JPS62165912A - Plasma vapor growth device - Google Patents

Abstract

PURPOSE:To improve the quality of a deposit film by supplying the connecting sections of each reaction vessel with hydrogen gas, making the pressure of the connecting sections lower than pressure in respective reaction vessel and preventing the mutual mixing of mixed gases in each reaction vessel. CONSTITUTION:Reaction chambers 21, 22, 23 and a winding tank 30 are evacuated, and SiH4, a hydrogen gas base, B2H6 and H2 are each introduced into the chamber 21 at the predetermined flow rates, SiH4 and H2 into the chamber 22 at the prescribed flow rates and SiH4, the hydrogen gas base, PH3, and H2 into the chamber 23 at the fixed flow rates. Intermediate tanks 25, 26 are supplied with H2 gas by feeders 32. The flow rates of the feeders 32 are controlled by a pressure controller. High-frequency energy at predetermined frequency is fed into the chambers 21-23, and plasma at a low temperature is generated. Consequently, P-type, I-type and N-type semiconductor films are each formed into the chambers 21, 22, 23. The pressure of the intermediate tanks 25, 26 is made lower than that of the chambers 21, 22, 23 at that time, thus improving the quality of the deposit films without scaling up a device.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to plasma vapor deposition (CVD).
l Vapor Deposition) method,
The present invention relates to a plasma vapor phase epitaxy apparatus for forming thin films, and relates to a plasma vapor phase epitaxy apparatus used to continuously produce semiconductors that are stacked to form a junction, that is, solar cells.

In the conventional plasma vapor phase epitaxy method, a substrate is held in a vacuum container, and while a compound gas containing the constituent elements of the thin film to be formed is supplied, the compound gas is excited by high frequency energy to coat the surface of the substrate. This is a method of forming a thin film on the surface of a substrate by placing it in that plasma atmosphere. This method is
Because it utilizes the activity of plasma, it can be heated up to 400°C from room temperature.
It has the characteristic that film formation can be performed at low temperatures down to about ℃.

An example of a conventional plasma vapor phase growth apparatus for carrying out the above-mentioned plasma vapor phase growth method is shown in FIG. 3, and will be described below.

A first reaction vessel 1 for forming a P-type semiconductor layer, a first intermediate tank 5, and a second reaction vessel 2 for forming a p-type semiconductor layer.
, the second intermediate tank 6 and the N-type semiconductor layer are connected. 1st. Second. A vacuum pump 4 is connected to each of the third reaction vessels 1, 2 and 3 to create a reduced pressure atmosphere inside the vessel. A vacuum evacuation device 8 is connected to the second intermediate tanks 5 and 6 to create a reduced pressure atmosphere inside them.

Next to the first reaction vessel 1 is an unwinding tank 1o for unwinding a hoop-shaped and long base material 9 to be plated, and next to the third reaction vessel 3 is a winding layer 11 of the base material. are airtightly connected. The unwinding tank 1o and the winding tank 11 are connected to an exhaust device 12 for creating a reduced pressure atmosphere inside the unwinding tank 10.The base material 9 unwound from the unwinding tank 10 is sequentially sent to various containers through the slit 7. and is wound up in the winding tank 11.
The operation of the plasma vapor deposition apparatus constructed as described above will be described below with reference to FIGS. 3 and 4.

First, after evacuating the first reaction vessel 1, second reaction vessel 2, third reaction vessel 3, first intermediate tank 6, second intermediate tank θ, unwinding tank 10, and winding tank 11 to a reduced pressure atmosphere, In the first reaction chamber 1, monosilane (S I H4) r diporane (
B2H6) and hydrogen (H2), a mixed gas of monosilane (S I H4) and hydrogen (H2) in the second reaction vessel 2, and monosilane (SiH2) in the third reaction vessel.
l Phosphine (PH3).

A mixed gas of hydrogen (H2) is introduced. Next, by generating low-temperature plasma using high-frequency power in the first reaction vessel 1, second reaction vessel 2, and second reaction vessel 3, P-type, engineering-type, and N-type semiconductor layers are laminated on the base material 9. and form it. At this time, the pressure in the first intermediate tank 5 and the second intermediate tank θ is
The pressure in the reaction vessel 1, the second reaction vessel 2, and the third reaction vessel 3 is set to about 1 Torr, and the pressure in the first intermediate tank 5 and second intermediate tank 6 is set to a high level of about 0.1 to 0.001 Torr. Hold in vacuum.

FIG. 4 shows the experimental results obtained by SIMS analysis of the distribution of boron (B) and phosphorus (P) mixed into the molded semiconductor layer.

Problems to be Solved by the Invention However, in the above configuration, when the mixed gas in the first reaction vessel 1 passes through the first intermediate tank 6 and diffuses into the second reaction vessel 2 to form an I-type semiconductor film, However, it had the disadvantage of deteriorating the film quality. Further, the second reaction chamber 2 and the third reaction chamber 3 also had similar drawbacks.

That is, as shown in FIG. 4, since there is a large amount of boron (B) and phosphorus (P) mixed in the semiconductor layer, a conversion efficiency of only about 3 cm can be obtained as a solar cell with a PIN structure. As a countermeasure, the first intermediate tank 5 and the second intermediate tank 6 are
Attempts have been made to increase the exhaust capacity of the vacuum evacuation device 8 in order to increase the length of the base material 9 in the traveling direction and to lower the gas concentration in the first intermediate tank 5 and the second intermediate tank 6.
The equipment becomes larger.

In view of the above problems, the present invention aims to increase the size of the apparatus when forming an I4 semiconductor film between the first reaction chamber 1 and the second reaction chamber 2 and between the second reaction chamber 2 and the third reaction chamber 3. Deterioration of the film quality can be prevented without causing any damage.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a plasma-type vapor phase growth apparatus for successively depositing at least two thin films of different materials on a surface to be formed on a substrate. at least two reaction vessels for forming a vapor grown film;
An evacuation means for evacuating the reaction product; and a reactive gas introduced into each reaction vessel by connecting each reaction vessel to each other in an airtight manner and maintaining the pressure at the connected portion lower than the pressure inside the reaction vessel. and a gas supply means for preventing the gases from mixing with each other during the plasma gas phase reaction.

Function The present invention has the above-described configuration, and by supplying hydrogen gas to the connecting portions of each of the reaction vessels, the pressure in the connecting portions is made lower than the pressure inside each reaction vessel, and each reaction It is possible to prevent the mixed gases in the container from mixing with each other, and it is possible to prevent the mixed gases from mixing with each other.

Example A first embodiment of the present invention shown in FIG. 1 will be described.

A first reaction vessel 21 for forming a P-type semiconductor layer, a first
The intermediate tank 26, the second reaction vessel 22 for forming an I-type semiconductor layer, the second intermediate tank 26, and the third reaction vessel 23 for forming an N-type semiconductor layer are successively connected in an airtight manner. A vacuum pump 2 is provided in the first reaction container 21, the second reaction container 22, and the third reaction container 23 to reduce the pressure inside them.
4 is connected. Next to the first reaction vessel 21 is an unwinding tank 29 for unwinding a hoop-shaped and long base material 28 to be plated, and next to the third reaction vessel 23 is a winding tank 30 for unwinding the base material 28. are airtightly connected to each other. A vacuum evacuation device 31 is connected to the unwinding tank 29 and the winding tank 30 to reduce the internal pressure to a reduced pressure atmosphere, and hydrogen gas is supplied to the first intermediate tank 25 and the second intermediate tank 26. A hydrogen gas supply device 32 for this purpose is connected.

Note that the base material 9 unwound from the unwinding tank 10 has a slit 2.
It is sequentially sent to each container through 7 and wound up in a winding tank 11.

The operation of the plasma vapor deposition apparatus constructed as described above will be explained below with reference to FIGS. 1 and 2.

First, after evacuating the first reaction vessel 21, second reaction vessel 22, third reaction vessel 23, unwinding tank 29, and winding 4!30, monosilane (S I
H4), hydrogen gas space (concentration 0.6%), diporan (B2H6), and hydrogen (H2) at 80 SCCM and 16
At a flow rate of 0 SCCM and 200 SCCM, the second reaction chamber 22
Inside are 2 each of monosilane (SiH4) and hydrogen (H2).
At flow rates of 50SCCM and 900SCCM, the third reaction chamber 2
3 contains monosilane (S i H4), hydrogen gas space (concentration o, 5%), phosphine (PH3), hydrogen (H
2) for each haosccM, aosccM, 280SCC
Introduce at a flow rate of M. Next, the first intermediate tank 26 and the second
Hydrogen gas is introduced into the intermediate tank 26 from the hydrogen gas supply device 32 . In addition, the pressure control means is used to control the first reaction chamber 21 and the second reaction chamber 21,
The pressures in the reaction chamber 22 and the third reaction chamber 23 are maintained at 1 Torr, and the pressures in the first intermediate tank 25 and second intermediate tank 26 are maintained at 1 Torr.
to 100 Torr.
control and maintain the flow rate.

Next, the first reaction chamber 21, the second reaction chamber 22, and the third reaction chamber 2
A low-temperature plasma is generated by supplying high-frequency energy with a frequency of 13.58 MHz to the inside of 3. Through these operations, a P-type semiconductor film is formed on the base material 28 in the first reaction vessel 21 , an engineered semiconductor film is formed in the second reaction vessel 22 , and an N-type semiconductor film is formed in the third reaction vessel 23 .

FIG. 2 shows the experimental results obtained by SIMS analysis of the distribution of poron (B) and phosphorus (P) mixed into the molded semiconductor layer. As can be understood from Figure 2, there is almost no mixing of boron (B) atoms and phosphorus (P) atoms into the I-type semiconductor layer, and the conversion efficiency as a solar cell is 8.6.
I was able to get %.

As described above, according to this embodiment, the first reaction vessel 21.
A hydrogen gas supply device 32 is provided for supplying hydrogen gas to the first intermediate tank 25 and the second intermediate tank 26, which are the connecting portions of the casing 2 reaction vessel 22 and the γ-dohani 3 reaction vessel 23. The pressure of the first intermediate tank 26 and the second intermediate tank 26 is
By setting the pressure lower than that of the second reaction vessel 22 and the third reaction vessel 23, the quality of the deposited film could be improved without increasing the size of the apparatus.

In this example, the gas introduced into the first intermediate tank 25 and the second intermediate tank 26 was hydrogen gas, but monosilane (
S*H4) It may be used as a gas. In addition, in this example,
Although the application to the case of creating a solar cell with a PIN type structure has been described, the same effect can be obtained when the present invention is applied to a plasma vapor phase epitaxy apparatus that sequentially deposits two types of thin films. Furthermore, the base material on which the thin film is formed is not limited, and may be made of glass, ceramic, etc., depending on the purpose, in addition to semiconductor wafers.

Effects of the Invention According to the present invention, by providing a gas supply device for supplying hydrogen gas or monosilane gas to the intermediate tank which is a continuous part of each reaction vessel, it is possible to prevent the mixed gases in each reaction chamber from mixing with each other. Therefore, the quality of the deposited film can be improved without increasing the size of the apparatus.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of a plasma vapor phase epitaxy apparatus according to an embodiment of the present invention, Fig. 2 is a schematic diagram of a plasma vapor phase epitaxy apparatus obtained using the apparatus of the present invention, and Fig. 4 is a schematic diagram of a plasma vapor phase epitaxy apparatus obtained using the apparatus of the present invention. FIG. 2 is a diagram showing the results of investigating the distribution in the depth direction of boron (monomer) and phosphorus (P) mixed into the molded semiconductor layer in the device. 21...First reaction container, 22...Second
Reaction container, 23...Third reaction container, 24...
...Vacuum pump, 25...First intermediate tank, 26
...Second intermediate tank, 27...Slit,
28... Base material, 29... Unwinding tank, 3
0... Winding tank, 31... Vacuum exhaust device, 32... Hydrogen gas supply device. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 3
Figure No. 4 (71/In-1

Claims (1)

[Claims] A plasma vapor phase growth apparatus that sequentially deposits at least two thin films of different materials on a surface to be formed on a substrate includes at least two reaction vessels for forming plasma vapor phase growth films and a reaction product. An evacuation means for evacuation and connecting each reaction container airtightly to each other,
It is characterized by comprising a gas supply means for keeping the pressure of the connecting part lower than the pressure inside the reaction vessels and for preventing the reactive gases introduced into each reaction vessel from mixing with each other in the plasma gas phase reaction. Plasma vapor phase growth equipment.