Method for manufacturing self-aligned thin-film transistor and structure thereof

a thin-film transistor and manufacturing method technology, applied in the direction of transistors, semiconductor devices, electrical devices, etc., can solve the problems of non-uniform capacitance between the gate and the drain, difficult to implement a self-alignment process, and the manufacturing procedures of the conventional tft with a bottom gate structure are more complicated than that of the tft with a top gate structure. achieve the effect of enhancing the contrast ratio of lcd, accurate manufacturing, and high absorption characteristi

Inactive Publication Date: 2011-01-06
NAT CHIAO TUNG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
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Benefits of technology

[0013]In the method for manufacturing the self-aligned TFT and the structure thereof according to the present invention, the oxide gate having a high absorbing characteristic on the ultraviolet light serves as the bottom gate and the mask, and only exposes the photoresist layer other than that corresponding to the oxide gate, such that the source and the drain are accurately manufactured during the subsequent manufacturing procedures.
[0014]Furthermore, the oxide gate according to the present invention does not affect the penetration of a visible light of a backlight source, such that an opening ratio of an LCD having the TFT structure according to the present invention is greatly improved, thereby enhancing a contrast ratio of the LCD.

Problems solved by technology

However, the conventional TFT with a bottom gate structure encounters a serious problem that does not occurs to a TFT with a top gate structure, that is, it is difficult to implement a self-aligned process.
When the exposing process is executed, if a position of the mask is not accurately aligned with a preset position, the source / drain and the gate electrode are overlapped or non-uniformly contact with each other, such that a capacitance between the gate and the drain (Cgd) is non-uniform, which is a main reason for causing the mura phenomenon in the LCD.
In addition, the manufacturing procedures of the conventional TFT with a bottom gate structure are more complicated than that of the TFT with a top gate structure.
A plurality of photolithography processes is required, and after the TFT with a bottom gate structure is finished, a larger parasitic capacitance exists, such that the whole characteristics of the TFT are deteriorated.

Method used

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first embodiment

[0027]Through the above steps, the TFT 200 of a bottom gate type according to the present invention as shown in FIG. 2F is finished. The TFT 200 comprises the transparent substrate 210, and the oxide gate 220, the dielectric layer 230, the source 240, the drain 250, and the active layer 270 disposed on the transparent substrate 210 in sequence.

[0028]FIG. 4 and FIGS. 5A to 5G are respectively a flow chart of steps and schematic views of detailed steps according to a second embodiment of the present invention. Referring to FIG. 5A and the descriptions of the steps of FIG. 4, in a method for manufacturing a self-aligned TFT according to the second embodiment of the present invention, firstly, a transparent substrate 210 is provided (Step 100), in which the transparent substrate 210 has a first surface 211 and a second surface 212 opposite to each other (that is, respectively a top surface and a bottom surface of the transparent substrate 210). The transparent substrate 210 according to...

second embodiment

[0034]Through the above steps, the TFT 200 of a bottom gate type according to the present invention as shown in FIG. 5G is finished. The TFT 200 includes the transparent substrate 210, and the oxide gate 220, the dielectric layer 230, the source 240, the drain 250, and the active layer 270 disposed on the transparent substrate 210 in sequence.

[0035]In the method for manufacturing the self-aligned TFT and the structure thereof according to the present invention, the oxide gate serves as a bottom gate and a mask. The oxide gate has a high absorbing characteristic for the ultraviolet light, so as to shield the ultraviolet light irradiated on the photoresist layer corresponding to the oxide gate. Thus, the source and the drain are accurately manufactured in a self-aligned manner during the subsequent steps, without any deviation on the disposition positions thereof, and accordingly, the steps for manufacturing the TFT are greatly simplified.

[0036]Furthermore, the oxide gate according to...

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Abstract

A method for manufacturing a self-aligned thin-film transistor (TFT) is described. Firstly, an oxide gate, a dielectric layer, and a photoresist layer are deposited on a first surface of a transparent substrate in sequence. Then, an ultraviolet light is irradiated on a second surface of the substrate opposite to the first surface to expose the photoresist layer, in which a gate manufactured by the oxide gate serves as a mask, and absorbs the ultraviolet light irradiated on the photoresist layer corresponding to the oxide gate. Then, the exposed photoresist layer is removed, and a transparent conductive layer is deposited on the unexposed photoresist layer and the dielectric layer. Then, a patterning process is executed on the transparent conductive layer to form a source and a drain, and an active layer is formed to cover the source, the drain, and the dielectric layer, so as to finish a self-aligned TFT structure.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 098122334 filed in Taiwan, R.O.C. on Jul. 1, 2009, the entire contents of which are hereby incorporated by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to a method for manufacturing a thin-film transistor (TFT), and more particularly to a method for manufacturing a self-aligned TFT and a structure thereof, which are capable of performing a self-aligned process by using a bottom gate structure.[0004]2. Related Art[0005]A TFT may be applied to a driver of a liquid crystal display (LCD), for example, applied to a driver of an active LCD, or applied to a static random access memory (SRAM) for serving as an active load. A photoelectric element manufactured by using an oxide TFT has characteristics of a simple manufacturing process and composite functions, for example, the photoelectric...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): H01L29/786H01L21/34
CPCH01L29/4908H01L29/78603H01L29/66765H01L29/45H01L29/7869
Inventor CHOU, CHENG WEIZAN, HSIAO WENTSAI, CHUANG CHUANG
Owner NAT CHIAO TUNG UNIV
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