压阻式微型压力传感器微型 化限制因素的研究

本文初步探讨了对压阻式传感器的微型化起限制作用的多种因素:根据(100)晶面硅片各向异性腐蚀的特点,得出了器件芯片最小尺寸与硅片厚度的关系;根据方膜和矩形膜上应力分布曲线,得出了在一定的图形位置偏差下压力灵敏度与硅膜几何尺寸的关系曲线;讨论了硅片厚度均匀性与力敏电阻尺寸对器件总尺寸的限制作用,比较了全桥结构和横向压阻X型结构对器件几何尺寸的要求。最后介绍了两种实用的微型压力传感器设计与其主要技术参数。

A Study on Factors Affecting Miniaturization of Piezoresistive Pressure Sensors

Discussed in this paper are some factors which affect the dimensional limits of miniaturized piezoresisti ve press me sensors. The miniaturization is directly limited by the wafer thickness, because of the (111) slopes resulted from anisotropic etching of (100) wafer. The variation of relative piezore-sistive sensitivities with diaphragm dimensions and wafer thickness are discussed for both square and rectangular designs; the central gauge on a rectangular diaphragm shows much less variation than the edge resistors on square diaphragm. It is also found that the offset voltage is smaller for a transverse voltage type sensor than for a full bridge configuration for the same dimensional tolerence. As practical examples, two miniaturized pressure sensors are described with one of full bridge design and another of single element design.