JP2000012291A - Plasma processing equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the sealing performance of a sealing plate covering a microwave introduction window due to the action of high temperature generated inside a reaction vessel during plasma processing, and physical properties of the sealing plate Is prevented from changing, and stable plasma processing can be performed over a long period of time. SOLUTION: In a configuration in which a microwave introduction window 2 opened on one side of a reaction vessel 1 is sealed by a plurality of sealing plates 3, 3 ... supported by a support frame 30 provided on the same. The medium flow path 7 is provided in the support frame 30, cooling water is supplied to the medium flow path 7, and the sealing plates 3, 3. The cooling is performed by heat exchange with the cooling water flowing in the medium flow path 7 together with the rings 6, 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a plasma by introducing a microwave into a reaction vessel, and applying an etching, ashing, CVD (Chemica
The present invention relates to a plasma processing apparatus configured to perform a process such as 1 Vapor Deposition.

[0002]

2. Description of the Related Art In an LSI or LCD manufacturing process, a plasma is generated by externally applying excitation energy to a reaction gas inside a reaction vessel, and a semiconductor substrate disposed in the reaction vessel is generated by the action of the plasma. Various processes such as etching, ashing, and CVD are widely performed on materials to be processed such as glass substrates for flat panel displays. In particular, dry etching using plasma is performed on LSIs and LCDs. It has become an indispensable basic technology in the manufacturing process.

As one of the apparatuses for performing the above-described processing, a plasma processing apparatus using microwaves as excitation means for generating plasma has been proposed. This type of plasma processing apparatus has a simple configuration and is easy to operate, and has the advantage of being able to generate high-density plasma at low temperatures, but has the advantage of generating uniform plasma over a large area. However, there is a problem that it is difficult to apply to a large-sized material to be processed, such as a large-diameter semiconductor substrate and a glass substrate for a flat panel display.

In order to solve such a drawback, the present applicant has proposed a plasma processing apparatus using a dielectric line as disclosed in Japanese Patent Application Laid-Open No. Hei 8-1.
No. 7595. FIG. 4 is a longitudinal sectional view schematically showing the configuration of the plasma processing apparatus disclosed in Japanese Patent Application Laid-Open No. 8-17595.

In this plasma processing apparatus, a microwave introduction window 2 having a large area is formed on one side (upper side) of a reaction vessel 1 having a hollow rectangular parallelepiped shape over substantially the entire surface.
A plurality of dielectric sealing plates 3, 3... Capable of transmitting microwaves are hermetically sealed, and a dielectric line made of a dielectric is provided on the other side of the sealing plates 3, 3. Are arranged side by side as a microwave waveguide 4.

[0006] A cooling water channel 10 is provided around the entire outer periphery of the peripheral wall of the reaction vessel 1, and supply pipes 11, 11 for reactant gas are connected to one or more places of the peripheral wall. ing. Further, one or a plurality of exhaust pipes 12 for vacuum evacuation are connected to the bottom of the reaction vessel 1, and a mounting table 13 for placing the workpiece W is provided at the bottom of the reaction vessel 1. Are arranged. The microwave introduction window 2 is opened facing the upper surface of the mounting table 13 serving as the mounting surface of the workpiece W,
A lattice-like support frame 30 is provided on the introduction window 2. The illustrated support frame 30 is a rectangular lattice-shaped metal frame in which the introduction window 2 is divided vertically and horizontally into three portions to provide nine openings, and the plurality of sealing plates 3, 3,. Are supported at the respective peripheral edges of the opening of the support frame 30.

FIG. 5 is an enlarged sectional view showing the vicinity of the support portion of the sealing plate 3. At the lower periphery of the opening of the support frame 30 that supports the sealing plate 3, as shown, a support edge 31 that extends inward to a suitable length is provided, and the support edge 31 is formed on the upper surface thereof. An O-ring 6 as a sealing member is mounted in the groove, and the sealing plate 3 is supported on the supporting rim 31 of the corresponding opening via the O-ring 6 to hermetically seal the inside of the reaction vessel 1. To be sealed.

The waveguides 4 on the other side of the sealing plates 3, 3,... Are formed over a substantially entire area of the introduction window 2 on the upper portion of the reaction vessel 1 so as to cover the outside thereof by a metal waveguide vessel 40. The microwave oscillator 5 is attached to the other end of the waveguide 41 connected to one side of the waveguide container 40.

In the plasma processing apparatus configured as described above, a material W to be processed, such as a semiconductor substrate or a glass substrate for a flat panel display, is placed inside the reaction vessel 1 with its processing surface facing the introduction window 2. A suitable amount of reaction gas is supplied via supply pipes 11 and 11 into the reaction vessel 1 evacuated by the exhaust pipes 12 and 12 while the microwave oscillator 5 is operated. By doing so, plasma processing is performed.

That is, the microwave oscillated from the microwave oscillator 5 is introduced into the dielectric waveguide 4 through the waveguide 41, and a standing wave is generated inside the waveguide 4, thereby generating a standing wave. An electric field reaching the inside of the reaction vessel 1 is formed near the waveguide 4, and acts on the reaction gas supplied into the reaction vessel 1 to generate plasma, and the plasma is placed on the mounting table 13 by the plasma. A desired process such as etching, ashing, or CVD is performed on the surface of the processed material W. During this time, the reaction vessel 1 is cooled from the surroundings by the cooling water supplied to the cooling water passage 10, and is protected from the high temperature accompanying the generation of plasma.

During the plasma processing performed as described above, since the inside of the reaction vessel 1 is in a negative pressure state,
Are pressed toward the inside of the reaction vessel 1 by the pressure difference between the inside and outside, and are strongly pressed against the respective O-rings 6, 6,. This is ensured, and the airtightness inside the reaction vessel 1 is kept good. Also, during the plasma processing, each of the sealing plates 3, 3... Has a mechanical stress due to the action of the negative pressure inside the reaction vessel 1 and a pressure from the inside of the reaction vessel 1 which becomes high in temperature with the generation of plasma. Although thermal stress is generated by heating, these sealing plates 3, 3,... Have a flat area sufficiently smaller than the opening area of the introduction window 2, and the above-mentioned stress is reduced. .

[0012]

As described above, Japanese Patent Application Laid-Open No. Hei 8-1
The plasma processing apparatus disclosed in Japanese Patent Publication No. 7595 is an excellent apparatus that can be applied to a large-sized material to be processed and can also prevent the sealing plate from being damaged by the above-described stress.

However, the high temperature generated inside the reaction vessel 1 during the above-described plasma processing causes the sealing plates 3, 3,.
.. Also act on the O-rings 6, 6,... For maintaining airtightness via a metal supporting frame 30 for supporting them, and these O-rings 6, 6,. And the hermetically sealed state between the reaction vessel 1 and the airtight interior of the reaction vessel 1 cannot be maintained satisfactorily.

The O-rings 6, 6,...
A rubber O-ring having heat resistance is generally used, but the temperature of the O-rings 6, 6,.
The temperature may reach as high as 00 ° C. or more. In particular, in the sealing plate 3 supported by the opening at the center of the support frame 30, the other sealing plates 3,
3, the degree of temperature rise is large, and the corresponding O-ring 6 is significantly deteriorated, and it is difficult to prevent the above-mentioned decrease in sealing performance.

The sealing plates 3, 3,... For sealing the microwave introduction window 2 are generally made of quartz glass (S
iO ₂ ) or alumina (Al ₂ O ₃ ) is used.
However, when a fluorine-based gas is used as a reaction gas, the sealing plates 3, 3,... Made of quartz glass are seriously damaged by the action of the reaction gas, and there is a problem that the replacement frequency increases.

On the other hand, alumina sealing plates 3, 3...
Can be used irrespective of the type of reaction gas, but its physical property value is highly temperature-dependent and the dielectric loss increases due to the high temperature inside the reaction vessel 1 during the plasma treatment. , The characteristics of the microwaves after passing through change the plasma generation state in the reaction vessel 1, and there is a possibility that stable plasma processing may not be performed.

The present invention has been made in view of such circumstances, and the sealing performance of a sealing plate covering a window for introducing microwaves is deteriorated due to a high-temperature action generated inside a reaction vessel during plasma processing. It is an object of the present invention to provide a plasma processing apparatus capable of performing stable plasma processing for a long period by reducing the change in physical properties of the sealing plate due to the action of the high temperature.

[0018]

According to the plasma processing apparatus of the present invention, a support frame having a plurality of openings is provided on a microwave introduction window provided on one side of a reaction vessel for generating plasma, and In the plasma processing apparatus in which the openings are sealed by separate sealing plates supported on the respective peripheral portions via sealing members, the supporting frame includes the peripheral portions of the plurality of openings. And a medium supply means for supplying a temperature adjusting medium to the medium flow path.

In the present invention, a medium flow path is formed on a support frame supporting a plurality of sealing plates, including a peripheral portion of an opening corresponding to each of the sealing plates, and a cooling medium is formed in the medium flow path. By supplying a temperature adjusting medium such as water, and by exchanging heat with the medium, the sealing plate and the sealing member supported on the peripheral portion of each opening are cooled, and a high temperature action inside the reaction vessel is performed. A reduction in sealing performance and a change in physical properties of the sealing plate are alleviated, and stable plasma processing is realized over a long period of time.

Further, the sealing plate is made of alumina or aluminum nitride.

In the present invention, a sealing plate made of alumina which can be used regardless of the type of plasma generated in the reaction vessel is used, and the sealing plate is made effective by heat exchange with the temperature control medium. Cool to reduce the change in physical properties. In addition, a sealing plate made of aluminum nitride (AlN) that can be used regardless of the type of plasma and has excellent heat resistance is used, and the sealing plate is further exchanged with the temperature control medium by heat exchange. Effective cooling to reduce physical property changes.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. FIG. 1 is a longitudinal sectional view schematically showing a configuration of a plasma processing apparatus according to the present invention. This plasma processing apparatus introduces microwaves into the reaction vessel 1 to generate plasma, and applies a material to be processed W such as a semiconductor substrate disposed in the reaction vessel 1 and a glass substrate for a flat panel display. Etching, ashing,
A plasma process such as CVD is performed.

The reaction vessel 1 is made of aluminum (Al).
It is a hollow rectangular parallelepiped container made of a metal material such as As in the plasma processing apparatus shown in FIG. 4, a cooling water channel 10 is provided around the entire outer periphery of the peripheral wall of the reaction vessel 1, and a supply of a reaction gas is provided at one or more locations of the peripheral wall. Tubes 11, 11 are connected. The inside of the reaction vessel 1 is connected to a vacuum exhaust device (not shown) through one or a plurality of exhaust pipes 12 connected to the bottom thereof. A mounting table 13 on which W is mounted is disposed with its mounting surface facing upward.

At the upper part of the reaction vessel 1 as described above, a microwave introduction window 2 is opened over the entire surface thereof, and a support frame 30 is erected on the introduction window 2. This support frame 30
As shown in FIG. 2, is a rectangular lattice-shaped metal frame in which the introduction window 2 is divided into three parts vertically and horizontally to provide nine openings, and each of the openings is Are hermetically sealed by separate sealing plates 3, 3... The number of the sealing plates 3, 3,... Is not limited to nine as shown, and the shape of the sealing plates 3, 3,. You may.

A microwave waveguide 4 is formed on the upper portion of the reaction vessel 1 in which the introduction window 2 is opened. The waveguide 4 is a solid body made of a dielectric such as fluororesin, polystyrene, polyethylene, etc., having a small dielectric loss.
Are arranged to face substantially the entire area. A waveguide 41 is connected to one side of the waveguide container 40, and a microwave oscillator 5 is attached to the other end of the waveguide 41, and the microwave oscillated by the microwave oscillator 5 transmits the microwave. Waveguide 4 via waveguide 41
It is designed to be introduced inside. As shown in the figure, the end face of the waveguide 4 on the side where the microwave oscillator 5 is mounted is a tapered surface whose upper part is inclined toward the microwave oscillator 5 side. It has been introduced efficiently.

FIG. 3 is an enlarged sectional view showing the vicinity of the support portion of the sealing plate 3. As shown in FIG. 2, the sealing plate 3 is made of alumina (Al ₂ O ₃ ) or aluminum nitride (AlN).
And has a rectangular shape corresponding to the opening of the support frame 30. Each of the plurality of openings of the support frame 30 for supporting the sealing plate 3 is provided with a support edge 31 projecting inward from a lower peripheral edge thereof, as shown in FIG.
An O-ring 6 as a sealing member is mounted in a groove formed on the upper surface of 31. The sealing plate 3 is supported on the supporting edge 31 of the corresponding opening via the O-ring 6, and the inside of the reaction vessel 1 is hermetically sealed by the action of the O-ring 6.

Further, in the plasma processing apparatus according to the present invention, the medium flow path 7 is formed by making a part of the frame body which surrounds the opening of the support frame 30 hollow. The medium flow path 7
Are parallel to each other, as indicated by the broken lines in FIG.
Each of the frames of the support frame 30 is extended over the entire length of each of the frames of the book, and these ends are alternately connected by a flow path extending along an outer edge orthogonal to each frame. It can be formed in an appropriate form including the periphery of the opening.

Both ends of the medium flow path 7 are connected to a cooling water circulating device 8 (see FIG. 1) disposed outside the reaction vessel 1 via a water supply / drain pipe (not shown). By operation, cooling water of a predetermined temperature as a temperature adjusting medium is circulated inside the medium flow path 7 as shown by an arrow in FIG.

The medium flow path 7 is formed as shown in FIG. 2 including the peripheral portions of the plurality of openings formed in the support frame 30, and the cooling water circulating in the medium flow path 7 is The heat exchange is performed with the O-rings 6, 6 attached to the supporting edges 31, 31,... Of the openings, and the sealing plates 3, 3,. , 6 and the sealing plates 3, 3,.

In the plasma processing apparatus according to the present invention configured as described above, the processing target material W such as a semiconductor element substrate or a glass substrate for a flat panel display is placed on the mounting table 13 inside the reaction vessel 1. The processing surface is placed toward the introduction window 2, and the inside of the reaction vessel 1 is evacuated through the exhaust pipes 12 and 12 by the operation of the vacuum evacuation device. By supplying an appropriate amount of reaction gas through the components 11 and 11 and oscillating microwaves by the operation of the microwave oscillator 5, plasma is generated inside the reaction vessel 1. Desired plasma processing is performed on the upper processing target material W.

That is, the microwave oscillated from the microwave oscillator 5 is introduced into the waveguide 4 through the waveguide 41, and a standing wave is generated in the entire inside of the waveguide 4 having a small dielectric loss.
An electric field reaching the inside of the reaction vessel 1 is formed in the vicinity of the waveguide 4, and acts on the reaction gas supplied into the reaction vessel 1 to generate plasma. Desired processing is performed on the surface of the placed workpiece W.

During the plasma processing, the inside of the reaction vessel 1 is heated to a high temperature by the action of the plasma generated as described above, and this high temperature acts on the inner wall of the reaction vessel 1. The container 1 is cooled from the surroundings by cooling water supplied to the cooling water passage 10, and is protected from high temperatures caused by generation of plasma.

The high temperature inside the reaction vessel 1 acts on the sealing plates 3, 3... For sealing the microwave introduction window 2 and these support frames 30, and further, on the periphery of the opening of the support frame 30. , Acts on the O-rings 6, 6, ... for hermetic sealing interposed between the sealing plates 3, 3, ..., the support frame 30, and the O-rings 6, 6,. ... is heated.

The plasma processing apparatus according to the present invention has a support frame
30 is provided with a medium flow path 7 formed as described above, and this medium flow path 7 is provided during the above-described plasma processing.
Cooling water at a predetermined temperature as a temperature adjusting medium supplied from the cooling water circulating device 8 is circulated. Therefore, the support frame 30 is cooled by direct heat exchange with the cooling water, and the O-rings 6, 6, ... are cooled by heat exchange with the cooling water via the metal support frame 30. These are protected from the high temperature inside the reaction vessel 1. Thus, the deterioration of the O-rings 6, 6,... Is reduced, and the sealing state with the sealing plates 3, 3,.

Further, the cooling water flowing in the medium flow path 7 also exchanges heat with the sealing plates 3, 3,... Supported by the support frame 30, and the sealing plates 3, 3,. Cooled.
Therefore, due to the temperature difference between the inside and outside of the reaction vessel 1, the sealing plate 3,
3 are alleviated, the change in the physical properties of the sealing plates 3, 3 made of alumina or aluminum nitride is reduced, and a synergistic effect with the maintenance of the sealing performance by protecting the O-rings 6, 6 is provided. Accordingly, stable plasma processing can be performed for a long period of time.

Finally, during operation of the plasma processing apparatus according to the present invention configured as described above, the case where cooling water is supplied to the medium flow path 7 and the case where cooling water is not supplied are as follows.
The results of measuring the temperatures of the support frame 30 and the sealing plates 3, 3,... Will be described.

In the plasma processing apparatus used for this measurement, the plasma generation area in the reaction vessel 1 was set to 400 × 400 mm ² , and the sealing plates 3, 3.
Using nine alumina (Al ₂ O ₃ ) plates of m ² and 5 mm in thickness, the upper portions of these sealing plates 3, 3.
It is configured to be covered with a quartz glass (SiO ₂ ) plate having a thickness of 0 mm ² and a thickness of 10 mm.
The pressure was set to 0.3 Torr, an appropriate amount of a mixed gas of O ₂ and CF ₄ was supplied as a reaction gas into the inside of the reaction vessel 1, and plasma was generated at a microwave power of 3 kW. The medium flow path 7
The circulation rate of the cooling water inside was 2 liters / min, and the temperature of the cooling water was kept at 20 ° C.

As a result of measuring the temperature under the above operating conditions, when the cooling water was not supplied, the temperature of the support frame 30 was 170 ° C. and the temperature of the central sealing plate 3 was 240 ° C. In contrast, when cooling water was supplied, the temperature of the support frame 30 dropped to 30 ° C. and the temperature of the central sealing plate 3 dropped to 100 ° C., and a sufficient cooling effect was obtained. confirmed. At this time, it is clear that the temperature of the O-rings 6, 6,... For hermetic sealing is kept at 100 ° C. or lower, and this temperature is a temperature at which sufficient resistance can be obtained by the rubber O-ring O
.. Can be effectively reduced.

In the above embodiment, the cooling water is used as the temperature adjusting medium to be supplied to the medium flow path 7, but it is needless to say that another medium may be used. In the above embodiment, the O-rings 6, 6 are used as sealing members for sealing the introduction window 2 between the sealing plates 3, 3,.
Are used, but other sealing members such as V-rings and X-rings may be used.

[0040]

As described in detail above, in the plasma processing apparatus according to the present invention, the peripheral frame of the opening corresponding to each sealing plate is provided on the support frame of the plurality of sealing plates for sealing the microwave introduction window. Forming a medium flow path including the portion, and configured to supply a temperature adjusting medium such as cooling water to the medium flow path, the sealing plate and the sealing member supported by the peripheral portion of each opening. However, it can be effectively cooled by heat exchange with the temperature control medium, and deterioration of the sealing member due to high temperature generated inside the reaction vessel during plasma processing can be reduced and good sealing performance can be maintained. In addition, a change in physical properties of the sealing plate due to the action of the high temperature is reduced, and stable plasma processing can be performed for a long period of time.

Further, since a sealing plate made of alumina or aluminum nitride is used as the sealing plate, it can be used regardless of the type of plasma generated in the reaction vessel, and changes in the physical properties of this sealing plate Is reduced by heat exchange with the temperature adjusting medium, and therefore, the present invention has excellent effects such as performing a stable plasma treatment for a long period of time.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view schematically showing a configuration of a plasma processing apparatus according to the present invention.

FIG. 2 is a plan view of a support frame and a sealing plate.

FIG. 3 is an enlarged sectional view of the vicinity of a supporting portion of a sealing plate in the plasma processing apparatus according to the present invention.

FIG. 4 is a longitudinal sectional view schematically showing a configuration of a conventional plasma processing apparatus.

FIG. 5 is an enlarged sectional view of the vicinity of a supporting portion of a sealing plate in a conventional plasma processing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction container 2 Introducing window 3 Sealing plate 6 O-ring 7 Medium flow path 8 Cooling water circulation device 30 Support frame 31 Support edge W Material to be treated

Continuation of the front page (72) Inventor Takahiro Yoshinori 4-33 Kitahama, Chuo-ku, Osaka City, Osaka Prefecture F-term in Sumitomo Metal Industries, Ltd. 4K030 FA02 JA10 KA30 KA41 KA45 4K057 DA16 DD01 DM29 DM39 5F004 BA20 BB14 BB29 BC01 BD01 BD04 5F045 AA09 DP02 EB03 EB05 EH03 EJ04 EJ09

Claims (2)

[Claims] 1. A support frame having a plurality of openings is provided on a microwave introduction window provided on one side of a reaction vessel for plasma generation, and said plurality of openings are sealed with sealing members at respective peripheral portions. In the plasma processing apparatus sealed by each of the separate sealing plates supported via the same, a medium flow path formed including the periphery of the plurality of openings in the support frame; A plasma processing apparatus comprising: a medium supply unit that supplies an adjustment medium. 2. The plasma processing apparatus according to claim 1, wherein said sealing plate is made of alumina or aluminum nitride.