The main thrust in active matrix technology is directed towards establishing cost-effective manufacturing of amorphous silicon AMLCDs. Substantial capital investments have been made by many companies in factories for laptop computer displays. These factories are not yet running at capacities probably because the yields are too low compared with prices that the high volume market will support.

In this environment, technical resources are committed to fixing factory and product issues and are not able to concentrate on the next generation of display research. The results of researchers' labors tend to be closely held and only bits and pieces are published and openly discussed.

Specific technical achievements have included lower resistance gate metallization systems, multiple/layer gate insulators and superb prototype displays pushing out both the resolution (1920 x 1600 TFTs) and size (15-inch) boundaries.

Seiko-Epson and Toshiba continue to develop MIM technologies and have demonstrated products and prototypes. Nonetheless, MIMs are expected to only serve limited applications in which cost is more severely constrained than performance.

Research is continuing on low temperature polysilicon because it is generally perceived to be a promising technology. Nonetheless, although there has been progress and consistent achievements, no technical breakthroughs have appeared, probably because the Japanese level of effort is much reduced (and is applied to amorphous silicon factory startup problems). The market niche that drives polysilicon currently is for viewfinders and projection light valves, both of which are low volumes in terms of area production. In these applications, the ability to integrate the drive electronics onto the AM substrate provides a significant, and at times enabling, advantage.

Published: June 1992; WTEC Hyper- Librarian