TWI391505B - In situ method for depositing a cuins2 film and a solar device comprising the same - Google Patents

Description

Method for depositing CuInS 2 film layer in situ and solar component including the same

The present disclosure is directed to a method of forming a CuInS ₂ film layer in situ without breaking a vacuum, and a solar cell element comprising the formed CuInS ₂ film layer.

In recent years, the development of solar-related technologies has been quite rapid, and CuInS ₂ thin films have been widely used for manufacturing photovoltaic elements, such as thin film solar cells, because of their high absorption coefficient. CuInS ₂ thin film solar cells are known to have a total area efficiency of 12.2% over a small area of 0.38 square centimeters (D. Braunger et al., Proc. 25 IEEE Photovoltaic Specialists Conf. IEEE, New York, May 13-17, 1996, p. 1001).

A conventional method for forming a CuInS ₂ film includes first preparing a Cu-In film which can be used as a precursor, followed by heat-treating the precursor film, and performing a sulfurization reaction to form a desired CuInS ₂ film. The entire process will require the use of two different processing chambers, including a deposition chamber where a precursor film can be deposited, and a reaction chamber for heat treatment and sulfurization. In the process, after the deposition of the precursor film is completed, the deposited precursor film is removed from the deposition chamber and transferred to another reaction chamber for heat treatment and vulcanization. Since the substrate needs to be transferred between different processing chambers, the process becomes complicated and the substrate is easily contaminated during the transfer.

In view of this, there is a need in the art for a new solution that can reduce the probability of substrate contamination by simplifying the process without detracting from the properties of the CuInS ₂ film itself.

Accordingly, a first aspect of the present disclosure is to provide a method of depositing a CuInS ₂ film, comprising:

(a) providing a substrate to a processing chamber;

(b) depositing indium and copper elements on the substrate by physical deposition to form a Cu-In film having a two-layer structure;

(c) thermally annealing the Cu-In film;

(d) vulcanizing the Cu-In film to form the CuInS ₂ film;

Wherein, during the processing of the respective steps, the processing chamber is always maintained in a state where the vacuum is not broken.

In one example, the substrate is made using any material selected from the group consisting of ruthenium, plastic, glass, a Group III-V compound, or an oxide. In one embodiment, the physical deposition in step (b) is thermal evaporation and is performed without heating the substrate. The heat treatment in the step (c) is carried out at about 150 ° C for at least about 2 hours. The step (d) further comprises the steps of: introducing a sulfur-containing gas into the processing chamber; heating the substrate to about 350 ° C to about 550 ° C; and processing the substrate at a pressure of about 8.5 Pa to about 1000 Pa. Up to 2 hours. In a specific example, the step (d) is carried out for about 1 hour at a pressure of about 146.7 Pa and a temperature of about 550 ° C; in another specific example, the step (d) is at a pressure of about The temperature was 1000 Pa and the temperature was lower than about 450 ° C for about 1 hour. The CuInS ₂ film formed by the method has an average thickness of about 1830 nm and a copper/indium ratio of about 1.13.

In another example, the step (b) is repeated at least three times to form a Cu-In film having a six-layer structure, and the Cu-In film formed has an overall thickness of about 800 nm, and the Cu- The copper/indium ratio in each layer structure of the In film is about 1.8. In a specific example, the step (d) is carried out for about 1 hour at a pressure of about 146.7 Pa and a temperature of about 550 ° C; in another specific example, the step (d) is at a pressure of about The temperature was 1000 Pa and the temperature was lower than about 450 ° C for about 1 hour. The CuInS ₂ film formed by the method described in this example has an average thickness of about 1220 nm, and wherein the copper/indium ratio has decreased to about 1.13.

Another particular embodiment of the invention provides a solar component. The solar element comprises a substrate characterized by comprising a CuInS ₂ film deposited by the foregoing method. In one example, the CuInS ₂ film is formed by a Cu-In film having a two-layer structure, which is formed by thermal annealing and vulcanization, and has an overall thickness of about 1830 nm; in another example, the CuInS ₂ film. The film is formed of a Cu-In film having a six-layer structure, which is also formed by thermal annealing and vulcanization, and has an overall thickness of about 1220 nm. Further, cadmium sulfide, essential zinc oxide, aluminum-doped zinc oxide and a nickel/aluminum electrode layer may be sequentially grown on the formed CuInS ₂ film to form a solar element. In one example, a solar cell is fabricated using the above-described substrate including a CuInS ₂ film, and the solar cell produced has a photoelectric conversion efficiency of about 3%.

These and other features of the present disclosure will become more apparent from the following detailed description. The above summary and the following detailed description are merely illustrative, and are not intended to limit the scope of the disclosure.

The main content of the present invention is to provide a method for forming a CuInS ₂ film layer in situ, which is characterized in that the process chamber is continuously in a vacuum state during the whole process, that is, the CuInS ₂ film is formed in situ without breaking the vacuum. The layer can thereby effectively improve the problem of film contamination caused by vacuum interruption in the prior art process without detracting from the characteristics of the CuInS ₂ film layer.

In the novel in-situ process disclosed, a Cu-In film suitable as a precursor is formed on a substrate by thermal evaporation, and then a heat treatment and a vulcanization reaction are performed to obtain a CuInS ₂ film layer. Substrate. This substrate can be made into an application component, such as a solar component, for subsequent applications.

Hereinafter, the related art of the present invention will be described by taking an embodiment in which a substrate including a CuInS ₂ film layer is manufactured as an example.

Accordingly, a first aspect of the present invention provides a method of depositing a CuInS ₂ film layer comprising the steps of:

(a) providing a substrate to a processing chamber;

(b) depositing indium and copper elements on the substrate by physical deposition to form a Cu-In film having a two-layer structure;

(c) thermally annealing the Cu-In film;

(d) vulcanizing the Cu-In film to form the CuInS ₂ film;

Wherein, during the processing of the respective steps, the processing chamber is always maintained in a state where the vacuum is not broken.

In step (a) of the process of the invention, a substrate is first provided into a processing chamber. Materials suitable for use in the substrate of the method of the invention include, but are not limited to, any material selected from the group consisting of ruthenium, plastic, glass, a Group III-V compound, or an oxide thereof. As for the processing chamber, any chamber suitable for physical deposition, such as the PVura chamber of the Endura series manufactured by Applied Materials, Inc., can be used.

Next, in the step (b) of the method of the present invention, indium and copper elements on the indium and copper targets are sequentially deposited on the surface of the substrate by physical deposition in the processing chamber (the substrate is It is held on a susceptor by electrostatic, magnetic or other means, thereby forming a Cu-In film having a two-layer structure suitable as a CuInS ₂ film precursor. Suitable physical deposition methods include thermal evaporation, electron beam physical vaporation, sputter deposition, pulsed laser deposition, or cathodic arc discharge deposition. (cathodic arc deposition). In one example, this Cu-In film is deposited using thermal evaporation. Thermal evaporation is generally carried out by heating a coating material (for example, metal Cu) under vacuum using an electric resistor to evaporate and spray it on a substrate or a sample surface, thereby achieving the purpose of depositing a thin film. The step (b) is characterized in that the deposited film layer is made uniform by rotating the susceptor for holding the substrate in the processing chamber during thermal evaporation, but the substrate is not heated. A Cu-In film having a two-layer structure having a thickness of about 800 nm is formed by sequentially depositing indium elements and copper elements on the substrate. In another specific embodiment, step (b) is repeated at least 3 times to form a Cu-In film having a 6-layer structure alternately stacked by Cu/In/Cu/In/Cu/In. In the Cu-In film, the copper/indium ratio in each layer structure is controlled to be about 1.8, and each layer has substantially the same thickness, so that the Cu-In film has an overall thickness of about 800 nm.

Next, in the step (c), the formed Cu-In film having a two-layer structure or the Cu-In film having a six-layer structure is subjected to thermal annealing treatment. Generally, the thermal annealing treatment is carried out at a temperature of from about 100 ° C to about 200 ° C for about 1 to 3 hours. In one example, this thermal annealing treatment is carried out at about 150 ° C for about 2 hours. It has been found that the surface of the heat treated film has better surface uniformity. Therefore, in a preferred embodiment of the present invention, a Cu-In film (having a 2- or 6-layer structure) which has been heat-treated for 2 hours is used as a starting material to carry out a vulcanization reaction, and the Cu-In film is completely converted into a film. CuInS ₂ film.

In the step (d), first, a sulfur-containing gas suitable for performing a sulfurization reaction, such as H ₂ S gas, is mixed with an inert carrier gas into a gas mixture at an appropriate ratio, and then introduced into the gas mixture. Processing in the chamber. Suitable carrier gases include, but are not limited to, inert gases such as helium, nitrogen, helium or argon which do not participate in the sulfurization reaction. In one example, a gas mixture consisting of H ₂ S and Ar, wherein the volume ratio of H ₂ S is about 10%, is introduced into the processing chamber. Next, the substrate of the Cu-In film containing the 2 or 6 layer structure is heated to about 350 ° C to about 550 ° C. Then, the substrate is subjected to a vulcanization reaction with the introduced sulfur-containing gas at a pressure of about 8.5 Pa to about 1000 Pa for about 1 to 2 hours. In one example, a 2-layer Cu-In film or a 6-layer Cu-In film is used as a starting material, and the reaction is carried out at a pressure of 146.7 Pa and a vulcanization temperature of 550 ° C to obtain an average of the CuInS ₂ film layer. The particle sizes are approximately 1830 nm and 1220 nm, respectively. In another example, the chamber pressure is increased to 1000 Pa, and a Cu-In film having a two-layer structure is used as a starting material, and reacted at 450 ° C, 500 ° C, and 550 ° C vulcanization temperatures, respectively, to obtain a CuInS ₂ film layer. The average particle size is about 2000 nm, 2100 nm, and 2230 nm, respectively. In another embodiment, the Cu-In film having a 6-layer structure is used as a starting material, and reacted at 450 ° C, 500 ° C, and 550 ° C vulcanization temperature, and the average particle size of the obtained CuInS ₂ film layer is about 1640 nm, respectively. 1940 nm and 2220 nm.

In a particularly preferred embodiment, the step (d) is carried out for about 1 hour at a pressure of about 146.7 Pa and a temperature of about 550 °C. In another particularly preferred embodiment, the step (d) is carried out for about 1 hour at a pressure of about 1000 Pa and a temperature of less than about 450 °C. After the step (d), the CuInS ₂ film formed has an average thickness of about 1830 nm, and wherein the copper/indium ratio is about 1.13.

It is important that in the method of the invention disclosed in steps (a) through (d), the processing chamber is always maintained without interrupting the vacuum, thereby avoiding interruption of the chamber vacuum The problem of film contamination is caused, and a CuInS ₂ film layer having a better surface morphology and roughness can be provided.

Accordingly, another aspect of the present disclosure is to provide a solar energy component. The solar component comprises a substrate characterized by comprising a layer of a CuInS ₂ film contained in the above method. In a specific example, a solar element is fabricated by a substrate comprising a CuInS ₂ film layer formed by the method of the present invention, and the solar element has a photoelectric conversion efficiency of about 3% under simulated sunlight.

The embodiments and the proper nouns are used to illustrate the invention and are not intended to limit the scope of the disclosure. The scope of the disclosure is also not specifically disclosed herein, but other embodiments that can be readily inferred by those skilled in the art after reading this disclosure.

Unless otherwise defined, all professional and scientific terms used herein have the same meaning as those skilled in the art. In addition, any methods and materials similar or equivalent to those described may be employed in the methods of the invention. The preferred embodiments and materials described herein are for illustrative purposes only. All references cited in this application are hereby incorporated by reference in their entirety to the extent of the disclosure of the disclosure of the disclosure. Moreover, the documents discussed herein merely disclose prior art techniques of the present application. And there is no literature showing that the present invention has been disclosed in the prior art. The actual data obtained in the context of the present invention may differ from the data disclosed in the present disclosure by the present invention.

It should be noted that the specific terms such as "one ("a" or "an")" and "the" are used in the content of the specification and the scope of the appended claims unless specifically stated otherwise. Its plural form.

The preferred embodiments of the present disclosure are described in detail below, examples of which are illustrated in the accompanying drawings. The same elements in the respective drawings are denoted by the same element numbers.

Example

The following examples are presented to illustrate the specific aspects of the disclosure and to assist those skilled in the art to understand and implement the present disclosure. However, the scope of the disclosure is not limited to these embodiments.

Example 1 Manufacturing CuInS ₂ film 1.1 Manufacture of Cu-In precursor film

First, a glass substrate having a size of 2.5 mm x 2.5 mm was placed in a processing chamber to hold the substrate with an electrostatic chuck. The chamber pressure of the processing chamber is lowered to about 2.4 x 10 ^-4 Pa by vacuuming. Next, in the first set of experiments, indium elements and copper elements were separately deposited on the substrate by thermal evaporation to form a Cu-In precursor film having a two-layer structure with a thickness of about 800 nm. In the second set of experiments, indium elements and copper elements were alternately deposited at least 3 times to form a Cu-In film having a 6-layer structure alternately stacked by Cu/In/Cu/In/Cu/In. In the Cu-In film, the ratio of copper/indium in each Cu-In layer is controlled to about 1.8, and each Cu-In layer has substantially the same thickness, so that the overall thickness of the Cu-In film is about 800 nm. During the thermal evaporation, the sink film layer is made uniform by rotating the electrostatic chuck for holding the substrate, but the substrate is not heated.

Next, the deposited film layer was heat-treated at a temperature of about 150 ° C, including a Cu-In precursor film having a two-layer structure and a Cu-In film having a six-layer structure, for about 1 or 2 hours. The crystal structure of the deposited film was analyzed by glazing incident X-ray diffraction (GIXRD) (Rigaku D/MAX 2500), and the surface of the film was analyzed by scanning electron microscopy (SEM). form.

Fig. 1 is an XRD spectrum of a Cu-In film having a 2-layer or a 6-layer structure. As can be seen from the figure, although the process can successfully deposit a Cu-In film having a desired Cu ₁₁ In ₉ phase (Fig. 1, ▲), a small amount of copper can be found in each phase. (Fig. 1, indicated by Δ). At the same time, SEM scan analysis also found that the film heat treated at 2 hours had better surface uniformity (not shown) than the film heat treated only for 1 hour. Therefore, in the subsequent CuInS ₂ thin film process, a Cu-In film (having a 2- or 6-layer structure) which was heat-treated for 2 hours was used as a starting material for the vulcanization reaction.

1.2 Manufacturing CuInS ₂ film

A Cu-In film having a 2-layer or 6-layer structure and heat-treated for 2 hours, which was prepared in the above Example 1.1, was used as a starting material, and was subjected to a vulcanization treatment in the following procedure to prepare a desired CuInS ₂ film. Briefly, a 10% H ₂ S/Ar gas mixture is introduced into the processing chamber and at different pressures of about 8.5 Pa, 81.3 Pa, 146.7 Pa, and 1000 Pa, respectively, and between about 350 ° C and about 550 ° C. At a temperature, a vulcanization reaction is carried out for about 1 to 2 hours to produce a different CuInS ₂ film.

Similarly, the crystal structure of the obtained CuInS ₂ film was analyzed by GIXRD, and the results are shown in Fig. 2. It can be seen from the curve (A) of Fig. 2 that Cu ₁₁ In ₉ (curve A, ▲) and Cu can be observed on the film layer after vulcanization at 8.5 Pa pressure and 450 ° C for 2 hours. The peak (shown by curve A, Δ) indicates the temperature and pressure vulcanization reaction conditions, which is insufficient to completely cure the Cu-In film.

It was found that for the Cu-In film with two or six layers, the chamber pressure and reaction temperature were increased to 146.7Pa and 400 °C, respectively, and the reaction time was maintained at about 1 hour, which could effectively improve Cu. - The extent to which the In film is vulcanized. Moreover, as the vulcanization temperature increases, the proportion of Cu-In in the film layer gradually decreases (Fig. 2, curve A vs curve B), and the components of each component can be analyzed by energy dispersion spectroscopy (EDS). It was found that the Cu/In ratio in the CuInS ₂ film has been reduced to about 1.13. When the reaction time and pressure are kept constant and the reaction temperature is raised to 500 ° C, the fully vulcanized state can be reached (Fig. 2, curve C). At this time, only the CuInS ₂ phase exists in the film layer, and EDS analysis shows that CuInS ₂ The Cu/In ratio in the film was maintained at about 1.13 and did not change. When the reaction temperature is further increased to 1000 ° C, in addition to the CuInS ₂ phase, a peak of Cu ₂ S (Fig. 2, curve D) appears; for a Cu-In film having a 6-layer structure, here At the reaction temperature of 1000 ° C, a Cu ₂ S peak also appeared (results not shown).

It was found that the Cu-In film of 2 or 6 layers was used as the starting material under the pressure of 146.7 Pa and the vulcanization temperature of 550 ° C. The average particle size of the obtained CuInS ₂ film layer was about 1830 nm and 1220 nm, respectively. If the pressure is increased to 1000 Pa, the Cu-In film having a two-layer structure is used as a starting material, and the average particle size of the obtained CuInS ₂ film layer is about 2000 nm and 2100 nm at 450 ° C, 500 ° C and 550 ° C vulcanization temperatures, respectively. And 2230nm. Similarly, the Cu-In film having a six-layer structure was used as a starting material, and the average particle size of the obtained CuInS ₂ film layer was about 1640 nm, 1940 nm, and 2220 nm at 450 ° C, 500 ° C, and 550 ° C vulcanization temperatures, respectively. Figure 3 is a diagram showing a Cu-In film having a six-layer structure starting from (A) 400 ° C, (B) 450 ° C, (C), according to a specific embodiment of the present invention. Scanning electron micrographs after vulcanization at 500 ° C or (D) 550 ° C for 1 hour. It can be estimated from the electrographic photograph that the average particle size of the obtained CuInS ₂ film layer at about 400 ° C, 450 ° C, 500 ° C or 550 ° C is about 188 nm, 380 nm, 1012 nm and 1709 nm, respectively. It can be observed from the above experiments that the Cu-In film having a 2-layer or a 6-layer structure is used as a starting material, and the vulcanization reaction is carried out at different temperatures, and as the vulcanization temperature increases, the film thickness also increases, and at the same time, The higher the pressure during the vulcanization reaction, the faster the particles grow, the smaller the particle size, and the higher the surface roughness of the film layer, as shown in Fig. 4.

Next, the surface resistance of the produced CuInS ₂ film layer was measured with a 4-point carbon needle equipped with a computer controller KEITHLEY 2400 power meter. It was found that the surface resistivity is made of CuInS ₂ film method according to the invention is quite low, of about 10 ^-l Ω-cm. For example, at a pressure of 146.7 Pa and a vulcanization temperature of 550 ° C, the surface resistance of a CuInS ₂ film layer made of a Cu-In film having a 2-layer or a 6-layer structure is 0.81 Ω-cm, respectively. And 0.46 Ω-cm; if the reaction pressure is increased to 1000 Pa, the surface resistance of the produced CuInS ₂ film layer is 0.50 Ω-cm and 0.51 Ω-cm, respectively. This result is reported in the prior art as a H ₂ S vulcanization process by thermal evaporation (see Antony et al., Sol. Emergy Mater. Sol. Cells 81 (2004) 402), electron beam evaporation process (see Park). Et al., Sol. Emergy Mater. Sol. Cells 49 (1997) 365) or spray pyrolysis process (see Cayzac et al., CR Chim 11 (2008) 1016) for surface resistance of CuInS ₂ film Consistent.

Next, various optical properties of the CuInS ₂ film layer produced in accordance with the above procedure were measured with an optical microscope (PerkinElmer Lambda 950), and the results are shown in Figures 5 and 6. Figure 5 is a CuInS ₂ film layer produced by vulcanization at a temperature of 450 ° C, 500 ° C or 550 ° C for 1 hour using a Cu-In film having a 2-layer or 6-layer structure at each wavelength. Absorption coefficient diagram. The results show that some CuInS ₂ film layers have an absorption coefficient of more than 10 ⁴ cm ^-1 , and the absorption coefficient is related to the surface roughness of the film layer. The higher the surface roughness of the film layer, the higher the absorption coefficient. Figure 6 shows.

Other embodiments

The CuInS ₂ film layer produced in the above Example 1 can be applied to a solar cell element.

According to a general method for manufacturing a thin film solar cell, a metal back electrode (for example, molybdenum metal) of about 400 nm and a absorbing layer of about 1 to 2 μm are sequentially deposited on the glass substrate (for example, CuInS according to the embodiment 1). ₂ film layer), a buffer layer of about 50 nm (for example, CdS), a layer of about 100 nm of essential zinc oxide, a layer of about 500 nm of zinc oxide, and a layer of a top electrode layer (for example, a nickel/aluminum electrode) to produce a solar energy element. The photoelectric conversion rate of this solar element under a solar analog light source is about 3%.

Industrial utilization

The present disclosure provides a method for forming a CuInS ₂ film layer in situ without breaking the vacuum. Compared with the prior art, the method of the present invention can effectively improve the prior art process without detracting from the characteristics of the CuInS ₂ film layer. The middle layer is susceptible to contamination problems. The substrate comprising the CuInS ₂ film layer produced by the method of the present invention can be used to fabricate solar elements.

The present disclosure has been disclosed in the above embodiments, but it is not intended to limit the disclosure, and any person skilled in the art can make various changes and refinements without departing from the spirit and scope of the disclosure. The scope of protection of the disclosure is subject to the definition of the scope of the patent application.

The above and other objects, features, advantages and embodiments of the present disclosure will become more apparent and understood.

1 is an XRD spectrum diagram of a Cu-In precursor film having a two-layer structure heat-treated at 150 ° C according to an embodiment of the present invention;

2 is an XRD spectrum diagram of a CuInS ₂ film prepared by using a Cu-In film having a 2 or 6 layer structure as a starting material, wherein (A) is a Cu layer having a 6-layer structure. -In film is vulcanized at 8.5 Pa, 450 ° C for 2 hours, (B) is a Cu-In film having a two-layer structure, vulcanized at 146.7 Pa, 550 ° C for 1 hour, and (C) is a Cu-In having a 6-layer structure. The film was vulcanized at 146.7 Pa, 550 ° C for 1 hour, and (D) was an XRD spectrum of a Cu-In film having a two-layer structure after vulcanization at 1000 Pa and 500 ° C for 1 hour;

Figure 3 is a diagram showing a Cu-In film having a six-layer structure starting at 1000 Pa at (A) 400 ° C, (B) 450 ° C, (C) 500 ° C or (D) according to an embodiment of the present invention. a scanning electron micrograph of a CuInS ₂ film after vulcanization at a temperature of 550 ° C for 1 hour;

4 is a view showing a relationship between a particle size of a CuInS ₂ film layer and a vulcanization temperature or a surface roughness by a vulcanization reaction of a Cu-In film having a 2-layer or a 6-layer structure according to an embodiment of the present invention;

Figure 5 is a CuInS ₂ film layer produced by vulcanization at a temperature of 450 ° C, 500 ° C or 550 ° C for 1 hour using a Cu-In film having a 2-layer or 6-layer structure at each wavelength. Absorption coefficient diagram; and

Fig. 6 is a graph showing the relationship between the absorption coefficient and the surface roughness of a CuInS ₂ film layer produced according to an embodiment of the present invention.

Claims (21)

A method for depositing a CuInS ₂ film, comprising: (a) providing a substrate to a processing chamber; (b) depositing indium and copper elements on the substrate by physical deposition to form a film having 2 a Cu-In film of a layer structure; (c) thermally annealing the Cu-In film; and (d) vulcanizing the Cu-In film to form the CuInS ₂ film; wherein, during the processing of the respective steps, the film is maintained The processing chamber is in a state where the vacuum is not broken. The method of claim 1, wherein the substrate is made of any material selected from the group consisting of ruthenium, plastic, glass, a III-V compound or an oxide. The method of claim 1, wherein the step (b) is carried out without heating the substrate, and the physical deposition method is thermal evaporation. The method of claim 1, wherein the step (c) is carried out at 150 ° C for at least 2 hours. The method of claim 1, wherein the step (d) comprises: introducing a sulfur-containing gas into the processing chamber; heating the substrate to 350 ° C to 550 ° C; and at a pressure of 8.5 Pa to 1000 Pa The substrate was treated for 1 to 2 hours. The method of claim 5, wherein the sulfur-containing gas comprises H ₂ S. The method of claim 5, wherein the step (d) is carried out for 1 hour under the conditions of a pressure of 146.7 Pa and a temperature of 550 °C. The method of claim 5, wherein the step (d) is carried out for 1 hour under conditions of a pressure of 1000 Pa and a temperature of less than 450 °C. The method of claim 7 or 8, wherein the thickness of the CuInS ₂ film is 1830 nm and the copper/indium ratio in the CuInS ₂ film is 1.13. The method of claim 1, further comprising repeating the step (b) at least 3 times to form a Cu-In film having a 6-layer structure. The method of claim 10, wherein the Cu-In film has an overall thickness of 800 nm, and a copper/indium ratio in each of the Cu-In layers is 1.8. The method of claim 10, wherein the substrate is made of any material selected from the group consisting of ruthenium, plastic, glass, a III-V compound or an oxide. The method of claim 10, wherein the step (b) is carried out without heating the substrate. The method of claim 10, wherein the step (c) is carried out at 150 ° C for at least 2 hours. The method of claim 10, wherein the step (d) comprises: introducing a sulfur-containing gas into the processing chamber; heating the substrate to 350 ° C to 550 ° C; and at a pressure of 8.5 Pa to 1000 Pa The substrate was treated for 1 to 2 hours. The method of claim 15, wherein the sulfur-containing gas comprises H ₂ S. The method of claim 15, wherein the step (d) is carried out for 1 hour under the conditions of a pressure of 146.7 Pa and a temperature of 550 °C. The method of claim 15, wherein the step (d) is carried out for 1 hour under conditions of a pressure of 1000 Pa and a temperature of less than 450 °C. The method of claim 17 or 18, wherein the CuInS ₂ film has a thickness of 1220 nm, and the Cu/S ₂ film has a copper/indium ratio of 1.13. A solar element comprising a substrate on which a film layer is sequentially deposited: a back electrode layer; an absorbing layer which is a CuInS ₂ film formed by the method of claim 8 or 17; a buffer layer; a zinc layer; and a top electrode layer. The solar component of claim 20, wherein the solar component has a photoelectric conversion rate of 3%.