| 摘要 |
PURPOSE:To prevent a light beam from diffusing in the lateral direction, and to manufacture an optical mask which is suitable for forming a fine pattern, by providing an area having a higher refractive index than that of a glass substrate, on an area where a light screening film of said substrate is not formed. CONSTITUTION:A light screening film 2 consisting of Cr, etc. is formed on the surface of a glass substrae 1. Subsequently, the film 2 is made a mask, and a high refractive index (1.8 refractive index in case of Tl) area 5 is formed to about 0.5mu depth from the surface of the substrate 1 by implanting either one ion of Tl, Pb, Ta, Th, La and Ba. The high refractive index area 5 can be formed by means of ion exchange, thermal diffusion, etc., instead of ion implantation. In this way, the area 5 forms a convex lens, and peripheral light beam are condensed. Accordingly, when said mask is used for a photomask, the diffusion of a light beam is reduced in the lateral direction of the exposure part, and the pattern width accuracy is elevated. An optical filter is also obtained in the same way, and the condensing degree of a transmission light beam is elevated. |
