JP2000286095A - Structure of radial line slot antenna in plasma surface treatment device for semiconductor base - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the deformation of a slot plate caused by thermal expansion by pressing an outer peripheral part of the metallic slot plate mounted on a lower surface side of a disc-shaped dielectric plate packed in a flat recessed part of a lower surface of a metallic antenna guide connected to a wave guide for microwave, by a spring means, and supporting its lower surface side by a dielectric supporting plate. SOLUTION: A lower electrode 15 is positioned at a lower part of a slot plate 4 connected to a conductive wiring 8 in a wave guide 7 on an upper surface of an antenna guide 2 comprising a dielectric plate 6 in a lower surface recessed part 3. The slot plate 4 of which an outer peripheral part is closely contacted with a lower surface of the antenna guide 2 is mounted on a bracket body 1 through a ring bode 9, and pressed by a coned disc spring 11 comprising a plurality of loosely fitted bolts 10, and further an outer peripheral part of a suporting plate 12 closely contacted with a lower surface of the slot plate is supported by a ring body 9. Accordingly the slot plate 4 can be freely thermally expanded radially outwardly, and the downward expansion can be prevented. The downward microwave from a slot hole 5 is hardly interferred by the dielectric support 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a radial line slot antenna for generating a plasma by a microwave in a plasma surface treatment apparatus in which a semiconductor substrate such as a silicon wafer is surface-treated with plasma. Things.

[0002]

2. Description of the Related Art In general, a plasma surface treatment apparatus using a radial line slot antenna of this type, as is well known, has a flat recess formed on the lower surface of an antenna guide made of metal such as aluminum. Is formed, and a dielectric plate formed in a disc shape with quartz or alumina ceramic is laterally loaded into the recess, and a large number of slot holes are formed on the lower surface side of the dielectric plate. While a metal slot plate is disposed so as to extend in parallel with the dielectric plate, a microwave waveguide having a built-in conductor wiring to the slot plate is connected to a central portion of the upper surface of the antenna guide, and a radial waveguide is provided. By constituting a line slot antenna and introducing a microwave into the antenna guide, the microwave is directed outward in the radial direction by the dielectric plate. After spreading over the body, plasma is generated downwardly from each slot hole in the slot plate to generate plasma between the semiconductor substrate mounted on the upper surface of the lower electrode disposed therebelow. The plasma is used to form various coatings on the surface of the semiconductor substrate or to perform a surface treatment such as etching the surface of the semiconductor substrate.

[0003] In this case, the radial line slot antenna in the conventional plasma surface treatment apparatus is configured such that the slot plate disposed on the lower surface side of the dielectric plate is turned outward until its outer peripheral edge is in close contact with the lower surface of the antenna guide. After being extended, it is configured to be attached to the antenna guide by fastening a plurality of locations on the circumference with set screws.

[0004]

However, since the slot plate is heated to a high temperature due to the heat of the plasma or the like, the attachment of the throttle plate to the antenna guide is performed as described above. When a plurality of locations on the outer peripheral edge of the slot plate are fastened with set screws, the dielectric plate on the upper surface of the slot plate is made of quartz or alumina ceramic having a low thermal conductivity. The heat release from is limited only to the outer peripheral edge in contact with the antenna guide, and thermal expansion occurs due to heat storage in the inner part,
A portion inside the outer peripheral edge of the slot plate is deformed into a shape that swells downward due to the thermal expansion, and is narrow and wide at a space between the slot plate and a semiconductor substrate disposed therebelow. , The emitted microwave becomes non-uniform. Therefore, the plasma formed in the process area of the semiconductor substrate becomes non-uniform and unstable, so that the surface of the semiconductor substrate can be processed unevenly.

Therefore, in recent radial line slot antennas, in addition to screwing the outer peripheral portion of the slot plate to the antenna guide, a plurality of locations inside the slot are also connected to the dielectric plate. It is screwed, but even with this configuration,
Since the slot plate is deformed and deformed so as to swell downward at a portion between the set screws, there is a problem that the strain deformation due to thermal expansion in the slot plate cannot be fundamentally eliminated.

It is a technical object of the present invention to provide an apparatus capable of reliably reducing distortion deformation due to thermal expansion in the slot plate.

[0007]

Means for Solving the Problems To achieve this technical object, a first invention is to provide a metal antenna guide having a flat recess formed on the lower surface, and a disk-shaped antenna guide loaded in the recess. A radial line slot antenna comprising a dielectric plate and a metal slot plate disposed on the lower surface side of the dielectric plate, wherein a waveguide for introducing microwaves is connected to the antenna guide; The outer peripheral portion of the slot plate is pressed against the lower surface of the antenna guide by a spring means, and a support plate made of a dielectric material for supporting the lower surface of the slot plate is provided on the lower surface side of the slot plate. A support plate made of a plate is provided. "

[0008] A second aspect of the present invention relates to a metal antenna guide having a flat concave portion formed on a lower surface, a disk-shaped dielectric plate loaded in the concave portion, and a lower surface side of the dielectric plate. A metal slot plate disposed so that an outer peripheral portion thereof is attached to the antenna guide, and a waveguide for introducing microwaves is connected to the antenna guide. At least a portion adjacent to the inside of the mounting portion with respect to the antenna guide has an expansion absorbing portion formed by punching a hole so as to leave a deformable narrow piece connecting the outside portion and the inside portion. The slot plate is provided so as to extend in a ring shape, while a support plate made of a dielectric material for supporting the slot plate is provided on the lower surface side of the slot plate, or a support plate made of a perforated metal plate is provided. . I was in the configuration to say. "

[0009]

According to the first aspect of the present invention, the slot plate can freely thermally expand outward in the radial direction while the lower surface of the slot plate is supported by the support plate. , A support plate that supports the lower surface of the slot plate,
The slot plate is made of a dielectric material or a perforated metal plate, so that the transmission of microwaves emitted downward from each slot hole in the slot plate can be slightly prevented. Can be reliably reduced under the condition that the transmission of microwaves is not hindered.

Further, by configuring the slot plate as in the second aspect, it is possible to prevent the radial expansion of the slot plate outwardly from reaching the mounting portion of the slot plate with respect to the antenna guide. In the state where the slot plate is supported by the support plate that does not hinder the transmission of the slot plate, the width of the slot plate can be significantly reduced by the deformation of the narrow strip in the expansion absorbing portion. It is possible to surely reduce the wave in a state where the wave transmission is not hindered.

Therefore, according to the present invention, in the surface treatment of a semiconductor substrate with plasma, there is an effect that the occurrence of processing unevenness due to distortion deformation of the slot plate can be surely and significantly reduced.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show a first embodiment of the present invention.

In this figure, reference numeral 1 denotes a bracket attached to a chamber (not shown) in the plasma surface treatment apparatus, and reference numeral 2 denotes an aluminum antenna guide having a flat recess 3 formed on the lower surface. Reference numeral 4 denotes a slot plate made of a metal plate disposed on the lower surface of the antenna guide 2.

A disk-shaped dielectric plate 6 is loaded in the recess 3 of the antenna guide 2, and a microwave is introduced into the recess 4 on the upper surface of the antenna guide 2. A waveguide 7 electrically connected to the slot plate 4 is provided in the waveguide 7, and the slot plate 4 is further provided with a microwave facing downward. A large number of slot holes 5 for discharging are formed.

Below the slot plate 4, there is provided a lower electrode 15 on which a semiconductor substrate 16 to be processed is placed on the upper surface.

In the present invention, the slot plate 4 is superimposed on the lower surface of the antenna guide 2 so that the outer peripheral portion thereof is in close contact with the lower surface. After the ring body 9 is sandwiched between the antenna guide 2, the slot plate 4, and the bolt holes 2a, 4a, and 9a formed in the ring body 9, a plurality of disc springs provided on a plurality of bolts 10 loosely fitted. It is attached to the bracket body 1 by pressing with spring means such as 11.

Further, a support plate 12 made of a dielectric material is disposed on the lower surface side of the slot plate 4 so as to be in close contact with the slot plate 4, and an outer peripheral portion of the support plate 12 is supported by the ring body 9. Constitute.

With this configuration, the slot plate 4 can be thermally expanded radially outward while the lower surface of the slot plate 4 is supported by the support plate 12, while the lower surface of the slot plate 4 is Is made of a dielectric material, it is possible to slightly hinder the transmission of microwaves emitted downward from each slot hole 5 in the slot plate 4, so that the slot plate 4
Can be reliably reduced under the condition that the transmission of microwaves is not hindered.

In this case, the support plate for supporting the lower surface side of the slot plate 4 is replaced with the dielectric support member 12 as in the first embodiment, and FIGS.
As in the second embodiment shown in FIG. 6, a support plate 12 'made of a metal plate such as a copper plate is formed so that the slot plate 5 in the slot plate 4 is not covered with the support plate 12' as much as possible. It is also possible to adopt a configuration in which a large number of cut holes 12a 'are formed.

Each of the holes 12a 'in the support plate 12' is not limited to a sector shape as shown in FIG. 5, but may have a circular shape as shown in FIG. And the number of the slot holes 5 in which the number of the slot holes 5 is as small as possible.

Next, FIGS. 7 to 9 show a third embodiment.

In the third embodiment, the antenna guide 2, the slot plate 4, and the ring body 9 are attached to the bracket body 1 by pressing a spring means such as a disc spring 11 instead of the bracket body 1. In this case, the antenna guide 2, the slot plate 4, and the ring body 9 are fixedly attached by fastening a plurality of bolts 13 passing therethrough. In this case, FIG. As shown, a hole is formed in a portion of the slot plate 4 adjacent to the inside of the mounting portion for the antenna guide 2 so as to leave a deformable narrow piece 14a connecting the outside portion and the inside portion. An expansion absorbing portion 14 formed by drilling 14b is provided so as to extend annularly over the entire circumference, while a support plate 12 made of a dielectric is disposed on the lower surface side of the slot plate 4 so as to be in close contact therewith. This The outer periphery of the support plate 12, which is constituted so as to support at the ring member 9.

With such a configuration, the thermal expansion of the slot plate 4 in the radially outward direction reaches the portion where the slot plate 4 is attached to the antenna guide 2, and the slot plate 4 transmits the microwave. While supported by the support plate 12 which does not hinder the expansion absorbing portion 1
4 can be greatly reduced by the deformation of the narrow pieces 14a, so that the deformation of the slot plate 4 so as to swell downward can be reliably reduced in a state where the transmission of microwaves is not hindered. is there.

Also in this case, the supporting plate for supporting the lower surface side of the slot plate 4 is replaced with a supporting plate 12 "made of a metal plate such as a copper plate as shown in FIGS.
The support plate 12 "may be provided with a hole 12a" which is formed so as not to block the slot hole 5 of the slot plate 4 as much as possible. Each hole 12 in ""
It is needless to say that a ″ may be formed into an appropriate shape such as a circular hole as in FIG. 6 in the second embodiment.)

It is needless to say that the number of the annular expansion absorbing portions 14 is not limited to one as shown in the figure, but may be a double or triple plural number.

Further, by providing the expansion absorbing portion 14 of the slot plate 4 at a portion of the outer peripheral portion of the slot plate 4 which is in contact with the lower surface of the antenna guide 2,
Either the holes 14b in the expansion absorbing portion 14 are closed by the antenna guide 2, or the holes 14b are formed on one or both of the front and back surfaces of the slot plate 4. Alternatively, the configuration in which the support plate 12 ″ made of a metal plate is used to block the leakage of microwaves from each of the holes 14b can be prevented. It is possible to avoid disturbing the jet flow of the microwave from 5.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view showing a first embodiment of the present invention.

FIG. 2 is a diagram showing an exploded state of FIG. 1;

FIG. 3 is a longitudinal sectional front view showing a second embodiment of the present invention.

FIG. 4 is a diagram showing an exploded state of FIG. 3;

FIG. 5 is a bottom view as viewed from the line VV in FIG. 4;

FIG. 6 is a view showing a modification of the support plate in the second embodiment.

FIG. 7 is a longitudinal sectional front view showing a third embodiment of the present invention.

FIG. 8 is a bottom view as viewed in the direction VIII-VIII of FIG. 7;

FIG. 9 is a view showing a modification of the slot plate in the third embodiment.

FIG. 10 is a vertical sectional front view showing a fourth embodiment of the present invention.

FIG. 11 is a plan view taken along the line XI-XI in FIG. 9;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Bracket body 2 Antenna guide 3 Recess 4 Slot plate 5 Slot hole 6 Dielectric plate 7 Waveguide 8 Conductor wiring 10, 13 Bolt 11 Belleville spring 12, 12 ', 12 "Support plate 12a', 12a"

Claims (4)

[Claims] 1. A metal antenna guide having a flat recess formed on a lower surface thereof, a disk-shaped dielectric plate loaded in the recess, and a metal dielectric disposed on a lower surface side of the dielectric plate. A radial line slot antenna comprising a slot plate and a waveguide for introducing microwaves connected to the antenna guide, wherein an outer peripheral portion of the slot plate is spring-mounted with respect to a lower surface of the antenna guide. A structure of a radial line slot antenna in a plasma processing apparatus for a semiconductor substrate, wherein a dielectric support plate for supporting the slot plate is provided on the lower surface side of the slot plate while being pressed. 2. A metal antenna guide having a flat concave portion formed on the lower surface, a disk-shaped dielectric plate loaded in the concave portion, and a metal antenna disposed on the lower surface side of the dielectric plate. A radial line slot antenna comprising a slot plate and a waveguide for introducing microwaves connected to the antenna guide, wherein an outer peripheral portion of the slot plate is spring-mounted with respect to a lower surface of the antenna guide. A structure of a radial line slot antenna in a plasma processing apparatus for a semiconductor substrate, wherein a supporting plate made of a perforated metal plate is provided on a lower surface side of the slot plate for pressing while being pressed. 3. A metal antenna guide having a flat concave portion formed on the lower surface, a disk-shaped dielectric plate loaded in the concave portion, and an outer peripheral portion on the lower surface side of the dielectric plate. A radial line slot antenna comprising a metal slot plate disposed so as to be attached to the antenna guide, and a waveguide for introducing microwaves being connected to the antenna guide, wherein at least the antenna guide of the slot plate corresponds to the antenna guide. An expansion absorbing portion having a hole formed in a portion adjacent to the inner side of the mounting portion so as to leave a deformable narrow piece connecting the outer portion and the inner portion, extends in an annular shape over the entire circumference. Wherein a dielectric support plate for supporting the slot plate is provided on the lower surface side of the slot plate. The structure of a line slot antenna. 4. A metal antenna guide having a flat concave portion formed on the lower surface, a disk-shaped dielectric plate loaded in the concave portion, and an outer peripheral portion provided on the lower surface side of the dielectric plate. A radial line slot antenna comprising a metal slot plate disposed so as to be attached to the antenna guide, and a waveguide for introducing microwaves being connected to the antenna guide, wherein at least the antenna guide of the slot plate corresponds to the antenna guide. An expansion absorbing portion having a hole formed in a portion adjacent to the inner side of the mounting portion so as to leave a deformable narrow piece connecting the outer portion and the inner portion, extends in an annular shape over the entire circumference. In the plasma surface treatment apparatus for a semiconductor substrate, a supporting plate made of a perforated metal plate for supporting the slot plate is provided on the lower surface side of the slot plate. Radial line slot antenna structure.