Back channel etching oxide thin film transistor process architecture

Abstract

The disclosure relates to a back channel etching oxide thin film transisto process architecture. A method for fabricating a back channel etching (BCE) oxide thin film transistor (TFT) for a liquid crystal display is provided. The method includes forming a first metal layer having a first portion and a second portion over a substrate, depositing a gate insulator over the first metal layer, and disposing a semiconductor layer over the gate insulator. The method also includes depositing a half-tone photoresist to cover a first portion of the semiconductor layer and the first portion of the first metal layer. The half-tone photoresist has a first portion and a second portion thicker than the first portion. The first portion has a through hole above the second portion of the first metal layer. The second portion of the half-tone photoresist covers the first portion of the first metal layer. The method further includes etching a portion of the gate insulator through the via hole such that the second portion of the first metal layer is exposed, removing the first portion of the half-tone photoresist while remaining the second portion of the half-tone photoresist, and etching to remove a second portion of the semiconductor layer that is not covered by the half-tone photoresist.

Description

[0001] Cross References to Related Applications [0002] This application claims priority to US Nonprovisional Application No. 13 / 664240, entitled "Back Channel Etching Oxide Thin Film Transistor Process Architecture," filed October 30, 2012, the contents of which are hereby incorporated by reference in their entirety. technical field [0003] Embodiments described herein generally relate to process architectures for oxide thin film transistors (TFTs) in active matrix liquid crystal displays (AMLCDs). More particularly, certain embodiments relate to processes for back channel etch (BCE) oxide TFTs. Background technique [0004] Liquid crystal displays (LCDs) generally display images by utilizing the action of liquid crystals to transmit or block light. LCDs have been used in a variety of computing displays and devices, including notebook computers, desktop computers, tablet computing devices, mobile phones (including smart phones), vehicle in-cabin displays, and in home app...

AI Technical Summary

Problems solved by technology

Often, very different etch rates between the passivation layer and the gate insulator create undercuts in the vias, which can lead to interruptions in the conductive material used to coat the vias, thereby interfering with the operation of the TFT

[0007] A conventional fabrication scheme for BCE oxide TFTs uses a dedicated mask for etching SiO alone 2 and SiN x , which increases production time and reduces yield

Additionally, each mask used increases the chances that the resulting TFT will not be operable

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