Pressure transducer with sealed conductors

Abstract

A pressure transducer (10; 10') having a silicon diaphragm (14; 14') and an insulating glass base (11; 11'). Surfaces (16, 12; 16', 12') of the diaphragm and glass base are anodically bonded together to form a hermetic seal for an internal reference cavity (24; 24') therein and also to provide hermetic protection for critical areas (70, 77; 70', 80, 81) on the silicon diaphragm. A plurality of semiconductor components are synthesized in an area (70; 70') in the silicon diaphragm. A plurality of conductors (71-73; 71'-73') are embedded (sealed) in the glass base so as to provide external electrical access to the semiconductor components without disrupting the hermetic seal provided between the silicon diaphragm and the glass base. This occurs by virtue of embedded pins (71-73; 71'-73') in the glass base extending between top and bottom surfaces (12, 13; 12', 13') of the glass base with flat ends of these pins, which ends are coplanar with the base surfaces to be anodically bonded, forming a silicon gold eutectic with bonding pads (77; 77') on the silicon diaphragm during anodic bonding. The bonding pads are within outer peripheral areas (18; 18') of a bottom surface (16; 16') of the silicon diaphragm that are hermetically bonded to outer peripheral areas (22; 22') of a top surface (12; 12') of the glass base during the anodic bonding process.