Method for discriminating nonlinearity of pressure sensors under influence of internal stress

Abstract

The invention provides a method for discriminating the nonlinearity of pressure sensors under the influence of internal stress. The method includes measuring Young modulus and initial internal stress values of thin films of structural layers of chips of the pressure sensors; building structural models of the chips of the pressure sensors by the aid of ANSYS software and Solid 186 unit types, and dividing grids of the models after the models are geometrically built and material parameters are defined; applying displacement constraint conditions, fixing peripheral edges of the models, constraining degrees of freedom in an X direction, a Y direction and a Z direction, applying external pressures, and solving stress and deflection distribution to obtain equivalent stress cloud pictures; introducing initial internal stress of the thin films by the aid of an equivalent thermal stress process, simulating input-output characteristics of the pressure sensors under different internal stress conditions and computing the nonlinearity of the pressure sensors. The method has the advantages of simplicity and high accuracy. Besides, nonlinearity errors and sensitivity of the pressure sensors can be quickly balanced, so that optimal designs of the performance of the pressure sensors can be guided.

Description

technical field [0001] The invention relates to a nonlinear discrimination method of a pressure sensor under the influence of internal stress. Background technique [0002] Due to the development of micromachining technology, the piezoresistive pressure sensor has made its sensitive components miniaturized, mass-produced and low-cost, and has established its leading position in the field of pressure measurement. Compared with the traditional membrane potentiometer, the force balance Type, variable inductance, variable capacitance, metal strain gauge and semiconductor strain gauge sensors are much more advanced in technology, with high sensitivity, fast response, good reliability, high precision, low power consumption, and easy miniaturization It has a series of advantages such as integration and integration, and has a wide range of applications in the fields of industry, automobiles and medicine. [0003] In general, the processing methods of piezoresistive pressure sensors...

AI Technical Summary

Problems solved by technology

[0004] The surface micromachined pressure sensor chip usually introduces initial internal stress due to the structural factors and defects of the film itself, or the thermal expansion coefficient mismatch between the substrate and the diaphragm during the preparation process. The initial internal stress of the film usually affects the pressure sensor. The measurement accuracy at work, the current literature has proposed that the tension internal stress will reduce the sensitivity of the sensor; in addition, the initial internal stress on the resistive passivation layer will also affect the output nonlinearity of the sensor

[0005] The existence of internal stress in the film has a great influence on the mechanical properties of the film. When the stress is too large, it may cause the film to fall off, crack, and cause the film structure to be damaged and lead to failure.

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