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Browse Prior Art Database

Thin-Film Transistor/Liquid Crystal Display Structure

IP.com Disclosure Number: IPCOM000104544D
Original Publication Date: 1993-May-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Matino, H: AUTHOR

Abstract

This article describes an structure of Thin-Film Transistor (TFT) type liquid crystal display which has a transparent conductor (e.g. ITO) and metal(s) as a gate, and said transparent conductor formed in the same deposition process is used for display electrodes. Also this structure introduces reduction of photo-engraving process steps and of number of photo-mask for a process. The figure shows an example of photo-engraving process steps and masks by this invention. Usually seven or eight photo masks would be used in TFT/LCD fabrication.

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Thin-Film Transistor/Liquid Crystal Display Structure

      This article describes an structure of Thin-Film Transistor
(TFT) type liquid crystal display which has a transparent conductor
(e.g. ITO) and metal(s) as a gate, and said transparent conductor
formed in the same deposition process is used for display electrodes.
Also this structure introduces reduction of photo-engraving process
steps and of number of photo-mask for a process.  The figure shows an
example of photo-engraving process steps and masks by this invention.
Usually seven or eight photo masks would be used in TFT/LCD
fabrication.

      The figure showing 5 mask - 6 photo-engraving process includes
the following steps.

      Step 1.  ITO/Mo/Al deposition and photo etching ...  MASK 1

      Step 2.  SiOx gate insulator deposition, a-Si deposition SiN
deposition and photo etching process by self-align.

      Step 3.  n+ deposition / Mo deposition and photo etching ...
MASK 2

      Step 4.  SiN, i-Si, SiOx photoetching ...  MASK 3

      Step 5.  Mo/Al deposition and photo etching ...  MASK 4

      Step 6.  passivation insulator deposition and photo etching ...
MASK 5

      The figure shows the cross-sectional structure of TFT formed by
the 5 mask and 6 photo process.  Gate electrodes consist of ITO, Mo
and Al which have low series resistance.  ITO is effective to reduce
photo-process steps.  Self-align black shade structure would be
formed by application...