JPH02246111A - Plasma treatment device - Google Patents

Abstract

PURPOSE:To form plasma atmosphere of approximately the same concentration without leaking plasma discharge outside and enclosed space and to enable formation of a coating of good uniformity even on a substrate of a large area by forming the closed space with a substrate susceptor which is movable in one direction and a pair of electrode shields. CONSTITUTION:A pair of shields 4 are provided between a reaction chamber inner wall and a discharge electrode 3. The electrode shield 4 forms a closed space with a substrate susceptor 5 for arranging a plurality of substrates 1 between the discharge electrodes 3 unparallel thereto. The substrate susceptor 5 is movable in one direction, therefore, plasma treatment can be carried out successively by moving the susceptor whereto a plurality of substrates are held before and after plasma treatment.

Description

Detailed Description of the Invention (a) Field of Application of the Invention The present invention relates to a photoelectric conversion device made of an amorphous or polycrystalline non-single crystal semiconductor mainly composed of silicon, or a non-single crystal semiconductor mainly composed of silicon. The present invention relates to a plasma processing apparatus that can be applied to forming elements such as thin film field effect transistors on large substrates.

(b) Conventional technology Non-single-crystal semiconductor thin films mainly composed of silicon and insulator thin films such as silicon oxide and silicon nitride formed by plasma chemical vapor deposition (hereinafter referred to as plasma processing equipment) are used for solar cells, It is widely applied as a material for photoelectric conversion devices such as image sensors, thin film field effect transistors used in liquid crystal display devices, etc. These electronic devices are composed of laminated layers of multiple thin films with different properties, and as these devices become larger and lower in price, efforts are being made to industrially manufacture these laminated films over large areas and in large quantities. The conventional plasma processing equipment is shown below.

Figure 2 shows plasma C using the most common parallel plate electrodes.
A schematic cross-sectional view of a VD device is shown.

In this case, one vacuum pre-chamber (26) and one reaction chamber (
23) is shown. The substrate (1) is attached to the substrate support (21
), and the gate valve (2) is installed together with the support (21).
2) to the reaction chamber (23). The reaction chamber (
In step 23), the substrate (1) is heated by a heater (24), and after reaching a predetermined temperature, the reactive gas is decomposed and activated by a discharge electrode (25) to form a thin film on the substrate. be.

As is clear from the figure, in this method, the substrate and the electrodes are parallel, so when forming a thin film on a large-area substrate, it was necessary to increase the area of the electrodes.

Furthermore, since the thin film can be formed only in an area approximately equal to the electrode area in the second thin film forming process, it is insufficient for processing a large amount of substrates.

As one method for solving these problems, there is a plasma gas phase reactor (Japanese Patent Application No. 59-79623) proposed by the present applicant, and a schematic sectional view of the reaction chamber of this device is shown in FIG.

As shown in the drawing, the film forming substrate (1) is placed between the parallel plate electrodes (31)? By arranging several substrates perpendicular to the electrodes, we were able to process more than 10 times as many substrates as before, and at the same time, the floor space of the equipment was almost the same as the conventional equipment. . As the distance between the upper and lower discharge electrodes (31) increases, it becomes possible to produce a film on a larger substrate, but in reality, as the distance between the upper and lower electrodes (31) increases, plasma discharge becomes unstable. The electrode spacing is within twice the length of one side of the electrode. Such a large area,
Plasma vapor phase reaction methods for bulk substrate processing also have some drawbacks.

That is, since the distance between the electrodes is quite long, the film formed on the substrate has a film thickness distribution in the direction between the electrodes except under specific film forming conditions. The situation is shown in Figure 4 (^), (B
), (C), and (D). This is the fourth diagram showing a schematic diagram of how a film is formed when a non-single crystal silicon semiconductor is produced on a glass substrate using the plasma vapor phase reactor shown in Figure 3.
As shown in area I in Figure 4(A), when the reaction pressure is high and the input power of high-frequency power is low, formations are formed on the upper and lower parts of the substrate in the direction of the electrodes as shown in Figure 4(B). The number of coatings increases and the film thickness distribution is like this. During the production of this film, the plasma emission region in the reaction chamber where the plasma reaction is occurring was observed to be concentrated near the upper and lower electrodes. , the area marked ■ in FIG. 4(^), and the coating formed near the center of the substrate in the direction of the electrodes, as shown in FIG. 4(0), are often formed and have such a film thickness distribution.

Furthermore, although it was a narrow range, it was possible to obtain a substantially uniform film thickness distribution as shown in FIG. 4(C) in region (2) of FIG. 4(^).

Such non-uniform film thickness distribution on a large-area substrate causes severe variations in the characteristics, especially the physical and electrical characteristics, of each semiconductor element configured on the same substrate, and it is difficult to Even if a photoelectric conversion device was produced, it had no industrial value.

(c) Object of the Invention The present invention compensates for the drawbacks of the conventional method described above, and relates to an apparatus for producing a film having a uniform thickness distribution on a large number of large-area substrates under a wide range of conditions.

(d) Structure of the Invention The present invention relates to a plasma processing apparatus that solves the above-mentioned problems, and includes a pair of electrode shields (4) provided between the inner wall of the reaction chamber and the discharge electrode (3), and the electrode shield ( 4
) is a substrate susceptor (1) for arranging a plurality of substrates (1) between discharge electrodes (3) in a non-parallel manner with these electrodes.
5) to form a closed space, this substrate susceptor can move in one direction, and when installed at a predetermined position in the reaction chamber, forms a closed space with the electrode shield mentioned above.

With this configuration, a pair of discharge electrodes and a plurality of substrates are all surrounded by an electrode shield and a substrate susceptor, and plasma discharge does not leak outside of these enclosed spaces and is distributed almost equally between each substrate. A dense plasma atmosphere is formed, making it possible to form a film with good uniformity even on large-area substrates.

Further, the substrate susceptor is movable in one direction and forms a closed space with the electrode shield at a predetermined position. Therefore, by moving a susceptor holding a plurality of substrates before and after plasma processing, plasma processing can be performed continuously.

An example of the structure of this electrode shield and substrate susceptor is shown in the first example.
Illustrated.

In FIG. 1(A), the substrate susceptor (5) is movable to the right in the drawing, and forms a closed space with the electrode shield (4).

An enlarged schematic view of the overlapping portion of the substrate susceptor (5) and the electrode shield (4) is shown in Figure (B). With this structure, the substrate susceptor is movable and close to the electrode shield. Configure space.

Further, FIG. 5 shows examples of combinations of other electrode shields and substrate susceptors.

The present invention is not particularly limited to the structures shown above, and the idea of the present invention can be reflected in other structures.

The present invention will be explained below with reference to Examples.

r Example In this example, a plasma vapor phase reaction apparatus shown in FIG. 6 was used to form a non-single crystal semiconductor film on a glass substrate. In the figure, a glass substrate (1) with a size of 300 mm x 400 mm is set on a substrate susceptor (5) so as to be arranged perpendicularly to the electrodes. In the case of this example, ten glass substrates (1) are placed on the same susceptor (5).
However, if the distance between the glass substrates (1) facing each other is 20 mm or more, discharge will occur with good reproducibility, and it will be possible to form a film on more substrates, but the film thickness on the substrates will not be uniform. Considering the performance, in the case of this embodiment, about 10 to 15 sheets is good. It is not appropriate to fix the plane to - because the distance between the substrates changes depending on other factors such as the pressure during film production.

In addition, the electrode shield (4) and the substrate susceptor (5) are
It has the structure shown in Figure 1, and these electrode shields,
The substrate susceptor is made of nickel, a metal material.

It is possible to use stainless steel, aluminum, ceramics, etc. with a conductive material formed on the surface.

In this embodiment, these are made of aluminum material with punched holes of 10 m1φ. This punched hole was provided to improve the flow of reactive gas and to shorten the initial exhaust time, but no plasma leaked through this punched hole.

Furthermore, in this example, the electrode shield and the substrate susceptor were grounded so that more uniform plasma was generated only between the discharge electrodes. As a result, each substrate was placed under a more uniform plasma atmosphere.

The susceptor (5) with the glass substrate set thereon is put into the plasma reaction chamber from the preliminary chamber (62), and after evacuation is performed, the gate valve (63) is opened, and the first After moving to the reaction chamber (64), the heaters for heating the substrate located on the front and back sides parallel to the paper surface of Fig. 6 are heated to a film forming temperature of 200 to 300°C, although they are not shown in the figure. It can be heated to a certain degree.

In this state, 50 SCC of silane gas is added into the reaction chamber (64).
By introducing H at a flow rate and controlling the conductance of the exhaust system, the pressure inside the reaction chamber can be maintained at 0.01 to 0.1 torr.

Next, 13.56M1 is placed between the upper and lower parallel plate electrodes (61).
A high-frequency power of 1z is applied, and the plasma discharge is confined in the space formed by the upper and lower electric excavation shields (4) and the side surfaces of the substrate support susceptor (5), and does not reach the inner wall of the reaction chamber (@). Therefore, the film formed is only formed inside the above-mentioned space, and there is no need to clean the inner wall of the reaction chamber, or the number of times of cleaning can be greatly reduced.

Using the device of the present invention, 300+u+ X 400a+
P on the substrate of m, 1. 500 solar cells having an N structure (element area: 1.05 cm") were manufactured. Their characteristics are shown in Table 1 below.

As shown in the table, the variation in photoelectric conversion efficiency is extremely small. This is particularly because there is a deep relationship with the extremely small variation in film thickness of the summer type semiconductor layer of the PIN type solar cell.

(e) Effects With the configuration of the present invention, the plasma generation space can be limited to only between the electrodes where the substrate is placed, and more uniform plasma can be generated.

Furthermore, since the substrate susceptor that limits the plasma generation space is movable, a large amount of substrates can be continuously processed.

Moreover, when a film is produced using the apparatus of the present invention, it becomes possible to form a very uniform film on a large-area substrate. This increases the number of elements that can be taken out from a large-area substrate, and also makes it possible to obtain uniform characteristics.

Furthermore, in large-area devices such as solar cells, the quality of the film on the substrate is uniform, so that overall characteristics can be improved.

[Brief explanation of drawings]

1 and 5 show the combination of the electrode shield and substrate susceptor of the present invention. FIG. 2 shows a conventional plasma CVD apparatus. FIG. 3 shows a plasma CVD apparatus used in the present invention. The worst part is that it is directly manufactured by Fuenai U City.・Substrate, electrode, electrode shield, substrate susceptor

Claims (1)

[Claims] 1. Plasma treatment is performed on the plurality of substrates by arranging the surfaces of the plurality of substrates between a pair of parallel plate electrodes in a reaction chamber that can be maintained in a reduced pressure state at positions not parallel to the electrodes. In the plasma processing apparatus, an inner wall of the reaction chamber, a pair of electrode shields provided between the electrodes, and a susceptor that holds the plurality of substrates constitute a closed space, and in the closed space, is provided with the electrode and the plurality of substrates,
A plasma processing apparatus characterized in that plasma generated by the electrode exists only in the closed space, and the susceptor can be drawn out in one direction. 2. A plasma processing apparatus in which the surfaces of a plurality of substrates are arranged at positions not parallel to the electrodes between a pair of parallel plate electrodes in a reaction chamber that can be maintained in a reduced pressure state, and plasma processing is performed on the plurality of substrates. By moving the susceptor holding the plurality of substrates from a predetermined direction and placing it at a predetermined position, a pair of electrode shields provided between the inner wall of the reaction chamber and the electrodes and the susceptor A plasma processing device that creates a space that confines plasma. 3. A plasma processing apparatus according to claims 1 and 2, characterized in that the electrode shield and the susceptor are made of a material having a conductive surface, and each is grounded similarly to the reaction chamber. .