TW201311923A - The method for preparing multilayer thin films by using the AZO target - Google Patents

Abstract

The present invention provides a method for preparing multilayer thin films by using the AZO target. A ZnO1-xSx film as a buffer layer is deposited on a substrate for solar cells by sputtering the AZO target in an atmosphere of Ar and H2S. The i-ZnO film as a window layer is deposited on the buffer layer by sputtering the AZO target in an atmosphere of O2. The AZO film as a transparent electrode layer is formed on the window layer by sputtering AZO target. In the present invention, by using only one AZO target in combination with three different sputtering atmospheres was in-situ deposited three kinds of films in series of buffer layer, window layer and transparent electrode layer on a substrate for application in manufacturing solar cells.

Description

Method for preparing multilayer film by using alumina zinc target

The invention relates to a method for preparing a film, in particular to a method for preparing a multilayer film by using an alumina zinc target.

Paying attention to environmental protection, energy saving and carbon reduction is an international trend today. Solar cells can generate electricity through sunlight during the day and store them in batteries. They can also be used at night or on rainy days, thus becoming the most eye-catching green energy source. . There are quite a variety of solar cells, such as a monocrystalline silicon solar cell, a polycrystalline silicon solar cell, a thin film solar cell, an organic solar cell, and the like. Among them, single crystal germanium solar cells and polycrystalline germanium solar cells have higher production costs due to high raw materials, and are not suitable for large-area or building-use solar power generation; organic material solar cells are mainly dye-sensitized solar cells (dye-sensitized solar cells). , DSSC) and polymers (polymers), dye-sensitized solar cells need to use photosensitive materials as light-absorbing materials, but currently can use a variety of dyes and electrolytes, low photoelectric conversion performance and short life, so the above It is difficult for solar cells to replace traditional power generation methods on a large scale.

In addition, compound semiconductors are used as solar cells, including gallium arsenide (GaAs) of group III-V materials, cadmium telluride (CdTe) of group II-VI, and copper-indium gallium selenide of group I-III-V [Cu (In, Ga)Se ₂ , CIGS], etc., in which CIGS solar cells have higher absorption coefficients than other materials, so they can be made only 1 to 2 μm. The thickness of the copper indium gallium selenide solar cell can be effectively absorbed, and the copper indium gallium selenide solar cell has high photoelectric conversion efficiency, can be prepared on different materials of the substrate and low cost, so the application of the copper indium gallium selenide solar cell Can be quite extensive.

The layered structure of the copper indium gallium selenide solar cell from bottom to top is made of glass as a substrate, and then a layer of high temperature resistant and chemically stable molybdenum metal (Mo) is deposited on the glass as a back electrode (connected to the positive electrode). Physical vapor deposition of CIGS film as an absorber layer, deposition of cadmium sulfide (CdS) as a buffer layer by chemical deposition, followed by deposition of intrinsic zinc oxide (intrinsic ZnO) by sputtering Alumina zinc (AZO) is deposited as a transparent electrode layer as a window layer and a sputtering method, and then a metal electrode is connected and connected to the negative electrode.

Since copper indium gallium selenide solar cells use cadmium sulfide as a buffer layer, and cadmium (Cd) is a toxic element, it will cause environmental pollution and does not meet the purpose of environmental protection. Therefore, zinc sulfide (ZnS) and zinc selenide are currently available. Materials such as ZnSe), zinc oxide (ZnO), magnesium oxide (MgO) or indium sulfide (In ₂ S ₃ ) may be substituted. At present, in the process of preparing a buffer layer, a light transmissive layer and a conductive layer of a copper indium gallium selenide solar cell, sputtering is performed in three reaction chambers with three different target targets. Preparation is not only costly but also requires a long cycle time.

In view of the fact that the buffer layer, the light transmissive layer and the conductive layer of the copper indium gallium selenide solar cell are prepared in three reaction chambers respectively, the cost is high and requires a long cycle time; SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of preparing a film for use in a solar cell using only a single target and utilizing an alumina zinc target in a single reaction chamber.

In order to achieve the above object, the present invention provides a method for preparing a multilayer film using an alumina zinc target, which comprises the steps of: subjecting an alumina zinc target to an argon (Ar) and hydrogen sulfide (H ₂ S) gas. Sputtered on a substrate to form a ZnO _1-x S _x film as a buffer layer; then the aluminum oxide target is sputtered on ZnO _1-x S _x film in argon and oxygen (O ₂ ) To form a high-resistance aluminum oxide zinc (ZnO:Al ₂ O ₃ ) film as a light-transmitting layer; then directly spray the aluminum-zinc target on a high-resistance aluminum oxide zinc film to form aluminum oxide A zinc (AZO) film serves as an electrode conductive layer.

Preferably, the substrate comprises a substrate, and a back electrode and a copper indium gallium selenide film sequentially stacked on the substrate, wherein the buffer layer, the light transmissive layer and the conductive layer are sequentially formed on the copper Above the indium gallium selenide film. Preferably, the sputtering system comprises direct current sputtering (DC sputtering) or radio frequency sputtering (RF sputtering).

Preferably, the sputtering is performed to form each film layer in the same reaction chamber.

Preferably, the flow ratio of the argon gas to the hydrogen sulfide gas of the ZnO _1-x S _x film is between 5:1 and 2:1, and the thickness of the ZnO _1-x S _x film is between 25 Up to 100 nanometers (nm).

Preferably, the ZnO _1-x S _x film has an energy gap of 2.8 to 3.7 electron volts (eV).

Preferably, the flow rate of argon gas to oxygen of the high-resistance aluminum oxide zinc film is between 20:1 and 3:1, and the thickness of the high-resistance aluminum oxide zinc film is between 50 and 150. Nano (nm).

Preferably, the thickness of the aluminum oxynitride film is between 100 and 300 nanometers (nm).

The advantages of the preparation method of the invention are:

1. Compared with the current three kinds of targets and three reaction chambers, the buffer layer, the light transmissive layer and the electrode conductive layer can be obtained. The present invention only needs to use an alumina zinc target in the same reaction chamber, which is different. Under gas sputtering, a film of different composition can be formed to prepare a buffer layer, a light transmissive layer and an electrode conductive layer, which not only reduces the cost but also saves time.

2. The energy gap and resistance value of the film of the buffer layer, the light transmissive layer and the electrode conductive layer may vary depending on the amount of the reaction gas to be added.

3. Due to the simple manufacturing method and greatly reduced cost, it is suitable for mass production.

The method of the invention can be applied to the fabrication of a copper indium gallium selenide solar cell, which can sequentially form a back electrode and a copper indium gallium selenide film on a substrate in a reaction chamber, and then the aluminum zinc target is argon. Sputtering in gas (Ar) and hydrogen sulfide (H ₂ S) gas to form a ZnO _1-x S _x film as a buffer layer, the buffer layer having an energy gap of 2.8 to 3.7 electron volts (eV), and The amount of hydrogen sulfide gas introduced to adjust the conductivity of the ZnO _1-x S _x film, wherein the flow ratio of argon to hydrogen sulfide gas is between 5:1 and 2:1; Sputtered in argon and oxygen (O ₂ ), wherein the flow ratio of argon to oxygen is between 20:1 and 3:1 to form a high-resistance aluminum oxide zinc (ZnO:Al ₂ O ₃ ) film. The light-transmitting layer is further directly sputtered to form an aluminum oxide zinc film as an electrode conductive layer.

The invention is further illustrated by the following examples which are not intended to limit the invention.

Example

Example 1 : Preparation of ZnO _1-x S _x film as a buffer layer

In this embodiment, an alumina zinc target is placed in the reaction chamber and an argon gas having a flow rate of 40 sccm and a hydrogen sulfide gas having a flow rate of 10 sccm are introduced; the radio frequency sputtering has an electric density of 1.5 per square centimeter watt (W/ Cm ₂ ), the sputter thickness is 500 A; the vacuum pressure is 60 mTorr; the target to substrate spacing (T/S spacing) distance is 5 cm (cm); the temperature is 200 ° C.

Aluminum (Al), sulfur (S) and oxygen (O) in the alumina zinc target, as shown in the following reaction formulas (1) to (3), generate aluminum sulfide (Al ₂ S ₃ ) and oxidize after the reaction. Aluminum (Al ₂ O ₃ ), the aluminum sulfide (Al ₂ S ₃ ) and alumina (Al ₂ O ₃ ) are relatively stable dielectric materials and do not affect the ZnO _1-x S _x film. nature.

(1) Zn+S _x +O _1-x →ZnO _1-x S _x

(2) 2Al+3S _x →Al ₂ S ₃

(3) 2Al+3O→Al ₂ O ₃

A ZnO _1-x S _x film was formed by sputtering of the process parameters of Table 1, and used as a buffer layer. The ZnO _1-x S _x film was identified and analyzed by EDX (X-ray fluorescence analyzer), and zinc oxide was found therein: The sulfur ratio was 0.8:0.2, the thickness was 50 nm (nm), and the energy gap was 2.89 electron volts (eV).

Example 2 : Preparation of High Resistivity Alumina Zinc (ZnO:Al ₂ O ₃ ) Film as Light Transmissive Layer

In this embodiment, an alumina zinc target is placed in the reaction chamber and an argon gas having a flow rate of 40 sccm and an oxygen gas having a flow rate of 10 sccm are introduced; the sputtering power density is 2.5 per square centimeter watt (W/cm ₂ ). The sputtering thickness is 1000 A; the vacuum pressure is 50 mTorr (mTorr); the distance between the target and the substrate is 5 cm (cm); and the temperature is 200 °C.

Oxygen and alumina zinc target, as shown in the following reaction formulas (4) to (5), react to form alumina, which is an amorphous dielectric material and does not affect high-resistance alumina. The nature of the zinc film.

(4) Zn+O→ZnO

(5) 2Al+3O→Al ₂ O ₃

A high-resistance aluminum oxide zinc film is formed by sputtering of the process parameters of Table 2, and is used as a light-transmitting layer. It is known by EDX (X-ray fluorescence analyzer) that the thickness of the zinc oxide film is 100 nm (nm). The energy gap is 3.35 electron volts (eV) and the transmittance is greater than 90%.

Example 3 : Preparation of an alumina zinc (AZO) film as an electrode conductive layer

In this embodiment, an alumina zinc target is placed in the reaction chamber and an argon gas having a flow rate of 50 sccm is introduced; the power density of the DC sputtering is 2 watts per square centimeter (W/cm ₂ ), and the sputtering thickness is 1500 A; vacuum pressure of 5 mTorr (mTorr); target to substrate separation distance of 5 cm (cm); temperature of 200 ° C.

An aluminum oxyhydroxide film was formed by sputtering of the process parameters of Table 3, and was identified as an electrode conductive layer by an EDX (X-ray fluorescence analyzer) method, wherein the thickness of the aluminum oxynitride film was 150 nm (nm). The resistivity is 4.2E ^{- 4} ohm-cm (ohm-cm) and the transmittance is greater than 85%.

Figure 1 is a flow chart of the steps of the present invention.

Figure 2 is a schematic illustration of an embodiment of the invention.

Claims (10)

A method for preparing a multilayer film by using an aluminum oxide zinc target, comprising: sputtering an alumina zinc target on a substrate in a reaction chamber of argon gas and hydrogen sulfide gas to form ZnO _1-x S _x a thin film; an alumina zinc target is sputtered on the ZnO _1-x S _x film in argon gas and oxygen gas to form a high-resistance aluminum oxide zinc film; and the aluminum zinc target is directly under argon gas After sputtering on the high-resistance zinc oxide film, an aluminum zinc oxide film is formed. The method for preparing a multilayer film using aluminum silicate according to claim 1, wherein the substrate comprises a substrate, and a back electrode and a copper indium gallium selenide film sequentially stacked on the substrate, the ZnO _{A 1-x} S _x film, a high-resistance aluminum oxide zinc film, and an aluminum zinc oxide film are sequentially formed on the copper indium gallium selenide film. The method for preparing a multilayer film using aluminum silicate according to the first aspect of the invention, wherein the sputtering method comprises direct current sputtering (DC sputtering) or radio frequency sputtering (RF sputtering). A method of producing a multilayer film using aluminum silicate according to any one of claims 1 to 3, wherein sputtering is carried out to form each film layer in the same reaction chamber. A method of producing a multilayer film using aluminum silicate according to any one of claims 1 to 3, wherein the ZnO _1-x S _x film has an energy gap of 2.8 to 3.7 electron volts (eV). The method for preparing a multilayer film using aluminum silicate according to claim 1, wherein the flow ratio of argon gas to hydrogen sulfide gas of the ZnO _1-x S _x film is between 5:1 and 2:1. The method for preparing a multilayer film using aluminum silicate according to claim 1, wherein the high-resistance aluminum oxide zinc film has a flow ratio of argon gas to oxygen of from 20:1 to 3:1. The method for producing a multilayer film using aluminum silicate according to claim 1, wherein the ZnO _1-x S _x film has a thickness of 25 to 100 nanometers (nm). The method for preparing a multilayer film using aluminum silicate according to claim 1, wherein the high-resistance aluminum oxide zinc film has a thickness of 50 to 150 nanometers (nm). The method for producing a multilayer film using aluminum silicate according to claim 1, wherein the thickness of the aluminum zinc oxide film is between 100 and 300 nanometers (nm).