High conductivity gate metallurgy for TFT/LCD's

Abstract

Amorphous silicon based thin film transistor liquid crystal displays (TFT/LCD) have become the dominant technology used for flat panel displays for notebook computers. The need for higher resolution, larger diagonal displays for both notebook and desktop applications is discussed. Calculations have shown that the use of high conductivity gate metal such as aluminum or copper, together with the implementation of improved groundrules, can significantly extend today's technology. Aluminum suffers from problems with hillock formation during PECVD processing, and copper typically has poor adhesion to glass, reaction problems with silicon and other PECVD films, and difficulties in contacting it to other metals. Approaches to solving problems with both materials are presented, and a novel reduced mask process to fabricate high resolution, high aperture ratio 10.5 inches SXGA (1280×1024) displays is described. The process uses copper gate metallurgy with redundancy, without the need for extra processing steps. The resulting displays have 150 dpi color resolution, an aperture ratio of over 35%, and excellent image quality, making them the first high resolution displays that are suitable for notebook applications.