A study on silicon-diaphragm buckling

An attempt to search for the mechanisms of diaphragm buckling is made and a set of experiments with qualitative analyses on the buckling of p/sup +/ silicon diaphragms is presented. A series of experiments is designed to explore the effects of wafer doping, size and shape of rectangular diaphragm, sequence of diffusion process (predisposition and drive-in), oxidation and annealing on buckling. It is found that all samples with predeposition as the last thermal process are flat. A qualitative analysis is presented, and the conclusions are: there is no plastic deformation due to oxide layer in all the thermal processes; the residual stress in p/sup +/ is dependent upon the last thermal process; the stress in the p/sup +/ layer is relieved by 50% by a drive-in process; and the buckling of the diaphragm can be controlled by making the last process boron diffusion predeposition. It is suggested that when the substrate is etched to form diaphragms, the redistribution and generation of stresses on the edges cause the buckling of the diaphragms.<
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