N.sup.+ amorphous silicon thin film transistors for matrix addressed liquid crystal displays
First Claim
1. A process for the fabrication of thin film field effect transistors in active matrix liquid crystal display devices, said process comprising the sequential steps of:
- disposing a gate metallization layer pattern on a portion of a first major surface of an insulative substrate, said gate metal comprising titanium, said pattern including gate electrodes and;
disposing a pixel electrode pattern on a portion of the first major surface of said substrate, said pixel electrode material comprising indium tin oxide;
disposing a layer of protective insulative material over said first major substrate surface including said gate metal pattern and said pixel electrode pattern;
disposing a layer of intrinsic amorphous silicon over said protective insulative material;
disposing a layer of N+ amorphous silicon over said intrinsic amorphous silicon;
patterning said protective insulative material, said intrinsic amorphous silicon and said N+ amorphous silicon layers so as to form islands over said gate metal, whereby each island formed includes protective insulative material, intrinsic amorphous silicon and N+ amorphous silicon layers;
disposing a source and drain metallization layer over the first major surface of said substrate; and
patterning said source and drain metallization layer and said N+ silicon layer so as to form field effect transistor devices.
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Accused Products
Abstract
A thin film FET switching element, particularly useful in liquid crystal displays (LCDs) employs particular materials and is fabricated via a particular process to ensure chemical compatibility and the formation of good electrical contact to an amorphous silicon layer while also producing FETs with desirable electrical properties for LCDs. These materials include the use of titanium as a gate electrode material and the use of N+ amorphous silicon as a material to enhance electrical contact between molybdenum source and drain pads and an underlying layer of amorphous silicon. The process of the present invention provides enhanced fabrication yield and device performance.
40 Citations
15 Claims
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1. A process for the fabrication of thin film field effect transistors in active matrix liquid crystal display devices, said process comprising the sequential steps of:
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disposing a gate metallization layer pattern on a portion of a first major surface of an insulative substrate, said gate metal comprising titanium, said pattern including gate electrodes and; disposing a pixel electrode pattern on a portion of the first major surface of said substrate, said pixel electrode material comprising indium tin oxide; disposing a layer of protective insulative material over said first major substrate surface including said gate metal pattern and said pixel electrode pattern; disposing a layer of intrinsic amorphous silicon over said protective insulative material; disposing a layer of N+ amorphous silicon over said intrinsic amorphous silicon; patterning said protective insulative material, said intrinsic amorphous silicon and said N+ amorphous silicon layers so as to form islands over said gate metal, whereby each island formed includes protective insulative material, intrinsic amorphous silicon and N+ amorphous silicon layers; disposing a source and drain metallization layer over the first major surface of said substrate; and patterning said source and drain metallization layer and said N+ silicon layer so as to form field effect transistor devices. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A process for the fabrication of thin film field effect transistors in active matrix liquid crystal display devices, said process comprising the sequential steps of:
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disposing a gate metallization pattern on a portion of a first major surface of an insulative substrate, said gate metal comprising titanium, said pattern including gate electrodes and disposing a pixel electrode pattern on a portion of the first major surface of said substrate, said pixel electrode material comprising indium tin oxide; disposing a layer of protective insulative material over said first major substrate surface including said gate metal pattern and said pixel electrode pattern; disposing a layer of intrinsic amorphous silicon over said protective insulative material; disposing a layer of N+ amorphous silicon over said intrinsic amorphous silicon; disposing a layer of molybdenum over said N+ silicon layer; patterning said molybdenum layer so as to form islands over said gate metal; patterning said protective insulative material, said intrinsic amorphous silicon and said N+ amorphous silicon layers so as to form islands said gate metal, the islands being substantially the same size or slightly larger than said molybdenum island on insulative material layer, the intrinsic amorphous silicon layer, the N+ amorphous silicon layer and the molybdenum layer disposing a source and drain metallization layer over the first major surface of said substrate; and patterning said source and drain metallization layer and said N+ silicon layer so as to form field effect transistor devices. - View Dependent Claims (14, 15)
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Specification