KR20080036502A - Polycrystal silicon thin film and method for manufacturing thereof - Google Patents

Abstract

A polycrystal silicon thin film and a method for manufacturing the same are provided to prevent metal pollution and impurity contamination during a thermal treatment process by using a cover layer disposed between an amorphous silicon layer and a metal. An insulating substrate(10), an buffer layer(20), an amorphous silicon layer(30), and a cover layer(40) are sequentially deposited. A metal(50) is directly deposited on an upper surface of the cover layer. The insulating substrate is preferably one among glass, quartz, and a single crystal wafer covered with an oxide layer. The amorphous silicon layer is formed by sputtering, CVD(Chemical Vapor Deposition), or a pyrolysis method. The cover layer diffuses uniformly the metal into the amorphous silicon layer and protects a thin film from unnecessary organics and metal contamination. The buffer layer, the cover layer, and an insulating layer on a metal substrate are made of a silicon oxide layer, a silicon nitride layer, a silicon oxynitride layer, a silicate layer, or an organic layer. Alternatively, the buffer layer, the cover layer, and the insulating layer are made of a single layer or a multi-layer of homogeneous or heterogeneous species.

Description

Polycrystalline silicon thin film and method for manufacturing thereof

1 is a process flow diagram for producing a polycrystalline silicon thin film, in accordance with the present invention.

2A and 2B are photographs of secondary ion mass spectrometry using a time-of-flight method for the distribution of metals in a conventional polycrystalline silicon thin film according to the present invention.

3A and 3B are optical micrographs of a polycrystalline silicon thin film according to the present invention.

4A to 4C are cross-sectional views without amorphous silicon and optical micrographs of partially polycrystalline silicon, a schematic diagram showing the distribution of metal in a disk shape after crystallization, and a schematic diagram showing the distribution of metal after heat treatment of crystallized polycrystalline silicon; to be.

5A to 5C are schematic diagrams showing the deposition of metal on the polycrystalline silicon layer, schematic diagram showing the diffusion of the metal during the heat treatment, and schematic diagram showing the growth of grain by the metal diffusion to the grain boundary of the polycrystalline silicon layer after the heat treatment. to be.

The present invention relates to a polycrystalline silicon thin film, by dispersing a metal between an amorphous silicon layer and a metal through a cover layer, and by removing a cover layer and depositing a metal on a crystallized polysilicon layer after the cover layer is removed, It is possible to solve the contamination problem of impurities that may occur during metal contamination and heat treatment process, and because the surface of the amorphous silicon layer is protected by the cover layer, it is possible to significantly reduce the surface roughness and to deposit the metal deposited on the polysilicon layer. It relates to a polycrystalline silicon thin film that can move to this grain boundary and control grain growth.

A thin film transistor (TFT) is a switching device that uses a polysilicon thin film as an active layer, and is generally used in active devices of active matrix liquid crystal displays, switching devices of electroluminescent devices, and peripheral circuits. .

Such thin film transistors are usually manufactured using direct deposition, high temperature heat treatment or laser heat treatment. Among them, the laser heat treatment method is capable of crystallization (or phase change, hereinafter referred to as phase change) at a low temperature of 400 ° C or lower than the former two methods, and can realize high field effect mobility. It is preferred because it has. However, while the phase change is uneven and expensive equipment is required, there is a problem that is not suitable when manufacturing polycrystalline silicon on a large-area substrate due to low productivity.

Another method of crystallizing amorphous materials, especially amorphous silicon, is the solid phase crystallization method, which can obtain uniformly phase-changed crystals using low-cost equipment. However, this method has a disadvantage in that the glass substrate cannot be used because of the low productivity and high crystallization temperature due to the long time required for crystallization.

On the other hand, the method of changing the phase of the amorphous material using a metal has been studied a lot of advantages in that the phase change is possible in a short time at a lower temperature than the solid phase crystallization method. Metal induced crystallization is one of them.

Metal-induced crystallization is a method of directly changing at least one portion of a specific type of metal on the amorphous material thin film and laterally changing the phase from the contacted portion or doping the metal into the amorphous material thin film to change the amorphous material from the injected metal. .

According to the conventional method, device characteristics are reduced due to metal contamination. Therefore, there is a problem that the productivity is significantly lowered, such as the addition of a process for removing the contaminated parts separately.

In addition, in the thin film transistor, when the thin film is implemented by patterning the source and drain regions or when the thin film is implemented after patterning on one part of the source and drain, the amorphous material may not be completely phase-changed and the amorphous material region may remain. All.

In other words, the use of the metal-induced crystallization method of the conventional amorphous material has the advantage of lowering the crystallization temperature, while the original characteristics of the thin film are degraded due to contamination by the metal penetrating into the phase-changed thin film.

After all, in order to use the metal-induced crystallization method of amorphous material, it is desirable to minimize the contamination of the thin film from the metal, and to minimize the contamination of the thin film, it is most important to reduce the amount of metal used. For this purpose, a high temperature treatment, rapid heat treatment, or laser irradiation by depositing a thin film ion concentration of 10 ¹⁴ to 10 ¹⁶ cm ⁻² or a thin film of about 5 μs through an ion implanter, and viscosity in the conventional metal induction crystallization method A method of phase change of an amorphous material has been proposed by depositing a thin film by spin coating by mixing an organic thin film and a liquid metal and then performing a heat treatment process.

However, even in the case of the proposed method, it is not possible to greatly improve the contamination of the thin film by the metal used, and there are still problems in terms of the size of the grain size, the uniformity and the large area.

The present invention was devised to solve the problems of the prior art as described above, and the method of diffusing the metal through the cover layer between the amorphous silicon layer and the metal and depositing the metal on the crystallized polysilicon layer after removing the cover layer By taking the heat treatment method, it is possible to solve the problem of contamination of impurities that may occur during metal contamination and heat treatment process, and because the surface of the amorphous silicon layer is protected by a cover layer, the surface roughness can be significantly reduced. It is an object of the present invention to provide a polycrystalline silicon thin film capable of controlling the growth of grain by moving the metal deposited on the polycrystalline silicon layer to grain boundaries.

The constituent means for forming the polycrystalline silicon thin film of the present invention proposed to solve the technical problem as described above, in the polycrystalline silicon thin film, after forming an amorphous silicon layer and a metal on an insulating substrate continuously, and heat treatment of the amorphous silicon layer By crystallization by, a polycrystalline silicon thin film divided into grains and grain boundaries is formed, wherein the average density per unit volume of metal present in the grains and grain boundaries is greater than the average density per unit volume of metal present in the grains. It is characterized by.

On the other hand, the constituent means of the polycrystalline silicon thin film of the present invention according to another embodiment, in the polycrystalline silicon thin film, by forming an amorphous silicon layer, a cover layer and a metal on an insulating substrate in succession, and heat treatment of the amorphous silicon layer After the polycrystalline silicon layer is formed, the cover layer is removed, a metal is formed on the polycrystalline silicon layer, and a heat treatment is performed to form a polycrystalline silicon thin film divided into grain and grain boundaries, wherein the grain and grain The average density per unit volume of metal present at the interface is greater than the average density per unit volume of metal present within the grains.

The insulating substrate may be any one of glass, quartz, a single crystal wafer covered with an oxide film, and a metal substrate having flexibility covered with an insulating film.

The insulating film may be formed by stacking at least one of a silicon oxide film, a silicon nitride film, a silicon oxynitride film, a silicate film, and an organic film.

In addition, the metal is characterized in that formed by any one of ion implantation, PECVD, sputtering, spin coating, printing, immersion method.

In addition, the metal is preferably nickel (Ni).

In addition, the polycrystalline structure of the polycrystalline silicon thin film is grown in a disk shape, characterized in that consisting of grains of polygonal structure.

In addition, the average density per unit volume of metal present in grains and grain boundaries of the polycrystalline silicon thin film is greater than the average density per unit volume of metal present in the grains.

In addition, the average density per unit volume of the metal present in the center region in the grain is characterized in that it is larger than the average density per unit volume of the metal present in the whole grain region.

In addition, the grain boundary is characterized in that formed in a straight line.

In addition, the grain diameter is characterized in that the range of 5㎛ ~ 100㎛.

On the other hand, the constituent means for forming a polycrystalline silicon thin film manufacturing method of the present invention comprises the steps of depositing an amorphous silicon layer on an insulating substrate, including the metal in the amorphous silicon layer, and heat treatment of the amorphous silicon layer, Gathering together to form a nucleus, wherein the nuclei are laterally moved to crystallize the amorphous silicon layer, and the grains of the crystallized polycrystalline silicon layer collide with each other to form grain boundaries.

Further, the surface density of the metal contained in the amorphous silicon layer is 10 ¹² ~ 10 ¹⁴ cm ^- characterized in that the ^two. In addition, the metal is preferably nickel (Ni).

In addition, the grain boundary formed by the impact of the grains is characterized in that formed in a straight line.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of the polycrystalline silicon thin film of the present invention consisting of the above configuration means.

In the polycrystalline silicon thin film according to the present invention, after the amorphous silicon layer and the metal are continuously formed on the insulating substrate, the amorphous silicon layer is crystallized by heat treatment, thereby forming a polycrystalline silicon thin film divided into grains and grain boundaries. The average density per unit volume of the metal present in the grain and grain boundaries is greater than the average density per unit volume of the metal present in the grain. That is, the polycrystalline silicon thin film according to the present invention is characterized in that grain and grain are clearly distinguished.

On the other hand, the constituent means of the polycrystalline silicon thin film of the present invention according to another embodiment, in the polycrystalline silicon thin film, by forming an amorphous silicon layer, a cover layer and a metal on an insulating substrate in succession, and heat treatment of the amorphous silicon layer After the polycrystalline silicon layer is formed, the cover layer is removed, a metal is formed on the polycrystalline silicon layer, and a heat treatment is performed to form a polycrystalline silicon thin film divided into grain and grain boundaries, wherein the grain and grain The average density per unit volume of metal present at the interface is greater than the average density per unit volume of metal present within the grains. In other words, the distinction between grain and grain through two heat treatments is characterized.

1 is a process flowchart illustrating a method of manufacturing a polycrystalline silicon thin film applied to the present invention. Hereinafter, only the polycrystalline silicon thin film formed by using the cover layer and performing two heat treatments will be described. It is apparent that the procedure described below can infer a method of manufacturing a grain and a fine polycrystalline silicon thin film by one heat treatment without using a cover layer.

First, as shown in FIG. 1A, the insulating substrate 10, the buffer layer 20, the amorphous silicon layer 30, and the cover layer 40 are sequentially deposited. As shown in FIG. 1B, the metal 50 is directly deposited on the upper surface of the cover layer 40.

The insulating substrate 10 is not particularly limited, but it is preferable to use one of glass, quartz, and oxide-coated single crystal wafers in consideration of the temperature and thin film uniformity applied for the crystallization of the amorphous silicon layer. An insulating film formed on a metal substrate may be used.

The buffer layer 20 may be omitted because it is not an essential element in the process, but in the present invention, the buffer layer 20 is more preferably deposited.

The amorphous silicon layer 30 is preferably formed using any one of sputtering, chemical vapor deposition, and thermal decomposition. Although the amorphous silicon layer 30 may be replaced with various amorphous materials, the amorphous silicon layer 30 is not limited to one amorphous material, and preferably includes amorphous silicon.

The cover layer 40 serves to uniformly diffuse the metal 50 into the amorphous silicon layer 30 and to protect the thin film from unnecessary organic substances and metal contamination.

The insulating layer on the buffer layer 20, the cover layer 40, and the metal substrate may all use a silicon oxide film, a silicon nitride film, a silicon oxynitride film, a silicate film, an organic film, or the like. It is also possible to form two or more films of the same kind or different kinds by laminating them.

The silicon nitride film is generally formed by a chemical vapor deposition method using xylene (SiH 4), ammonia and nitrogen gas, or by a sputtering method using a nitride film target.

When the nitride film is used as the cover layer, the metal may be diffused even at a thickness of 350 nm. However, since the heat resistance is weak, the cover layer is often broken when heat treatment or laser irradiation is performed at 600 degrees or more.

The silicon oxide film is generally formed by blowing oxygen at a high temperature, by a chemical vapor deposition method using a gas of xylene (SiH 4) and oxygen, or by a sputtering method using an oxide film target. When used as a cover layer, since the metal is difficult to diffuse at a thickness of 10 nm or more, there is a limit to be formed to a thickness of several nm.

The silicon oxynitride film is formed by chemical vapor deposition using a gas of xylene (SiH 4), ammonia or nitrogen as a nitrogen source, and nitrogen oxide or oxygen as an oxygen source. Or the sputtering method using the target of an oxynitride film is also possible.

When the oxynitride film is used for the cover layer or the like, the metal can be diffused even at a thickness of 350 nm like the nitride film, and there is an advantage in that the problem of the nitride film in which the thin film is broken at high temperature can be solved. This is because the thin film is strengthened by the bonding of oxygen in the general nitride film, thereby preventing the cover layer from being broken even during heat treatment or laser irradiation of 600 degrees or more.

The cover layer 40 is preferably formed to a thickness within the range of 0.1 to 1000 nm at a temperature of 650 ℃ or less, the deposition method is most preferably by the plasma enhanced chemical vapor deposition (PECVD) method, but The present invention is not limited, and may be deposited by a general chemical vapor deposition method, a deposition method using pyrolysis, a printer or a spin coating method, or the like.

On the other hand, the metal 50 deposited on top of the cover layer 40 acts as a crystallization medium or inducer of the amorphous material, it is preferably deposited to a thickness of 0.001 nm or more and 1000 nm or less.

As a method of depositing the metal 50 on the cover layer 40, a method using an ion implanter, a PECVD method, a CVD method, an ALD method, a sputter method, a method using a shadow mask, or the like may be used. , A coating method using a liquid metal dissolved in an acid solution, a spin coating method of mixing an organic film and a liquid metal, a printing method, a immersion method, and a method using a gaseous gas containing a metal. In particular, the present invention is not limited thereto, and may be deposited by other methods.

The metal 50 is deposited on top of the cover layer 40 is surface density of 10 ¹² to 10 ¹⁸ cm ^- it is desirable to be deposited as a thin film in the ^second range, the nickel (Ni), cobalt (Co), palladium (Pd), platinum (Pt), iron (Fe), copper (Cu), silver (Ag), gold (Au), indium (In), tin (Sn), arsenic (As), antimony (Sb), etc. Although it is possible to use a single element metal or an alloy including one or more of the above elements, nickel (Ni) is most preferable.

And since it is not easy to deposit the metal 50 into a uniform thin film of 0.2 nm or less, first, a thickness of 0.2 nm or more and 1000 nm or less is deposited to a desired thickness, and then a desired thickness of 0.2 nm or less through a separate etching process. The etching method can also be used.

After the amorphous silicon layer 30, the cover layer 40, and the metal 50 are sequentially deposited as described above, the amorphous silicon layer 30 undergoes a crystallization step, and the crystallization of the amorphous silicon layer 30 is performed. The thermal energy is applied from the outside to diffuse the metal 50 into the amorphous silicon layer 30, and grains are grown in the amorphous silicon layer through the diffused metal.

As a thermal energy application method, methods such as heat treatment, rapid heat treatment, laser or ultraviolet irradiation are frequently used. In the present invention, heat treatment is performed to crystallize the amorphous silicon layer 30.

Preferably, the heat treatment is performed in a temperature range of 200 ° C. to 1400 ° C. The heat treatment method may include, but is not limited to, a halogen lamp, an ultraviolet lamp, a furnace, and the like.

In addition, crystallization of the amorphous silicon layer 30 may be performed in a state where an electric field, a magnetic field, or an electromagnetic field is applied.

When the heat treatment method is selected, it is preferable to crystallize at a temperature range of 200 to 1400 ° C. It is also possible to use either one of the methods of rapid heat treatment or long heat treatment within the above temperature range, or both. .

The rapid heat treatment method is preferably a method of heat treatment several times or more within a time of several tens of seconds within the temperature range of 500 to 900 ℃, the long-term heat treatment method is a method of heat treatment for more than 1 hour in the 400 to 500 ℃ temperature range, Since this temperature range is not absolute, rapid or long-term heat treatment may be performed at other temperature ranges as necessary.

When the heat treatment is performed to crystallize the amorphous silicon layer 30 by the above method, as shown in FIG. 1C, the metal 50 is diffused into the cover layer 40. The precipitate is formed in the amorphous silicon layer 30 to form crystallization. In the case of amorphous silicon, a metal dissilicide nucleus (MSi ₂ , precipitation) is formed.

Grain grows laterally around the nucleus formed as described above, and grain boundaries are formed between adjacent grains to form the polycrystalline silicon layer 31. When the grains continue to grow until they are in contact with adjacent grains and can no longer grow, the crystallization of the amorphous silicon layer is completed.

That is, the amorphous silicon layer is heat-treated to form the nucleus by gathering the metals, and the nuclei are moved laterally to crystallize the amorphous silicon layer. The grains of the crystallized polycrystalline silicon layer hit each other, resulting in grain boundaries.

The surface density of the metal included in the amorphous silicon layer is preferably 10 ¹² to 10 ¹⁴ cm ⁻² , and the metal is preferably nickel (Ni). In addition, it is preferable that the grain boundary resulting from the collision of the grains is formed in a straight line.

It is preferable that the thickness of the polycrystalline silicon layer formed as described above is in a range of 15 nm to 150 nm, and the polycrystalline structure of the polycrystalline silicon layer is formed in a disk shape, and is composed of grain of polygonal structure.

By the above process, after the amorphous silicon layer 30 is crystallized, the metal 50 and the cover layer 40 are removed by an etching process. As shown in FIG. 1D, a metal 60 is formed on the polycrystalline silicon layer 31. Thereafter, as shown in FIG. 1E, heat treatment is performed to form a final polycrystalline silicon thin film 33. At this time, the size of the grain becomes larger than the grain obtained by (c) of FIG.

2A and 2B are photographs of secondary ion mass spectrometry using a time-of-flight method for the distribution of metals in a conventional polycrystalline silicon thin film according to the present invention. As shown in Figure 2a, it can be seen that the metal is formed in the area where the grain and the grain has grown and collided. However, it can be seen that the grain boundaries are not clear as shown in FIG. 2B. That is, as the present invention is applied, it can be seen that the grain boundary becomes clearer, which indicates that most of the metal has moved to the grain boundary during the heat treatment.

The polycrystalline structure of the polycrystalline silicon thin film according to the present invention formed as described above is grown in a disk shape. The polycrystalline structure is composed of grains having a polygonal structure.

Finally, when the polycrystalline silicon thin film is formed, the average density per unit volume of the metal present in the grain and grain boundaries of the polycrystalline silicon thin film is greater than the average density per unit volume of the metal present in the grain. It can be seen that most of the metal is formed by moving to the grain boundary.

Further, the average density per unit volume of the metal present in the center region (less than 1/3 of each grain area) in each grain becomes greater than the average density per unit volume of the metal present in the whole grain region. In other words, in the grain, the metal acting as the nucleus is present in the central region, and the rest moves to the grain boundary.

Meanwhile, the grain boundaries have a straight line shape, and the grain size (diameter) is formed in a range of 5 μm to 100 μm. And, the optimum grain size is preferably formed in the range between 10㎛ 50㎛.

3A and 3B are optical micrographs of a final polycrystalline silicon thin film formed by depositing and thermally treating a metal after removing a cover layer according to the present invention. This photo is formed by forming a metal content of 8.47 × 10 ¹³ cm ^-2 and crystallizing at 500 ° C for 30 hours, removing the cover layer after crystallization, forming a metal (Ni) layer, and heat-treating at 560 ° C for 25 hours. Micrograph of a polycrystalline silicon thin film.

As shown in FIG. 3B, according to the present invention, the first grains were formed by the first heat treatment (by the process of FIG. 1C), and the heat treatment after the second metal deposition (FIG. 1E). By the process of), a second grain was formed by growing at the first grain boundary. In the first crystallization, the grain size ranged from 5 to 50 µm, and in the second heat treatment, the grain size grew from 5 µm to 20 µm at the first grain boundary.

4A is an optical micrograph of a cross section of amorphous silicon and partial polycrystalline silicon in the central portion. In the portion “B” shown in FIG. 4A, the box-shaped portion is a portion in which amorphous silicon does not exist, and the “A” portion is a portion in which amorphous silicon is present. This sample was subjected to heat treatment at 560 ° C for 7 hours after crystallization. 4B is a schematic diagram showing the distribution of metal in a disk shape after crystallization, and FIG. 4C is a schematic diagram showing the distribution of metal after heat treatment of crystallized polycrystalline silicon.

5A to 5C are schematic diagrams illustrating metal (Ni) distribution and diffusion in a polycrystalline silicon thin film having a disk shape. FIG. 5A shows the formation of a metal (Ni) layer on the polycrystalline silicon layer, FIG. 5B shows the diffusion of the metal (Ni) during the second heat treatment, and FIG. 5C shows the movement of the metal (Ni) to the grain boundaries. . As shown in FIG. 5B, as the metal moves to the grain boundary, the interface becomes thicker as shown in FIG. 5C.

According to the polycrystalline silicon thin film of the present invention having the above-described configuration and preferred embodiments, a method of diffusing a metal between an amorphous silicon layer and a metal via a cover layer and depositing a metal on the crystallized polysilicon layer after removing the cover layer Because it takes the method of heat treatment, it is possible to solve the problem of contamination of impurities which may occur in metal contamination and heat treatment process, and to protect the surface of the amorphous silicon layer with a cover layer, it is possible to significantly reduce the clean and surface roughness, The metal deposited on the polysilicon layer is moved to the grain boundary, thereby controlling the growth of grain.

In addition, since the grain growth of the polycrystalline silicon can be controlled by using the phase change method and the metal (Ni) to obtain a macro grain and a uniform polycrystalline silicon thin film, laser technology can be substituted, and the polycrystal manufactured by the present invention Silicon thin film has an advantage that can be applied to the manufacture of flat panel displays, solar cells, semiconductor devices.

Claims (16)

In the polycrystalline silicon thin film, After the amorphous silicon layer and the metal are formed on the insulating substrate, the amorphous silicon layer is crystallized by heat treatment to form a polycrystalline silicon thin film which is divided into grains and grain boundaries, per unit volume of metal present on the grain boundaries. The average density is a polycrystalline silicon thin film, characterized in that greater than the average density per unit volume of the metal present in the grain. In the polycrystalline silicon thin film, After forming an amorphous silicon layer, a cover layer and a metal on an insulating substrate, and heat treating the amorphous silicon layer to form a polycrystalline silicon layer, the polycrystalline silicon layer on which the cover layer is removed is divided into grain and grain boundaries. The average density per unit volume of the metal present in the grain boundary is greater than the average density per unit volume of the metal present in the grain. The method according to claim 1 or 2, The insulating substrate is a polycrystalline silicon thin film, characterized in that any one of glass, quartz, a single crystal wafer covered with an oxide film and a metal substrate having flexibility covered with an insulating film. The method according to claim 1 or 2, The metal is a polycrystalline silicon thin film, characterized in that nickel (Ni). The method according to claim 1 or 2, The polycrystalline structure of the polycrystalline silicon thin film is grown in a disk shape, polycrystalline silicon thin film, characterized in that consisting of grains of polygonal structure. The method according to claim 5, And a mean density per unit volume of metal present in the center region of the grain is greater than a mean density per unit volume of metal present in the whole grain region. The method according to claim 5, The average density per unit volume of the metal present in the grains and grain boundaries of the polycrystalline silicon thin film is greater than the average density per unit volume of the metal present in the grain. The method according to claim 5, The boundary surface of the grains is a polycrystalline silicon thin film, characterized in that formed in a straight line. The method according to claim 5, The grain size of the polycrystalline silicon thin film, characterized in that the range of 5㎛ ~ 100㎛. The method according to claim 9, The grain size of the polycrystalline silicon thin film, characterized in that the range of 10㎛ ~ 50㎛. The method according to claim 1 or 2, And a buffer layer is further included between the insulating substrate and the amorphous silicon layer. In the polycrystalline silicon thin film manufacturing method, Depositing an amorphous silicon layer on an insulating substrate and including a metal in the amorphous silicon layer; Heat treating the amorphous silicon layer to form nuclei by gathering the metals and moving the nuclei laterally to crystallize the amorphous silicon layer; A method for producing a polycrystalline silicon thin film, comprising the step of forming grain boundaries when the grains of the crystallized polycrystalline silicon layer collide with each other. The method according to claim 12, Surface density of the metal contained in the amorphous silicon layer is 10 ¹² ~ 10 ¹⁴ cm ^- the polycrystalline silicon thin film, it characterized in that the ^second method. The method according to claim 13, The metal is nickel (Ni) polycrystalline silicon thin film manufacturing method characterized in that. The method according to claim 12, The grain boundary surface formed by the impact of the grains is characterized in that formed in a straight line. The method according to claim 12, The metal is a method of producing a polycrystalline silicon thin film, characterized in that formed using any one of the ion implantation method, CVD method, sputtering method, spin coating method, printing method, PECVD method, ALD method and immersion method.

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