JP2000003800A - Plasma processing equipment - Google Patents

Abstract

(57) [Summary] [PROBLEMS] In a plasma processing apparatus in which a microwave introduction window opened on one side of a reaction vessel is sealed with a plurality of sealing plates, a plasma distribution generated inside the reaction vessel is reduced. In addition, the unevenness due to the influence of the metal supporting frame supporting the sealing plate is reduced. 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 side of the sealing plates 3, 3... Facing the microwave waveguide 4 is covered with a dielectric cover plate 6 including these support frames 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a process for producing a plasma by introducing a microwave into a reaction vessel, and by using the plasma, a non-processed material placed in the reaction vessel is treated with
Etching, ashing, CVD (Chemical
The present invention relates to a plasma processing apparatus configured to perform processing such as Vapor Deposition.

[0002]

2. Description of the Related Art A plasma is generated by externally applying an excitation energy to a reaction gas inside a reaction vessel, and the action of this plasma causes a semiconductor substrate, a glass substrate for a flat panel display, etc. to be placed in the reaction vessel. Various processes such as etching, ashing, and CVD are widely performed on non-processed materials. In particular, dry etching using plasma is an indispensable basic technology in an LSI manufacturing process. I have.

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 generating high-density plasma at low temperatures, but has the advantage of generating uniform plasma over a large area. And it is difficult to apply to large-sized non-processed materials 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 developed a plasma processing apparatus using a dielectric line, for example,
This is proposed in JP-A-62-5600. This apparatus is one side (upper side) of a hollow rectangular parallelepiped reaction vessel.
In addition, a large-area microwave introduction window which is opened over the entire surface is formed, and this introduction window is made of quartz glass (SiO ₂ ), alumina (Al ₂ ) having excellent heat resistance and small dielectric loss.
While sealing with a sealing plate made of a dielectric material such as O ₃ ), a dielectric line made of a dielectric material is similarly juxtaposed as a microwave waveguide on the other side of the sealing plate. A microwave oscillator is attached to the end of the waveguide connected continuously to the above.

[0005] The microwave oscillated by the microwave oscillator is introduced into the waveguide formed as a dielectric line via the waveguide, and an electric field reaching the inside of the reaction vessel is formed near the waveguide. Is done. At this time, the inside of the reaction vessel is in a state in which an appropriate amount of reaction gas is sealed under high vacuum, and the electric field acts on the reaction gas to generate plasma,
By this plasma, a process such as etching, ashing, or CVD is performed on the material to be processed, which is disposed inside the reaction vessel so as to face the introduction window.

[0006] In the plasma processing apparatus configured as described above, a uniform electric field is formed on the entire surface of the sealing plate that seals the introduction window that opens to one side of the reaction vessel. A uniform plasma can be generated over a large area, and a large-sized non-processing material such as a large-diameter semiconductor substrate or a glass substrate for a flat panel display can be subjected to plasma processing.

However, in the plasma processing apparatus configured as described above, the sealing plate that seals the window for introducing microwaves is mechanically acted on by a negative pressure inside the reaction vessel that is brought into a high vacuum during the plasma processing. When a high stress is applied and the sealing plate is heated with the generation of plasma, there is a problem that a temperature difference occurs in the sealing plate and thermal distortion occurs. In particular, in a plasma processing apparatus for processing a glass substrate for a flat panel display, which may be 400 mm × 400 mm or more, a large-sized sealing plate corresponding to the glass substrate is damaged by the mechanical stress described above. In order to avoid this, it is necessary to ensure that the sealing plate has a sufficient thickness, which inevitably increases the weight of the device, and that the sealing plate made of a dielectric is expensive,
There is a problem that the cost of the apparatus is increased. On the other hand, even if the sealing plate is made thick, the problem of thermal distortion cannot be solved, and some materials cannot be applied depending on the material.

The applicant of the present invention has divided the sealing plate for sealing the microwave introduction window into a plurality of sheets, and reduced the area of each sealing plate to solve the above-mentioned problem. Is proposed in JP-A-8-17595.

FIG. 4 is a longitudinal sectional view schematically showing the configuration of a plasma processing apparatus disclosed in Japanese Patent Application Laid-Open No. H8-17595. In the figure, reference numeral 1 denotes a reaction vessel having a hollow rectangular parallelepiped shape. A cooling water channel 10 is provided around the entire outer periphery of the peripheral wall of the reaction vessel 1, and reaction gas supply pipes 11, 11 are connected to one or a plurality of locations of the peripheral wall. Further, at the bottom of the reaction vessel 1, one or more exhaust pipes for evacuation are provided.
12 and 12 are connected, and a mounting table 13 for mounting the workpiece W is provided.

The microwave introduction window 2 is set up over the entire upper surface of the reaction vessel 1 so as to face the upper surface of the mounting table 13, and the introduction window 2 has a lattice-like support frame 30. It is erected. The support frame 30 shown in the figure is arranged so that the introduction window 2 is arranged vertically and horizontally.
A rectangular lattice-shaped frame body provided with four divided openings, and these openings are hermetically sealed by separate sealing plates 3, 3... Mounted on respective frame edges. Is sealed.

On the upper part of the reaction vessel 1 in which the introduction window 2 is opened, a metal waveguide vessel is formed over substantially the entire area of the introduction window 2.
A waveguide 4 made of a dielectric material is formed so as to cover the outside thereof by 40, and a waveguide 41 connected to one side of the waveguide container 40 is formed.
A microwave oscillator 5 is attached to the other end.

In the plasma processing apparatus configured as described above, a workpiece W such as a semiconductor substrate or a glass substrate for a flat panel display is processed on a mounting table 13 inside the reaction vessel 1 as shown in FIG. The surface is placed toward the introduction window 2, and an appropriate amount of reaction gas is supplied through the supply pipes 11 and 11 into the reaction vessel 1 evacuated by the exhaust pipes 12 and 12 while the microwaves are supplied. By operating the oscillator 5, a desired plasma process is performed on the workpiece W inside the reaction vessel 1 as described below.

That is, a microwave oscillated by the operation of 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. As a result, an electric field is formed inside the reaction vessel 1 near the waveguide 4. Then, the electric field acts on the reaction gas supplied as described above into the reaction vessel 1 to generate plasma, and the plasma causes the surface of the workpiece W mounted on the mounting table 13 to have a Etching, ashing,
A desired process such as CVD is performed. 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 high temperatures caused by generation of plasma.

During the plasma processing performed as described above, the inside of the reaction vessel 1 is in a high vacuum state, and is in a high temperature state due to the generation of plasma, and the microwave introduction window 2 is sealed. The stop plates 3, 3,... Generate mechanical stress due to the action of the negative pressure inside the reaction vessel 1, and also generate stress due to thermal distortion caused by the action of the high temperature inside the reaction vessel 1. Since each of the sealing plates 3, 3,... Has a plane area sufficiently smaller than the opening area of the introduction window 2,
The above-mentioned mechanical and thermal stresses are reduced, and the above-mentioned problems can be alleviated.

[0015]

As described above, Japanese Patent Application Laid-Open No. Hei 8-1
The plasma processing apparatus disclosed in Japanese Patent No. 7595 can be applied to a large-sized non-processed material, reduces mechanical and thermal stress of the sealing plate, and reduces damage to the sealing plate. It is an excellent device that can be prevented. However, in this plasma processing apparatus, it may be difficult to generate plasma in the reaction vessel 1 with a uniform distribution over the entire area, and the plasma processing apparatus may have a non-uniform distribution on the processing surface of a large-area material to be processed. There is a risk that plasma processing will be performed.

The non-uniformity of the plasma distribution is caused by the existence of the support frame 30 for supporting the sealing plates 3, 3,. The support frame 30 secures a strength capable of stably supporting the sealing plates 3, 3...
Further, it is generally made of metal because it is necessary to have ease of molding into a desired shape.

On the other hand, the process in which the microwave introduced into the waveguide 4 as described above penetrates the sealing plates 3, 3... And is introduced into the reaction vessel 1 will be described in detail. The standing wave generated in the whole area inside the waveguide 4 is guided to the sealing plates 3, 3... By the action of the electric field, and the outer surface of each of the sealing plates 3, 3 (the surface facing the waveguide 4). A surface wave is generated, and the surface wave propagates inside each of the sealing plates 3, 3,..., Reaches the respective inner surfaces, and follows a process of being introduced into the reaction vessel 1 as a microwave.

In the microwave introduction process, the metal support frame 30 exists in the propagation path of the surface wave generated in each of the sealing plates 3, 3. The impedance change in the propagation direction of the surface wave is large, and a part of the surface wave is reflected by the support frame 30, so that the distribution of the microwave radiated from the sealing plates 3, 3,. This is because the distribution of plasma generated inside the reaction vessel 1 by the action of the microwave becomes non-uniform.

The present invention has been made in view of the above circumstances, and has a structure in which a microwave introduction window opened on one side of a reaction vessel is sealed with a plurality of sealing plates. Plasma processing that can mitigate uneven distribution of plasma generated inside the reaction vessel due to the effect of the metal support frame that supports the plate, and can perform more uniform plasma processing on large-area materials to be processed. It is intended to provide a device.

[0020]

According to the plasma processing apparatus of the present invention, a microwave introduction window provided on one side of a reaction vessel and a plurality of openings of a support frame provided on the introduction window are provided. A plurality of sealing plates for separately sealing, comprising a microwave waveguide arranged opposite to the introduction window, the microwave propagating in the waveguide through the plurality of sealing plates In the plasma processing apparatus configured to be introduced into the reaction vessel, a dielectric cover plate that covers the side of the plurality of sealing plates facing the waveguide including the support frame may be provided. Features.

In the present invention, the side of the plurality of sealing plates supported by the support frame facing the waveguide is covered by a cover plate made of a dielectric material. Surface waves having a uniform distribution are generated on the entire surface of the cover plate, and the surface waves are transmitted to a plurality of inner sealing plates, and are radiated from the respective sealing plates into the inside of the reaction vessel. As a result, the change in impedance is reduced, and the distribution of microwaves inside the reaction vessel is made uniform. The cover plate is a large-area plate material that collectively covers a plurality of sealing plates, but is separated from the inside of the reaction container via the sealing plate, and is a machine that is operated by the negative pressure inside the reaction container. It is not necessary to secure strength against thermal distortion due to the effect of thermal stress and the temperature difference in the sealing plate.

Further, the waveguide extends substantially parallel to a window surface of the introduction window.

According to the present invention, the microwave inside the waveguide is applied to the cover plate which covers the support frame and the sealing plate provided on the window surface of the introduction window which is parallel to the waveguide, and covers the entire surface of the cover plate. The surface waves are transmitted uniformly over the entire surface, and surface waves are generated in a uniform distribution on the upper surface of the cover plate.

[0024]

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 performs etching, ashing, and CV processing on a non-processing material W such as a semiconductor substrate or a glass substrate for a flat panel display disposed inside a reaction vessel 1.
A plasma process such as D is performed.

The reaction vessel 1 is a hollow rectangular parallelepiped vessel made of a metal material such as Al. Similar to the plasma processing apparatus shown in FIG. A water channel 10 is provided in the periphery, and reaction gas supply pipes 11, 11 are connected to one or more places of the peripheral wall. 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 formed which is open over the entire surface. The introduction window 2 is provided in the same manner as the plasma processing apparatus shown in FIG. A lattice-like support frame 30 is provided. As shown in FIG. 2, the 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 each of the openings is provided. Are hermetically sealed by separate sealing plates 3, 3... Placed on the edges of these frames. The number of the sealing plates 3, 3,... Is not limited to nine as shown, but may be four as in the plasma processing apparatus shown in FIG. 4, or may be another number. Further, the support frame 30
The shape of the opening formed in the hole is not limited to a rectangle, but may be another shape such as a circle.

A microwave waveguide 4 is formed on the upper part of the reaction vessel 1 in which the introduction window 2 is opened. The waveguide 4 is formed of a flat plate made of a dielectric material such as fluororesin, polystyrene, polyethylene, etc., having a small dielectric loss. The outside of the waveguide 4 is covered by a metal waveguide container 40 and substantially the entire area of the introduction window 2. In addition, they are arranged to be substantially parallel to the window surface and to face each other. 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 is guided. The light is introduced into the waveguide 4 through the wave tube 41. The end face of the waveguide 4 on the side where the microwave oscillator 5 is attached is a tapered face whose upper part is inclined toward the microwave oscillator 5 side as shown in the figure, so that the microwave can be efficiently transmitted from the waveguide 41. It is being introduced.

In the plasma processing apparatus according to the present invention, a sealing plate 3 for sealing the microwave introduction window 2 is further provided.
A cover plate 6 is arranged between 3 and a waveguide 4 made of a dielectric material which is disposed on the upper part of the dielectric waveguide. This cover plate 6
Are flat plates made of a dielectric material such as quartz glass or alumina having a small dielectric loss, as in the case of the sealing plates 3, 3,..., As shown in FIG. Support frame
It is arranged to cover including 30.

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 11 and 11 and supplying cooling water to the cooling water channel 10 to cool the reaction vessel 1 from the outside, the microwave is oscillated by the operation of the microwave oscillator 5. ,
Plasma is generated inside the reaction vessel 1, and a desired plasma process is performed on the workpiece W on the mounting table 13 by the action of the plasma.

That is, the microwave oscillated from the microwave oscillator 5 is introduced into the waveguide 4 via the waveguide 41, and a standing wave is generated inside 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 4.

In the plasma processing apparatus according to the present invention,
As described above, the microwave traveling toward the reaction vessel 1 first reaches the cover plate 6 directly facing the waveguide 4, and a surface wave is generated on the upper surface of the cover plate 6. At this time, the waveguide 4
Extend substantially parallel to the window surface of the introduction window 2, while the cover plate 6 is arranged to cover the entire surface of the plurality of sealing plates 3, 3. And is in a state directly facing the waveguide 4. Therefore, the microwave propagates uniformly over the entire surface of the cover plate 6.

Since the cover plate 6 through which the microwave propagates is a flat plate made of a dielectric material over the entire surface, the upper surface of the cover plate 6 is uniformly spread over the entire surface by the propagation of the microwave. A surface wave is generated with such a distribution. The surface waves generated in this way propagate through the inside of the cover plate 6 and reach the lower surface, are transmitted to the plurality of sealing plates 3 covered by the lower portion of the cover plate 6, and are transmitted therethrough. Each sealing plate 3,3
Are introduced into the reaction vessel 1 from the lower surface thereof, and act on the reaction gas inside the reaction vessel 1 to generate plasma. The plasma acts on the workpiece W on the mounting table 13 to perform etching and ashing. , A desired process such as CVD.

As described above, in the plasma processing apparatus according to the present invention, the surface waves generated in a uniform distribution over the entire surface of the cover plate 6 are passed through the plurality of sealing plates 3, 3. , The distribution of the microwaves inside the reaction vessel 1 becomes uniform, and a uniform plasma is generated by the action of the microwaves.

Also, during the plasma processing performed as described above, a mechanical stress is generated in each of the sealing plates 3, 3... By the action of the negative pressure inside the reaction vessel 1, and with the generation of the plasma. Temperature difference is generated inside each of the sealing plates 3, 3,..., And thermal distortion occurs in these sealing plates 3, 3,. It has a flat area sufficiently smaller than the opening area of, and is firmly supported by the metal support frame 30, so that it can bear the above-mentioned mechanical and thermal stress with a margin. As shown in the figure, it can be made of a small-sized and thin-walled plate material.

On the other hand, the cover plate 6 that covers the outside of the sealing plates 3, 3,... Is a large-area flat plate having the same size as the opening area of the introduction window 2, and this cover plate 6 3,3
Are separated from the inside of the reaction vessel 1 by the above-mentioned components, and the above-mentioned mechanical and thermal distortions are hardly generated, and can be made of a thin plate material like the sealing plates 3, 3,. .

Finally, in the plasma processing apparatus according to the present invention (the apparatus of the present invention) configured as described above, and the plasma processing apparatus without the cover plate 6 (the conventional apparatus),
The results of an experiment performed to examine the uniformity of plasma inside the reaction vessel 1 will be described. In this experiment, plasma was generated under the same conditions in the apparatus of the present invention and the conventional apparatus, and the uniformity of the generated plasma was evaluated by measuring the ion current at this time.

The plasma generation area in the reaction vessel 1 is 400 × 400 mm ² , and the sealing plates 3, 3.
Alumina (Al ₂ O) with a plane area of 130 × 130 mm ² and a thickness of 5 mm
₃ ) Using a plate, the cover plate 6 has a flat area of 450 ×
A quartz glass (SiO ₂ ) plate having a thickness of 450 mm ² and a thickness of 10 mm was used. The internal pressure of the reaction vessel 1 was set at 0.3 Torr, an appropriate amount of O ₂ gas was supplied as a reaction gas into the reaction vessel 1, and plasma was generated at a microwave power of 3 kW.

FIG. 3 is a diagram showing the results of an evaluation test of the uniformity of generated plasma, and shows the distribution of ion current in the traveling direction of microwaves obtained under the above-described conditions.
The horizontal axis of the figure indicates a planar measurement position inside the reaction vessel and the center thereof is set to 0, and the vertical axis similarly indicates the measured value of the ion current at each measurement position.

In the figure, ○ indicates a measurement result in the apparatus of the present invention, and similarly, ● indicates a measurement result in the conventional apparatus. According to these comparisons, in the apparatus of the present invention including the cover plate 6, a substantially uniform ion current distribution state was obtained over the entire region of the reaction vessel 1, whereas the cover plate 6
In the conventional device not provided with, a distribution state of the ion current, which is higher on the microwave incident side where the coordinate value of the horizontal axis is negative and gradually decreases toward the opposite side, is obtained,
It has been clarified that the uniformity of the plasma can be obtained by installing the cover plate 6.

In the above embodiment, a large-sized single plate capable of covering the entire surface of the sealing plates 3, 3,... Is used as the cover plate 6, but a plurality of cover plates are used for sealing. The stop plates 3, 3 ... may be covered together with the support frame 30,
At this time, if each cover plate is brought into contact with the sealing plates 3, 3,..., The same effect can be obtained in terms of microwaves.

[0041]

As described above in detail, in the plasma processing apparatus according to the present invention, a plurality of sealing plates for sealing a microwave introduction window opened on one side of a reaction vessel are provided with a microwave waveguide. The surface of the cover plate is covered with a dielectric cover plate on the side opposite to the surface wave, so that the surface wave having a uniform distribution is generated on the entire surface of the cover plate due to the propagation of the microwave from the waveguide, and the surface wave is formed by a plurality of inner sealing members. The microwaves are transmitted to the plate and introduced into the reaction vessel, the distribution of the microwaves inside the reaction vessel is made uniform, and the plasma can generate a uniform distribution by the action of the microwaves. On the other hand, more uniform plasma processing can be performed.

The cover plate is a large-area plate material that covers a plurality of sealing plates at a time. However, since the cover plate is isolated from the inside of the reaction container via the sealing plate, the inside of the reaction container is removed. No mechanical stress due to the action of the negative pressure and no thermal distortion due to the action of the high temperature inside the reaction vessel.

Further, since the microwave waveguide extends substantially in parallel with the window surface of the introduction window, the microwave inside the waveguide extends over the entire surface of the cover plate covering the introduction window. The present invention has excellent effects, such as being transmitted evenly, generating a surface wave in a uniform distribution on the upper surface of the cover plate, and making the plasma distribution inside the reaction vessel even more uniform.

[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 a diagram showing the results of an evaluation test for uniformity of generated plasma.

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

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 reaction vessel 2 introduction window 3 sealing plate 4 waveguide 5 microwave oscillator 6 cover plate 13 mounting table 30 support frame W workpiece

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Takahiro Yoshinori 4-33 Kitahama, Chuo-ku, Osaka-shi, Osaka Sumitomo Metal Industries, Ltd. F-term (reference) 4K030 FA02 KA12 KA30 4K057 DA16 DD01 DM29

Claims (2)

[Claims] 1. A microwave introduction window opened on one side of a reaction vessel, a plurality of sealing plates for separately sealing a plurality of openings of a support frame provided on the introduction window, A plasma processing apparatus comprising a microwave waveguide disposed opposite to the introduction window, and configured to introduce the microwave propagating in the waveguide into the reaction vessel through the plurality of sealing plates. The plasma processing apparatus according to claim 1, further comprising a dielectric cover plate that covers the side of the plurality of sealing plates facing the waveguide including the support frame. 2. The plasma processing apparatus according to claim 1, wherein the waveguide extends substantially parallel to a window surface of the introduction window.