Patent ID: 7897068

Claim:
A thin film for an optical information recording medium prepared by a process comprising the step of forming the thin film by sputtering a sputtering target that is a sintered compact of powder having an average grain size of 1 μm or less before sintering, that has a relative density of 90% or more, and that contains a compound having as its principal component zinc oxide satisfying A X B Y O (KaX+KbY)/2 (ZnO) m , wherein 1<m, X≦m, 0<Y≦0.9, and X+Y=2, and where A and B are respectively different positive elements of trivalence or more, and the valencies thereof are respectively Ka and Kb, said thin film being amorphous and stably retaining an amorphous nature when heated to 600° C., and wherein a range of variation of positive elements other than zinc in the target is within 0.5% and a range of variation of density in the target is within 3%.