The effect of surface roughness on in-situ intrinsic tensile stress behavior in Cu thin films.

Intrinsic stress of Cu thin films, which grows in Volmer-Weber type, is reported to show the three unique stress stages, such as initial compressive, broad tensile and incremental compressive. The tensile stress stage may be related to the volume contraction through grain growth and coalescence to reduce over-piled ad-atom on surface. We observed the in-situ stresses behavior of Cu thin films during deposition using multi-beam curvature measurement system attached to a thermal evaporation device. We adopted the 100 microm Si(111) substrate with different surface roughness. The effect of substrate surface roughness was assessed on in-situ tensile stress. Intrinsic tensile stress increase when substrate surface roughness increase due to the increment of surface area deposited.