Ois Optical Imaging Systems, Inc.

Energy Conversion Devices, Inc.

Ovonic Imaging Systems, Inc.

Mohshi Yang

Willem Den Boer

Zvi Yaniv

Walter E Chapelle

Shui-Chih A Lien

David Vesey

A thin film transistor (TFT) array in an active matrix liquid crystal display (AMLCD) including a centrally located round source electrode completely surrounded by a substantially annular or circular shaped drain electrode. The geometric design of the TFT of this invention provides for a thin film transistor having a reduced parasitic capacitance and decreased photosensitivity. The TFTs of this invention are located at the intersections of gate and drain lines of an active matrix LCD array thereby increasing the size of the pixel display openings of the matrix array.

Method of making an array of TFTs having reduced parasitic capacitance

A thin film transistor (TFT) array in an active matrix liquid crystal display (AMLCD) including a centrally located round source electrode substantially completely surrounded by a substantially annular or circular shaped drain electrode. The geometric design of the TFT of this invention provides for a thin film transistor having a reduced parasitic capacitance and decreased photosensitivity. The TFTs of this invention are located at the intersections of gate and drain lines of an active matrix LCD array thereby increasing the size of the pixel display openings of the matrix array.

TFT with reduced parasitic capacitance

A light influencing display is provided which has a plurality of pixel group, each pixel of which includes a first electrode formed on a first surface and an opposing, second electrode formed on a second surface. A separate three terminal control device of deposited semiconductor material is formed on the first surface in association with each pixel. Each control device has a control terminal and two current path terminals, a first of which is connected to the first electrode of the control device's associated pixel. A voltage supply lead is formed on the first surface in association with each pixel group, and is connected to the second current path terminals associated with its pixel group. Similarly, a control lead is formed on the first surface in association with each pixel group, and is connected to the control terminals associated with its pixel group. A plurality of conductive data leads is formed on the second surface, with a data lead being electrically connected to each second electrode of a given pixel group. As a result, a desired voltage can be applied between the electrodes of a given pixel by using a selected control lead to turn on the control devices of that pixel's pixel group, and by using a selected data lead to supply a data voltage to its second electrode. The present invention allows x - y addressing of an active matrix display without crossing address lines on either the first or second surface, avoiding the risk of short circuits between such lines. It also allows the voltage supply and control leads associated with adjacent pixel groups to be combined, greatly reducing the number of lines required in such a display.

Active display matrix addressable without crossed lines on any one

Methods for producing field effect transistors having short current-conduction channels and reduced parasitic capacitance are disclosed. The methods allow the channel length to be substantially less than the minimum feature size of the photolithographic mask if desired, thereby enabling very short channel length transistors to be formed using conventional ten micron photolithography. An exemplary method involves: (a) depositing a thick film of photoresist over a multilayered sandwich structure forming part of the transistor, said structure having a bottom gate electrode, an insulator layer thereover, followed by a layer of deposited semiconductor material and a thin film of etchable conductive material thereover; (b) exposing the photoresist through a mask; (c) wetting the photoresist to cause it to swell before development to create an overhang, if desired; (d) etching the etchable material to undercut a portion of the photoresist, and (e) shadow depositing material on top of the uncovered semiconductor layer beyond the shadow of the undercut and overhanging photoresist, thereby locating said channel, and one of the two current-carrying electrodes of the transistor.

Growing community of inventors

Troy, MI, United States of America

Mohshi Yang