Active solid-state devices (e.g. – transistors – solid-state diode – Non-single crystal – or recrystallized – semiconductor... – Amorphous semiconductor material
Patent
1995-09-22
1997-08-12
Crane, Sara W.
Active solid-state devices (e.g., transistors, solid-state diode
Non-single crystal, or recrystallized, semiconductor...
Amorphous semiconductor material
257 72, 257 66, 257225, 257443, 257459, H01L 2701
Patent
active
056568240
ABSTRACT:
A thin film transistor (TFT) having a reduced channel length and method of making same are disclosed for liquid crystal display (LCD) applications. The method of making the TFT includes the following process steps: (i) depositing and patterning the gate on a substrate; (ii) depositing and patterning an intrinsic a-Si layer, a n+ a-Si layer, and a source metal layer (e.g. Cr) over the gate; (iii) depositing and patterning an ITO layer to form a pixel electrode portion and a TFT source portion; (iv) etching the source metal layer so that it remains only under the ITO source portion so as to form the TFT source electrode; (v) depositing and patterning a metal (e.g. Mo) to form the drain of the TFT; and (vi) etching the n+ a-Si layer in the TFT channel area so that only the intrinsic semiconductor layer remains between the source and drain. The resulting TFT has a reduced channel length (e.g. less than about 4 .mu.m) less than the feature size of the lithography used so as to maximize I.sub.ON /C.sub.gs(ON) of the TFT. Maximizing I.sub.ON /C.sub.gs(ON) reduces pixel flickering, gray scale non-uniformity, and image retention in LCD applications.
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Boer Willem den
Gu Tieer
Crane Sara W.
Hardy David B.
OIS Optical Imaging Systems, Inc.
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