Effects of substrate bias on the resistivity and microstructure of molybdenum and molybdenum silicide films

Abstract

A continuous series of Mo-Si alloys (Mo_xSi_1-x), with 0.3 ≤ x ≤ 1, have been deposited by reactive magnetron sputtering of molybdenum in silane and argon plasma. The effects of sputter deposition parameters such as the deposition rate, substrate temperature, substrate bias and gas flow conditions on the resistivity of molybdenum and molybdenum silicide films are reported. The resistivity of molybdenum films shows a pronounced decrease with an increase in the negative substrate bias and the rate of film growth. An electrical resistivity as low as 7.8 μΩ cm has been obtained in molybdenum films by optimizing the deposition conditions. The resistivity of MoSi₂ films, measured after annealing them at 1000°C for 1 h in nitrogen ambient, shows a broad minimum at -75 V bias. However, the effect of bias is not as pronounced as for molybdenum. The changes in the resistivity of molybdenum and MoSi₂ films are attributed to the degree of oxygen contamination and microstructural modifications during growth.