KR100209586B1 - Method of fabricating poly silicon thin film transistor - Google Patents

Abstract

The present invention relates to a poly-crystal silicon thin film transistor (p-Si TFT), and more particularly to a-Si containing hydrogen as a precursor of polycrystalline silicon on an insulating substrate. And a layer below the a-Si: H layer as a hydrogen source for hydrogen annealing, to produce a polycrystalline silicon thin film transistor.

In the present invention, it is possible to provide a method for effectively annealing hydrogen by a simple operation of controlling a gas supplied to a reaction chamber when forming a p-Si precursor film, and an a-Si layer containing no hydrogen as a p-Si precursor film. By using the dual structure of the a-Si layer containing and hydrogen, the pre-annealing process for releasing hydrogen during laser annealing can also be omitted.

In addition, according to the present invention, a separate hydrogen annealing process and a pre-annealing process at the time of laser annealing are omitted, thereby improving productivity and cost reduction according to the simplification of the process, and evenly and effectively hydrogen annealing over the entire surface of the p-Si active layer. The characteristics of the transistor can be improved.

Description

Method of manufacturing polycrystalline silicon thin film transistor

1 is a cross-sectional view of a polycrystalline silicon thin film transistor according to the prior art.

2 is a manufacturing process diagram of a polycrystalline silicon thin film transistor according to the prior art.

3 is a cross-sectional view of a polycrystalline silicon thin film transistor according to the present invention.

4 is a manufacturing process diagram of a polycrystalline silicon thin film transistor according to the present invention.

* Explanation of symbols for main parts of the drawings

1 Insulation substrate 2 Polycrystalline silicon

3: gate insulating film 4: gate electrode

5 source and drain diffusion regions

6 interlayer insulating film 7 source electrode

8 drain electrode 9 a-Si: H

10: a-Si

The present invention relates to a poly-crystal silicon thin film transistor (p-Si TFT), and more particularly to a-Si containing hydrogen as a precursor of polycrystalline silicon on an insulating substrate. And a layer below the a-Si: H layer as a hydrogen source for hydrogen annealing, to produce a polycrystalline silicon thin film transistor.

Recently, the importance of polycrystalline silicon is increasing in semiconductor technology. This is because the degree of freedom of device design and configuration processors increases, and the application range of wires, electrodes, floating electrodes, device isolation, diffusion sources, and diffusion masks is becoming increasingly widespread.

Polycrystalline silicon thin film transistors are used in high-definition liquid crystal display (liquid crystal display), in particular, it is effective for high resolution and low cost of the liquid crystal panel (panel) used in the video projector.

The manufacturing process of the low temperature polycrystalline silicon thin film transistor according to the prior art is as follows.

A-Si: H (9), a precursor layer of polycrystalline silicon (p-Si), is deposited on the insulating substrate 1 in a hydrogen atmosphere by PCVD (Plasma Chemical Vapor Deposition), sputtering, and vacuum deposition. (FIG. 2 (a)). The a-Si: H (9) layer is crystallized into p-Si (2) (FIG. 2 (b)). When using a low-cost glass substrate as the insulating substrate (1), the temperature should be maintained at a temperature lower than 600 ℃, annealing by the XeCl excimer laser (effectively annealing) is effective as a method for low temperature crystallization. During laser annealing, hydrogen contained in the a-Si: H (9) film is released, and pre-annealing is performed with smaller laser energy to prevent voids and other defects caused by abrupt emission. There is a need.

Thereafter, the gate insulating film 3 and the gate electrode film 4 are formed in sequence, and the gate electrode 4 is patterned (FIG. 2C).

Ion implantation is performed to form the source and drain diffusion regions 5 using the gate electrode 4 as a mask (FIG. 2D) and the gate insulating film 3 is etched (FIG. 2). e)).

The interlayer insulating film 6 is applied and the contact holes are patterned (FIG. 2 (f)), and the metal films for the source 7 and the drain electrode 8 are formed and patterned (FIG. 2 (g)). ).

In the case of fabricating a polycrystalline silicon thin film transistor (FIG. 1) according to the prior art as described above, in order to obtain sufficient device characteristics, defects such as dangling bonds at the crystal grain interface of polycrystalline silicon (p-Si, 2) are obtained. A hydrogen annealing method of substituting with hydrogen is generally used. In the hydrogen annealing method, a method of treating with a hydrogen plasma after fabrication of a device is most common, and Japanese Patent Laid-Open No. Hei 1-29460 proposes a method of using SiOxHy as an interlayer insulating film and using hydrogen released from the SiOxHy film by heat treatment. . However, in the former case, additional heat treatment is required due to damage of the surface of the thin film by hydrogen plasma, and in the latter case, the gate electrode 4 covers the passage portion between the source and the drain. .

Accordingly, an object of the present invention is to realize a high-quality liquid crystal display by improving the characteristics of the polycrystalline silicon thin film transistor through improving the manufacturing process of the polycrystalline silicon thin film transistor in order to solve the conventional problems.

In order to achieve the above object, the present invention uses a-Si which does not contain hydrogen as a precursor of p-Si in place of a-Si: H of the prior art to effectively perform hydrogen annealing without any additional process. In the lower layer, a-Si: H layer was placed as a hydrogen source for hydrogen annealing to prepare a polycrystalline silicon thin film transistor.

Hereinafter, the manufacturing process of the polycrystalline silicon thin film transistor according to the present invention will be described in more detail.

The a-Si: H (9) layer and a-Si (10) are formed on the insulating substrate 1 sequentially through a single process treatment using a sputtering method (FIG. 4 (a)). A-Si: H (9) is prepared by magnetron sputtering in hydrogen and argon (Ar) atmospheres using Si as a target, and a-Si (10) is prepared by magnetron sputtering in Ar atmospheres. That is, by interrupting the hydrogen gas supply, the a-Si (10) layer can be continuously produced after the a-Si: H (9) layer.

The a-Si layer is crystallized using a short wavelength laser such as an XeCl excimer laser (Fig. 4 (b)). Thereafter, the gate insulating film 3 and the gate electrode film 4 are sequentially formed by the magnetron sputtering method, and the gate electrode is patterned (FIG. 4C).

Ion implantation is performed to form the source and drain diffusion regions 5 using the gate electrode as a mask (Fig. 4 (d)) and the gate insulating film is etched (Fig. 4 (e)).

A contact hole was patterned by applying an interlayer insulating film (FIG. 4 (f)), and a metal film for source and drain electrodes was formed by a sputtering method and then patterned to manufacture a polycrystalline silicon thin film transistor of the present invention. (Figure 3)

In the above it is possible to crystallize the a-Si 10 by laser annealing. a-Si: H (9) may contain up to 30 atomic% hydrogen at manufacturing conditions, for example at low substrate temperatures, and 350 When the temperature is heated above, this hydrogen starts to be released. Thus, it becomes possible to evenly anneal all parts of the crystallized p-Si (2) which is the active region of the TFT.

In the manufacturing process of the polycrystalline silicon thin film transistor, the source 7 and the drain electrode 8 are 400 to 450 in the process of forming and sintering an Al film by a sputtering method. Since heat treatment is performed at a temperature of 20 to 60 minutes at this time, hydrogen annealing can be performed at the same time, so that an additional step is unnecessary.

Accordingly, the present invention provides a method capable of effectively hydrogen annealing with a simple operation of controlling the gas supplied to the reaction chamber when forming the p-Si precursor film. In addition, by using a-Si containing no hydrogen as the p-Si precursor film, the pre-annealing process for releasing hydrogen during laser annealing can be omitted.

In addition, according to the present invention, a separate hydrogen annealing process and a pre-annealing process at the time of laser annealing are omitted, thereby improving productivity and cost reduction according to the simplification of the process, and evenly and effectively hydrogen annealing over the entire surface of the p-Si active layer. The characteristics of the transistor can be improved.

Claims (2)

In manufacturing a thin film transistor including polycrystalline silicon crystallized in amorphous silicon as an active layer, a-Si: H layer is formed on an insulating substrate, and a-Si without hydrogen is formed thereon to form a precursor of polycrystalline silicon. A method of manufacturing a polycrystalline silicon thin film transistor, wherein an amorphous silicon two-layer structure is used as a film. The method of claim 1, wherein the a-Si: H is used as a hydrogen source for hydrogen annealing.