JPH0338730B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mass-production thin film production apparatus that simultaneously produces thin films on a large number of substrates in one reaction chamber by plasma CVD, such as is used in the production of amorphous silicon solar cells, for example.

FIG. 1 shows a well-known amorphous silicon film production apparatus, in which a substrate 3 is placed on an electrode (susceptor) 2 arranged horizontally in a reaction tank 1, and a substrate 3 is heated by a heater in the electrode 2. With the flat electrodes 3 facing each other, the air is evacuated from the exhaust port 5 and the air is discharged from the cylinder 6.
SiH ₄ gas, H ₂ gas from cylinder 7, Ar gas from cylinder 8, B ₂ H ₆ gas from cylinder 9 for forming a P-type film, and PH from cylinder 10 for forming an N-type film. A reaction gas containing a mixture of the _three gases is introduced into the reaction tank 1 through an introduction pipe 11, and a glow discharge is generated between the electrodes 2 and 4 by a high frequency power source 12 or a DC power source 13. This decomposes SiH ₄ and forms an amorphous silicon film on the substrate. However, when such an apparatus is expanded to simultaneously process a large number of substrates in one reaction chamber, the reaction chamber requires a large area and is therefore not structurally suitable as a vacuum chamber. In addition, there is a risk that the film of by-products deposited on the inner wall of the reaction chamber may peel off and adhere to the substrate surface, causing defects in the produced film. That is difficult. In order to eliminate these drawbacks, electrode plates that support substrates such as semiconductor wafers and also serve as electrodes are arranged vertically in multiple layers inside a quartz tube, and these are electrically connected alternately to two conductor rods. A method is known in which the electrodes are divided into two groups and a voltage is applied between them.
-Refer to Publication No. 134663).

However, with this method, the voltage must be distributed to each electrode within the reaction tube using conductor rods, so when high voltage or high frequency power of megahertz or higher is supplied, the voltage must be distributed only between the electrode plates. However, there is a drawback that abnormal discharge occurs between the conductor rod and the electrode plate or between the conductor rods, and stable discharge cannot be obtained. Moreover, in this method, the substrate is heated from the outside of the reaction tube, so when applied to a large-area substrate, the outer periphery of the substrate becomes hotter than the center, and the reaction tube wall is exposed to high temperatures. thermal CVD occurs on the quartz tube wall at the same time.
There is a big practical problem.

It is an object of the present invention to eliminate such drawbacks, provide a mass-produced thin film production device that requires only a small area of the reaction chamber, and is free from the risk of objects falling from the inner wall of the reaction chamber adhering to the substrate surface. .

The purpose of this is to generate a glow discharge by applying a voltage between a first electrode housed in the reaction chamber and a second electrode parallel to it, decomposing the reaction gas and converting its components into a thin film. In a device that generates on a substrate supported by electrodes, a large number of first electrodes and second electrodes are alternately arranged vertically at equal intervals, and both sides of the first electrode sandwiched between two second electrodes are used. This is achieved by supporting the substrates respectively.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 partially shows the bottom surface of a reaction chamber according to an embodiment of the present invention, in which an electrode (susceptor) 21 containing a heater and a counter electrode 22 are vertically erected alternately and parallel to each other on the bottom surface 23 of the reaction chamber. ing. The bottom surface 23 of the reaction chamber consists of an insulating part 24 and a conductive part 25, and electrodes 21 and 22 are fixed to the conductive part 25. The electrode 21 also has a built-in magnet, and attracts and supports a substrate 26 made of a ferromagnetic material, for example, ferrite stainless steel such as JISSUS430, on both sides. A voltage is applied between these electrodes 21 and 22, and the substrate 2 is heated by plasma CVD method.
A thin film is produced on 6. In this case, since the substrate 26 is vertical, byproducts that peel off from the inner wall of the reaction chamber and fall vertically do not adhere to the substrate surface.
Furthermore, since the substrates 26 are attached to both sides of the vertical electrode 21, thin films can be produced on a large number of substrates in a reaction chamber with a small area, which is advantageous in terms of floor space efficiency and vacuum structure.

FIG. 3 shows another vertical support method for the substrate, in which the ends of the substrate 26 are placed on the bases of both sides of the electrodes 21 by the guide plates 2.
It is narrowly attached to 7.

In FIG. 4, all electrodes, except for the counter electrode 22 in FIGS. 2 and 3, are mounted on a susceptor 2 with a built-in heater.
1, and every other susceptor 21 is connected to one pole of the power source to generate discharge. Each susceptor 21
Since the substrates 26 are attached to both sides, it is possible to process about twice as many substrates as in the case of FIGS. 2 and 3. Furthermore, since the low-temperature electrode 22 is not present, the number of locations where by-products adhere is reduced, and the ambient air in the reaction chamber is kept clean with less by-products being mixed in, resulting in improved film quality.

In the above example, the electrodes 21 and 22 are erected on the bottom surface 23 of the reaction chamber, but they may be fixed to the side wall of the reaction chamber.

As described above, in the present invention, a large number of two types of electrodes to which a voltage is applied between for glow discharge are arranged parallel to each other, alternately and vertically, in one reaction chamber. This allows a large number of substrates to be supported on the electrode compared to the occupied area, and also prevents by-products adhering to the reaction chamber walls from falling and adhering to the substrate surface when peeled off. It is possible to produce high-quality films with high quality, and can be used extremely effectively, especially for mass production of amorphous silicon solar cells. Furthermore, by applying a voltage to generate a glow discharge between the first and second electrode groups via a wiring network outside the reaction chamber, both electrodes can be connected using a conductive rod. Unlike the supported conventional device, there is no abnormal discharge other than between the electrodes, stable discharge is obtained, and film formation performance can be significantly improved, especially in mass-produced devices using large-area substrates.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional example of an amorphous silicon film production device, FIG. 2 is a partially cutaway perspective view of a thin film production device according to an embodiment of the present invention, and FIG.
The figure is a cross-sectional view of another embodiment of the electrode portion, and FIG. 4 is a cross-sectional view of a further different embodiment. 21... Electrode (susceptor), 22... Counter electrode,
23...Bottom surface of the reaction chamber, 26...Substrate.

Claims (1)

[Claims] 1. Glow discharge is generated by applying a voltage between a first electrode housed in a reaction chamber and a second electrode facing it, decomposing the reaction gas and converting its components into a thin film. In the case where a large number of first electrodes and second electrodes are formed on a substrate supported by one electrode, a large number of first electrodes and second electrodes are arranged on the reaction chamber wall alternately at equal intervals, and a discharge voltage can be applied to each electrode. The first and second electrode groups are directly fixed vertically to the wall of the reaction chamber via a conductive part that also serves as a conductor, and a glow discharge is generated between the first and second electrodes via a wiring network outside the reaction chamber. What is claimed is: 1. A mass-produced thin film production device, characterized in that a voltage is applied thereto, and substrates are supported on both sides of a first electrode sandwiched between two second electrodes. 2. In the device according to claim 1,
A mass-produced thin film production device characterized in that the first electrode has a built-in magnet and the substrate is made of a ferromagnetic material. 3. In the device according to claim 1,
1. A mass-produced thin film production device characterized in that the ends of the substrates are sandwiched between the base of a first electrode and a guide plate, each of which is fixed to one wall of a reaction chamber. 4. A mass-produced thin film production device according to any one of claims 1 to 3, characterized in that a substrate is supported on the second electrode as well as on the first electrode.