Resistance is futile

Mitsubishi Electric and SPC have jointly developed resist removal technology for use in the manufacture of LCDs that does not use expensive chemicals.

In the manufacture of LCDs, the processes of pattern fabrication — film deposition, resist coating, exposure, development, etching, resist removal, and substrate washing — are repeated several times, then transistors are formed on the glass substrate.

Previously, removal liquid was used in the resist removal process. And a combination of ultraviolet light irradiation and water washing was used for cleaning the substrate. However, the removal liquid was expensive, and was used in large quantities. Consequently, the cost of the removal liquid and the environmental impact of the waste were important issues. With Mitsubishi’s new equipment, however, there is no need to treat the waste water — including the removal liquid — thus enabling the environmental impact to be reduced by one tenth or less. What is more, running costs can be reduced to 1/5 of that of conventional equipment.

The use of ozone in the new process permits the resist removal process to be integrated with the substrate washing process too. This enables installation space of the equipment to be reduced by about one half. The equipment can also handle large LCD substrates, such as those that are used for television sets.

In November 2000, SPC will start to test samples from LCD manufacturers. It will also exhibit panels showing the new resist removal equipment for LCD manufacturing at the LCD/PDP International 2000 Exhibition between October 25th and 27th, and will commence marketing the new equipment in January 2001.

In addition to LCD resist removal, Mitsubishi Electric intends to apply the new technology to semiconductor resist removal and wafer washing as well.