JPS60123021A - Amorphous semiconductor film forming device - Google Patents

Abstract

PURPOSE:To obtain an amorphous semiconductor film forming device enable easily to control discharge, and moreover to generate plasma having the large depositing speed of a semiconductor film by a method wherein hollow electrodes being hollow and having openings toward an anode, and the end parts of raw material gas introducing pipes are positioning in the inside spaces thereof are used. CONSTITUTION:Hollow electrodes 9 manufactured of hollow cylindrical metals perform DC discharge between a meshy anode 11 to generate plasma 10. The hollow cathodes 9 of the plural number of pieces are arranged lengthwise and breadthwise at a proper interval according to the size of a substrate 3. The substrate 3 is put on a mount 12 established on the opposite side from the discharge part interposing the meshy anode 11 between them, a heater 14 is equipped to the mount 12, and can be set at an arbitrary temperature. Raw material gas is supplied in the hollow cathodes 9 through insulator pipes 17 from a raw material gas introducing pipe 7, ionized or dissociated thereat having favorable efficiency in high density negative glow plasma formed in the cathodes, and products are deposited on the substrate 3 passing through the meshy anode 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field to which the Invention Pertains] The present invention relates to an amorphous semiconductor film producing apparatus in which a compound gas is decomposed by a plasma reaction using glow discharge and deposited on a substrate.

[Prior art and its problems]

FIG. 1 shows a typical generation device conventionally used for decomposing conductor material gas by a plasma reaction using glow discharge and depositing a semiconductor film. The following will explain the case of forming an amorphous silicon semiconductor film using silane (SiH) gas as an example. A raw material gas, silane or a mixed gas of silane and hydrogen, is introduced into the reaction chamber 6 connected via the vacuum exhaust pipe 8 through the introduction pipe 7, and the electrodes 1 and 2 are heated under reduced pressure around ITorr.
A glow discharge is generated in between. As a result, active species of silane and hydrogen are generated in the discharge plasma due to the collision of high-speed electrons, and these are heated by the heater 4 at the lower electrode 2.
is deposited on the substrate 3 placed on top of the substrate 3 to produce a semiconductor film.

The characteristics of the semiconductor film thus created depend largely on the characteristics of the discharge plasma. Direct current (hereinafter DO) is used to generate plasma.
There are two types of voltage application methods: the high-frequency (hereinafter referred to as R and F) voltage application methods, but currently the 'E
The LF applied force type is mainly used. However, in RF discharge, it is difficult to artificially control plasma other than Kugata power, and research methods for evaluating the physical properties of plasma have not been sufficiently established both theoretically and experimentally. There is a point. Therefore, it is difficult to apply the optimal discharge conditions for growing a semiconductor film of a certain quality in one generation device to another generation device.Furthermore, in the generation device with the structure shown in Fig. 1, RF discharge, D
Since the substrate 3 is directly exposed to the plasma regardless of the C discharge, an ion sheath is formed between the plasma and the substrate, and a large potential difference is generated between them. Positive ions accelerated by this potential difference collide with the substrate at high speed, which may deteriorate the characteristics of the semiconductor film. In order to avoid these problems, a method has been proposed in which a mesh electrode is placed between the substrate and the counter electrode, the discharge is performed between the mesh electrode and the counter electrode, and the deposition on the substrate is performed outside the plasma. In this case, it is easy to control and it is possible to use O discharge even for insulating substrates, but the disadvantage is that the deposition rate is slow regardless of whether RF discharge or DC discharge is used. 0 [Object of the Invention] The present invention was made in order to eliminate the drawbacks seen in the above-mentioned conventional devices, and provides a method for generating plasma that is easy to control discharge and has a high deposition rate of a semiconductor film. An object of the present invention is to provide a semiconductor film production device using the same.

[Key points of the invention]

According to this invention, a raw material compound gas is introduced into a vacuum reaction chamber, a DC voltage is applied between opposing electrodes provided in the reaction chamber to generate a glow discharge, the compound is decomposed, and the compound is placed near the anode and heated. In a device for depositing a semiconductor film on a substrate, the cathode is hollow and opens toward the anode, and the end of the raw material gas introduction tube is located in the interior space of the cathode. By using a hollow electrode, a high-density, high-energy plasma that cannot be obtained by DC discharge or RF discharge of a normal flat electrode is generated in the hollow cathode, and the excitation, dissociation, and ionization of the source gas are made more active. It was designed to be carried out in the following manner. Furthermore, by supplying the raw material gas by passing it through the hollow cathode, all of the raw material gas is exposed to high-energy plasma, thereby improving the utilization rate of the raw material gas, and as a result, the above object can be achieved.

[Embodiments of the invention]

FIG. 2 shows an embodiment of the invention, and parts common to those in FIG. 1 are given the same reference numerals. Reference numeral 9 in the figure indicates a hollow cylindrical hollow cathode made of metal, which generates plasma 10 by performing DC discharge between it and the mesh anode 11. In this case, a plurality of hollow cathodes 9 are arranged vertically and horizontally at appropriate intervals depending on the size of the substrate 3 on which the semiconductor thin film is to be formed. The substrate 3 is placed on a mount 12 which is installed on the opposite side of the discharge part with the mesh anode 11 in between.The mount 12 is equipped with a heater 14, and the substrate can be set to any temperature. .

In the embodiment shown in FIG. 2, the board mount 12 is installed at the top to prevent flakes and dust attached to the electrodes from falling onto the board. In order to obtain a spatially uniform plasma, each hollow electrode 9 and a DC power source 15 are connected via an independent variable resistor 16, so that the current flowing through each hollow electrode 9 can be adjusted.

The raw material gas is passed from the raw material gas introduction pipe 7 to the insulating pipe 17.
The products are supplied to the hollow cathode through the mesh anode 1, where they are efficiently ionized or dissociated in the high-density negative glow plasma generated within the cathode.
1 and is deposited on the substrate 3.

By making the distance from the mesh anode 11 to the hollow cathode 9 or the substrate 3 variable, the properties and deposition rate of the deposited film can be controlled by changing these distances. For example, when the distance from the mesh anode to the substrate is increased under certain discharge conditions, the ion density decreases as it moves away from the mesh anode due to spatial recombination with electrons, and at the same time, the electron energy (electron temperature) also rapidly increases with distance. decreases to The potential difference that occurs in the ion sheath between the plasma and the insulating substrate is proportional to the electron temperature, so in plasmas where the electron temperature is low, this potential difference becomes extremely small, making it possible to avoid the effects of ion collisions on the produced film.

Since the hollow cathode discharge is a DC discharge, the effect of ions can also be controlled by the DC bias power supply 17ζ connected between the anode 11 and the substrate mount 12 as shown in FIG. The hollow chest pole 9 is not limited to a hollow cylindrical shape, but may be a hollow conical shape.

〔Effect of the invention〕

In this invention, the plasma formed for the decomposition of raw material gas is generated by applying a DC voltage between a hollow cathode and an anode. Ionization and dissociation occur more actively than in normal glow discharge. Therefore, the semiconductor film deposition rate increases, and by supplying the raw material gas through the hollow cathode, the entire gas encounters a high-energy discharge, which enables effective use of the gas and improves the raw material efficiency. In particular, great effects can be obtained in the production of amorphous silicon conductor films for solar cells or photoreceptors.

[Brief explanation of the drawing]

FIG. 1 is an explanatory sectional view of a conventional glow discharge amorphous medium conductor generating device, and FIG. 2 is a sectional view of an embodiment of the present invention. 3... Substrate, 6... Vacuum reaction chamber, 7.17... Raw material gas introduction tube, 9... Hollow cathode, 11... Mesh anode, 12... Substrate mounting stand, 14... ·heater,
15...DC power supply. Figure 1 Figure 2

Claims (1)

[Claims] 1) A raw material compound gas is introduced into a vacuum reaction chamber, and a direct current voltage is applied between opposing electrodes provided in the reaction chamber to generate glow discharge, decomposing the compound and heating the substrate placed near the anode. 1. An amorphous semiconductor film production device for depositing a semiconductor film thereon, wherein the cathode is hollow and opens toward the anode, and the end of a raw material gas introduction pipe is located in the interior space of the cathode.