Site: TOSHIBA & DTI

Date Visited: October 3, 1991

Report Author: W. Doane

ATTENDEES

JTEC:

Doane
Hoffman
Firester
Thompson

HOST:

S. Arai

Senior Manager, LCD Marketing and Engineering Department

K. Kawasaki

Manager, Simple Matrix LCD

T. Sumita

Executive Director, DTI

M. Ikegaki

General Manager, Electronic Development and Engineering Lab, Toshiba

Himeji works employs 5,000 people and has the following production volumes:

CRT:

450,000 per year

Transistors:

412 million per month

Diodes:

325 million per month

SAW devices:

6 million per month

Fluorescent tubes:

6 million per month

LCD:

250,000 - 260,000 per month

Between 50% and 60% of Toshiba LCDs are used internally on Toshiba products. They supply displays for NEC and IBM products as well as their own.

TOSHIBA STN

They focus on large-size STN products with resolution of 640 x 200 and 640 x 480. They have developed their own drivers and controllers and developed the TAB bonding in their own Engineering Manufacturing Department. They produce two VGA displays on a 300 x 360-mm substrate.

The process sequence is as follows:

  1. Starting material, ITO-coated glass, is purchased
  2. Clean -- ultrasonic, detergent and water cleaning
  3. Resist coat -- they use Nakan roller coater with moving drip feed for better uniformity
  4. Dry
  5. Expose -- proximity aligner
  6. Etch
  7. Clean
  8. Polyimide coat -- Shibairi Coater
  9. Bake
  10. Rub -- Toshiba machine, developed internally
  11. Print seal -- screen printing
  12. Apply spacers -- spacers are sprayed on one plate of the cell using a proprietary machine developed internally. Spacers are 6-7 microns with a 0.03-microns tolerance. The spacer population is monitored after spraying.
  13. Curing to obtain better gap uniformity
  14. Assembly
  15. Filling -- liquid crystal is filled on many cells clamped together and dipped in the liquid crystal in a vacuum system.

Cassettes contain 25 substrates.

This entire operation was contained on the third floor of their LCD building. There is a TFT line on the floor below. The LCD line is operated three shifts a day, and there is a facility clean-up after each shift. 50,000 LCDs are produced per month per line, and there are two lines. A third line was to be added in April 1992.

Having toured the sample matrix LCD line, we went to the DTI facility, which is on the same site but is separated from the Toshiba facility by a security fence.

DTI -- AMLCD

DTI was established on November 6, 1989, as a joint venture between Toshiba and IBM Japan. It occupies 27,600 sq. meters of land and has 28,300 sq. meters of building floor space, with an investment of 30 billion yen. As of 10/1/91, it had 377 employees, about one-third of whom were on assignment from Toshiba and IBM Japan; the other two-thirds were new employees who had received six months' training at the Toshiba TFT facility.

There are ten members of the board, five each from Toshiba and IBM Japan. The management structure is shown in figure DTI.1.


Figure DTI.1.

DTI is a manufacturing company only and has no marketing; 50% of the products are delivered to Toshiba, and 50% to IBM Japan.

DTI will produce large-size (10") AMLCDs for office automation applications. Toshiba has its own line, which is supplying other applications and produces mostly smaller sizes. The layout of the site is shown schematically in figure DTI.2.


Figure DTI.2.

Substrates were 300 x 400 mm Corning 7059, stacked in cassettes of 25 plate capacity.

Third Floor

Six Tokuda CDE 702 dry etchers were used for gate metal. Four plasma etchers were used for SiN etch. Two Canon MPA 2000s were used for alignment, and the resist was spray-developed. Canon was apparently preferred over Nikon for cost and throughput reasons.

There were many PECVD machines. The one we could see was a seven-chamber system, the recent Anelva model. A schematic of what was deduced is shown in figure DTI.3.

A window frame holder for four substrates was used in PECVD, with manual loading at the time of our visit. Presumably, this was a double-sided deposition machine, which means that eight substrates were processed in each chamber. Automatic loading was being evaluated on one of the PECVD machines.

Manual transportation of cassettes was used, with automatic loading from transportation cassettes to machine cassettes.

Second Floor

Half of this floor was used to finish the TFT process and contained Kashiyama dry etchers, RIE etchers for MoAl, and two more Canon aligners. The pad metal was sputtered MoAlMo.

The rest of this floor was used for the liquid crystal process. We saw seven glass cutters, four filling machines, and a Nikon particle-inspection machine. ITO and signal line are wet-etched.

First Floor

This was a class 1000 room used for TAB assembling to LCD.

No TFT repair is used because of the high labor content: 70 people operate each shift in the facility. For three shifts, 120 people are used on array production, 40 on cell production, and 50 on module assembly. When the process is mature, the number of operators should be reduced by one half. The cycle time for production is as follows: 3 weeks TFT, 1 week cell, and 1 week module assembly and test.

The transportation of cassettes is done without boxes, but they are considering using closed boxes in the future.

Our DTI hosts said the hardest part of the process is dust control in photolith and CVD. They believe control of the electrostatic charging problem is the equipment vendor's responsibility. The major materials costs are color filters (which they buy), substrates, and drivers.

The AMLCD capacity in this facility will be 1 million per year by 1995. This was an outstanding visit, and our hosts were very open and informative.


Figure DTI.3.


Published: June 1992; WTEC Hyper- Librarian