| 摘要 |
<p>A piezoresistive pressure transducer employing a sapphire force collector diaphragm (18) having piezoresistive films (44) of silicon epitaxially formed on a major surface thereof, preferably in a Wheatstone bridge pattern. The silicon piezoresistive film is preferably of a thickness of from 1,000 to 60,000 angstroms and is doped with boron in the range of from 5x10<1><7> to 9x10<2><0> atoms/cc. Electrical lead traces (50) and electrical contact pads (48) are also formed on the major surface (42) of the force collector diaphragm (18). The diaphragm is mounted on a pressure cell base (20) having a cavity (22) in the upper surface thereof, the diaphragm enclosing the cavity so as to form a chamber with the piezoresistive silicon films within said chamber. The diaphragm is hermetically bonded by a ceramic glass (58) to the base in a vacuum such that the chamber provides a vacuum pressure reference. The contact pads are positioned over a matching number of feed through tubes (26) in the pressure cell base and electrical leads (24) are fed through the tubes for carrying electrical signals from the piezoresistive film within the chamber. A pressure cell fitting (16) encloses the upper surface of the pressure cell base including the sapphire diaphragm with a port (28) providing the medium to be pressure monitored to the exposed surface of the sapphire diaphragm. A shell (17) encloses the remainder of the pressure cell thereby insulating it from external shock or pressure. The pressure cell base, fitting and sapphire diaphragm are all of matching thermal expansion characteristics.</p> |
