Date Visited: October 3, 1991

Report Author: L.E. Tannas, Jr.

ATTENDEES

JTEC:

Covert
Credelle
Hoffman
Tannas

HOSTS:

Hiroo Hori

Yasuhisa Oana

Makoto Ikegaki

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 were made:

• 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 frame.

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 Laboratory
• 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 future.
• 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 later.
• 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 foreseeable future.
• 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 machinery.

• 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 80%.
• 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