Glass Industry

Asahi Glass and Tokyo Denpa Succeed in the Development

Asahi Glass Co., Ltd. and Tokyo Denpa Co., Ltd. have joined forces to successfully develop a synthetic quartz crystal material with a dramatically improved resistance to laser light as a lens material for the semiconductor exposure lens systems. The co-developed synthetic quartz is a revolutionary material with the rate of deterioration due to light transmission reduced to 1/5 or less of that of the conventional material, which is expected to bring about a cost reduction by lowering the material replacement frequency in semiconductor manufacturing and the improvement of the quality and reliability of semiconductor exposure lens systems.

For exposure lens systems using the excimer laser in semiconductor manufacturing, synthetic quartz crystal with the characteristics of (1) high transmittance, (2) comparatively low price, and (3) ease of processing, as a material of polarizing the optical devices, such as depolarizing plates and wave plates, and diffractive optical devices, including diffractive lenses, have been attracting attention. However, if synthetic quartz crystal, generally manufactured by the hydrothermal synthesis method, is radiated with short wavelength and high power light, such as excimer laser, for an expanded period of time, it is susceptible to the deterioration of optical characteristics, in particular, light transmittance. For this reason, a quartz material with a high resistance to laser light has been called for.

Tokyo Denpa has continued its research and development for providing high quality synthetic quartz crystal ever since it started the production of synthetic quartz crystal in 1977. In 1994, the company succeeded for the first time in the practical application of a platinum autoclave as a high-pressure autoclave for the synthetic quartz crystal production and established the mass production technology for high-quality synthetic quartz crystals with very few crystal defects.

Asahi Glass, on the other hand, has received a high reputation in the market with its leading-edge synthetic quartz glass for the semiconductor device lithography and commercialized SiC, CMP slurry, etc. to accumulate diverse know-how concerning the semiconductor manufacturing equipment.

In the present development, in which Tokyo Denpa took charge of the trial production and production of synthetic quartz crystal and Asahi Glass, of polishing and evaluation, the content of a few impurities included in the synthetic quartz crystal as a cause of deterioration has been reduced to a certain amount. This has resulted in the reduction of the rate of deterioration to 1/5 or less of that of the conventional material.

From now on, Asahi Glass will bring the material to the market for the expected release by the end of fiscal 2007 as a new product of the lithography material.

Source: Asahi