Control of stress in metal films by controlling the atmosphere during film deposition

摘要

Materials such as titanium are vapor-deposited in the presence of, e.g., oxygen to form a film on a substrate, such as to provide an adhesion layer between a silicon movable structure in an optical MEMS device and a gold layer serving as a reflecting surface. The resulting film contains titanium and oxygen. Varying the conditions under which the film is deposited varies the intrinsic stress of the film, which varies the change in substrate shape caused by the presence of the film. A film having a desired intrinsic stress may be obtained by control of the oxygen partial pressure when the film is deposited. In one embodiment, the oxygen partial pressure in the atmosphere present during titanium deposition is greater than about 2x10^-7 Torr, and preferably between about 1x10^-6 Torr and about 2x10^-6 Torr.