KR101462498B1 - Fabrication Method of CIGS Absorber Layers and its application to Thin Film Solar Cells - Google Patents

Abstract

The present invention relates to a CIGS absorption layer manufacturing method capable of reducing processing costs and increasing the efficiency of a thin solar cell and to a thin solar cell manufacturing method using the same. The CIGS absorption layer manufacturing method of the present invention includes: a substrate settling step of settling a substrate in a sputtering device; a rear electrode forming step of forming a rear electrode by depositing a molybdenum on the substrate; a Cu-Se thin film depositing step of depositing a Cu-Se thin film on the rear electrode by the sputtering of a Cu-Se sputtering target; a liquefaction step of liquefying the Cu-Se thin film; and a CIGS thin film depositing step of depositing a CIGS thin film on Cu-Se liquid by the sputtering of a CIGS single target by using a single process sputtering.

Description

TECHNICAL FIELD The present invention relates to a CIGS absorber layer, a thin film solar cell manufacturing method using the CIGS absorber layer,

More particularly, the present invention relates to a method for manufacturing a CIGS absorption layer capable of improving the crystallinity of a CIGS absorption layer thin film to reduce defects in the thin film and improving the adhesion of the thin film solar cell to the substrate A thin film manufacturing method using the same, and a thin film solar cell.

As interest in clean energy has increased recently, there is a growing interest in generating electricity using solar light.

A solar cell is generally referred to as a solar cell or a solar cell. Solar cells are classified into a silicon solar cell and a dye-sensitized solar cell according to their structures. In recent years, CIGS thin film solar cells that have a bandgap of about 1.04 eV, which is ideal for absorbing sunlight, and which employ CIGS (Copper, Indium, Gallium and Selenide) having a high conversion efficiency as a light absorption layer have.

Generally, a CIGS thin film solar cell is formed by sequentially laminating a back electrode, a light absorbing layer composed of CIGS, a buffer layer, and an upper electrode layer formed of a transparent electrode on a substrate made of glass or metal.

At this time, the buffer layer is generally made of cadmium (CdS) and the upper electrode layer is made of zinc oxide (ZnO).

Meanwhile, the light absorption layer is formed by a manufacturing method such as a co-evaporation method or a two-stage process of a metal precursor.

At the same time, the simultaneous vapor deposition method evaporates copper (Cu), indium (In), gallium (Ga), and selenium (Se), which are unit elements at the same time, Cu), indium (In), gallium (Ga), and selenium (Se) are consumed so that the utilization efficiency of each unit element is low and it is difficult to apply it to a large area substrate.

Also, as shown in FIG. 1, a selenization method of a metal precursor, which is also referred to as a two-step process, is a two-step process including a precursor deposition process and a selenization process in which heat treatment is performed. since the forming of copper (Cu), indium (in), gallium (Ga) and selenium (Se) selenide perform processes the light absorption of the precursor at a high temperature and then vacuum-deposited in sequence consisting of from H ₂ from the selenide process Se, the concentration of selenium is not uniform, and the composition ratio of the CIGS thin film is difficult to control.

In the selenization method of the metal precursor, counter diffusion occurs between the unit elements constituting the electrode layer and copper (Cu), indium (In), gallium (Ga) and selenium (Se) at the interface between the electrode layer and the light absorption layer There is a problem that the arrangement of the conductive bands varies.

Also, since the interface detachment phenomenon occurs due to volume expansion during the selenization process of the metal precursor, the CIGS thin film characteristics are deteriorated.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems of the prior art that the present selenification process requires installation of a facility for treating toxic gas (H ₂ Se) to be used, Since the process time due to the heat treatment is increased and the composition control of the thin film is limited, omitting the selenization process in the present invention eliminates the need for a toxic gas treatment facility, thereby lowering the unit cost of the CIGS absorption layer manufacturing process and the process cost, A CIGS thin film can be fabricated by using a one-step sputtering method to produce a CIGS thin film with almost the same composition as that of a sputtering target. The crystallographic, optical and electrical properties of the CIGS thin- Not only is it possible to produce thin films with the same characteristics, but also to have better crystallographic properties A CIGS absorption layer of high quality is prepared by using a Cu-Se layer as an intermediate layer.

According to another aspect of the present invention, there is provided a method of fabricating a CIGS absorption layer, including: placing a substrate in a sputtering apparatus; Forming a back electrode by depositing molybdenum on the substrate; A Cu-Se thin film deposition step of sputtering a Cu-Se sputtering target to deposit a Cu-Se thin film on the rear electrode; A liquefaction step of liquefying the Cu-Se thin film; And a CIGS thin film deposition step of depositing a CIGS thin film on a Cu-Se liquid phase by sputtering a CIGS single target using single process sputtering.

In the present invention, the step of depositing the Cu-Se thin film is performed at a pressure of 0.1Pa to 1.0Pa in a state of RF power of 50W to 500W (RF Power Density: 0.637 to 6.366W / cm2) and argon gas of 10 to 50sccm Is applied.

In the present invention, the Cu-Se thin film deposition step is characterized in that the substrate temperature is maintained at room temperature.

In the present invention, the step of depositing the Cu-Se thin film is performed such that a distance between the substrate and the Cu-Se sputtering target is 10 mm to 200 mm.

In the present invention, the liquefaction step is characterized in that the Cu-Se thin film is subjected to post-heat treatment at a temperature of 600 ° C to 700 ° C to be liquefied.

In the present invention, the CIGS thin film deposition step is performed by applying a pressure of 0.1Pa to 1.0Pa in the state of RF power of 50W to 500W (RF Power Density: 0.637 to 6.366W / cm2) and argon gas of 10 to 50sccm .

In the present invention, the CIGS thin film deposition step may be performed such that a distance between the substrate and the CIGS single target is 10 mm to 200 mm.

In the present invention, the CIGS single target is Cu _y In _1-x Ga _x Se ₂ (x = 0 to 1, y = 0.5 to 1).

In the present invention, the CIGS thin film deposition step is performed at a substrate temperature ranging from room temperature to 700 ° C.

A thin film solar cell manufacturing method of the present invention includes: a substrate placing step of placing a substrate in a sputtering apparatus; Forming a back electrode by depositing molybdenum on the substrate; A Cu-Se thin film deposition step of sputtering a Cu-Se sputtering target to deposit a Cu-Se thin film on the rear electrode; A liquefaction step of liquefying the Cu-Se thin film; A CIGS thin film deposition step in which a CIGS thin film is deposited on a Cu-Se liquid by sputtering a CIGS single target using single process sputtering; Forming a buffer layer on the CIGS thin film; And forming an upper electrode layer on the buffer layer.

In the present invention, the substrate temperature is maintained at a room temperature, and the Cu-Se sputtering target is spaced 10 mm to 200 mm apart from the substrate.

In the present invention, the liquefaction step is characterized in that the Cu-Se thin film is subjected to post-heat treatment at a temperature of 600 ° C to 700 ° C to be liquefied.

In the present invention, the CIGS thin film deposition step is performed by applying a pressure of 0.1Pa to 1.0Pa in the state of RF power of 50W to 500W (RF Power Density: 0.637 to 6.366W / cm2) and argon gas of 10 to 50sccm And the distance between the substrate and the CIGS single target is 10 mm to 200 mm.

In the present invention, the CIGS single target is Cu _y In _1-x Ga _x Se ₂ (x = 0 to 1, y = 0.5 to 1).

In the present invention, the CIGS thin film deposition step is performed at a substrate temperature ranging from room temperature to 700 ° C.

The thin film solar cell of the present invention is manufactured by the above-described method of manufacturing a thin film solar cell.

As described above, according to the present invention, since the sequential deposition process or the selenization process of the metal precursor is omitted, the process time can be drastically shortened, and since the CIGS thin films are combined with each other in the liquefied Cu-Se layer, The efficiency of the thin film solar cell can be increased.

1 is a schematic view showing a step of fabricating a two-step light absorbing layer using a precursor sputtering process and a selenization process according to the prior art.
2 is a schematic view showing a CIGS absorption layer manufacturing method and a thin film solar cell manufacturing method using the same according to an embodiment of the present invention.
3 is a cross-sectional and surface image of a CIGS thin film grown on a substrate at a temperature of 450 < 0 > C.
4 is a cross-sectional and surface image of a CIGS thin film grown on a substrate at a temperature of 550 ° C.
5 is a graph showing an XRD pattern of a CIGS / CLG thin film according to a substrate temperature.
6 is an SEM image showing a CIGS thin film deposited on a Cu-Se layer by single-process sputtering with a Cu-Se layer grown on a substrate.
7 is a graph showing an XRD pattern of a CIGS thin film formed in a liquefied Cu-Se layer.
8 is a graph showing Raman characteristics of a CIGS thin film formed in a liquefied Cu-Se layer.
9 is a graph showing the optical bandgap characteristics of a CIGS thin film formed in a liquefied Cu-Se layer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the detailed description of known functions and configurations incorporated herein will be omitted when it may unnecessarily obscure the subject matter of the present invention.

The same reference numerals are used for portions having similar functions and functions throughout the drawings.

In addition, when a part is referred to as being "connected" with another part throughout the specification, it includes not only a direct connection but also indirectly connecting the other parts with each other in between. Also, to "include" an element does not exclude other elements unless specifically stated otherwise, but may also include other elements.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a schematic view showing a CIGS absorption layer manufacturing method and a thin film solar cell manufacturing method using the same according to an embodiment of the present invention.

As shown in FIG. 2, a CIGS absorption layer manufacturing method according to an embodiment of the present invention includes: a substrate placing step of placing a substrate in a sputtering apparatus; Forming a back electrode by depositing molybdenum on the substrate; A Cu-Se thin film deposition step of sputtering a Cu-Se sputtering target to deposit a Cu-Se thin film on the rear electrode; A liquefaction step of liquefying the Cu-Se thin film; And a CIGS thin film deposition step of depositing a CIGS thin film on a Cu-Se liquid phase by sputtering a CIGS single target using single process sputtering.

In this case, a soda lime glass (SLG) is used as the substrate, a Cu-Se thin film is deposited on molybdenum to a thickness of 20 nm to 400 nm, a Cu: Se sputtering target is Cu: 1 is used, and Cu _y In _1-x Ga _x Se ₂ (x = 0 to 1, y = 0.5 to 1) is used as a CIGS single target.

The CIGS grains grown in the Cu-Se liquid phase undergo a nucleation process in a direction lowering the surface energy, and the nuclei grown in island form are sputtered CIGS grains or several It binds with the island nuclei to increase the particle size (ostwald ripening).

Meanwhile, the CIGS absorption layer manufacturing method described above maintains a pressure of 0.1 Pa to 1.0 Pa in a state where argon gas (Ar gas) of 10 to 50 sccm, preferably 30 sccm is injected, and maintains a pressure of 50 W to 500 W (RF Power Density: The Cu-Se sputtering target and the CIGS single target are sputtered in a state in which the substrate and the Cu-Se sputtering target (or the CIGS single target) are arranged to be separated from each other by 10 mm to 200 mm by RF power of 0.637 to 6.366 W / The reason for this is as follows.

Generally, in a sputtering apparatus, after an inert gas (for example, argon gas) is injected into a vacuum chamber, electrons emitted from the cathode by an RF voltage applied to the cathode collide with argon atoms and are ionized with argon ions At this time, the argon atoms are ionized and energy is released by the electrons lost, and a glow discharge is generated. In the vacuum chamber, a purple plasma in which ions and electrons coexist is formed.

At this time, when the argon ions in the plasma accelerate toward the cathode and collide with the target surface, neutral target atoms are separated and deposited on the substrate. If the amount of argon gas in the vacuum chamber is too small, glow discharge is not formed, And the yield of the neutral atoms falling from the sputtering target is small, so that the process time becomes long.

Also, when the amount of argon gas is too large, the number of neutral atoms colliding with the argon ions (Ar +, Ar) and atoms in the plasma when the neutral ion atoms separated from the surface of the sputtering target are deposited on the substrate, It is preferable to inject 10 to 50 sccm of argon gas.

The process pressure, which is calculated by the sum of the pressure in the vacuum chamber and the pressure of the inert gas, is preferably at most 1.0 Pa or less according to the principle of the partial partial pressure (the amount of argon gas) 0.1Pa), the plasma is formed through the glow discharge. Therefore, when the CIGS thin film is manufactured using the single process sputtering, the vacuum chamber is maintained at a pressure of 0.1Pa to 1.0Pa in a state where Ar gas of 10 ~ 50sccm is injected do.

On the other hand, when the RF power is too small (less than 50 W) when the CIGS thin film is manufactured using the single process sputtering, plasma is not formed and the amount of argon ionized is too small to deposit a thin film on the substrate If process time is required and the RF power is too high (ie, greater than 500 W), there is an advantage in increasing the energy and amount of sputtered particles from the target surface, but too large a current density will flow toward the cathode, It is preferable that the RF power is applied in the range of 50W to 500W.

Accordingly, the RF Power Density calculated from the applied RF Power / target area value has 0.637 to 6.366 W / cm 2 (4 inch target is used in the present invention).

Since the Cu-Se thin film has a liquefaction temperature of 800 K (about 530 ° C.) on the phase equilibrium when the composition ratio of Cu-Se is 1: 1, the Cu-Se insertion layer deposited at room temperature is heated at 500 ° C. to 700 ° C. Followed by liquefaction by heat treatment.

On the other hand, the temperature increase of the substrate during CIGS thin film fabrication using single process sputtering increases the mobility of the particles when the sputtered particles are deposited on the substrate (that is, the kinetic energy of the particles increases due to the thermal energy of the base) The crystallization and densification of the thin film are affected by the presence of the particles, so that a proper process temperature is important. In general, there is no problem in performing the thinning process at a normal temperature, but when the process temperature is too high (i.e., (Or melting point) of the sputtering target is lower than the role of contributing to the stabilization by supplying energy to the sputtered particles, the original physical properties are lost, so that the process temperature (or the substrate temperature) is in the range of room temperature to 700 Lt; 0 > C.

Finally, the distance between the substrate and the target, which refers to the distance the sputtered particles reach the substrate portion, can be described by the concept of a " mean ferr path ", where the distance between the substrate and the target is short ) As the sputtered particles migrate to the substrate, collisions with various radicals, neutral atoms, ions, electrons in the plasma sheath degrade the deposition rate and the film quality, If the length is too long (i.e., more than 200 mm), there is an advantage that the free movement path for sputtered particles to the substrate becomes longer and the quality of the thin film is improved. However, since the loss rate of the sputtered particles increases, It is preferable that the substrate and the target are arranged so as to be separated from each other by 10 mm to 200 mm.

Example 1

In Example 1, Cu: In: Ga: Se = 0.7: 0.7: 0.3: 2: 2 was formed on a substrate in a state where no Cu-Se liquid phase was formed on molybdenum in the first embodiment. CIGS thin films were deposited on a substrate using a single process sputtering process.

To this end, a RF power of 300 W (3.820 W / cm 2) is applied to the sputtering apparatus, the substrate temperature is maintained at 450 ° C. and 550 ° C., and the pressure of 0.43 Pa is maintained in the state where 30 sccm of argon gas is injected.

At this time, the substrate temperature rises at a rate of 1 to 15 占 폚 / min, preferably 9 占 폚 / min (for example, when the temperature rises from 450 to 450 占 폚 to 550 占 폚) The temperature is maintained for 30 minutes to 3 hours, preferably 1 hour (for example, the substrate temperature is maintained at 550 占 폚 for 1 hour), and then the CIGS thin film is grown on the substrate through single process sputtering.

In this embodiment, a soda lime glass substrate having a size of 100 x 100 mm < 2 > is used, and the substrate and the CIGS single target are spaced apart from each other by 150 mm, Cu _0.7 In _0.7 Ga _0.3 Se ₂ is used as a CIGS single target.

When a CIGS thin film is deposited on a substrate by sputtering a CIGS single target using single process sputtering under these conditions, the roughness of the CIGS thin film surface is very large as shown in FIGS. 3 and 4, and the grain size is relatively large It can be seen that the efficiency of the CIGS thin film solar cell device manufactured using the absorption layer thin film is reduced.

That is, when the roughness of the thin film is large, the buffer layer and the TCO layer to be deposited on the absorber layer are affected and the uniformity of the thin film is degraded. When the CIGS absorber layer having a small particle size is formed, boundary of the carrier caused by the defect in the carrier is disturbed to cause the efficiency drop.

Also, a peak showing a look at the XRD pattern of the CIGS thin film, the CIGS diffraction peaks {112, 220, 312}, and the secondary phase (Cu ₂ Se) representing the chalcopyrite phase as shown in Figure 5 at the same time It can be seen that no CIGS thin film with crystallographically complete chalcopyrite structure is formed.

Example 2

A Cu-Se (Cu: Se = 50: 50, at.%) Thin film is first deposited on a substrate to have a thickness of 300 nm, and then a heater The Cu-Se thin films were liquefied by setting the temperature at 600 ° C, 650 ° C, and 700 ° C, and CIGS thin films were deposited on the Cu-Se liquid phase by a single process sputtering process in a continuous process.

At this time, the Cu-Se thin film is formed on the substrate by sputtering a Cu-Se target of Cu: Se = 1: 1, and the CIGS thin film is formed to a thickness of 1 to 1.1 μm.

The process conditions for depositing the Cu-Se thin film and the CIGS thin film as described above are as follows.

RF power of 300 W (3.820 W / cm 2) was applied to the sputtering apparatus for sputtering of Cu-Se sputtering target and CIGS single target, substrate temperature was maintained at RT (room temperature), and 30 sccm of argon gas was injected A pressure of 0.43 Pa is maintained.

The Cu-Se insertion layer is deposited on the substrate by sputtering a Cu-Se target at room temperature and then liquefied at 600 ° C, 650 ° C and 700 ° C respectively. When the process temperature is stabilized, the CIGS absorption layer is liquefied Lt; RTI ID = 0.0 > Cu-Se < / RTI >

In other words, since the Cu-Se insertion layer has a liquefaction temperature of 800K (about 530 ° C) on the phase equilibrium when the composition ratio of Cu-Se is 1: 1, the Cu-Se insertion layer is deposited at room temperature, 650 ° C and 700 ° C, respectively, to prepare a CIGS absorption layer thin film on the liquefied Cu-Se insertion layer.

At this time, the heater temperature rises at a rate of 1 to 15 ° C / min, preferably 9 ° C / min (for example, when the temperature rises from RT to> 600 ° C, 650 ° C to> 700 ° C) (For example, the substrate temperature is maintained at 650 占 폚 for 1 hour) at a temperature of 30 占 폚 to 3 hours, preferably 1 hour, followed by single-step sputtering to form a CIGS thin film .

In this embodiment, a soda lime glass substrate having a size of 100 x 100 mm < 2 > is used. The substrate is spaced apart from the CIGS single target by 110 mm, Cu _0.7 In _0.7 Ga _0.3 Se ₂ is used as a CIGS single target.

When a CIGS thin film is deposited on a liquid Cu-Se thin film using such a condition, a single CIGS thin film having no boundary between the Cu-Se layer and the CIGS thin film is formed as shown in FIG. 6, As shown in Fig.

That is, in the liquefied Cu-Se layer, the CIGS particles are not formed in a form having a small particle size but are combined with each other to increase the CIGS particle size.

Comparing FIG. 3 and FIG. 4 without the Cu-Se layer, it can be seen that the particle size of the cross section and the surface are significantly different from the CIGS thin film formed on the substrate without the Cu-Se layer, Layer can improve the efficiency of the CIGS thin film solar cell.

The XRD pattern of the CIGS thin film formed in the liquefied Cu-Se layer as shown in FIG. 7 reveals that only diffraction peaks {(112), (220), (312)} representing the chalcopyrite structure are confirmed have.

If a liquefied Cu-Se layer is present, the associated diffraction peak should be observed, but as can be seen from FIG. 7, only a single CIGS phase without secondary phase is present.

As described above, it can be seen that the liquefied Cu-Se layer plays a role of increasing the particle size while the CIGS thin film has a single-phase shape.

As shown in FIG. 8, the peak position of the Cu-Se phase was confirmed in the region of about 260 cm ^-1 , and the Cu-Se phase is not observed but only CIGS A1 peak showing only the chalcopyrite structure is observed, which shows that a crystallographically stable CIGS thin film is formed together with the XRD result.

9 is a graph showing optical characteristics of a CIGS thin film formed in a liquefied Cu-Se layer.

9 is an optical bandgap graph obtained by plotting the transmittance data with (? Hv) ² , and shows a bandgap of 0.98-1.6 eV according to the ratio (0-1) of Ga / (In + Ga) The Ga / (In + Ga) ratio of the CIGS thin film fabricated by the single process sputtering using the Cu-Se layer is 0.3, and the band gap energy of the CIGS thin film is 600 ° C., 650 ° C., 1.16, 1.13, and 1.15 eV, respectively, for 700 ° C.

As can be seen from this, although there is a slight band gap difference according to the process temperature, it can be seen that the ratio of Ga / (In + Ga) has a value close to the band gap characteristic at 0.3, It can be seen that the CIGS thin film formed using the Cu-Se layer has the same Ga / (In + Ga) composition ratio of the single-process sputtering target.

Meanwhile, a method of fabricating a thin film solar cell according to an embodiment of the present invention includes: a substrate placing step of placing a substrate in a sputtering apparatus; Forming a back electrode by depositing molybdenum on the substrate; A Cu-Se thin film deposition step of sputtering a Cu-Se sputtering target to deposit a Cu-Se thin film on the rear electrode; A liquefaction step of liquefying the Cu-Se thin film; A CIGS thin film deposition step in which a CIGS thin film is deposited on a Cu-Se liquid by sputtering a CIGS single target using single process sputtering; Forming a buffer layer on the CIGS thin film; And forming an upper electrode layer on the buffer layer.

At this time, detailed description of the Cu-Se thin film deposition step, liquefaction step and CIGS thin film deposition step has been described in detail in the above-described CIGS absorption layer production method, and therefore, the detailed description will be replaced with the above description.

Also, a thin film solar cell according to an embodiment of the present invention is manufactured by the thin film solar cell manufacturing method described above.

As described above, the CIGS absorption layer fabrication method and the thin film solar cell fabrication method using the same according to the embodiment of the present invention can obviate the sequential deposition process or the sulfuration process of the metal precursor, The CIGS thin film is bonded to each other to increase the particle size, thereby increasing the efficiency of the CIGS thin film solar cell.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit of the invention. Therefore, the scope of the present invention should not be limited to the embodiments described, but should be defined by the following claims as well as equivalents thereof.

Claims (16)

Placing a substrate in a sputtering apparatus;
Forming a back electrode by depositing molybdenum on the substrate;
A Cu-Se thin film deposition step of sputtering a Cu-Se sputtering target to deposit a Cu-Se thin film on the rear electrode;
A liquefaction step of liquefying the Cu-Se thin film; And
A CIGS thin film deposition step of depositing a CIGS thin film on a Cu-Se liquid by sputtering a CIGS single target using single process sputtering. The method according to claim 1,
The step of depositing the Cu-Se thin film is performed by applying RF power of 50 W to 500 W (RF Power Density: 0.637 to 6.366 W / cm 2) and argon gas of 10 to 50 sccm in a pressure of 0.1 Pa to 1.0 Pa ≪ / RTI > The method according to claim 1,
Wherein the Cu-Se thin film deposition step maintains the substrate temperature at room temperature. The method according to claim 1,
Wherein the Cu-Se thin film deposition step is performed in a state where a distance between the substrate and the Cu-Se sputtering target is 10 mm to 200 mm. The method according to claim 1,
Wherein the Cu-Se thin film is subjected to post-heat treatment at a temperature of 600 ° C to 700 ° C to liquefy the Cu-Se thin film. The method according to claim 1,
The CIGS thin film deposition step is characterized in that a pressure of 0.1Pa to 1.0Pa is applied in a state where RF power of {50 W to 500 W (RF Power Density: 0.637 to 6.366 W / cm 2)} and argon gas of 10 to 50 sccm are injected Gt; CIGS < / RTI > The method according to claim 1,
Wherein the CIGS thin film deposition step is performed in a state where a distance between the substrate and the CIGS single target is 10 mm to 200 mm. The method according to claim 1,
Wherein the CIGS single target is Cu _y In _1-x Ga _x Se ₂ (x = 0 to 1, y = 0.5 to 1). The method according to claim 1,
Wherein the CIGS thin film deposition step is performed at a substrate temperature between room temperature and 700 ° C. Placing a substrate in a sputtering apparatus;
Forming a back electrode by depositing molybdenum on the substrate;
A Cu-Se thin film deposition step of sputtering a Cu-Se sputtering target to deposit a Cu-Se thin film on the rear electrode;
A liquefaction step of liquefying the Cu-Se thin film;
A CIGS thin film deposition step in which a CIGS thin film is deposited on a Cu-Se liquid by sputtering a CIGS single target using single process sputtering;
Forming a buffer layer on the CIGS thin film; And
And forming an upper electrode layer on the buffer layer. The method of claim 10,
Wherein the step of depositing the Cu-Se thin film is performed at a substrate temperature maintained at a room temperature, and a distance between the substrate and the Cu-Se sputtering target is 10 mm to 200 mm. The method of claim 10,
Wherein the Cu-Se thin film is subjected to post-heat treatment at a temperature of 600 ° C to 700 ° C to liquefy the Cu-Se thin film. The method of claim 10,
In the CIGS thin film deposition step, a pressure of 0.1Pa to 1.0Pa is applied in a state of RF power of 50W to 500W (RF Power Density: 0.637 to 6.366W / cm2) and argon gas of 10 to 50sccm being injected, Wherein the CIGS single target is spaced 10 mm to 200 mm apart from the substrate and the CIGS single target. The method of claim 10,
Wherein the CIGS single target is Cu _y In _1-x Ga _x Se ₂ (x = 0 to 1, y = 0.5 to 1). The method of claim 10,
Wherein the CIGS thin film deposition step is performed at a substrate temperature between room temperature and 700 ° C. A thin film solar cell produced by any one of claims 10 to 15.

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