Investigation of the effect of processing steps on stress in a polysilicon structural membrane

Stress control in low-pressure chemical vapour deposition (LPCVD) polysilicon is important for micromechanical processes involving surface micromachining. This paper outlines work determining the effect of processing steps on the stress in blanket films of sensor polysilicon after deposition, implant and anneal processing. The measured stress in the blanket films was then correlated with interferometry images of the microfabricated pressure sensor devices after each processing step.