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

摘要: 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 stress blanket films sensor after deposition, implant and anneal processing. The measured was then correlated with interferometry images microfabricated pressure devices each step. There were small reductions tensile stress, films, a number steps. However, reflow borophosphosilicate glass (BPSG) interlayer dielectric, at 950 °C, caused most significant change resulting transition from to compressive deposited higher temperatures. layer contact during influenced final film. For tetraethylorthosilicate oxide (TEOS) membrane processing, film sealing When LPCVD or nitride, tensile. values corresponded well fabricated devices. TEOS exhibited deflected, device buckled, patterned exhibiting post-sealing characteristics. At end these membranes remained deflected.