Backside contact of sensor microstructures

Abstract

A sensor microstructure contact scheme is provided for making backside electrical, mechanical, fluidic, or other contact to mechanical microstructures. The contact scheme is applicable to pressure sensors, shear stress sensors, flow rate sensors, temperature sensors, resonant microactuators, and other microsensors and microactuators. The contact scheme provides a microelectromechanical sensor body and support structure for backside contact of the sensor body, and features a support wafer substrate having one or more through-wafer vias each with a lateral span on the dimension of microns and a span that is more narrow at the wafer front surface than at the wafer back surface. An insulating film covers a portion of the support wafer substrate and sidewalls of the vias--with the lateral via span at the front surface being open. The front surface of the support wafer substrate is bonded to the front surface of a sensor body wafer substrate, such that contact of the front surface of the sensor body wafer substrate may be made through the support wafer substrate vias from the back surface of the support wafer substrate. The sensor body wafer substrate is adapted to define a mechanical sensor microstructure, and comprises a plurality of isolated substrate regions, each region corresponding to one of the support wafer substrate through-wafer vias. Each such region is circumscribed by an edge of the mechanical sensor microstructure and an isolating border region. Contact made through one of the support wafer substrate through-wafer vias to the corresponding one of the sensor body substrate regions is isolated and thereby prevented from making contact to any other sensor body substrate region.