An Excellent Platinum Piezoresistive Pressure Sensor Using Adhesive Bonding with SU-8
An excellent pressure sensor based a simple fabrication technology is presented. Differently from the present prevailing fabrication process of silicon piezoresistive pressure sensor: platinum is used as the sensing material, with a smaller but acceptable sensitivity and much simpler processes; adhesive bonding with SU-8 is used as an alternative choice to anodic bonding, and we choose a vacuum hot plate to avoid using a bonding machine. To achieve a successful bonding, it is found that pre-bake time and pumping time are the most important factors. Bonding quality is evaluated by inspection through the glass with 95% of the area successfully bonded and the failed area in the edge of the wafers. The measured bonding strength is 17.34 MPa. The Pressure-Voltage characteristic test results display a good linearity within 0.2% and especially a good precision within 0.035% in square fitting. The temperature drifting is also tested and the TCO is 1250 ppm/(°C FSO). The long-term stability of the sensor at a constant pressure is a fluctuation within 40 Pa (0.098% FSO) in 7 days. Both the simple fabrication process and the excellent performance of the sensor suggest that this sensor is a much good choice in measuring atmospheric pressure.
C. Pang et al., "An Excellent Platinum Piezoresistive Pressure Sensor Using Adhesive Bonding with SU-8", Advanced Materials Research, Vols. 60-61, pp. 68-73, 2009