Site: TOSHIBA ENGINEERING LABORATORY
Date Visited: October 3, 1991
Report Author: L.E. Tannas, Jr.
The Toshiba R&D visit was held at the Electron Device Engineering
Laboratory in Yokohama, where we discussed the issues of a-Si TFT LC and
related displays. At the conclusion of the meeting, the committee visited
Toshiba's exhibit room and saw operating examples of the 10.4-inch (640 x 480),
13.8-inch (1052 x 900), D-size (1024 x 1024) and 3ATI- size avionics displays,
all in color using a-Si TFT LCDs.
The discussions were open and free-flowing, and the following key points
- The Engineering Laboratory supports all other divisions in the Toshiba
ET&D Group, with over 90% of the activities on LCDs.
- The CRT group does its own research.
- The remaining 10% of the activities in the laboratory are advanced image
sensors and printer heads.
- This Engineering Laboratory supports the DTI (Joint IBM/Toshiba venture)
and Toshiba LCD factory in Himeji in basic device and process information and
in basic materials development.
- The Engineering Laboratory does work relating to a three-year time frame,
and the R&D Laboratory in Kawasaki does work relating to a five-year time
The goals of the Engineering Laboratory are focused on several products and
on high yield and productivity:
- a-Si TFT LCDs 10.4" VGA color
- Higher information content displays:
- 12" to 14" to 16" (1024 x 768 and 1024 x 1280)
- Advanced instrument displays for avionics
ARINC D (1024 x 1024) and 13.8" (1150 x 900) Sparc, Electronics
- Simple matrix LCDs:
High contrast, flicker-free, quicker response, brighter, gray scale,
cross-talk free, higher multiplexing
- Ferroelectric LCDs
- Polymer-dispersed LCDs
- Poly-Si TFTs
- LCD for video projectors
- Advanced image sensors and printer heads
Staffing of people involved in LCD research:
- 40-50 in Kawasaki
- 100 in Yokohama
- 200 in Toshiba Himeji
- 50 in DTI Himeji
Sales in LCD Division:
- 1990, $200M
- 1991, $300M
- STN will grow 10-15% per year
- TFT a new market
- STN and TFT by 1995, one trillion yen (moderate prediction 500-600 billion
yen), 70% STN, 30% TFT.
With more than 80% of the avionics cockpit CRT display market, Toshiba feels
it must continue its participation in the avionics market.
Toshiba is studying all forms of LCDs--ECB, PDLC, MIMs, FLCD, poly-Si TFTs,
Philips diode approach--and have decided to concentrate on STN and TFT
approaches. They are using a-Si TFTs but are continuing to study poly-Si. Even
for HDTV projectors, poly-Si may cost more than a-Si TFTs in 3" and 4", but
Toshiba will study more. Toshiba is studying low-temperature, laser-annealing,
thermal-annealing, and ion-doping aspects of poly-Si TFT LCDs.
The Toshiba representative made several important observations relative to
the future of LCDs:
- Toshiba does not have a strong interest in ECB or ferroelectric LCDs in the
- The STN LCD must be black and white or color because of future demand.
- Compensated STN and a-Si TFT LCDs will coexist for a long time and may
never cross over in market share.
- Color STN still has yield and speed problems due to color thickness
uniformity and cell thickness limitations.
- Toshiba buys pigment-type color filters from outside but continues to study
different methods. Strong interest in printing method.
- Toshiba is making its own LSI drivers with up to 240 outputs mounted on
"slim- tab," and will sell to anyone.
- Toshiba thinks that HDTV will be done with LCD projectors.
- There is a renewed interest in direct-view color plasma panels for large
displays and HDTV. However, there are developmental issues such as poor
brightness, efficiency, color gamut, drivers, and life.
- GTC's funding has been reduced from 10 billion yen to 2 billion yen and so
it is working on manufacturing technologies for the one-meter LCD panel rather
than making a one- meter panel. Hitachi, NEC, and Sharp may make a panel
- Toshiba sees 15 inches or 16 inches as the size limit for LCDs using
today's production methods. Anything larger will need a completely new
production technology. Toshiba does not see the adoption of 500 mm substrates
before the year 2000. SEMI has a standard for substrates of 300-500 mm on a
side of 50-mm steps. Toshiba is presently standardized at 300 mm x 320 mm.
- The crossover display size between CRT direct view and projection is
between 36 and 40 inches.
- The "TV on-the-wall" for consumers is too expensive now and for the
- 8.5 inches is too small for VGA; therefore, 300 micron pixel pitch is
appropriate for direct view. 150 micron pixel pitch is too small and is not
needed for direct-view displays.
- The FPD market will not be saturated in the next ten years.
- Toshiba will not be doing any more plasma or EL research. NEC has stopped
its plasma work.
- Toshiba Computer Division may have adopted plasma because of its fast
response time. Monochrome plasma displays are quite competitive with STN LCDs
for notebook computers.
The next phase will be in improvements in production processes and
- High throughput is the highest priority.
- PECVD needs improvement.
- Cleanliness improvements are needed to improve yield.
- Alignment layer still needs a lot of improvement. Presently, Toshiba uses a
polyimide rubbing technique.
- Glass shrinkage is a big problem due to 350 degrees centigrade processing
temperature; five ppm is too much.
- More automatic test equipment is needed and expected from the United States
in the next two to three years.
- Mobility is at 1.26 and is OK.
- Design rule used is six micron average, three micron for TFT, eight micron
for color filters and edge connections. Nikon Stepper can do one or two micron.
Canon Mirror can do 3 or 4 microns.
- Next generation design in 2-3 years will be designed for a yield of over
- Toshiba trying to stay completely away from repair. They do not repair
array with lasers. Only repair being used is in TAB bonding.
The tour of the Toshiba display room demonstrators gave a clear and lasting
impression of the accomplishments of Toshiba engineering and manufacturing.
Figure Toshiba.1. R & D Activities of LCD
Figure Toshiba.2. Electron Device Engineering Laboratory
Published: June 1992; WTEC Hyper-