JP3347383B2 - Microwave plasma processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus using microwave plasma, and more particularly, to a microwave plasma processing apparatus which supplies microwave power to plasma to stably generate plasma over a large area for a long time. About.

[0002]

2. Description of the Related Art In recent years, the problem of environmental pollution has become serious.
It does not cause environmental pollution problems associated with power generation, such as radioactive contamination due to electronic power generation and global warming due to thermal power generation, and the uneven distribution of energy sources because sunlight falls all over the earth. Attention is being paid to a clean power generation system that can respond to future increases in power demand without causing earth destruction, such as relatively low power generation efficiency without the need for complicated large-scale facilities. Various researches and developments are being conducted for practical sublimation.

By the way, in order to establish a power generation system using a solar cell to satisfy the power demand, the solar cell used has a sufficiently high photoelectric conversion efficiency and excellent characteristic stability. It is basically required to be capable of mass production.

[0004] In general, a solar cell having an output of about 3 kW per household is required to cover all the power required in a general home, and the photoelectric conversion efficiency of the solar cell is, for example, about 10%. If so, the area of the solar cell for obtaining the required output is about 30 m ² . And
For example, in order to supply necessary electric power to 100,000 households, a large area solar cell such as 3,000,000 m ² is required.

For this reason, a gaseous raw material gas such as silane, which is easily available, is used and decomposed by glow discharge or the like. Solar cells that can be manufactured by depositing semiconductor thin films have attracted attention because of their high mass productivity and the potential for low-cost production compared to solar cells manufactured using single-crystal silicon or the like. ,
Various proposals have been made for production equipment.

One of them is a microwave plasma processing apparatus. Since the microwave plasma processing apparatus has a high microwave frequency, it is possible to increase the energy density as compared with a case where a radio frequency of a conventional radio frequency is used, and to efficiently generate and maintain plasma. Therefore, it is suitable for film formation of a semiconductor such as a solar cell.

However, the conventional microwave plasma processing apparatus has a problem that the microwave introduction window is broken due to film adhesion to the microwave introduction window. Conventionally, for the purpose of reducing film adhesion to a microwave introduction window and preventing window destruction, for example, as described in JP-A-3-110798, a plurality of fins are arranged in a direction orthogonal to the direction of a microwave electric field. The microwave plasma generator provided is provided, for example, as described in Japanese Patent Application Laid-Open No. 3-122273, using a microwave having a dielectric component for maintaining a film forming process chamber at a predetermined pressure. In a film apparatus, a film forming apparatus has been considered in which a shielding article for preventing a film-forming material from adhering to the dielectric component is provided to the dielectric component without hindering the transmission of microwaves, thereby preventing film adhesion.

In order to replace the microwave introduction window, the inside of the vacuum device is once returned to the atmosphere for replacement. When the microwave device is to be used again, it is heated and evacuated to remove impurities such as gas and moisture in the atmosphere. Preparations for plasma treatment must be made by introducing an inert gas, which takes a considerable amount of time. The productivity is improved by reducing the number of replacements of the microwave introduction window as much as possible.

However, in the above-mentioned conventional microwave plasma film formation processing chamber, since the surface of the microwave introduction window into which the microwave is introduced is parallel to the surface of the substrate on which the film is formed, When a film is formed for a long time, there is a problem that film-forming particles (hereinafter sometimes referred to as dust) which are not deposited on the substrate easily adhere.

In the case where a semiconductor or the like is formed by plasma processing continuously for a long time, the amount of film-forming particles not deposited on the substrate is large, and the substrate on which the film is formed and the microwave introduction window are separated. In the case of being parallel, there is a problem that the deposition on the microwave window cannot be completely prevented.

[0011]

The present inventors have studied a comparative microwave plasma processing apparatus shown in FIG. 4 in order to solve the above problems. However, in the above-described plasma processing apparatus, a group of members (hereinafter, referred to as fins) for dividing microwaves in the direction of an electric field is arranged at the position of the substrate 2 on which the film is to be formed, as shown in FIG. There was a problem that a uniform film thickness distribution could not be obtained.

In particular, when the substrate is large with respect to the microwave introduction window, a non-uniform film thickness and non-uniform film quality result, which has a serious problem.

Further, a plasma is formed by about 90% of the microwave energy by the microwave, whereby a deposited film is formed on the substrate surface. However, about 10% of the microwave cannot be formed. However, there is a problem that the high-energy microwave may etch the deposited film formed on the contrary, and the quality of the deposited film may be deteriorated and non-uniform.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems, to provide a plasma processing apparatus which can reduce dust adhering to a microwave introduction window and can be used for a long time, and to provide a non-uniform film thickness. To provide a plasma processing apparatus that can achieve a uniform film thickness distribution regardless of the distance from the microwave introduction window, except for the problem of distribution, and to reduce the non-uniformity of the film quality formed by microwave etching. It is an object of the present invention to provide a plasma processing apparatus excluding the above.

[0015]

The gist of the present invention is to provide a vacuum processing chamber, a substrate provided in the vacuum processing chamber, a microwave waveguide connected to the vacuum processing chamber and supplying microwave power, Having two or more members for dividing microwaves in the direction of an electric field in the vicinity of a microwave introduction portion of a vacuum processing chamber;
The two or more members do not intersect orthogonally with the substrate surface subjected to the plasma treatment, and the two or more members are closer to the substrate.
It is a microwave plasma processing apparatus with a short length . Also,
The gist of the present invention resides in a vacuum processing chamber and a vacuum processing chamber.
And a microwave power supply connected to the vacuum processing chamber.
A microwave waveguide to be supplied, and a microwave in the vacuum processing chamber.
A member that splits microwaves in the direction of the electric field near the wave introduction part
And the substrate and the substrate to be subjected to plasma processing.
The substrate is not orthogonal to the plate surface, and the substrate is a continuous belt
It is a microwave plasma processing apparatus as a member.

Further, there is provided a microwave plasma processing apparatus wherein the member has a fin shape.

[0017]

Still further, there is provided a microwave plasma processing apparatus wherein the distal ends of the members are arranged at irregular intervals with respect to the substrate.

[0019]

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a plasma processing apparatus according to the present invention will be specifically described with reference to the drawings. Embodiment 1 FIG. 1 is a schematic sectional view of an embodiment of a film forming apparatus using the microwave plasma processing apparatus of the present invention.

The vacuum chamber 4 is connected to a vacuum exhaust device, a gas introduction pipe, and a microwave introduction device (not shown). The microwave introduction window 3 connected to the substrate 2 and the microwave waveguide is provided in the vacuum chamber 4. Each fin 1 made of stainless steel having a different length and connected to divide the direction of the electric field is accommodated therein.

When a film is formed on the substrate 2 using this apparatus, the vacuum chamber 4 is evacuated by a vacuum evacuation system attached to the vacuum chamber 4 and a source gas is introduced to maintain the pressure at about 0.7 Pa. This is performed by introducing microwaves through the microwave introduction window 3 and generating plasma at the tip of the fin group of the present invention. Using the apparatus of FIG.
An amorphous silicon-based (hereinafter a-Si) film was formed on 00 mm square glass (Corning 7059).

At this time, the film forming condition is such that the flow rate of SiH ₄ is 30.
0 SCCM, flow rate of diluent gas hydrogen 1Slm, pressure 0.
The film formation time is 2 minutes at a power of 7 Pa and a microwave μω of input power of 500 W. The fins are composed of 18 fins at a pitch of 6.5 mm, and the shape and arrangement of the fins are increased by an equal length so that 1 min = 20 mm and 1 max = 450 mm as shown in FIG. Are unequal length. A-S film formed under the above film forming conditions
The i film had a relatively uniform thickness. Further, in the state of the fins, the same result can be obtained at the position of the substrate 2-a and the position of 2-b shown in the figure. Further, even when the films were continuously formed, almost no problem occurred due to adhesion of dust to the microwave introduction window. Comparative Example 1 As shown in FIG. 4, except that all the fins of 1 min = 1max were equal in length,
-A Si film was formed. FIG. A-S films formed by the plasma processing apparatus of Example 1 having different fin lengths and the plasma processing apparatus of Comparative Example 1 having the same fin length
The thickness distribution of the i-film in the film thickness direction formed on the substrate was measured, and the thickness (μ) was plotted on the vertical axis, and the distance m from the tip of the fin was measured.
The data is recorded with the horizontal axis representing m.

As shown in FIG. 3, in the case of the unequal length (a) as compared with the case of the equal length (b), the plasma spreads over the 500 mm square substrate, so that the film thickness distribution is uniform. On the other hand, when the length is equal, the plasma density near the tip of the fin is high, so that the film thickness distribution is poor. Therefore, it can be seen that by introducing fins having different lengths, the film thickness distribution can be made uniform for a large-area substrate. Second Embodiment FIG. 6 is a schematic cross-sectional view of a second embodiment of the plasma processing apparatus according to the present invention, which is a plasma processing apparatus in which the tips of fins are arranged at irregular intervals with respect to the substrate 2. The distance between the fin 1A closest to the microwave introduction window 3 and the fin adjacent to the fin 1A is set to a minimum Pmin, and the microwave introduction window 3
The distance between the fin 1B furthest from the fin 1B and the fin 1B adjacent to the fin 1B is set to a maximum Pmax, and the intermediate fins are arranged with increasing distance from left to right in the figure.

Specifically, with respect to the number of fins, that is, Pmin = 18
The distance between the tip ends of the fins was increased so that 6.5 mm and Pmax = 57.5 mm, and the distance between the fin ends was made closer to parallel.

In general, since the decomposition rate of Ge is higher than that of Si, the plasma density of Ge at the tip of the fin increases, and the film thickness distribution changes due to the difference in the distance of the substrate surface from the tip of the fin. Therefore, when film formation is performed using SiGe or the like, the fin shape of FIG. 6 is preferable to the fin shape of FIG.

Under the same film forming conditions, a comparison was made between a film formed by using the plasma processing apparatus of the first embodiment and a film formed by using the present embodiment using a source gas containing Ge. And shown in FIG. In FIG. 7, a represents the film thickness distribution of the semiconductor film formed by the plasma processing apparatus of the first embodiment of the present invention, and b represents the film thickness distribution of the semiconductor film formed by the plasma processing apparatus of the second embodiment.

FIG. 7 shows that the semiconductor of Example 2 has a uniform film quality as compared with the film thickness of the semiconductor of Example 1. The film quality of the semiconductor was also excellent.

In this method, a plasma is formed by microwaves at about 90% of the microwave energy, thereby forming a deposited film on the substrate surface. It is considered that the high-energy microwaves may etch the deposited film formed on the contrary, and the quality of the deposited film may deteriorate and become non-uniform. Embodiment 3 As another embodiment of the present invention, there is a roll-to-roll type semiconductor film forming apparatus. As shown in FIG. 8, the belt-like substrate 2 is transported sequentially from the vacuum chamber 5a in which the bobbin 6a for unwinding the belt-like substrate 2 is housed, and the belt-like substrate 2 is wound through the plasma processing chamber 8 connected to the gas gate 7. This is a continuous plasma processing apparatus that winds the bobbin 6b to be taken up in a vacuum chamber 5b.

FIG. 9 is an enlarged view of the plasma processing chamber.
(A), and (b) is a schematic sectional view of (a). In (a) and (b), the same reference numerals represent the same items.

In FIG. 9, a microwave is emitted from a microwave introduction window 3 connected to a microwave generator (not shown) through a fin 1 of the present invention, plasma is formed, and a continuously moving strip-shaped substrate 2 is formed. A deposited film is formed thereon. Here, 9 is a bias bar. This bias rod 9
Is applied with a high frequency from the high-frequency power supply 10, and it is possible to form a denser film by increasing the collision speed of the atoms with the band-shaped substrate 2.

With the above structure, a semiconductor such as a solar cell having a uniform film thickness and having a uniform film thickness can be continuously applied for a long time while preventing film adhesion to the microwave introduction window and destruction of the window. A film can be formed.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of one embodiment of a microwave plasma processing apparatus according to the present invention.

FIG. 2 is a schematic view of a fin of the present invention installed in a vacuum chamber and a substrate surface.

FIG. 3 is a comparison diagram showing a state of a deposited film thickness when a plasma processing apparatus for comparison having the same fin length and a processing apparatus of the present invention having different lengths are used.

FIG. 4 is a schematic cross-sectional view of plasma generation in a plasma processing apparatus for comparison, and a schematic diagram showing a film thickness formed at that time.

FIG. 5 is a schematic cross-sectional view of plasma generation in a plasma processing apparatus according to one embodiment of the present invention, and a schematic diagram showing a film thickness formed at that time.

FIG. 6 is a schematic sectional view of another embodiment of the plasma processing apparatus of the present invention.

FIG. 7 is a diagram comparing the state of the formed film thickness when the shape of the fin is changed in the plasma processing apparatus of the present invention.

FIG. 8 is a continuous plasma processing apparatus using the present invention.

9 is an enlarged view of the plasma processing chamber 8 in FIG. 8, (a) is a schematic lateral view, and (b) is a schematic cross-sectional view.

[Explanation of symbols]

 Reference Signs List 1 fin 2 substrate on which film is formed 2-a substrate in position parallel to fin 2-b substrate at angle other than perpendicular to fin 3 microwave introduction window 4 vacuum chamber 5 vacuum chamber 6 bobbin 7 gas gate 8 Plasma processing chamber 9 Bias rod 10 High frequency power supply

Continuation of the front page (72) Inventor Akio Koganei 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Hiroshi Echizen 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Shuichiro Sugiyama 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP-A-3-229863 (JP, A) JP-A-3-122273 (JP, A) JP-A-3-110798 (JP, A) JP-A-1-290760 (JP, A) JP-A-2-230724 (JP, A) JP-A-4-287313 (JP, A) JP-A-4-287314 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 21/205

Claims (4)

(57) [Claims] A vacuum processing chamber; a substrate provided in the vacuum processing chamber; a microwave waveguide connected to the vacuum processing chamber to supply microwave power; has a 2 or more <br/> member for dividing the microwave in the direction of the electric field, the said and two or more members, not the cause and the substrate surface is perpendicular to undergo plasma treatment, the two or more members, the A microwave plasma processing apparatus characterized in that its length is shorter as it is closer to the substrate . 2. A vacuum processing chamber and a vacuum processing chamber.
Substrate and connected to the vacuum processing chamber to supply microwave power
Microwave waveguide and microwave in the vacuum processing chamber
A member for dividing the microwave in the direction of the electric field near the introduction portion,
And the substrate surface to be subjected to plasma processing
Is not orthogonal, and the substrate is a belt-shaped member that moves continuously. Wherein said member is a microwave plasma processing apparatus according to claim 1 or claim 2, wherein it has a fin-shaped. 4. The method of claim 1, characterized in that the tip of the member are arranged at unequal intervals with respect to the substrate or
The microwave plasma processing apparatus according to claim 2 .