CN100339756C - Multilayer diffusion barrier layer structure and manufacturing method of thin film transistor liquid crystal display - Google Patents

Abstract

A multi-layer diffusion barrier layer structure of low temperature poly-silicon (LTPS) thin film transistor liquid crystal display and the manufacturing method thereof. The roughness between each layer of the multi-layer diffusion barrier layer structure increased by plasma treatment or the low-density loose-structure impurity atom collecting layer formed between two layers of the multi-layer diffusion barrier layer structure is used for capturing the impurity atoms so as to effectively block the impurity diffusion.

Description

Multilayer diffusion barrier layer structure and manufacturing method of thin film transistor liquid crystal display

technical field

The invention relates to a manufacturing technology of a thin film transistor liquid crystal display, in particular to an improved multi-level diffusion barrier layer structure of a low temperature polysilicon (LTPS) thin film transistor liquid crystal display and an improved manufacturing method thereof.

Background technique

With the rapid progress of thin-film transistors (TFTs) manufacturing technology, liquid crystal displays (liquid crystal displays; LCDs), which have the advantages of thinness, lightness, power saving, and no radiation, have been widely used in computers and personal digital assistants. (PDA), watches, notebook computers, digital cameras, LCD monitors and cordless phones and other electronic products. Coupled with the industry's active investment in research and development and the adoption of industrialized production equipment, the production cost of liquid crystal displays has been continuously reduced, and the demand for liquid crystal displays has also increased significantly.

Most of the TFT panels currently on the market belong to the traditional amorphous silicon thin film transistor liquid crystal display (a-Si TFT LCD) technology. Due to the low temperature polysilicon (LTPS) thin film transistor liquid crystal display has various advantages such as resolution, brightness, size and anti-electromagnetic interference. Advantages in this field make the research and development focus of LCD manufacturers gradually shift to this field. Based on the consideration of film quality and output requirements, the low-temperature polysilicon manufacturing process usually adopts Excimer Laser Annealing technology (Excimer Laser Annealing), that is, using excimer laser as a heat source. After the laser light passes through the projection system, it will produce laser with uniform energy distribution. The light beam is projected on the glass substrate of the amorphous silicon structure. When the glass substrate of the amorphous silicon structure absorbs the energy of the excimer laser, it will transform into a polysilicon structure. The whole process is completed below 600°C, so the general glass substrate is applicable.

In the low-temperature polysilicon process, when the amorphous silicon is converted into polysilicon by laser irradiation, in addition to the heating of the silicon film, the surface of the glass substrate under the silicon film will also absorb the heat of the silicon film. The temperature rises. At this time, the impurities in the glass substrate will diffuse into the silicon film due to the high temperature, thus destroying the electrical properties of the silicon film and making it lose the performance of semiconductor. In order to solve this problem, a diffusion barrier layer (buffer layer) can be deposited between the silicon film and the glass substrate to block the diffusion of impurities.

In the prior art, in the manufacturing process of the diffusion barrier layer, the diffusion coefficient is generally reduced by increasing the density of the diffusion barrier film itself, and the effect of blocking impurity diffusion is enhanced. However, increasing film density has the side effect of increased stress. In addition, increasing the film thickness of the diffusion barrier layer is also used to increase the effect of blocking impurity diffusion, but this method usually reduces throughput.

Therefore, there is an urgent need to improve the existing manufacturing method of the diffusion barrier layer in the low-temperature polysilicon process, so as to effectively increase the effect of the diffusion barrier layer in blocking impurity diffusion.

Contents of the invention

The main purpose of the present invention is to provide a multi-level diffusion barrier layer structure of a low-temperature polysilicon (LTPS) thin film transistor liquid crystal display. purpose of the effect.

The present invention also provides a method for manufacturing the multi-level diffusion barrier layer of the low-temperature polysilicon thin film transistor that can effectively block impurity diffusion.

According to the technical solution of the present invention, a multilayer diffusion barrier layer structure of a low-temperature polysilicon thin film transistor is firstly provided, the structure is formed between the insulating substrate and the polysilicon film of the thin film transistor, and includes at least two diffusion barrier layers, Moreover, a discontinuous structure is provided between each diffusion barrier layer, so as to achieve the purpose of effectively blocking impurity diffusion. According to the present invention, the discontinuous structure between the diffusion barrier layers refers to any structure or treatment result that can absorb or trap impurity atoms, for example, it may be that plasma treatment is performed on the upper surface of the diffusion barrier layer to produce many depressions , to increase its surface roughness to capture impurity atoms, and it can also be a low-density porous structure for collecting impurity atoms.

According to a preferred solution of the present invention, the multi-level diffusion barrier layer of the provided low-temperature polysilicon thin film transistor is formed between the insulating substrate of the thin film transistor and the polysilicon film, and includes a first diffusion barrier layer and a second diffusion barrier layer, wherein, The first diffusion barrier layer is formed on the upper surface of the insulating substrate, and is treated with plasma to increase its roughness; and the second diffusion barrier layer is formed on the upper surface of the first diffusion barrier layer. The second diffusion barrier layer can be made of SiNx, SiOx and SiOxNy.

The present invention also provides another preferred embodiment of the multi-level diffusion barrier layer of the low temperature polysilicon thin film transistor. The multi-level diffusion barrier layer structure is formed between the insulating substrate of the thin film transistor and the polysilicon film, including a first diffusion barrier layer, a first impurity atom collection layer and a second diffusion barrier layer. Wherein, the first diffusion barrier layer is formed on the upper surface of the insulating substrate; the first impurity atom collection layer is formed on the upper surface of the first diffusion barrier layer, and is a low-density porous structure; and the second diffusion barrier layer is formed on the upper surface of the first impurity atom collection layer.

According to another aspect of the present invention, it is to provide a method for manufacturing the multi-level diffusion barrier layer of the above-mentioned low-temperature polysilicon (LTPS) thin film transistor liquid crystal display to improve the effect of the multi-level diffusion barrier layer blocking the diffusion of impurities, including: forming a first layer on the upper surface of the insulating substrate A diffusion barrier layer; performing plasma treatment on the first diffusion barrier layer to cause depressions on the surface of the first diffusion barrier layer; and forming a second diffusion barrier layer on the upper surface of the first diffusion barrier layer.

According to the manufacturing method of another low-temperature polysilicon (LTPS) thin film transistor liquid crystal display multi-level diffusion barrier layer structure provided by the present invention, comprising: generating a low-density porous (porous) impurity atom collection layer between the two diffusion barrier layers , also achieve the effect of improving the diffusion barrier layer blocking impurity diffusion.

Description of drawings

Fig. 1 is a kind of low temperature polysilicon (LTPS) thin film transistor liquid crystal display of the present invention multi-level diffusion barrier layer structural sectional view;

Fig. 2 is the impurity concentration distribution diagram having the structure of Fig. 1;

FIG. 3 is a cross-sectional view of another low-temperature polysilicon (LTPS) thin film transistor liquid crystal display with a multi-level diffusion barrier layer structure.

Explanation of the marks in the attached drawings:

1——insulating substrate

2——The first diffusion barrier layer

3—Second Diffusion Barrier Layer

4——Polysilicon film layer

5 - impurity atoms

2' - the upper surface of the first diffusion barrier layer

6——Impurity atom collection layer

Detailed ways

The technical content and many advantages of the present invention will be described below in conjunction with the detailed description of the accompanying drawings and embodiments, but they cannot be construed as limiting the present invention.

Referring to Fig. 1, this figure is the cross-sectional schematic diagram of the preferred embodiment of the multi-level diffusion barrier layer structure of the low-temperature polysilicon (LTPS) thin film transistor liquid crystal display of the present invention, taking the diffusion barrier layer with two-layer structure as an example, describe this in detail invention.

First, as shown in FIG. 1 , on a light-transmitting insulating substrate 1 , a first diffusion barrier layer 2 is deposited by chemical vapor deposition (CDV) or sputtering. Generally speaking, the light-transmitting insulating substrate 1 can be made of glass, quartz or similar materials. The first diffusion barrier layer 2 can be made of materials such _{as SiNx} , _SiOx or _SiOxNY .

Then, the first diffusion barrier layer 2 is subjected to corrosive plasma treatment (gas of NF ₃ or SF ₆ can be used) to increase the roughness of the first diffusion barrier layer 2, and in the first diffusion barrier layer 2 Many depressions are formed on the upper surface 2', and these depressions will catch the impurity atoms 5 diffused from the insulating substrate 1 due to the subsequent heating, so that they will not continue to diffuse upwards, thereby effectively blocking the impurities and preventing them from diffusing to the polysilicon thin film transistor. Polysilicon film layer 4 . Next, the second diffusion barrier layer 3 is deposited again. Thus, the multilayered diffusion barrier layer having a two-layer structure is formed. Afterwards, an amorphous silicon film layer is deposited, and the excimer laser annealing technique is used to transform the amorphous silicon film layer into polysilicon. on the interface with the second diffusion barrier layer. If the multilayer diffusion barrier layer has more than two layers, the above plasma treatment steps may be repeated between other layers of the multilayer diffusion barrier layer to achieve the desired barrier effect.

In another embodiment of the present invention, as shown in FIG. 3 , between the first diffusion barrier layer 2 and the second diffusion barrier layer 3, a layer of low-density porous impurity atom collection layer 6 is generated, such as a low-density SiO _X film layer. The impurity atom collecting layer 6 provides an environment for trapping the impurity atoms, because its structure is loose and there are many spaces for the impurity atoms to stay.

The impurity atom collection layer 6 can be formed by adjusting the process parameters. For example, if a low-density SiO _X film layer needs to be formed, the ratio of the reactant SiN ₄ to N ₂ O can be adjusted, or the reactant tetraethyl-ortho-silicic acid can be adjusted. Ratio of ester (TEOS, ie Tetra-Ethyl-ortho-Silicate) to _O2 or _O3 . Generally, the larger the content of SiN ₄ , the higher the porous property of the SiO _X film; and the smaller the oxygen content, the smaller the density of the SiO _X film. Similarly, if the multi-level diffusion barrier layer has more than two layers, other impurity atom collecting layers may be formed between other layers of the multi-level diffusion barrier layer to achieve the desired blocking effect.

From the above, it can be seen that the multi-level diffusion barrier layer structure manufactured by the present invention can not only effectively improve the effect of the diffusion barrier layer in blocking impurity diffusion, but also not produce side effects as in the prior art.

The preferred embodiments of the present invention have been described above, but they are not intended to limit the present invention. Modifications and changes to the embodiments disclosed herein may be made by those skilled in the art without departing from the scope and spirit of the invention.

Claims (9)

1. A multi-level diffusion barrier layer structure for a low-temperature polysilicon thin film transistor, which is formed between the insulating substrate of the thin film transistor and the polysilicon film, the multi-level diffusion barrier layer structure comprising: a first diffusion barrier layer, which is formed on the upper surface of the insulating substrate, and treated with a corrosive plasma to produce depressions on the upper surface of the first diffusion barrier layer; and A second diffusion barrier layer, which is formed on the upper surface of the first diffusion barrier layer. 2. The multi-layer diffusion barrier structure as claimed in claim 1, further comprising a third diffusion barrier layer formed on the upper surface of the second diffusion barrier layer, and the second diffusion barrier layer is treated with plasma to increase its roughness. 3. The multi-level diffusion barrier layer structure as claimed in claim 1, wherein the material _of the first diffusion barrier layer is selected from _SiNx , _SiOx or _SiOxNY . 4. The multi-level diffusion barrier layer structure as claimed in claim 2, wherein the material _of the second diffusion barrier layer is selected from _SiNx , _SiOx or _SiOxNY . 5. A multi-level diffusion barrier layer structure for a low-temperature polysilicon thin film transistor, which is formed between the insulating substrate of the thin film transistor and the polysilicon film, the multi-level diffusion barrier layer structure comprising: a first diffusion barrier layer, the barrier layer is formed on the upper surface of the insulating substrate; The first impurity atom collection layer is formed on the upper surface of the first diffusion barrier layer and has a low-density porous structure; and The second diffusion barrier layer is formed on the upper surface of the first impurity atom collection layer. 6. The multilayer diffusion barrier layer structure as claimed in claim 5, further comprising a third diffusion barrier layer and a second impurity atom collection layer, wherein the second impurity atom collection layer is formed on the second diffusion barrier layer The upper surface is formed and has a low-density porous structure, and the third diffusion barrier layer is formed on the upper surface of the second impurity atom collection layer. 7. The multi-level diffusion barrier layer structure as claimed in claim 5, wherein the first impurity atom collection layer is made of SiO _x material. 8. A method for manufacturing a multi-level diffusion barrier layer structure for low-temperature polysilicon thin film transistors, including: forming a first diffusion barrier layer on the upper surface of the insulating substrate; performing a corrosive plasma treatment on the first diffusion barrier layer to cause depressions on the upper surface of the first diffusion barrier layer; and A second diffusion barrier layer is formed on the upper surface of the first diffusion barrier layer. 9. The method as claimed in claim 8, further comprising performing plasma treatment on the second diffusion barrier layer, causing depressions on the upper surface of the second diffusion barrier layer, and forming a third Diffusion barrier layer.

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