A MEMS-based, high-sensitivity pressure sensor for ultraclean semiconductor applications

Process applications in the semiconductor industry require increasing levels of performance in pressure measurement and control. In addition, measurement and control of process mass flows are moving toward pressure-based mass flow controllers (MFCs). This work reports the development of a MEMS-based pressure sensor with the requisite performance for rigorous pressure and flow sensing sensing. The pressure sensing element consists of two capacitor plates, whose separation varies as a function of the radial distance from the center of the structure. The bottom capacitor plate is mechanically fixed, while the upper plate is a flexible silicon membrane. A variable separation between the plates is introduced by locating a hub in the center of the structure, and stretching the membrane over this structure. The theoretical principles, fabrication and performance of the structure are discussed.