Advances in micro miniaturization conceived in the electronics industry, have been applied to shrinking the size of components necessary to implement pressure transducers. The status of ongoing research specifically oriented to fabrication, performance, and application of micro sensors was first described from the viewpoint of their use for heat transfer and fluid flow measurements (Udell, 1990).
The application of this technology to other domains outside of the electronics industry has become known as "surface machining," and has emerged during the last thirty (30) years as a viable technology (Halbo). At first the technology was considered to be spin-offs from related microelectronics/integrated circuit technology. Some of the first usage of the technology came with the application associated with the mounting of miniature strain gauges on silicon and devices so generated became known as "etched anisotropic silicon" devices.
Sensor applications gave the main market impetus while the economies of scale derived from the microelectronics induced batch processing permitted low cost. Thus silicon micro machining was able to establish itself as a unique processing technology with an extremely distinctive feature set.
Fabrication capabilities have continued to grow over the last twenty years and have produced a large number of actuator assembly combinations that include miniature motors, tweezers, accelerometers, and pressure sensors. It is now feasible to consider using micro machining technology to fabricate chemical instruments and even miniature chemical laboratories (Ramsey, 1997).
Surface machined pressure sensors (Lin, 1998), have been designed, optimized and fabricated. Polysilicon diaphragms with thicknesses in the range of two micro microns, have been manufactured by utilizing Low Pressure Chemical Vapor Deposition (LPCVD)and as such form the core components in micro pressure transducers. The diaphragms so gener...