of the processing container 73, and is sealed inside the processing container 73. A processing space S is formed.
[0004]
In the processing container 73, a mounting table 77 on which the semiconductor wafer W is mounted is accommodated on the upper surface. The mounting table 77 is connected to a bias high-frequency power source 79 through a power supply line. A gas supply nozzle 81 for introducing a processing gas into the container is provided on the side wall of the processing container 73, and the nozzle 81 is connected to a processing gas source 83. Further, an exhaust port 85 connected to a vacuum pump (not shown) is provided at the bottom of the processing container 73.
[0005]
On the other hand, a planar antenna member 87 is provided on the upper part of the quartz plate 75 that seals the upper part of the processing vessel 73. The planar antenna member 87 is configured as a bottom plate of a radial waveguide box 89 formed of a disk-shaped hollow cylindrical container with a low height, and is attached to the upper surface of the quartz plate 75. The outer tube 93 </ b> A of the coaxial waveguide 93 whose other end is connected to the microwave generator 91 is connected to the center of the upper surface of the disc-shaped radial waveguide box 89. Further, the inner cable 93 </ b> B inside the coaxial waveguide 93 is connected to the center of the disc-shaped antenna member 87.
[0006]
The disk-shaped antenna member 87 is made of a copper plate, and a number of slots 95 are formed in the copper plate. Further, in the radial waveguide box 89, a dielectric 97 having a predetermined dielectric constant is accommodated in order to shorten the wavelength of the microwave to make the wavelength in the tube shorter.
[0007]
In such a configuration, the microwave generated by the microwave generator 91 propagates in the coaxial waveguide 93, spreads radially in the radial waveguide box 89, and downward from the slot 95 of the antenna member 87. Released and forms plasma in the processing vessel 73.
[0008]
[Problems to be solved by the invention]
However, the processing apparatus 71 has a problem in that the electric field formed below the planar antenna member 87 is non-uniform, resulting in uneven processing on the wafer W. That is, the electric field emitted downward from the slot 95 of the planar antenna member 87 is reflected by the inner wall of the processing vessel 73, and the electric field at the center thereof becomes stronger as shown in the lower part of the figure. For this reason, there has been a problem that unevenness occurs in the processing of wafers, particularly large-diameter wafers.
[0009]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a plasma processing apparatus capable of realizing a substantially uniform electric field distribution below an antenna member and enabling uniform wafer processing. To do.
[0010]
[Means for Solving the Problems]
A first feature of the present invention is that a processing container having a mounting table on which a target object is mounted is formed in a bottomed cylindrical shape, and a lid made of a dielectric that airtightly covers an upper opening of the processing container. A body, a microwave supply device for supplying a microwave, and one end side connected to the microwave supply device, extending from the microwave supply device toward the lid, and having a waveguide space therein The tube is connected to the other end of the waveguide, and is extended radially outwardly from the other end of the waveguide into a flange shape, and then extends downward as a side wall toward the lid body. A radial waveguide box having a waveguide space in the antenna, an antenna member that covers a lower end opening of the radial waveguide box, has a plurality of slots, and is arranged in parallel to the lid, and a central portion of the antenna member Projected toward the mounting table on the mounting table side It is, that by providing the metal reflector for reflecting the high-frequency electric field coming reflected in the processing vessel inner wall.
[0011]
The second feature of the present invention is that the reflector protrudes from the lid into the processing container.
[0012]
A third feature of the present invention is that the reflector does not protrude from the lid into the processing container.
[0013]
The 4th characteristic of this invention is that the front-end | tip part has entered the inside of the said cover body in the said reflector.
[0014]
A fifth feature of the present invention is that the reflector is formed in a cylindrical shape or a column shape.
[0015]
A sixth feature of the present invention is that the reflector is formed in a cylindrical shape or a columnar shape.
[0016]
A seventh feature of the present invention is that the reflector is formed in a polygonal cylinder shape or a polygonal column shape.
[0017]
An eighth feature of the present invention is that an absorbing material that absorbs a high-frequency electric field is disposed in the vicinity of the outer periphery of the radial waveguide box.
[0018]
A ninth feature of the present invention is that an absorbing material that absorbs a high-frequency electric field is disposed on the outer periphery of the space from the lower surface of the antenna member to the lower surface of the lid made of the dielectric.
[0019]
According to a tenth feature of the present invention, the waveguide includes an inner conductor and an outer conductor disposed coaxially with the inner conductor, and a microwave propagates between the inner conductor and the outer conductor. The radial waveguide box is connected to the end of the outer conductor on the lid side, and the center of the antenna member is connected to the end of the inner conductor on the lid side That is.
[0020]
An eleventh feature of the present invention is that the waveguide is a cylindrical waveguide that propagates TM mode microwaves.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a plasma processing apparatus according to the present invention will be described in detail with reference to FIGS. In this embodiment, the case where the plasma processing apparatus is applied to a plasma etching apparatus will be described, but it is needless to say that the present invention is not limited to this.
[0033]
FIG. 1 shows a first embodiment of the present invention. In this figure, the plasma etching apparatus 2 has a processing container 4 whose side walls and bottom are made of a conductor such as aluminum and whose entirety is formed in a bottomed cylindrical shape. A glass plate 8 having a thickness capable of withstanding the vacuum pressure is airtightly provided on the upper inner wall of the processing container 4 to form a sealed processing space S inside the container.
[0034]
In the processing container 4, a mounting table 10 on which a semiconductor wafer W as an object to be processed is mounted is accommodated on the upper surface. The mounting table 10 is formed in a substantially columnar shape having a central portion that is made flat with anodized aluminum. The lower part of the mounting table 10 is supported by a support table 12 which is also made of aluminum and is formed in a column shape. The support table 12 is installed on the bottom of the processing container 4 via an insulating material 14.
[0035]
An electrostatic chuck and a clamp mechanism (not shown) for holding the wafer are provided on the upper surface of the mounting table 10. The mounting table 10 is provided with a matching box 18 and a high frequency for bias via a feeder line 16. Connected to a power source 20. The support table 12 that supports the mounting table 10 is provided with a cooling jacket 22 for flowing cooling water for cooling the wafer during plasma processing.
[0036]
A gas supply nozzle 24 made of quartz pipe for introducing an etching gas as a processing gas into the container is provided on the side wall of the processing container 4. The nozzle 24 is connected to a processing gas source 32 via a mass flow controller 28 and an on-off valve 30 by a gas supply path 26.
[0037]
Further, magnetic field generating means 34 such as an electromagnetic coil and a permanent magnet is provided on the outer periphery of the side wall of the processing container 4 along the circumferential direction, and a plasma generated by generating a magnetic field in the processing space S is generated. Is supposed to be trapped. The magnetic field generating means 34 is not necessarily required for generating plasma and may be omitted.
[0038]
An exhaust port 36 connected to a vacuum pump (not shown) is provided at the bottom of the processing container 4 so that the processing container 4 can be evacuated to a predetermined pressure as required.
[0039]
A microwave generator 50 is provided above the glass plate 8 of the processing container 4. A coaxial waveguide 52 is connected to the microwave generator 50. The coaxial waveguide 52 has a cylindrical outer conductor 52A and an inner conductor 52B disposed coaxially inside the outer conductor 52A. A TEM mode microwave generated by the microwave generator 50 propagates between the outer conductor 52A and the inner conductor 52B. A radial waveguide box 54 is connected to the outer conductor 52 </ b> A of the coaxial waveguide 52. The radial waveguide box 54 includes a flange portion 56 that extends outward in the radial direction from the lower end of the outer conductor 52A, and a wall portion that extends downward from the outer peripheral edge of the flange portion 56 toward the glass plate 8. 58. A disc-shaped antenna member 60 is provided at the lower end opening of the radial waveguide box 54 so as to cover the opening, and a waveguide space is formed therein. The disk-shaped planar antenna member 60 is made of a copper plate, and a number of slits 62 are formed in the copper plate. The many slits 62 are arranged in a spiral shape from the center portion to the peripheral portion. An inner conductor 52 </ b> B is connected to the center portion of the disk-shaped antenna member 60 inside the radial waveguide box 54. Further, a metal cylindrical reflector 64 formed to protrude toward the mounting table 10 on the side opposite to the portion to which the inner conductor 52B of the disk-shaped antenna member 60 is connected, that is, on the mounting table 10 side. The cylindrical reflector 64 is provided so as to protrude into the processing container 4 beyond the glass plate 8. And the high frequency (microwave) electric field reflected on the inner wall of the processing container 4 is reflected again outward.
[0040]
The space defined by the radial waveguide box 54 and the disk-shaped antenna member 60 is filled with a dielectric 66. Further, an absorbing material 68 that absorbs a high frequency (microwave) electric field is provided on the outer periphery of the side wall 58 of the radial waveguide box 54 so as to prevent reflection of the electromagnetic field to some extent.
[0041]
Next, the operation of the present embodiment configured as described above will be described. First, the semiconductor wafer W is accommodated in the processing container 4 by a transfer arm via a gate valve (not shown), and the wafer W is mounted on the mounting surface on the upper surface of the mounting table 10 by moving a lifter pin (not shown) up and down. Put. Then, the etching gas is supplied from the gas supply nozzle 24 while controlling the flow rate while maintaining the inside of the processing container 4 at a predetermined process pressure. At the same time, microwaves from the microwave generator 50 are introduced into the processing space S to generate plasma, and an etching process is performed. In this case, by applying a bias high frequency power to the mounting table 10, a negative potential can be generated in the mounting table 10, and ions can be efficiently extracted from the plasma. The magnetic field generating means 34 provided on the side wall of the processing vessel 4 is for generating a magnetic field for confining the plasma. Even if this is not provided, the plasma is generated by the microwave from the disk-shaped antenna member 60. Can be generated.
[0042]
In such a configuration, the TEM mode microwave generated by the microwave generator 50 passes through the coaxial waveguide 52 and reaches the connection portion with the radial waveguide box 54. The microwave propagates from the connecting portion in the peripheral direction of the radial waveguide box. The microwave propagating in the peripheral direction emits an electromagnetic field to a processing space below the disk-shaped antenna member 60, and plasma is generated by the electromagnetic field. Here, the electromagnetic field emitted from the lower surface of the disk-shaped antenna member 60 is reflected by the inner wall of the processing container 4 and concentrated at the center of the processing space S. However, in this plasma processing apparatus, a metal reflector 64 that protrudes toward the mounting table 10 is provided on the opposite side of the portion where the inner conductor 52B of the disk-shaped antenna member 60 is connected. It has been. Therefore, the high-frequency (microwave) electric field reflected at the center of the processing space S can be reflected outward again. For this reason, the intensity of the electromagnetic field in the processing space S below the disk-shaped antenna member 60 is averaged as shown in the lower graph of FIG. Therefore, plasma can be generated uniformly and uniformly over a wide range, and even a large-diameter wafer can be uniformly processed in its surface.
[0043]
As described above, in this plasma processing apparatus, the processing container 4 which is formed in a bottomed cylindrical shape and has the mounting table 10 on which the workpiece W is mounted, and the upper part of the processing container 4 The glass plate 8 that covers the opening in an airtight manner, the microwave supply means 50, one end side is connected to the microwave supply means 50, and has an inner conductor 52B and an outer conductor 52A disposed coaxially with the inner conductor. The coaxial waveguide 52 in which the microwave propagates between the inner conductor 52B and the outer conductor 52A, and the other end of the outer conductor 52A of the coaxial waveguide 52 are connected to the outer conductor 52A. A radial waveguide box 54 extending from the other end of the flange to the outside in the radial direction as a side wall extending downward toward the glass plate 8 and having a waveguide space therein, and the radial waveguide box 54 Cover the bottom opening of the The other end portion of the inner conductor 52B is connected, has a plurality of slots 62 and is arranged in parallel to the glass plate 8, and the inner conductor 52B of the disc-shaped antenna member 60 is connected. On the opposite side of the portion, a metal reflector 64 is provided that protrudes toward the mounting table 10 and reflects the electric field reflected by the inner wall of the processing container 4, so that it is reflected at the center of the processing space S. The incoming high frequency (microwave) electric field can be reflected again, and the intensity of the electromagnetic field in the processing space S below the disk-shaped antenna member 60 can be averaged. Therefore, plasma can be generated uniformly and uniformly over a wide range, and even a large-diameter wafer can be uniformly processed in its surface.
[0044]
In the above embodiment, the metal cylindrical reflector 64 is provided on the opposite side of the portion of the disk-shaped antenna member 60 to which the inner conductor 52B is connected. However, the present invention is not limited to this. A cylindrical absorber (high resistance body) that protrudes into the processing container 4 beyond the glass plate 8 toward the mounting table 10 and absorbs a high frequency (microwave) electric field reflected by the inner wall of the processing container 4. ) May be provided. In this way, since a high frequency (microwave) electric field reflected by the inner wall of the processing container 4 can be absorbed in the central portion of the processing space S, an electromagnetic field is prevented from concentrating in the central portion of the processing space S. In addition, a uniform electromagnetic field can be formed. Accordingly, uniform plasma can be generated in the processing space S, and uniform wafer processing can be realized. As the material of the cylindrical absorber, single crystal silicon or the like that has excellent plasma resistance and does not cause contamination is preferable because it protrudes into the processing container 4 and is exposed.
[0045]
Next, FIG. 2 shows a second embodiment of the present invention. In this embodiment, the difference from the first embodiment of FIG. 1 is that the metallic cylindrical reflector 164 is located on the inner side of the glass plate 8 from the center of the disk-shaped antenna member 60 toward the mounting table 10. It is a point which protrudes and is not exposed in the processing container 4. Even in such a configuration, the high-frequency (microwave) electric field reflected by the inner wall of the processing container 4 can be reflected outward again. Therefore, in the processing space S below the disk-shaped antenna member 60, the intensity of the electromagnetic field can be made uniform, and plasma can be generated uniformly and uniformly over a wide range. In addition, by preventing the cylindrical reflector 164 from being exposed without protruding into the processing container 4 in this way, it is possible to prevent metal or the like from being deposited or adhered to the surface of the reflector protruding into the processing container 4. Therefore, it is possible to prevent the reflector from being excessively cleaned.
[0046]
In the embodiment described above, the metal cylindrical reflector 164 is provided at the center of the disc-shaped antenna member 60. However, the present invention is not limited to this, and the glass plate 8 faces the mounting table 10. A cylindrical absorber (high resistance body) that absorbs a high-frequency (microwave) electric field that protrudes to the inside and is reflected by the inner wall of the processing container 4 may be provided. In this way, since a high frequency (microwave) electric field reflected by the inner wall of the processing container 4 can be absorbed in the central portion of the processing space S, an electromagnetic field is prevented from concentrating in the central portion of the processing space S. In addition, a uniform electromagnetic field can be formed. Accordingly, uniform plasma can be generated in the processing space S, and uniform wafer processing can be realized.
In the second embodiment shown in FIG. 2, the cylindrical reflector 164 or the cylindrical absorber protrudes to the inside of the glass plate 8, that is, the position in contact with the upper surface of the glass plate 8. However, the present invention is not limited to this. The cylindrical reflector and the cylindrical absorber are not exposed to the inside of the processing chamber 4 from the lower surface of the glass plate 8 (the surface on the mounting table side). It may be inserted. In this way, not only can metal or the like be deposited or adhered to the cylindrical reflector or cylindrical absorber, but also electromagnetic waves transmitted through the glass plate 8 are inserted into the glass plate 8. Can be reflected or absorbed by a cylindrical reflector or a cylindrical absorber. Accordingly, uniform plasma can be generated in the processing space S, and uniform wafer processing can be performed.
[0047]
The reflector and absorber provided on the opposite side of the portion where the inner conductor 52B of the disk-shaped antenna member 60 is connected are formed in a cylindrical shape. However, the present invention is not limited to this. A cylindrical shape, a cylindrical shape, or a polygonal column shape may be used.
[0048]
In the above-described embodiment, the coaxial waveguide 52 is employed as the waveguide. However, the present invention is not limited to this, and a cylindrical waveguide that propagates TM mode microwaves may be used.
[0049]
The plasma processing apparatus can be applied to a film forming process other than etching and a film modifying process, and can also be applied to a process for a platform panel display substrate in addition to a wafer.
[0050]
【The invention's effect】
As described above, in the present invention, a processing container having a mounting base on which a target object is mounted and a dielectric that covers an upper opening of the processing container in an airtight manner. And a microwave supply device for supplying a microwave, and a waveguide having one end connected to the microwave supply device and extending from the microwave supply device toward the lid and having a waveguide space therein. A tube, and connected to the other end of the waveguide, extending radially outwardly from the other end of the waveguide in a flange shape, and extending downward as a side wall toward the lid body. A radial waveguide box having an antenna member, an antenna member covering a lower end opening of the radial waveguide box and having a plurality of slots arranged in parallel to the lid, and a mounting table on the mounting table side in the center of the antenna member Projecting toward the surface and reflecting off the inner wall of the processing vessel Since the metallic reflector that reflects the coming high frequency (microwave) electric field or the absorber that absorbs the high frequency (microwave) electric field is provided, the intensity of the electromagnetic field in the processing space below the antenna member is averaged. be able to. Therefore, plasma can be uniformly generated over a wide range, and uniform processing can be performed on the wafer.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a plasma processing apparatus according to a first embodiment of the present invention.
FIG. 2 is a longitudinal sectional view showing a plasma processing apparatus according to a second embodiment of the present invention.
FIG. 3 is a longitudinal sectional view showing a conventional plasma processing apparatus.
[Explanation of symbols]
2 Plasma etching apparatus 4 Processing container 8 Glass plate 10 Mounting table 50 Microwave generator 52 Coaxial waveguide 52A Outer conductor 52B Inner conductor 54 Radial wave guide box 60 Disc-shaped antenna member 62 Slit 64 Cylindrical reflector 68 Absorber 164 Cylindrical reflector W semiconductor wafer

Claims (11)

A processing container that is formed in a bottomed cylindrical shape and has a mounting table on which an object to be processed is mounted;
A lid made of a dielectric material that hermetically covers the upper opening of the processing container;
A microwave supply device for supplying microwaves;
One end of the waveguide is connected to the microwave supply device, extends from the microwave supply device toward the lid, and has a waveguide space inside.
Connected to the other end of the waveguide, and extended radially outward from the other end of the waveguide into a flange shape, then extended downward as a side wall toward the lid, and guided to the inside. A radial waveguide box having a space;
An antenna member that covers the lower end opening of the radial waveguide box, has a plurality of slots, and is arranged in parallel to the lid;
A metal reflector is provided on the mounting table side of the central portion of the antenna member so as to protrude toward the mounting table and reflect a high-frequency electric field reflected by the inner wall of the processing container. Plasma processing equipment.   The plasma processing apparatus according to claim 1, wherein the reflector protrudes from the lid into the processing container.   The plasma processing apparatus according to claim 1, wherein the reflector does not protrude from the lid into the processing container.   The plasma processing apparatus according to claim 3, wherein a tip portion of the reflector enters the inside of the lid.   The plasma processing apparatus according to claim 1, wherein the reflector is formed in a cylindrical shape or a column shape.   The plasma processing apparatus according to claim 1, wherein the reflector is formed in a cylindrical shape or a columnar shape.   The plasma processing apparatus according to claim 1, wherein the reflector is formed in a polygonal cylinder shape or a polygonal column shape.   The plasma processing apparatus according to claim 1, wherein an absorbing material that absorbs a high-frequency electric field is disposed in the vicinity of the outer periphery of the radial waveguide box.   The plasma processing apparatus according to claim 1, wherein an absorbing material that absorbs a high-frequency electric field is disposed on an outer peripheral portion of a space from the lower surface of the antenna member to the lower surface of the lid made of the dielectric.   The waveguide has an inner conductor and an outer conductor disposed coaxially with the inner conductor, and is a coaxial waveguide in which microwaves propagate between the inner conductor and the outer conductor. The radial waveguide box is connected to an end portion of the outer conductor on the lid body side, and a center portion of the antenna member is connected to an end portion of the inner conductor on the lid body side. The plasma processing apparatus as described.   The plasma processing apparatus according to claim 1, wherein the waveguide is a cylindrical waveguide that propagates TM mode microwaves.

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