The Research Of 100KPa Pressure Chip On Polysilicon Nanofilm

The semiconductor pressure sensors play an important role in the development and progress of modern science, so it is necessary for people to make scientific research on pressure sensors, and then increase their performance. The development of surfa-ce micromachining process and the research on piezoresistive properties of polysilicon nano-films(PSNF) provide technical support for the further improvement of performance.Make use of sacrificial technology to design the structure of the pressure sensor, the thickness of the elastic membrane was reduced greatly, and can be reduced to the micron level, thereby increase the sensitivity of the pressure sensor and reducing the chip size; make use of polysilicon nano-films to make strain resistances, the sensitivity was improved, the temperature rang of working was extended and the temperature drift was lowered, therefore in this paper I design and develop the chip of the pressure sensor with the sacrificial layer structure on the basics of the two technologies.During the optimization and design of the pressure sensor chip, due to the special structure of the sacrificial layer pressure sensor, so the stress distribution of the elastic membrane was analyzed correctly under the state of overload through the combination of finite-element linear analysis and nonlinear analysis in this paper., the overload ability of the pressure sensor was increasing about 180% through the appropriate contact of the elastic membrane and the substrate by adjusting the sacrificial layer thickness on the premise that the pressure sensor work on full scale range under the linear response.In the course of experimental producing pressure sensor chips, the process encounters some problems:after the cavity was corroded completely, the polysilicon membrane fell to pieces. The problem was solved successfully by adjusting the vapor temperature of the polysilicon at last.The samples were testing, and the test results were analyzed and summarized at last.Take 0.1 MPa full scale pressure for an example, the sensitivity is 60mv/0.1MPa, through simulated and optimized, the elastic membrane size that met the requirement for sensitivity was given, the length is 300μm, the width is 150μm, the membrane thickness 3μm and the sacrificial layer thickness is 3.5μm, which proved that the design concept of the sacrificial layer pressure sensor was rational.