An NiCr Alloy Piezoresistive Atmosphere Pressure Sensor based on Eutectic

In this paper, an nickel-chromium (NiCr) alloy piezoresistive atmosphere pressure sensor, based on eutectic bonding is presented. Compared with conventionally silicon piezoresistive pressure sensor, it has the advantages with low cost and easy fabrication processes. First, NiCr alloy (80:20 wt%) is used as the strain detecting material, with a smaller but acceptable sensitivity and simpler processes. Second, eutectic bonding technology based on silver-tin (Ag-Sn) alloy, which is 3.5%wt Ag and 20um thickness, is used as an alternative and easy bonding choice to complete the vacuum package. Bonding quality of eutectic bonding is evaluated by inspection through the deflection of diaphragm of silicon with more than 95% of the area successfully bonded. The Pressure-Voltage characteristic test results suggest a precision within 0.3% in square fitting. The temperature characteristics is also tested and theoretically analyzed. The temperature coefficient offset (TCO) is 620 ppm/(°C FSO).