Methods of forming thin film transistors

Details Methods of forming thin film transistors Methods of forming thin film transistors

1997-12-22

2003-07-08

Trinh, Michael (Department: 2822)

Semiconductor device manufacturing: process

Making field effect device having pair of active regions...

On insulating substrate or layer

C438S156000, C438S585000

Reexamination Certificate

active

06589821

ABSTRACT:

TECHNICAL FIELD
This invention relates specifically to thin film transistor technology.
BACKGROUND OF THE INVENTION
As circuit density continues to increase, there is a corresponding drive to produce smaller and smaller field effect transistors. Field effect transistors have typically been formed by providing active areas within a bulk substrate material or within a complementary conductivity type well formed within a bulk substrate. One additional technique finding greater application in achieving reduced transistor size is to form field effect transistors with thin films, which is commonly referred to as “thin film transistor” (TFT) technology. These transistors are formed using thin layers which constitute all or a part of the resultant source and drain regions, as opposed to providing both regions within a bulk semiconductor substrate.
Specifically, typical prior art TFT's are formed from a thin film of semiconductive material (typically polysilicon). A central channel region of the thin film is masked by a separate layer, while opposing adjacent source/drain regions are doped with an appropriate p or n type conductivity enhancing impurity. A gate insulator and gate are provided either above or below the thin film channel region, thus providing a field effect transistor having active and channel regions formed within a thin film as opposed to a bulk substrate.
It would be desirable to improve upon methods of forming thin film transistors and in improving thin film transistor constructions.


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IBM Technical Disclosure Bulletin, “Methods of Forming Small Contact Holes”, Jan. 1998, vol. 30, No. 8, pp. 252-253.

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