JPH04326525A - Manufacture of i-iii-vi compound semiconductor thin film - 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]

0001

[Industrial Application Field] The present invention is applicable to I
-Regarding a method for producing a III-VI group compound semiconductor thin film.

0002

2. Description of the Related Art Conventionally, the following methods have been known as methods for producing I-III-VI group compound semiconductor thin films. That is, a method in which copper and indium layers are electrodeposited sequentially or simultaneously on a substrate by electroplating and then heat treated in the presence of a selenium-containing gas to obtain CuInSe2, and elemental selenium is evaporated onto the copper and indium layer, JP-A No. 61-237476 discloses a method in which the material is then heat-treated in an inert gas atmosphere. In addition, a method using vacuum evaporation, such as simultaneous evaporation of component elements and evaporation of intermetallic compounds, is disclosed in JP-A-57-502196, in which copper, indium, and selenium are sequentially evaporated, and the amount of selenium is adjusted to the required stoichiometric amount. JP-A-1-231313 discloses a method in which heat treatment is performed in the presence of selenium and sulfur-containing gas in a state where the temperature is below stoichiometric. Further, JP-A-2-73674 discloses a method of forming a concentration distribution of Se and S in the film thickness direction by sequentially changing the solution supply ratio of selenium source and sulfur source using a spray pyrosis method.

According to the above method, I-III-V
The composition ratio, which greatly affects the performance of Group I compound semiconductors, especially the composition ratio between Group I elements such as Cu and Ag and Group III elements such as In and Ga, can be changed by changing the film thickness when stacking these elements. It was controlled. However, when III group elements such as In and Ga are deposited as a film, they tend to grow in a direction perpendicular to the substrate surface, resulting in a striped structure, making it difficult to smooth the film surface. Moreover, even if a smooth surface is obtained, I
When n and Ga are in a metallic state, Cu2Se and Cu
The production of low temperature stable intermediate products such as 2S was unavoidable. Such intermediate products do not completely disappear even when subjected to high-temperature heat treatment, making it extremely difficult to form the final product into a desired single compound phase.

That is, according to the above-mentioned conventional method, there is a problem in composition controllability, which is the most important, and microscopic segregation of components tends to occur, and in some cases, I-III-V
In addition to the group I chalcopyrite phase, Cu2Se and Cu2
There was a problem in that the mixing of intermediate products such as S was unavoidable.

On the other hand, in order to obtain a single-phase ternary compound without producing the above-mentioned intermediate products, there is a method of reacting with Se and S at a temperature of 200° C. or higher, or 2
At temperatures below 00°C, an inert gas atmosphere such as N2 is used, and at temperatures above 200°C, Se and S-containing gases are introduced. However, In and Ga each have a melting point of 153°C.
Since the temperature is extremely low at 30° C. and the surface tension is large, each element aggregates or forms a liquid phase of In and Ga before interdiffusion, that is, sulfidation and selenization begins. In this way, In and Ga aggregate and In
If a liquid phase of In or Ga is present, pinholes or film peeling may occur in the surrounding area, and the surface state of the final product, the ternary compound film, cannot directly reproduce the surface state of In or Ga. Therefore, there was a problem that the surface accuracy was poor and there were many irregularities.

[0006]

[Problems to be Solved by the Invention] The present invention solves the problems of the above-mentioned conventional techniques, improves composition controllability, eliminates micro-segregation, and has a smooth film surface.
It is an object of the present invention to provide a method for manufacturing a Group I compound semiconductor film.

[0007]

[Means for Solving the Problems] In order to solve the above problems, the present inventors conducted extensive research and found that they formed In and Ga as oxide films on Cu and Ag films, and
By heat treatment in a reducing gas atmosphere containing e and S, the reduction of the metal oxide and the selenization and sulfidation of the metal proceed simultaneously, resulting in a ternary compound thin film in which no intermediate products are present. We have discovered this and were able to provide the present invention.

That is, the present invention provides the general formula (Cu1-x
Agx )(In1-y Gay )(Se1-z S
z)2 (0≦x, y, z≦1) A method for producing a semiconductor thin film made of a group I-III-VI compound represented by 0≦x, y, z≦1; Gallium oxide, preferably In2
The above I-III-VI, characterized in that one or both of O3 and Ga2O3 is deposited individually or simultaneously, and then heat treated at a temperature of 200°C or higher in a reducing gas atmosphere containing a Se source and an S source. The present invention provides a method for manufacturing a group compound semiconductor thin film.

[0009] In the present invention, H2 Se is used as the Se source.
One or both of H2 gas and Se gas can be used, and one or both of H2 S gas and S gas can be used as the S source, and one or both of H2 and CO can be used as the reducing gas. be able to.

Further, the deposited film of Cu and Ag in the present invention may be a metal or an oxide, or may be a combination of a metal and an oxide.

[0011]

[Operation] In the present invention, as a method for depositing Cu and Ag films on a substrate, a commonly used vapor deposition method, sputtering method, electrodeposition method, or the like can be used. It has been confirmed on an industrial scale that these methods form a smooth film surface and are excellent in controlling the film thickness. Also, Cu
Even if Ag is an oxide or partially oxidized, there is no problem as long as the contents of Cu and Ag are known. This is because the ratio of group I elements to group III elements can be controlled by the thickness of the group III element oxide layer deposited later, and moreover, the ratio of group I elements to group III elements can be controlled by the thickness of the oxide layer of group This is because the oxide is much more easily reduced than In2 O3 and Ga2 O3, which are oxides of group III metals.

On the other hand, In2 O3 or Ga2 O3
Even in the case of depositing, there is no problem as long as a chemical deposition method such as a vapor deposition method, a sputtering method, or a dip coating method is used. This is In2 O3 and Ga2
O3 has a much higher melting point than metals In and Ga,
This is because it has excellent film forming properties, and Sn
This is clear from the fact that it is well known that a transparent conductive ITO film doped with O2 can be formed with high precision.

The laminated film produced as described above is subjected to heat treatment in a reducing gas atmosphere containing S and Se. In this case, since In2 O3 and Ga2 O3 do not exhibit any reaction even if S and Se gases are introduced at high temperatures, it is necessary to coexist S and Se gases with a reducing gas such as H2. In addition, the heat treatment temperature is 200℃
If the temperature is less than 200°C, the reduction reaction of the oxide will hardly proceed, so it is necessary to heat the temperature to 200°C or higher. 200
The fact that the reduction reaction does not proceed at a heat treatment temperature below .degree. C. means that no intermediate products are produced and a single-phase ternary compound can be easily obtained.

Furthermore, In2 O3 and Ga2 O3
is thermally stable and does not change in quality when heated to about 200°C. Therefore, the surface condition during film formation is maintained even at high temperatures during heat treatment, making it difficult for the surface of the resulting film to be uneven. Therefore, it is possible to perform selenization and sulfurization at the desired temperature while maintaining the surface condition at the time of film formation.
A high quality ternary compound thin film can be obtained. Note that until the temperature at which selenization or sulfidation is reached, N
2 There is no problem even under an inert gas atmosphere such as gas.

[0015] The present invention will now be explained in more detail with reference to Examples. However, the scope of the present invention is not limited by the following examples.

[0016]

[Example 1] In this example, a film with a thickness of 2000A (
In2O3 was laminated thereon by sputtering so that the atomic ratio of Cu:In was 1:1 and the film thickness was 5300A. Note that the In2O3 target in this sputtering method is prepared by press-molding In2O3 powder and
The material sintered at 0°C was used. Moreover, the surface roughness (Ra) of this laminated film was about 1000A.

Next, the laminated film was placed in a reaction tube and N2
The temperature was raised to 400°C at a rate of 5°C/min in a gas atmosphere. When the temperature reached 400℃, H2S and H
2Se with a flow rate molar ratio of H2S/(H2Se+H
2 S) = 0.9, and after 2 hours, N
2. Switched to gas and cooled to room temperature.

The film obtained as described above was grayish-black in color, and no pinholes or peeling were observed. In addition, when the chemical composition of the obtained film was investigated, it was found that Cu:I
n:S:Se=24.4:25.2:4.7
: 45.7 (atomic %), and a film having almost the target composition could be obtained. Furthermore, when we performed X-ray analysis on the obtained membrane, we found that
The single phase was chalcopyrite, and no other different phases were observed. The surface roughness (Ra) of the obtained film was approximately 2
000A, which was almost unchanged compared to before the heat treatment.

[0019]

Example 2 A film was produced in the same manner as in Example 1, except that In2 O3 was replaced with Ga2 O3 and Ga2 O3 was deposited to a thickness of 7300 Å by vacuum evaporation.

The obtained film was grayish black, and no pinholes or peeling were observed. The chemical composition of the obtained film is Cu:Ga:S:Se=23.8:
25.2:5.0:46.0 (atomic %),
A film having almost the target composition could be obtained. moreover,
When the obtained film was subjected to X-ray analysis, it was found that it had a single phase of chalcopyrite and no other different phases were observed. The surface roughness (Ra) of the obtained film was approximately 2200A.
The Ra before the heat treatment was about 1200 A, which was almost unchanged.

[0021]

[Example 3] Approximately 4% In2O3 was deposited by dual simultaneous vapor deposition.
A film was produced in the same manner as in Example 2 except that about 700 A of Ga2 O3 was laminated. In this example, the target atomic ratio of In2O3 and Ga2O3 was Ga:In=0.1:0.9.

The obtained film was gray-black in color, and no pinholes or peeling were observed. Moreover, the chemical composition of the obtained film is Cu:In:Ga:S:Se=23.9
: 24.2 : 2.3 : 4.8 : 44.8
(atomic %), and a film having almost the target composition could be obtained. Further, when the obtained film was subjected to X-ray analysis, it was found that it was a single phase of chalcopyrite and no other different phases were observed. In addition, the surface roughness of the obtained film (
Ra) was about 2700 A, which was almost unchanged compared to before the heat treatment.

[0023]

[Comparative Example 1] A film was prepared in the same manner as in Example 1 except that heat treatment was performed at 200° C. for 10 hours. The obtained film had no change in appearance from before the heat treatment. When the obtained film was subjected to X-ray analysis, it was found that Cu and In2O3
was observed, but no substitution reaction occurred.

[0024]

[Comparative Example 2] A film was produced in the same manner as in Example 1, except that Cu and In were sequentially laminated by vacuum evaporation, and the film thicknesses of Cu and In were set to 2000 Å and 4100 Å, respectively.

The obtained film was grayish-black in color, but peeling was observed in some places. In addition, the chemical composition of the obtained film was C
u:In:S:Se=27.8:21.7:
4.9: 44.6 (atomic %), which was a large deviation from the target composition. Furthermore, when we performed X-ray analysis on the obtained membrane, we found that
A peak considered to be CuS or Cu2S was present in addition to the chalcopyrite phase. Note that the surface roughness (Ra) of the obtained film was 4500 A before heat treatment and 18600 A after heat treatment, and the unevenness of the film surface was significantly increased.

[0026]

[Effects of the Invention] Through the development of the present invention, the I-III-V film is free from microscopic component segregation and has a smooth film surface.
It has become possible to manufacture Group I compound semiconductor films with good controllability of composition.

Claims (3)

[Claims] Claim 1: General formula (Cu1-x Agx) (I
I-III-V expressed as n1-y Gay )(Se1-z Sz )2 (0≦x, y, z≦1)
A method for producing a semiconductor thin film made of a Group I compound, the method comprising:
After depositing one or both of u and Ag and one or both of indium oxide and gallium oxide individually or simultaneously, heat treatment is performed at a temperature of 200 ° C. or higher in a reducing gas atmosphere containing a Se source and an S source. A method for producing the above-mentioned I-III-VI group compound semiconductor thin film. 2. The manufacturing method according to claim 1, wherein indium oxide and gallium oxide are In2 O3 and Ga2 O3, respectively. 3. The Se source comprises H2Se gas and S
Claim 1, wherein the S source is one or both of H2S gas and S gas, and the reducing gas is one or both of H2 and CO.
Manufacturing method described.