Modeling and simulation of DC characteristics of a novel NMOS based high pressure sensor

This work utilizes an 0.5 μm NMOS device as a pressure sensor by using a suspended metal gate technology. The gate electrode of Pressure Sensitive Insulated Gate Field Effect Transistor (PSIGFET) is freely suspended by four 1-Mender based serpentine springs at four corner and acts as a pressure sensing diaphragm. The large area requirement of diaphragm is minimizes be using a square shaped membrane of area 0.5 μm × 0.5 μm. The pressure measuring capacity is enhanced by using a Tungsten diaphragm (Modulus of Elasticity=410 GPa) and the device is capable of measuring Pressure in the range of 10-205 MPa. The spring constant of the membrane is determined from Coventorware Simulations of the diaphragm and compared with analytical value (3.8639133×10^-4 μm/MPa). The pressure sensitivity of the device is found to be quite good, in the range of 0.1355-0.3167 μA/MPa. The temperature stability of the sensor device is further investigated and the temperature coefficient of pressure sensitivity is found to quite low (0.01-0.02 μA/MPa/10^oC) at V_GS= 3V indicating that the device is stable again the temperature variation up to 77^oC.