In an almost universally ignored statement made during its annual investor’s meeting, held February 9th in New York, Corning said:

Ken Werner
Senior Analyst and Editor

Still in the early stages of the company’s innovation process is a technology known as silicon on glass or SiOG. In this area, Corning is evaluating various processes to deposit high-performance silicon films onto Corning display glass and transform the glass into an engineered substrate or electronic backplane onto which electronic circuits can be easily added by display glass customers.

Corning did not provide details, but last week at the USDC/Needham annual investors’ conference, four experienced industry analysts found themselves discussing the announcement at length. The analysts were David Barnes (DisplaySearch), Alfred Poor (Pacific Media Associates), Chris Chinnick (Insight Media) and Ken Werner (also Insight Media, who happens to be writing this Display Daily). Their discussion was short on facts, because facts weren’t available to them, but it was rich in insight and imagination.

First, it appears that when Corning spoke of "high-performance silicon films," it was referring to polycrystalline silicon materials with performance characterisctic in the range bracketed by low-temperature polysilicon (LTPS), high-temperature polysilicon (HTPS) or Sharp’s continuous-grain silicon (CGS). With these and similar formulations, you deposit conventional amorphous silicon and you then heat it and cool it to anneal the silicon. The trick is to heat and cool it evenly so it has consistent characteristics, while at the same time keeping the substrate from getting so warm it softens.

In the case of LTPS, the silicon is annealed with a laser, so the substrate remains relatively cool. With HTPS, an oven is used, so the substrated gets as hot as the silicon. The means standard display glass won’t work and a more expensive substrate with a higher melting point, such as optical quartz, must be used. This approach is prohibitively expensive for large displays, but it is exactly what’s done by Epson when it makes the LCD microdisplay imagers for 3LCD projectors. Current ways of fabricating LTPS are limited to Gen 4 because adequate consistency can not be maintained over larger areas than that.

When the "gang of four" speculated last week, they talked about the fact that one thing Corning has lots of when it makes glass is heat. If Corning has found away to deposit amorphous silicon to its cooling glass substrate in such a way that it anneals into polysilicon, they could have a much cheaper way of making the material and - perhaps - a way of making it on substrates larger than Gen 4. This would give Corning a higher-value product to sell and would be an enabler for AMOLED TV, which would greatly benefit from an inexpensive polysilcon that could be made on large substrates. Such a development would also devalue the investments TMD and Sharp have made in LTPS and CGS because it would put all panel makers on an even playing field as far as LTPS is concerned.

Apparently, Corning will be showing samples to customers this fall.