Curvature Model for an Ion-Machined Free-Standing Thin Film MEMS Device

摘要

The connection between processing effects and curvature of a free-standing poly-Si thin film MEMS structure is analyzed theoretically and compared to experimental data. Estimates are made for the strain resulting from processing and post-processing effects including Phosphorus implantation and chemically neutral ion-beam machining. The inferred strain distribution is used to predict the curvature of the free-standing structure upon release from its host substrate. Curvature predictions agree closely with experimental measurements for particular choices of the processing strain magnitudes. The analysis procedure is proposed as a means to determine the through-thickness stress distribution in a free-standing structure. The ion-beam machining procedure is found to be a useful method for planarizing free-standing thin film structures with undesirable curvature due to process-induced stress.