Patent ID: 7901842
Filing Date: 2011-03-08
Classification: G03F

Abstract:
1. A method of producing a photomask blank comprising: forming a light-shielding film containing chromium and nitrogen on a light-transmitting substrate by sputtering using a target composed of chromium in atmosphere containing nitrogen, and carrying out, after the formation of the light-shielding film, a plurality of heat treatments in which heat is applied to the light-shielding film; the method further comprising: anticipating a change in a film stress that is caused in the light-shielding film by the heat treatment at a highest temperature applied to the light-shielding film in the plurality of heat treatments; and adjusting, in consideration of an anticipated change in the film stress, the nitrogen content contained in the light-shielding film so as to cancel the change in the film stress that is caused in the light-shielding film by the heat treatment at the highest temperature applied to the light-shielding film.