Buckling behavior of boron-doped p/sup +/ silicon diaphragms

A set of experiments with qualitative analysis was carried out to determine the mechanism of the buckling behavior of boron-doped p/sup +/ silicon diaphragms. The experimental results indicated that buckling not only occurs for silicon diaphragms with drive-in in oxygen ambient as the last high-temperature process, but also occurs for diaphragms covered with nitride on the p/sup +/ surface and drive-in in nitrogen ambient. The proposed mechanism is that the residual stress in the diaphragm becomes compressive because the intrinsic tensile stress in the p/sup +/ layer is greatly reduced by the drive-in process, and the local compressive stress or bending moment at the edges is created when the cavity is etched on the back side of the wafer to form the diaphragm.<
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