Asahi Glass And Tokyo Denpa Succeed In The Development Of A Synthetic Quartz Crystal Material With High Resistance To Laser Light

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 esistance 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 echnology 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 ynthetic quartz crystal as a cause of deterioration has been  reduced to a certain amount. This has resulted in the reduction of the rate of eterioration to /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.