Cosputtered molybdenum silicides on thermal SiO2

Abstract

The silicides of molybdenum have been formed by cosputtering mixtures of molybdenum and silicon on oxidized silicon wafers. Alloys with as‐deposited Mo/Si nominal atomic ratios of 0.25 to 4 were sintered in a hydrogen ambient in the temperature range of 900–1150 °C. The formation of the silicide in these films was followed by the use of sheet resistance, by x‐ray diffraction and stress measuring techniques, and by the use of transmission electron microscopy. The resistivity was found to decrease with increasing molybdenum content, the lowest being ∼60 μ Ω cm. The stress was highest in films richer in the intermetallic MoSi₂. The coexistence of the three phases Mo₃Si, Mo₃Si₂, and MoSi₂ led to lower stresses due to void formation in the film. A comparison of the resistivity and the sintering behavior in Mo‐Si films has been made with that observed in Ta‐Si and Ti‐Si films. The role of the oxygen contamination has been emphasized as one of the rate controlling factors in the silicide formation.