Thin film transistor array panel

Details Thin film transistor array panel Thin film transistor array panel

2002-10-25

2003-11-18

Dudek, James (Department: 2871)

Liquid crystal cells, elements and systems

Particular excitation of liquid crystal

Electrical excitation of liquid crystal

Reexamination Certificate

active

06650379

ABSTRACT:

BACKGROUND OF THE INVENTION
(a) Field of the Invention
The present invention relates to thin film transistor (TFT) array panels for a liquid crystal display (LCD) and a method for manufacturing the same using four photolithography steps.
(b) Description of the Related Art
An LCD is one of the most widely used FPDs (flat panel displays). The LCD includes two panels having electrodes for generating electric fields and a liquid crystal layer interposed between the two panels. The transmittance of incident light is controlled by the intensity of the electric field applied to the liquid crystal layer.
The field-generating electrodes are typically provided at both or one of the panels, and one of the panels includes switching elements such as thin film transistors.
In general, a thin film transistor array panel is manufactured by a photolithography process using a plurality of photomasks. Conventionally, five or six photolithography steps are employed. Since the photolithography process is expensive, it is desirable to reduce the number of photolithography steps. Even though manufacturing methods using only four photolithography steps have been suggested, these proposed methods are not easy to implement.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a new manufacturing method for a thin film transistor array panel for a liquid crystal display using four photolithography steps.
It is another object of the present invention to prevent the current leakage in a liquid crystal display. Another object of the present invention is to reduce the step coverage of thin film transistor array panels for liquid crystal displays.
In order to achieve these and other objects, according to the present invention, a semiconductor layer and a protection layer of organic insulating material are patterned in a single step. Also, according to the present invention, a photoresist (PR) pattern is reflowed to form an upper layer. Thus, the reflowed PR pattern is used to form a lower layer under the upper layer such that the lower layer is extended outside the upper layer.


REFERENCES:
patent: 6380011 (2002-04-01), Yamazaki et al.
patent: 6525788 (2003-02-01), Nakagawa et al.
patent: 3-17809 (1994-11-01), None

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