January 20, 1998 (TOKYO) -- Sharp Corp. and Semiconductor Energy
Laboratory Co., Ltd. (SEL) said that they have developed a
technology called continuous grain silicon (CGS), for growing
thin-film single crystals of silicon on a glass substrate.
They have also produced a prototype 2.6-inch color thin-film
transistor liquid crystal display (TFT-LCD) panel for projection,
which uses the new technology.
With the technology, semiconductor devices, including
microprocessors and memory units, can be fabricated on a glass
substrate. Such semiconductor devices have been fabricated on a
single crystalline silicon wafer.
Use of a glass substrate to produce integrated circuits could
reduce costs substantially. A large number of ICs could be
fabricated on a 550mm x 650mm substrate designed for an LCD
A sheet-shaped personal digital assistant (PDA) could be produced
by fabricating an LCD panel, a microprocessor and memory devices
on a glass substrate.
To produce the CGS, amorphous silicon must be grown on a glass
substrate. The precise method for producing the CGS has yet to be
disclosed. Shumpei Yamazaki, president of SEL, said that it won't
be difficult for major companies to produce the glass-substrate
silicon once they understand how to do it.
The CGS has a high mobility of 300 cm2V-
1s-1. The high mobility of a single crystalline
silicon is 400 - 500 cm2V-1s-1,
and that of a polycrystalline silicon used for TFT-LCD is in the
range of tens of centimeters to 150 cm2V-
The two companies produced a nine-cascade ring oscillator using
the CGS. The operating frequency of a transistor was about 1GHz
and the driving voltage was 5V.
Sharp and SEL also have produced a prototype of a display that
integrates driving circuits on a substrate of an LCD panel. The
operating frequency of the driving circuits is 13.8MHz. The
display, designed for high definition televisions, has a high
resolution of 1280 x 1024 pixels, with a numerical aperture of 63
In addition, the two firms have produced a prototype of a rear-
projection display using the LCD panel. The display is 60 inches
in size, 900cd/ cm2 in luminance and 300:1 in
contrast, they said. A 370W metal-halide lamp is used as a light
They said they plan to commercialize the product by the end of