Low-Cost Surface Micromachined Pirani Pressure Sensor with Atmospheric Pressure Range

An innovative Pirani pressure sensor with atmospheric pressure operating range has been fabricated. The sensor´s heated element is a polysilicon resistor, which is separated from the substrate (the heatsink) by an equivalent nanometer size gap. By taking advantage of the surface roughness of the polysilicon heater and a simple process, an inexpensive nanometer size gap is formed between the heater and the heatsink, which significantly increases the upper sensing limit of the sensor. Our sensor showed good sensitivity to pressure up to 700 kPa, and has been fabricated with a simple 3-mask, Complementary Metal Oxide Semiconductor (CMOS) compatible process.