Design, fabrication and characterization of an annularly grooved membrane combined with rood beam piezoresistive pressure sensor for low pressure measurements

A novel structure piezoresistive pressure sensor with annularly grooved membrane combined with rood beam has been designed for low pressure measurements. By introducing high concentrated stress profile (HCSP) and partially stiffened membrane (PSM) into the sensitive regions, the strain energy was concentrated at the rib structure and an oversize deflection was avoided at the center of the membrane, which effectively improved the sensitivity and linearity of the sensor. The structure design and geometry optimization of the sensitive membrane were also studied by finite element method (FEM), which helped the sensor chip achieve a high sensitivity and small pressure nonlinearity (PNL). Finally, the fabrication of a sensor with annularly grooved membrane and rood beam was reported. Experimental results showed that the sensor obtained a sensitivity of 30.9 mV/V/psi and a pressure nonlinearity of 0.25% FSS in the operating range of 0-1 psi at room temperature. Such results indicate that this novel structure sensor is suitable to be applied in measuring absolute micro pressure lower than 1 psi.