JPS59229878A - Novel amorphous semiconductor element and manufacture thereof and device for manufacturing the same - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel amorphous semiconductor device. More specifically, the present invention relates to a novel amorphous semiconductor element particularly valuable as a solar cell, a method for manufacturing the same, and an apparatus for manufacturing the same.

Conventionally, amorphous solar cells having a pin junction have attracted attention because their production costs are extremely low compared to single-crystal solar cells, and in recent years they have been considered to be the favorite among solar cells.

In this case, the pin junction has a so-called stepped bonding state between the p/i interface and the i/n interface, and solar cells with such a stepped pin junction are usually produced mainly by glow discharge plasma decomposition method. manufactured, pJW%
The 1st layer and nJEf were sequentially formed in different film forming chambers separated by valves, gas curtains, actuated exhaust, etc. That is, in order to manufacture a stepped pin junction element, it has been thought that it is particularly necessary not to mix impurities into the i-layer.

However, the conventional three-chamber separation system described above has p.

Since each chamber in which the i and n layers are formed is separated by a valve or the like, it takes time to move between the chambers, which poses a problem in productivity. Furthermore, as the substrate holder moves through the three chambers, the dopant elements are re-released from the film attached to the substrate holder, resulting in variations in the quality of the bonding devices manufactured by this method.

As a result of intensive research in order to eliminate such drawbacks of the conventional technology, the present inventors have discovered that the dopant concentration can be gradually changed without having a pin junction in which the dopant concentration is changed rapidly in a stepwise manner. An amorphous semiconductor device in which the potential profile can be arbitrarily controlled without the interfaces of /i and i/n being clearly separated (
Also when manufacturing a tilted junction element (hereinafter referred to as a tilted junction element),
The present invention was achieved by discovering that the obtained device can function satisfactorily as a solar cell.

Therefore, a first object of the present invention is to provide an amorphous semiconductor device that can be easily manufactured.

A second object of the present invention is to provide a novel graded junction amorphous solar cell without the concept of junction.

A third object of the present invention is to provide a method for easily manufacturing a sloped junction element.

Furthermore, a fourth object of the present invention is to provide a manufacturing apparatus for manufacturing a tilted junction element.

That is, the present invention provides an amorphous semiconductor characterized by having a graded junction in which the concentration of a p-type dopant monotonically changes from the p layer to the first layer, and the concentration of the n-type dopant monotonically changes from the iii layer to the n layer. An element, a method for manufacturing the same, and an apparatus for manufacturing the same.

In the present invention, the p-layer, n-layer, and i-layer refer to a p-type semiconductor layer, an n-type semiconductor layer, and one layer of a semiconductor region with high electrical resistance located between 1m of these layers, so-called p-layer.
The term "in junction" refers to a junction state in which a clear change in dopant concentration exists at the interfaces between the p region and the i region and between the i region and the n region.

In the graded junction element of the present invention, the distribution of dopant elements changes continuously and does not change in a so-called step-like manner, so there is no clear boundary for each of p/i and i/n. , therefore, in the strict sense, the conventional [pin
It is not included in the scope of "semiconductor devices having junctions".

The principle of manufacturing the graded junction element of the present invention is extremely simple, and it can be manufactured by controlling the concentration of dopant gas during film formation over time and/or position using the so-called glow discharge plasma decomposition method. I can do it.

In the present invention, the glow discharge plasma decomposition method means that a raw material gas and, if necessary, a dopant gas are present in a reduced pressure reaction chamber, and a plasma state is generated by high-frequency discharge, low-frequency discharge, or direct current discharge. This refers to a method of forming a semiconductor thin film on a substrate by decomposing gas in a reaction chamber.

The gas pressure in the reaction chamber varies depending on the type of gas, but in the present invention, any pressure range may be used as long as a uniform discharge state can be obtained in relation to the electrodes and the applied voltage.

In the present invention, such pressure is 0.01=lOT
orr, preferably 0.05 to 2 Torrs, more preferably 0.3 to 0.6 Torr.

As the raw material gas used in the present invention, any gas that can be used when manufacturing semiconductors using the glow discharge plasma decomposition method can be used, but in particular, silane represented by 5inH2n+2 and For example, silane derivatives represented by SinXmH2n+2-m (X represents a halogen atom) and mixtures thereof are preferred.

Further, a gas for adjusting the film quality, such as a rare gas or hydrogen gas, can also be used in the reaction chamber.

The dopant gas used in the present invention is a gaseous compound of an element from group ① of the periodic table of elements when producing a p-type semiconductor thin film, and a gaseous compound of an element from group ① of the periodic table of elements when producing an n-type semiconductor thin film. It is a gaseous compound of group elements.

Among these dopant gases, hydrogen compounds are particularly suitable for making the reaction conditions during discharge constant and the performance of the produced thin film uniform, and can be preferably used.

In the present invention, in order to continuously control the concentration of the dopant in the semiconductor thin film, it is necessary to maintain the gas pressure in the film forming chamber at a dischargeable pressure while supplying new gas! It is necessary to use a flow system to exhaust the gas inside the membrane chamber. However, this flow system does not necessarily have to be continuous in time, and the concept also includes a case where a fixed amount of gas in the reaction chamber is replaced at fixed time intervals.

Specifically, firstly, the amount and type of dopant gas in the film forming chamber is controlled over time by the method described above, or secondly, the amount and type of dopant gas vary depending on the position of the film forming chamber. There are two methods of forming a semiconductor thin film by sequentially moving the substrates within the film forming chamber.

As an example of the gaseous atmosphere of the first method, for example, after completely mixing the dopant gas and making the dopant gas exist uniformly in the film forming chamber, the l''-pant gas is There is a method of changing from one to the other over time.The first method is suitable for manufacturing a small amount of semiconductors in a laboratory, but is not suitable for mass production.

The second method allows semiconductors to be manufactured continuously, so it is a preferred method especially when mass production is performed.

Next, an apparatus for manufacturing the inclined junction element of the present invention will be explained with reference to the drawings.

FIG. 1 shows an example of an apparatus for manufacturing the inclined junction element of the present invention.

1 in the figure is a *membrane chamber, which is connected to the vacuum preparatory chamber 2 via a border valve 3. Reference numeral 6 denotes a cathode electrode provided in the film forming chamber, and as shown in the figure, this can be divided into a plurality of cathode electrodes as required.

On the other hand, the anode electrode 7 on which the substrate 8 is mounted is movably arranged within the i-film chamber.

5 is a power source for discharging, which is, for example, a high frequency oscillator. 11 to 13 are gas cylinders, for example, 11 is a dopant gas cylinder for a p-type semiconductor thin film, 12 is a dopant gas cylinder for an n-type semiconductor thin film, and 13 is a raw material gas cylinder for one layer.

A specific method for manufacturing the inclined junction element of the present invention using the apparatus of the present invention is, for example, as follows.

First, the substrate (8) is placed on the anode electrode (7) in the preliminary chamber, and the preliminary chamber (2) is evacuated by the vacuum system (4). Next, the film forming chamber (1) is evacuated by the vacuum system (4).
of the gas supply ports (9), from the first supply port.
2% B2H5/SiH4 at 20SCCM (however, SCC
M is the volume of gas flowing in 1 minute under standard conditions, cm
It is supplied at a flow rate of 3if (expressed in 203 CCM) from the second to sixth supply ports.
The flow rate is 0.4% from the 7th supply port.
(7) PH3/S i H4 is supplied with IO3CCM,
A voltage is applied between the cathode and the anode through the power source (5) to start discharging. The supply gas is supplied into the film forming chamber through a flow meter and a fine adjustment valve such as a needle valve, while the gas within the film forming chamber is exhausted from a gas exhaust port (lO) through an exhaust system.

Next, open the edge cutting valve (3) and move the anode electrode with the substrate placed in the preparation chamber from part A in the film forming chamber to E.
By moving up to that portion, the inclined joining element of the present invention can be obtained. The photoelectric conversion efficiency of the semiconductor obtained in this specific example was 7.3% when measured under AMI irradiation, which is sufficient for use as a solar cell.

In this case, if the anode electrodes are set at regular intervals like a belt conveyor, semiconductors can be manufactured continuously.

If the anode electrode is not moved and the anode electrode with the substrate placed on each part A to E is fixed, the semiconductor obtained in parts A and B is p-type, and the semiconductor obtained in parts D and E is p-type. The semiconductor was n-type, and the electric conductivity of the crotch obtained at each part A to E was as shown in Figure 3.This result shows that when the substrate is moved from A to E, This allows us to estimate that the dopant elements are distributed in the obtained film with a continuous concentration gradient as shown in FIG.

The anode electrode used in the apparatus of the present invention may be a single continuous electrode, and therefore the substrate used in the present invention may be moved, for example, by a belt conveyor system as shown in FIG.

11 The amount of gas in the membrane chamber can be arbitrarily controlled by adjusting various valves provided in the apparatus of the present invention.
As shown in the figure, a baffle plate can be provided between each gas supply port to control the gas flow by moving it up and down.

The semiconductor manufacturing apparatus of the present invention includes a film forming chamber, a preliminary chamber, the position, size and number of gas supply ports, the position, size and number of exhaust ports, and the position, size and number of baffle plates. The size of the device and its constituent parts, such as valves and exhaust systems, can be optimally designed depending on the size of the semiconductor thin film to be manufactured, the moving speed, etc.

The semiconductor manufacturing method of the present invention is extremely easy because semiconductors can be manufactured by just 111 m of raw material gas and I-punt gas, and there is no need for edge-cutting valves, which are critical operations for semiconductor manufacturing. There is no need to worry about making mistakes. Furthermore, the structure of the device itself can be simplified, making it economical.

The semiconductor of the present invention manufactured simply and economically in this manner has sufficient photoelectric conversion efficiency, and is particularly suitable for use as a solar cell due to its economic efficiency.

[Brief explanation of the drawing]

FIG. 1 shows an example of a schematic diagram of an apparatus for manufacturing the inclined junction element of the present invention. The code 1 in the diagram is! ! movie room,
2 is a vacuum preliminary chamber, 3 is a cutting valve, 4 is a vacuum system, 5 is a high frequency oscillation device for discharge, 6 is a cathode electrode, 7 is an anode electrode, 8 is a substrate, 9 is a gas supply nozzle, 10 is a gas Exhaust ports 1112 and 1112 are respectively connected to dopant gas cylinders, 13 is connected to raw material gas cylinders, and 14 is a valve for adjusting the exhaust amount. Figure 2 shows another specific example of the M membrane chamber, in which reference numeral 6 is a cathode electrode, 7' is a belt-shaped anode electrode, 8 is a substrate, and 5 is a vertically movable electrode. It is a possible baffle board. Fig. 3 shows the use of the apparatus shown in Fig. 1, with the anode electrodes A,
It is a graph showing the relationship between the electrical conductivity of a semiconductor manufactured by fixing it at each position of BSC, D, and H and each position. FIG. 4 shows the concentration distributions of boron and phosphorus, respectively, as dopant gases in the graded junction element of the present invention and corresponding elements. The symbol 2° in the figure is a stainless steel substrate, 2
1 represents the p layer, 22 represents the 1st layer, and 23 represents the n layer, and the SIMS signal is the element concentration measured by the secondary ion mass spectrometer, (
a, u, ) represent arbitrary units. Patent Applicant Toa Fuel Industry Co., Ltd. No. 3 LL Figure 4

Claims (1)

[Scope of Claims] 1) An amorphous semiconductor device characterized in that the concentration of a p-type dopant changes monotonically from the p-layer to the i-layer, and the concentration of n-type dopant changes monotonically from the i-layer to the n-layer. 2) In a method of manufacturing an amorphous semiconductor using a glow discharge plasma decomposition method, by controlling the concentration of dopant gas in the source gas, the concentration of the dopant element in the manufactured semiconductor thin film is continuously changed. A method for manufacturing an amorphous semiconductor device in which each interface of a p-layer, an i-layer, and an n-layer is a tilted junction. 3) In an amorphous semiconductor manufacturing apparatus using a glow discharge plasma decomposition method, the film forming chamber for forming the p layer, 1ffit, and n layer is one common chamber, and the 1!
! An apparatus for manufacturing an amorphous semiconductor device, characterized in that the film chamber is a film forming chamber in which the concentration of dopant gas can be controlled depending on the position of the film forming chamber. 4) Made II! Claim 3, characterized in that the chamber is provided with one or more raw material gas supply ports and one or more gas exhaust ports for continuously controlling the concentration distribution of the dopant gas. An apparatus for manufacturing an amorphous semiconductor device according to item 1. 5) The amorphous semiconductor device according to claim 3 or 4, characterized in that one or more baffle plates are provided in the film forming chamber in order to control the concentration distribution of the dopant gas. Manufacturing equipment. 6) The amorphous semiconductor device manufacturing apparatus according to claim 5, wherein the baffle plate in the film forming chamber is provided along the flow of gas in the film forming chamber.