Design and Analysis of Electro-mechanical Characteristics of Micromachined Stainless Steel Pressure Sensor

In this paper, electro-mechanical characteristics of stainless steel diaphragm have been studied as a potential robust substrate and a diaphragm material for micromachined devices. Lamination process techniques combined with traditional micromachining processes have been investigated as suitable fabrication technologies. To illustrate these principles, capacitive pressure sensors based on a stainless steel diaphragm have been designed, fabricated and characterized. Each sensor uses a stainless steel substrate, a laminated stainless steel film as a suspended movable plate and a fixed, surface micromachined back electrode of electroplated nickel. The finite element method is adopted to investigate residual stresses formed in the process. The sensitivity of the device fabricated using these technologies is 9.03 ppm kPa-1 with a net capacitance change of 0.14 pF over a range 0~178 kPa.