Fabrication and electrostatic actuation of thin diaphragms

In this paper, two kinds of p⁺ diaphragms are fabricated. One is flat, and the other is corrugated to release the residual stress resulted from the diffusion process. The two diaphragms are electrostatically actuated, and the center deflections of the diaphragms are measured for various frequencies. The static deflections of the flat diaphragm and the corrugated one estimated from the test results are compared with the calculated static deflections under residual tensile stress. The experimental result and the calculated result agree in the case of the flat diaphragm with a reasonable residual stress, but it is not true for the corrugated diaphragm. In the calculation, it is estimated that the corrugated diaphragm deflects more than the flat one. In the experiment, however, the corrugated diaphragm deflects less than the flat one.