TFT process with high transmittance

Details TFT process with high transmittance TFT process with high transmittance

2000-05-22

2001-09-18

Booth, Richard (Department: 2812)

Semiconductor device manufacturing: process

Making device or circuit emissive of nonelectrical signal

Including integrally formed optical element

C438S151000

Reexamination Certificate

active

06291255

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for manufacturing TFT (Thin Film Transistor), and particularly relates to a method for manufacturing TFT that has high transmittance.
2. Description of the Prior Art
In fabricating TFT (Thin Film Transistor) LCD (Liquid Crystal Display) panel utilizing LTPS (Low Temperature Polycrystalline Silicon) technology, because the mobility of electrons can be greatly raised, the manufacture of high quality TFT-LCD panel is enabled, and the cost is lowered by reducing the number of connecting lines. Usually, the silicon nitride (SiNx) is utilized in the LTPS technology to form the interlayer or the passivation layer to been proceed with the hydrogenation process. The LTPS technology is designed to fabricate the LCD panel having high transmittance and high aperture rate, but the silicon nitride (SiNx) layer will lower the transmittance of the LCD panel. So the frequently utilized silicon nitride (SiNx) layer in the LTPS technology will degrade the performance of the LCD panel fabricated by the LTPS technology.
In the prior art LTPS technology utilized to form the TFT LCD, the silicon nitride layer is necessary for the hydrogenation process employed to improve the characteristic of the fabricated TFT panel. However the silicon nitride layer utilized in the LTPS technology reduces the transmittance of the LCD panel fabricated by the LTPS technology. The degradation mentioned above can be ignored when the request for the performance of the fabricated LCD panel is not so high. But, when the request for the resolution of the LCD panel is getting bigger, the request for transmittance of each pixel of the fabricated LCD panel is getting higher.
In the tide of high resolution, even a little degradation in transmittance of each pixel of the LCD panel will greatly reduce the transmittance of the entire LCD panel. When the request for the resolution of the LCD panel is not so high, the worse performance of the LCD panel can still be ignored. So the silicon nitride layer is still necessary in the fabricated TFT LCD. However, with the need for the transmittance and performance getting greater, the problem resulting from the silicon nitride layer must be resolved without causing other manufacturing problems.
SUMMARY OF THE INVENTION
Because of the need for high resolution, it is necessary to design the pixel of high aperture rate and it is also necessary to consider the transmittance of each semiconductor layer. But as the need for the transmittance of the LCD getting greater, it is very important to increase the transmittance of the TFT LCD panel.
According to the purpose mentioned above, the present invention proposes a method for manufacturing TFT panel, which can increase the transmittance of the TFT panel. The foregoing method includes an intermediate-layer process. After the intermediate-layer process has been executed, use the source conductive pattern and the drain conductive pattern are used the mask in an etching step to remove the silicon nitride layer without the shield of the source conductive pattern and the drain conductive pattern. So the transmittance of the fabricated TFT panel is greatly increased.
According to the present invention, the intermediate-layer process can have three aspects. In the first aspect, the first step is to bake the TFT panel, so the silicon nitride layer is utilized to proceed with the hydrogenation process. The following step is to form the contact hole in the insulating layer of the TFT panel. Finally, form the source conductive pattern and the drain conductive pattern are formed. In the second aspect, the first step is to form the contact hole in the insulating layer of the TFT panel, then form the source conductive pattern and the drain conductive pattern, followed by baking the TFT panel including the source conductive pattern and the drain conductive pattern. In the third aspect, the first step is to form the contact hole in the insulating layer of the TFT panel, then sputtering a metallic layer on the TFT panel followed by a baking step. Then the metallic layer is etched to form the source conductive pattern and the drain conductive pattern.
The TFT panel mentioned in the three aspects of the preferred embodiment of the present invention includes the source conductive pattern and the drain conductive pattern, the TFT panel includes the gate polysilicon, the gate channel layer, gate insulating layer, and the silicon nitride layer. In addition, the TFT panel is formed on the base -transparent substrate, and the transparent substrate in the present invention can be made of glass. Besides, the LTPS technology is used to fabricate the TFT panel and the gate channel can be made of poly-crystalline silicon. The baking step mentioned above remains at about 350-450° C. for more than about half an hour.


REFERENCES:
patent: 5403755 (1995-04-01), Chae
patent: 5956579 (1999-09-01), Yamazaki et al.
patent: 6010921 (2000-01-01), Soutome
patent: 6025216 (2000-02-01), Ha

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