An Absolute Capacitive Pressure Sensor Based on a SiMiT-Fabricated Vacuum Cavity

Requiring no etching of a sacrificial layer and allowing the use of conventional aluminum metallization, a simple fabrication process based on the silicon-migration technology (SiMiT) conducted in hydrogen is employed in the construction of a sealed vacuum cavity separating a thin silicon diaphragm from a rigid substrate. With the pressure-deformable diaphragm serving as a dielectrically insulated electrode, the cavity providing an absolute reference pressure and the substrate forming a counter-electrode, the combination makes a capacitive absolute pressure sensor. A prototype sensor has been demonstrated, exhibiting a sensitivity of ~2.3 aF/Pa.