| A new MEMS high temperature pressure transducer, which adopts silicon wafer as elastic diaphragm and Ni-Cr alloy as sensitive material, is developed by combining sputtered alloy film pressure sensitivity component with advanced process. It is known that pressure transducer of piezoresistance type can not work well in high temperature and size of traditional sputtered metal pressure transducer is too big. The new MEMS pressure transducer overcomes these disadvantages, and has some advantages such as simple process, short process periods, relative low cost, small volume, light weight and high temperature resistance, which is fit for measurement of hydro-medium and is a preferred choice of pressure transducer under oil well field. The thesis comprises 4 parts: (1) The principle of strain resistance conversion and sputtered pressure sensor are described in detail, and the sensitivity component and conversion circuit are analyzed. (2) The strain in the pressure sensor is simulated. The strain distribution of elastic membrane including rationality of the monolayer model, dimension of sensor and working temperature, etc. affecting the output of the sensor is presented. The best designing field of sensitive resistance can be determined and sensitivity of transducer can be improved. (3) The pressure transducer chip is designed. The theoretical analysis, design of the parameters including the diagram dimension, resistance and masks of sensor chip is presented in this section in detail. (4) The practical technical condition and experiments are studied. The section analyzes in detail the whole making technical project and key process such as anisotropic etching silica cup and plating film, especially in the anisotropic etching by using sputtering chrome as mask. Sensor chip is produced by advanced technology, and its working condition and surface morphology is studied. A summary of the thesis and the view of future designed pressure transducer are given in the end. |
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