KR100425821B1 - Method of manufacturing for poly-Silicone thin layer - Google Patents

Abstract

In the present invention, forming an amorphous silicon thin film on an insulating substrate; Adsorbing a small amount of nickel silicide (NiSi _X ) on the amorphous silicon thin film; Inducing movement of said nickel silicide phase; It provides a method for producing a polysilicon thin film comprising the step of crystallizing an amorphous silicon thin film into a polysilicon thin film using the nickel silicide phase as a crystal nucleus.

Description

Method of manufacturing poly-silicon thin layer

The present invention relates to a liquid crystal display device, and more particularly, to a thin film transistor used as a switching element in a liquid crystal display device.

In the current flat panel display field, active matrix liquid crystal display (AMLCD) is the mainstream. In an AMLCD, a thin film transistor (TFT) is used as a switching element to change the transmittance of a pixel by adjusting a voltage applied to a liquid crystal of one pixel.

Hydrogenated amorphous silicon (Amorphous-Silicon: H; hereinafter referred to as amorphous silicon) is mainly used as the switching element, which is easy to manufacture in large areas, high productivity, and deposition at a low substrate temperature of 350 ° C. or less. This is because a low cost insulating substrate can be used.

However, because hydrogenated amorphous silicon has a disordered atomic arrangement, weak Si-Si bonds and dangling bonds exist, and thus, the Si-Si is changed into a quasi-stable state when irradiated with light or applied with an electric field to be used as a thin film transistor device. Stability is a problem. In particular, amorphous silicon has a problem of deterioration in characteristics due to light irradiation, and is difficult to use in driving circuits due to electrical characteristics (low field effect mobility: 0.1 to 1.0 cm 2 / V · s) and reliability deterioration of display pixel driving elements.

That is, an amorphous silicon thin film transistor substrate connects an insulating substrate and a printed circuit board (PCB) using a tape carrier package (IC) integrated circuit (TCP), and a large portion of the cost for the driving IC and the actual equipment is used.

In addition, when the resolution of the liquid crystal panel for a liquid crystal display device is increased, the pad pitch outside the substrate connecting the gate wiring and the data wiring of the thin film transistor substrate with the TCP becomes short, and the TCP bonding itself becomes difficult.

However, polysilicon in the polycrystalline state has a higher field effect mobility than amorphous silicon, so that a driving circuit can be made on the substrate. When the polysilicon is made directly on the substrate, the driving IC cost can be reduced and the mounting is simplified. .

In addition, polysilicon has a higher field effect mobility than amorphous silicon, and is advantageous as a switching device of a high resolution panel. The polysilicon may be applied to a display device in which a lot of light is exposed due to less photocurrent compared to amorphous silicon.

The polysilicon manufacturing method is divided into low temperature process and high temperature process according to the process temperature. The high temperature process has the disadvantage of using expensive quartz substrate with high heat resistance because the process temperature is higher than 1000 ℃ and the temperature condition is higher than the deformation temperature of the insulating substrate. Therefore, it is crystallized using amorphous silicon that can be deposited at low temperature. Efforts are being made in many directions.

In addition, the polysilicon thin film deposited by the high temperature poly process has high surface roughness and low quality crystallinity such as fine grains during film formation, and device application characteristics are inferior to recrystallization of the amorphous silicon thin film by the low temperature poly process. It is known.

The low temperature poly thin film transistor liquid crystal display device is a next generation new concept technology having superior image quality, high reliability, and low power consumption than conventional amorphous silicon products.

In addition, the low temperature poly-process is suitable for a mobile phone in which high reliability and portability such as vibration, shock, and design are emphasized by embedding a driving circuit and a peripheral circuit in the process.

Among these low-temperature poly processes, MIC (Metal Induced Crystallization), MIC (Metal Induced Lateral Crystallization), and FE-MIC (Field Enhanced MIC), which form polysilicon using a catalyst metal material such as nickel (Ni) as crystal nuclei, Mainly used. All.

Among these, the FE-MIC method has been spotlighted as a crystallization method capable of lowering the crystallization time and the temperature required for crystallization by applying a high voltage of direct current to the catalytic metal-treated silicon thin film.

Hereinafter, a low temperature poly process using nickel as a catalyst metal material will be described in detail with reference to the accompanying drawings.

1A to 1C are cross-sectional views illustrating stepwise crystallization processes of an amorphous silicon thin film using a general FE-MIC method.

In FIG. 1A, a buffer layer 10 and an amorphous silicon layer 12 (a-Si) are sequentially formed on the insulating substrate 1, and then a small amount of nickel is deposited on the amorphous silicon layer 12. It is a step of adsorption using a method such as coating, implantation, etc.

In FIG. 1B, the nickel-adsorbed substrate 16 is heated to a temperature of 500 ° C. or lower, and an electric field is applied to the metal electrodes 13 provided at both ends of the substrate 16 to be deposited by the FE-MIC effect. Nickel and silicon of the amorphous silicon layer 12 react to transform into a nickel silicide (NiSi _X ; X = 0.5 to 2) phase, and then a crystallization reaction is induced while the nickel silicide phase moves.

In FIG. 1C, the polysilicon layer 20 is formed through the crystallization reaction.

In a subsequent step, the polysilicon layer 20 is patterned to form an active layer, and then a gate electrode, a source, and a drain electrode are sequentially formed to complete a thin film transistor.

In the crystallization process by the MIC or MILC method, although not shown in the drawings, the nickel-adsorbed amorphous silicon substrate is heated to a temperature of 500 ° C. or higher, and the nickel and silicon react with the thermal energy to transform into a nickel silicide phase. As the nickel silicide phase moves, a crystallization reaction is induced.

As described above, in the crystallization process of inducing crystallization of an amorphous silicon thin film using nickel as a catalyst metal, the reaction efficiency is lower than that of nickel silicide, which is a material used as a catalyst for the actual crystallization reaction, and in particular, the thin film is not involved in the reaction. Due to the nickel present therein, there is a problem in that device characteristics are degraded such as leakage current is generated during operation of the polysilicon thin film transistor formed through the crystallization process.

In order to solve the above problems, in the present invention, polysilicon thin film transistor device characteristics are prevented from deterioration, and even in a low temperature process, it may have uniform crystallinity and produce polysilicon using a catalytic metal material that can increase reaction efficiency. It aims to do it.

To this end, the present invention intends to directly use nickel silicide instead of nickel as a material used as a crystallization reaction catalyst.

1A to 1C are cross-sectional views showing step by step for the crystallization process of an amorphous silicon thin film using a conventional FE-MIC method.

Figure 2a to 2c is a cross-sectional view showing a step of manufacturing a polysilicon thin film using the FE-MIC method of the present invention.

3 is a cross-sectional view of a thin film transistor using a polysilicon thin film according to the present invention as a semiconductor layer.

<Description of the symbols for the main parts of the drawings>

100: insulating substrate 110: buffer layer

112: amorphous silicon layer

116: nickel silicide adsorbed substrate

118: metal electrode

In order to achieve the above object, a first aspect of the present invention comprises the steps of forming an amorphous silicon thin film on an insulating substrate; Adsorbing a small amount of nickel silicide (NiSi _X ) on the amorphous silicon thin film; Inducing movement of said nickel silicide phase; It provides a method for producing a polysilicon thin film comprising the step of crystallizing an amorphous silicon thin film into a polysilicon thin film using the nickel silicide phase as a crystal nucleus.

Before forming the amorphous silicon thin film, forming a buffer layer on the insulating substrate, and inducing the movement on the nickel silicide is characterized in that using the thermal energy.

In addition, inducing the movement of the nickel silicide phase may include using thermal energy and an electric field, and adsorbing the nickel silicide may target nickel silicide compounds to deposit nickel silicide particles on a substrate. The nickel silicide compound is characterized in that the material formed by depositing and sintering nickel on a single crystal silicon material. The sintering temperature is characterized in that 500 ℃ ~ 1,000 ℃.

In a second aspect of the present invention, there is provided a thin film transistor using a polysilicon thin film formed by the manufacturing method according to the first aspect as a semiconductor layer.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

Figure 2a to 2c is a cross-sectional view showing a step of manufacturing a polysilicon thin film using the FE-MIC method of the present invention.

2A illustrates that after depositing the first insulating material and the amorphous silicon on the insulating substrate 100, the buffer layer 110 and the amorphous silicon layer 112 are formed, respectively, and then on the amorphous silicon layer 112. Adsorption of trace amounts of nickel silicide.

In this case, the nickel silicide may be adsorbed by a sputter or chemical vapor deposition (CVD) apparatus, or a coating or injection method using a spin coating apparatus.

For example, in the case of the sputtering method, a target material must first be made. If a large amount of nickel is deposited on a general single crystal silicon material and then sintered at about 500 ° C to 1,000 ° C, a target of the nickel silicide compound can be made. . If the target is placed in a sputter chamber and sputtered in a general argon (Ar) or nitrogen (N ₂ ) atmosphere, the nickel silicide material can be adsorbed onto the amorphous silicon layer.

It is preferable that the first insulating material be a silicon oxide film (SiNx).

In FIG. 2B, the nickel silicide-adsorbed substrate 116 is heated to a temperature of 500 ° C. or lower, and an electric field is applied to the metal electrode 118 at both ends of the substrate 116, thereby causing nickel silicide by the FE-MIC effect. As the phase moves, the crystallization reaction of the amorphous silicon layer 112 is induced quickly.

In FIG. 2C, the polysilicon layer 120 is formed through the crystallization reaction.

In the present invention, when the polysilicon layer 120 is formed of nickel silicide using a catalytic metal material, the process of transforming nickel into nickel silicide may be omitted, thereby increasing reaction efficiency and minimizing residual nickel. Therefore, deterioration of device characteristics can be prevented.

In addition to the crystallization process according to the FE-MIC method, a crystallization process of an amorphous silicon thin film using nickel silicide, which is a catalytic metal material according to the present invention, may be applied to the MIC or MILC method.

3 is a cross-sectional view of a thin film transistor using a polysilicon thin film according to the present invention as a semiconductor layer, and a coplanar type thin film transistor having a source and a gate on one plane will be described as an example.

As shown in the figure, a buffer layer 130 is formed on the insulating substrate 100 over the entire surface of the substrate, and an active layer 132a made of polysilicon crystallized using nickel silicide as a catalyst metal material on the buffer layer 130. And a semiconductor layer 132 composed of an ohmic contact layer 132b made of impurity polysilicon on both sides of the active layer 132a, and a gate insulating film 134 and a gate electrode 136 formed on the active layer 132a. ) Are stacked in this order, and an interlayer insulating film 140 including first and second semiconductor layer contact holes 138a and 138b is formed on the gate electrode 136, and the first and second semiconductors are formed. Source and drain electrodes 142 and 144 are connected to the layer contact holes 138a and 138b, respectively, and a passivation layer 148 including a drain contact hole 146 on the source and drain electrodes 142 and 144. ) Is formed, and the above-mentioned protective layer 148 Through the drain contact hole 146 is connected to the drain electrode 144, a pixel electrode 150 is formed.

However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.

As described above, according to the low temperature crystallization technique of the amorphous silicon thin film using nickel silicide according to the present invention, by uniformly increasing the reaction rate and uniformity of all the crystallization process using nickel as the crystallization catalyst, uniform crystal at low temperature below 500 ℃ The polysilicon thin film can be manufactured, and by replacing the existing excimer laser method, it has the effect of reducing the equipment investment cost of the liquid crystal display device and improving the price competitiveness of the related field.

Claims (8)

Forming an amorphous silicon thin film on an insulating substrate; Adsorbing a small amount of nickel silicide (NiSi _X ) on the amorphous silicon thin film; Inducing movement of said nickel silicide phase; Crystallizing an amorphous silicon thin film into a polysilicon thin film using the nickel silicide phase as a crystal nucleus Method for producing a polysilicon thin film comprising a. The method of claim 1, Before forming the amorphous silicon thin film, forming a buffer layer on the insulating substrate. The method of claim 1, Inducing the movement of the nickel silicide phase, the method of producing a polysilicon thin film using the thermal energy. The method of claim 1, Inducing the movement of the nickel silicide phase, the method of producing a polysilicon thin film using a thermal energy and an electric field. The method of claim 1, The adsorbing nickel silicide may include depositing nickel silicide particles on a substrate using a nickel silicide compound as a target. The method of claim 5, wherein The nickel silicide compound is a method of manufacturing a polysilicon thin film which is a material formed by depositing and sintering nickel on a single crystal silicon material. The method of claim 6, The sintering temperature is 500 ℃ ~ 1,000 ℃ manufacturing method of polysilicon thin film. A thin film transistor using a polysilicon thin film formed by the method according to claim 1 as a semiconductor layer.