JP2562686B2 - Plasma processing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Use of the Invention The present invention comprises a photoelectric conversion device composed of amorphous and polycrystalline non-single-crystal semiconductors containing silicon as a main component or a non-single-crystal semiconductor containing silicon as a main component. The present invention relates to a plasma processing apparatus that can be applied to the formation of elements such as thin film field effect transistors on a large substrate.

(B) Conventional technology Non-single-crystal semiconductor thin films containing silicon as a main component and insulator thin films such as silicon oxide and silicon nitride formed by plasma enhanced chemical vapor deposition (hereinafter referred to as plasma CVD) are used for solar cells, It is widely applied as a material for photoelectric conversion devices such as image sensors and thin film field effect transistors used for liquid crystal display devices. These electronic devices are composed of a stack of multiple thin films with different properties, and with the increasing size and cost of these devices, these electronic devices are manufactured for the purpose of industrially producing a large area and mass. The conventional plasma processing apparatus that has been known is shown below.

Figure 2 shows the most common plasma using parallel plate electrodes.
The schematic sectional drawing of a CVD apparatus is shown.

In this case, one vacuum reserve chamber (26) and one reaction chamber (23) are shown. Substrate (1) is substrate support (21)
It is installed above and is conveyed to the reaction chamber (23) together with the support (21) through the sluice valve (22). The substrate (1) is heated by the heater (24) in the reaction chamber (23), and after reaching a predetermined temperature, the reactive gas is decomposed and activated by the discharge electrode (25) to form a thin film on the substrate. To form.

In this method, as is clear from the figure, the substrate and the electrode are parallel to each other, and therefore, it was necessary to increase the electrode area when forming a thin film on a large-area substrate.

Furthermore, since it can be formed only in an area almost equal to the electrode area in one thin film forming step, it is insufficient for large-scale processing of substrates.

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

As shown in the drawing, a plurality of film-forming substrates (1) are arranged between the parallel plate electrodes (31) so as to be perpendicular to the electrodes,
We achieved more than 10 times the number of substrates to be processed in a single treatment, and at the same time, the floor area 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 form a coating on a larger substrate.
Actually, the plasma discharge becomes unstable as the upper and lower electrode intervals become wider, and therefore the electrode interval is usually set within twice the one side of the electrode. There are some drawbacks in the plasma vapor phase reaction method for processing such a large area and a large amount of substrates.

That is, since the distance between the electrodes is considerably long, the coating film formed on the substrate has a film thickness distribution in the direction between the electrodes except under a specific film forming condition. This is shown in Fig. 4 (A),
Shown in (B), (C) and (D). This shows a schematic diagram of how to attach a film when a non-single crystal silicon semiconductor is produced on a glass substrate by the plasma vapor phase reaction apparatus of FIG. As shown in the region I of FIG. 4 (A), when the reaction pressure is high and the input power of the high frequency power is low, it is formed on the upper and lower parts of the substrate in the electrode direction as shown in FIG. 4 (B). The number of coatings formed increases, and the film has such a film thickness distribution. During the production of this film, it was observed that the plasma emission regions in the reaction chamber where the plasma reaction was performed were gathered near the upper and lower electrodes. Next, when the reaction pressure is low and the input power of high-frequency power is high, it is formed in the area III in FIG. 4 (A), near the central portion in the electrode direction of the substrate as shown in FIG. 4 (D). It has many coatings and has such a film thickness distribution.

Although it is a narrow range, it was possible to obtain a substantially uniform film thickness distribution as shown in FIG. 4 (C) in the region II of FIG. 4 (A).

In this way, the characteristics of each semiconductor element formed on the same substrate with a non-uniform film thickness distribution on a large-area substrate,
In particular, the physical and electrical characteristics were greatly varied, and there was no industrial value even if a TFT or a photoelectric conversion device was manufactured on a large area substrate.

(C) Object of the invention The present invention is to supplement the above-mentioned drawbacks of the conventional method, and relates to an apparatus for producing a coating having a uniform film thickness distribution on a large amount of large-area substrates under a wide range of conditions.

(D) Configuration of the invention The present invention relates to a plasma processing apparatus which solves the above-mentioned problems, and a pair of electrode shields (4) are provided between the inner wall of the reaction chamber and the discharge electrode (3), and the electrode shield ( 4) forms a closed space between the discharge electrodes (3) and a substrate susceptor (5) for disposing a plurality of substrates (1) in a state not parallel to the electrodes, and the substrate susceptor is It can move in any direction and forms a closed space with the above-mentioned electrode shield when it is installed at a predetermined position in the reaction chamber.

With such a configuration, the pair of discharge electrodes and the plurality of substrates are all surrounded by the electrode shield and the substrate susceptor, and the plasma discharge is not leaked to the outside from the enclosed space and the density is almost equal between the substrates. The plasma atmosphere described above is formed, and it becomes possible to form a film with good uniformity even on a large-area substrate.

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

An example of the structure of the electrode shield and the substrate susceptor is shown in FIG.

In FIG. 1 (A), the substrate susceptor (5) can be moved to the right in the drawing and forms a closed space together 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 FIG. 7B, and the substrate susceptor is movable with such a structure,
It forms an electrode shield and a closed space.

Further, FIG. 5 shows an example of a combination of another electrode shield and a substrate susceptor.

The present invention is not particularly limited to the structures shown in these and other structures can also reflect the idea of the present invention.

 The present invention will be described below with reference to examples.

Example In this example, the 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) having a size of 300 mm × 400 mm is set on the substrate susceptor (5) so as to be arranged perpendicularly to the electrodes. In the case of the present embodiment, ten glass substrates (1) are attached to the same susceptor (5), but if the distance between the glass substrates (1) facing each other is 20 mm or more, the discharge occurs reproducibly, and more Although it is possible to form a film on the substrate of No. 3, if the thickness of the film on the substrate is considered to be uniform, about 10 to 15 sheets are preferable in the case of this embodiment. Since this substrate interval changes depending on other factors such as the pressure at the time of forming the coating, it is not appropriate to fix it to one.

Also, the electrode shield (4) and the substrate susceptor (5)
Has the structure shown in FIG. 1, and these electrode shields and substrate susceptors can be made of metal such as nickel, stainless steel, aluminum, or ceramics having a conductive material formed on the surface thereof. In this embodiment, these are made of an aluminum material having a punching hole of 10 mmφ. This punching hole was provided to improve the flow of the reactive gas and to shorten the initial exhaust time, but the plasma did not leak from the punching hole.

Further, in this embodiment, the electrode shield and the substrate susceptor are grounded so that more uniform plasma is generated only between the discharge electrodes. As a result, each substrate was placed in a more uniform plasma atmosphere.

The susceptor (5) on which the glass substrate is set is put into the plasma reaction chamber from the preliminary chamber (62), and after vacuum evacuation, the gate valve (63) is opened and the first transfer mechanism (not shown) is used. After moving to the reaction chamber (64), it is omitted because it cannot be drawn in the figure, but the film forming temperature is set by the substrate heating heaters on the front side and the back side which are parallel to the paper surface of FIG.
It can be heated up to about 0-300 ℃.

In this state, silane gas was introduced into the reaction chamber (64) at a flow rate of 50 SCCM, and the pressure in the reaction chamber in which the conductance of the exhaust system was controlled can be maintained at 0.01 to 0.1 torr.

Next, high-frequency power of 13.56MHz is applied between the upper and lower parallel plate electrodes (61), and the plasma discharge is confined in the space defined by the side surfaces of the upper and lower electrode shields (4) and substrate support susceptor (5). Therefore, it has not reached the inner wall of the reaction chamber (64). Therefore, the coating film formed is formed only in the space described above, and it is not necessary to clean the inner wall of the reaction chamber, or the number of times of cleaning can be extremely reduced.

Using the device of the present invention, P, I, on a 300 mm × 400 mm substrate
500 solar cells having an N structure (device area 1.05 cm ² ) were prepared. The characteristics are shown in Table 1 below.

Thus, the variation in photoelectric conversion efficiency is extremely small. This is because it is closely related to the fact that the variation in the film thickness of the I-type semiconductor layer of the PIN solar cell is very small.

(E) Effect With the configuration of the present invention, the plasma generation space can be limited to only between the electrodes on which the substrate is placed, and more uniform plasma can be generated.

Further, 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. As a result, the number of elements that can be taken out from the large-area substrate is increased, and the characteristics can be made uniform.

Further, in a large-area element such as a solar cell, the quality of the film on the substrate is uniform, so that the characteristics can be improved as a whole.

[Brief description of drawings]

1 and 5 show the combination of the electrode shield and the substrate susceptor of the present invention. FIG. 2 shows a conventional plasma CVD apparatus. FIG. 3 shows the plasma CVD apparatus used in the present invention. FIG. 4 shows the result formed by the conventional method. FIG. 6 shows the plasma processing apparatus of the present invention. 1 ... Substrate 3 ... Electrode 4 ... Electrode shield 5 ... Substrate susceptor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-60-111415 (JP, A) JP-A-60-213020 (JP, A) JP-A-63-237409 (JP, A)

Claims (3)

(57) [Claims] 1. A plasma treatment in which the surfaces of a plurality of substrates are arranged in a position not parallel to the electrodes between a pair of parallel plate electrodes in a reaction chamber that can be maintained under reduced pressure, and plasma treatment is performed on the plurality of substrates. An apparatus, wherein a pair of electrode shields provided between the inner wall of the reaction chamber and the electrode and a susceptor holding the plurality of substrates are superposed to form a closed space, and the closed space is formed. The plasma processing apparatus is characterized in that the electrode and the plurality of substrates are provided inside, the plasma generated by the electrode exists only in the closed space, and the susceptor can be drawn out in one direction. . 2. A plasma treatment in which the surfaces of a plurality of substrates are arranged in a position not parallel to the electrodes between a pair of parallel plate electrodes in a reaction chamber that can be kept under a reduced pressure, and plasma treatment is performed on the plurality of substrates. A device, wherein a pair of electrode shields provided between the inner wall of the reaction chamber and the electrodes by arranging the susceptor holding the plurality of substrates in a predetermined position by moving the susceptor from a predetermined direction, A plasma processing apparatus in which a space for confining plasma is formed by overlapping the susceptor. 3. The electrode shield and the susceptor according to claims 1 and 2 are made of a material having a conductive surface, and each is grounded like the reaction chamber. Plasma processing equipment.