JPS5752056A - Photomask - Google Patents

Abstract

PURPOSE:To prevent the projection of dust, etc. on the surface of a photosensitive mateial by forming a fixed difference in level between the light shielding face and the light transmitting face of a photomask by etching a part except the light shielding pattern so as to locate the light transmitting face at the outside of the depth of the focus of a projective lens. CONSTITUTION:A light shielding film 13 of chromium oxide and a photosensitive material 16 are formed on a substrate 12 of quartz glass or the like in order. The material 16 is exposed through a patterned mask and developed. The film 13 is then etched with ion beams or the like, leaving the material 16 on the etched film 13. By further carrying out etching, a little material 16 is left on the film 13, and a part of the subtstrate 12 not covered with the film 13 is etched deeply and concavely to form a light transmitting face 14 having a difference (h). The material 16 is finally removed to obtain a photomask 11. Thus, even if dust, etc. are stuck to the face 14, they are not projected on the surface of a photosensitive material since the face 14 is not within the depth of the focus of the projective lens of an exposing device, and the formation of a defective pattern is prevented in the manufacture of an integrated circuit, etc.