Patent ID: 7718095

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, 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%, and wherein said compound is selected from the group consisting of In 1.5 Al 0.5 O 3 (ZnO) 4 , In 1.1 Ga 0.9 O 3 (ZnO) 4.2 , In 1.5 Fe 0.5 O 3 (ZnO) 4 , In 1.1 Ga 0.4 Al 0.5 O 3 (ZnO) 4 , and In 1.2 Y 0.3 Al 0.4 O 3 (ZnO) 4 .