Single-Side Fabricated Pressure Sensors for IC-Foundry-Compatible, High-Yield, and Low-Cost Volume Production

In this letter, a new low-cost and high-yield manufacturing technique for volume production of pressure sensors is proposed and developed. The IC-foundry-compatible process is conducted only from the front side of (111) silicon wafers, without double-sided alignment exposure, wafer bonding, and double-sided polished wafers needed. With the single-wafer-based single-side bulk-micromachining technique, the sensor chip size is as small as 0.6 mm x 0.6 mm that facilitates low-cost high-throughput IC-foundry batch fabrication. Compared with the conventional double-sided micromachining approach where the pressure-sensing diaphragm thickness is determined by back-side deep etching, the front-side micromachining scheme uses front-side shallow etching that provides more precise and uniform control to the thickness for higher yield. 0.087-mV/kPa sensitivity and +/- 0.09% FS nonlinearity are measured for the fabricated 750-kPa range sensor, and the temperature coefficient of offset (TCO) is as low as -0.032%/degrees C . FS. With the new technique, the sensors are promising in automotive and consumer electronics applications.