2014 Volume 55 Issue 11 Pages 1777-1780
When an average stress in metallic thin film was measured as a function of the film thickness during real time deposition, three distinct stress stages of initial compressive, tensile, and compressive were reported to occur for metals with relatively high mobility. A reversible stress shift to the tensile side was observed due to an abrupt interruption of deposition at the compressive stage. The stress shift occurred rapidly in the beginning and rather slowly later, to reach a saturation value.
The current study explored the stress shift caused by an abrupt interruption of deposition with focus on the state and magnitude of the thin film stress for the two metals, Al and Cr, with different levels of mobility. For Cr with relatively low mobility, only tensile stress was observed at room temperature deposition, but the three stress stages were observed for Cr deposited at 300°C. It is argued that mobility is a possible factor for the stress evolution mode of the thin film as the diffusivity of Cr at 300°C has a similar order of magnitude as that of Al at the room temperature. No stress shift was observed when deposition interruption occurred at the tensile stress state, but the shift was observed only at the compressive stress state for both Al and Cr. The total amount of stress shift increased as the magnitude of compressive stress at the point of interruption increased for Al.