A batch process to deposit amorphous metallic Mo–Si–N films

Abstract

A process for depositing amorphous electrically conducting Mo–Si–N films in a batch-type reactive sputtering system has been developed. Each elemental constituent in the film is individually adjustable: molybdenum and silicon through the electrical power applied to the separate targets, and nitrogen through the gas flow rate. Argon is used for the tuning of the intrinsic stress. The amorphous structure of a Mo₃₁Si₁₈N₄₅ film is confirmed by cross-sectional transmission electron microscopy and electron diffraction. The structure remains unchanged up to at least 700 °C for 1 min of annealing in an argon ambient. In the process, the room-temperature resistivity decreases from an initial value of about 1.1 to about 1.0 mΩ cm with no change in the film thickness. After 1100 °C for one minute, grains nucleate and the film resistivity falls by two-thirds. The intrinsic stress in Mo–Si–N films is significantly more uniform throughout the film area than in polycrystalline molybdenum films. These results hold promise for applications of Mo–Si–N films in micromechanical devices. Self-supported beams and membranes have been successfully delaminated from their silicon substrates; molybdenum-rich films are more ductile than silicon-rich films.