| 摘要 |
PROBLEM TO BE SOLVED: To execute the formation of a transparent film uniform over a large area at an intermediate refractive index at a high speed by forming a film of a specified refractive index by using a target contg. the oxide of Nb and the oxide of Si, and in which the content of oxygen is poorer than that in a stoichiometric compsn. SOLUTION: It is preferable that, by using a sputtering target contg. the oxide of Nb and the oxide of Si, and in which the content of oxygen is poorer than that in a stoichiometric compsn., an oxide film contg. the oxide of Nb and the oxide of Si and having 1.6 to 1.9 refractive index is produced. The content of the oxide of Nb expressed in terms of Nb2O in this target is desirably controlled to 40 to 80 wt.% to the total of the oxide of Nb and the oxide of Si expressed in terms of SiO2. Moreover, by incorporating the target with one or more kinds of oxides selected from the groups of the oxide of B, the oxide of Al and the oxide of Pb so as to control the contents of B2O3, Al2O3 and PbO to about 0.05 to 40 wt.%, discharge at the time of sputtering can be stabilized. |
