JPH09184064A - Production of chalcopyrite base thin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a chalcopyrite base thin film such as CuInSe2 of good quality. SOLUTION: This method contains a stage (A) in which a thin film of the group Ib elements contg. at least one of Cu and Ag is formed by a suitable method such as vapor deposition, sputtering or the like and a stage (B) in which the surface of this thin film of the group Ib elements is fed with the group IIIb elements containing at least one among Al, Ga and In and the group VIb elements containing at least one among S, Se and Te using a hot wall device.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a chalcopyrite-based semiconductor thin film such as a CuInSe ₂ thin film which is a semiconductor thin film used as an absorption layer of a solar cell.

[0002]

_2. Description of the Related Art Conventionally, as a manufacturing method of a CuInSe ₂ semiconductor thin film used as an absorption layer of a solar cell, a sputtering method, an electrodeposition (electroplating) method, a three-source deposition method, a selenization method, a printing method, etc. It has been known.

[0003]

Of the above-mentioned conventional CuInSe ₂ thin film manufacturing methods, it is difficult to obtain a high-quality one because of the influence of plasma in the sputtering method, and it is easy for impurities to be mixed in in the electrodeposition method. There is a problem that it is difficult to obtain high quality products. On the other hand, although the three-source evaporation method and the selenization method can obtain a good quality CuInSe ₂ thin film, the three-source evaporation method has a problem that it is difficult to increase the area. It is necessary to use hydrogen selenide having a high temperature, and there is a problem that the cost becomes high for safety management. Further, as a problem common to all of the above methods, there is a problem that the deposited In evaporates when the substrate is heated to a high temperature.

II-VI, such as CdS, which has a relatively low boiling point
For the group compound semiconductor crystal and the IV-VI group compound semiconductor crystal such as PbTe, a film formation method by a hot wall method is known. The hot wall method has the advantages of excellent composition controllability, simple apparatus configuration, and low cost, since the crystal growth is performed in a state close to the thermochemical equilibrium state. However, when applying this hot wall method to CuInSe ₂ film formation, if the vapor pressure of Cu, which has a high boiling point (2630 ^o C), is increased to a practical range in consideration of film formation production time, There is a problem that a high temperature exceeding the upper limit temperature of the tube is required.

As represented by CuInSe ₂ described above, Ib
In the thin film of chalcopyrite compound produced by combining each element of group IIIb, group VIb and group VIb in the ratio of the number of atoms of 1: 1: 2, the boiling point of group Ib element such as Cu, Ag, Au IIIb group elements such as B, Al, Ga, In, Tl and S, Se, T
Since it has a higher value than the boiling points of VIb group elements such as e and Yb, it has the same problem as in the case of CuInSe ₂ described above.

[0006]

A method for producing a chalcopyrite-based thin film according to the present invention which solves the above-mentioned problems of the prior art includes at least one of Cu and Ag on a substrate.
A step of forming a thin film of the Ib group element, on the thin film of the Ib group element, using a hot wall device, Al, Ga, IIIb element containing at least one of In, Se, And a VIb group element containing at least one of Te. That is, for the elements of Group Ib for which it is difficult to apply the hot wall method due to the high boiling point, a thin film is formed in advance by another appropriate method such as vapor deposition or sputtering, and the hot wall method is applied only to the remaining low boiling point element. To be done.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION According to an embodiment of the present invention, a step of forming a thin film of a group Ib element on a substrate, and a hot wall device on the thin film of a group Ib element are used to form a group IIIb element. The step of depositing the element of group VIb and the element of group VIb are alternately repeated multiple times in the same vacuum apparatus. According to the embodiment of the present invention, Cu, In, and Se are selected as the elements of Group Ib, Group IIIb, and Group VIb, and CuInSe ₂ is produced.

[0008]

EXAMPLE FIG. 1 shows CuInSe _{2 according to an} example of the present invention.
FIG. 6 is a cross-sectional view for explaining the method of manufacturing a thin film. First,
As shown in (A), a substrate 10 made of soda glass is placed on a quartz holder 15 in a vacuum chamber with its surface facing downward, and a resistance heating type tungsten boat is mounted. After placing a high-purity copper piece in 16, the inside of this vacuum chamber is evacuated. With the pressure in the vacuum chamber reaching about 10 ^-6 Torr, an electric current was passed through the tungsten boat 16 to resistance-heat it up to around the boiling point of copper, 2630 ^° C, to obtain a Cu film with a thickness of about 0.2 μm. A thin film 11 of the element is formed on the surface of the substrate 10.

Next, as shown in FIG. 1B, the substrate 10 on which the Cu thin film 11 is formed is placed on a holder 21 in another vacuum device having a hot wall device incorporated therein,
Evacuated until the inside the vacuum apparatus to a pressure of about 3 × 10 ^{over 7} Torr. After exhaustion, the temperature of each part in the hot wall device is raised to a predetermined temperature, and after confirming that the temperature of each part is stable, the substrate 10 together with the holder 21 is moved above the hot wall device.

This hot wall device has a large-diameter quartz tube 23 having a closed bottom and an open top, and a closed bottom extending from the bottom of the quartz tube 23 through the bottom to the inside thereof. Small diameter quartz tube 24 with open top
A wall heater 25 for heating the upper portion of the large diameter quartz tube 23, a source heater 26 for heating the bottom portion of the large diameter quartz tube 23, and a bottom portion of the small diameter quartz tube 27. And a substrate heater 28 for heating the substrate 28.

The source portion formed at the bottom of the quartz tube 23 holds a mass of In ₂ Se _{3 as} a source material, and the reservoir portion formed at the bottom of the quartz tube 24 holds a mass of Se as a reservoir material. Has been done. By adjusting the heating value of the heater of each part, the temperature of the wall part is 550 ^o C, the temperature of the source part is 650 ^o C, the temperature of the reservoir part is 200 ^o C, and the temperature of the substrate is 400 ^o C. It is set. The substrate 10 on which the Cu thin film 11 is formed is allowed to stay for 15 minutes above the hot wall apparatus in which such temperature control is performed, and then the holder 21 is carried away from above.

At this time, the Cu formed on the surface of the substrate 10
In and Se containing a compound of In ₂ Se ₃ are supplied onto the thin film of No. ₃ for 15 minutes to form a thin film of CuInSe ₂ having a thickness of about 1.5 μm. In order to keep the ratio of the number of atoms of each element necessary to obtain the desired compound CuInSe ₂ , 1: 1: 2,
The thickness of the Cu film formed in advance and the amounts of In and Se supplied to this Cu film are controlled. The control of the supply amounts of In and Se is controlled by the heater temperatures of the source part and the reservoir part of the hot wall device and the dwell time of the Cu thin film above the device.

FIG. 2 shows the result of crystal structure analysis by the X-ray diffraction method performed on the sample prepared under the above-mentioned conditions. The horizontal axis represents the X-ray incident angle (2θ), and the vertical axis represents the X-ray reflection intensity. The X-rays irradiated on the sample are Cu-based αX-rays generated by irradiating a pure copper target with an electron beam of 30 KV and 16 mA. The incident angle resolution is
The scanning speed is 0.020 ^o and the scanning speed is 5.00 ^o / min. 27
CuInSe with chalcopyrite structure at the incident angle of ~ 28 ^o
It can be seen that a sharp reflection intensity peak indicating the presence of ₂ appears, and the peak indicating the presence of another structure is extremely small. That is, it was revealed that the prototype sample was made of extremely high quality chalcopyrite structure CuInSe ₂ .

The structure in which the copper thin film is formed in one vacuum chamber and the remaining steps are performed by the hot wall device formed in another vacuum chamber has been described above. However, it is preferable to form a copper thin film and use a hot wall device.
Supply of In and Se is performed in the same vacuum chamber. Also,
The composition of supplying In ₂ Se ₃ and Se after forming a Cu thin film was illustrated, but from different evaporation sources in the hot wall device,
In and Se may be separately supplied. Further, Se may be supplied from the outside of the hot wall device.

Further, instead of forming a CuInSe ₂ thin film having a desired thickness all at once, a step of forming a Cu thin film shown in FIG. 1A and a Cu thin film by the hot wall method shown in FIG. 1B. By repeating the step of supplying In and Se to the surface of the same in a plurality of times in the same vacuum chamber, alternately.
It may be configured to improve the uniformity in the thickness direction.

Although the case of forming a CuInSe ₂ thin film has been illustrated, generally, Ag or the like is selected as the element of the Ib group in addition to Cu, and In addition to In as the element of the group IIIb. A
l, Ga, etc. are selected and other than Se as the VIb group element.
By selecting S, Te or the like, the production method of the present invention can be applied to the production method of a thin film of any compound belonging to the chalcopyrite system.

[0017]

As described above in detail, in the method for producing a chalcopyrite-based thin film according to the present invention, for the elements of Group Ib for which the hot wall method is difficult to apply due to the high boiling point, vapor deposition, sputtering, etc. Since a thin film is previously formed on the surface of the substrate by another appropriate method and the hot wall method is applied only to the remaining low boiling point elements, it is within the upper limit temperature range of the quartz tube or the like constituting the hot wall device. The effect that a high-quality chalcopyrite thin film can be formed is obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a method of manufacturing a CuInSe ₂ thin film according to an embodiment of the present invention.

FIG. 2 is CuInSe manufactured according to the manufacturing method of the above example.
₂ is data showing the result of analysis of the crystal structure by the X-ray diffraction method performed for ₂ .

[Explanation of symbols]

10 Glass substrate 11 Cu thin film 12 CuInSe ₂ semiconductor thin film 21 Holder 22 Tungsten boat 23,24 Quartz tube 25 Wall heater 26 Source heater 27 Reservoir heater 28 Substrate heater

Claims (5)

[Claims] 1. A step of forming a thin film of an Ib group element containing at least one of Cu and Ag on a substrate by an appropriate method such as vapor deposition or sputtering, and a thin film of the Ib group element. And a step of supplying a group IIIb element containing at least one of Al, Ga and In and a group VIb group containing at least one of S, Se and Te using a hot wall apparatus. A method for producing a chalcopyrite-based thin film, comprising: 2. The step of forming a thin film of the Ib group element on a substrate according to claim 1,
Using a hot wall device on a thin film of group Ib element
A method of manufacturing a chalcopyrite thin film, characterized in that the step of supplying the group IIIb element and the group VIb element are performed in the same vacuum apparatus. 3. The step of forming a thin film of an Ib group element on the substrate according to claim 2,
The step of supplying the IIIb group element and the VIb group element by using a hot wall device on the thin film of the Ib group element,
Cu characterized by being alternately repeated multiple times
InSe ₂ thin film manufacturing method. 4. The element according to claim 1, wherein the group Ib element is Cu, and the group IIIb element and VIb.
Cu, characterized in that the elements of the group are In and Se, respectively
InSe ₂ manufacturing method. 5. The step of supplying In and Se onto the Cu thin film by using a hot wall apparatus according to claim 4, wherein In ₂ Se ₃ is supplied from the source section and Se is supplied from the reservoir section at the same time. A method of manufacturing a CuInSe ₂ thin film, comprising the steps of: