基于GaAs MMIC技术的残余应力测试结构的模拟与设计

Simulation and Design on Test Structure for Residual Stress Based on GaAs MMIC Technology

残余应力对开关梁的力学特性有着重要的影响。梁的弹性系数k由梁的形状和材料特性(杨氏模量和残余应力)来决定。应力梯度会使悬臂梁发生卷曲,对k也会产生影响。由残余应力引起的梁的长度变化量在微米级别,一般实验仪器难于测量。基于GaAs基和Si基的器件残余应力不同,相应的测试结构需重新设计。为了克服这些问题,本论文重新模拟并优化了微旋转式残余应变测试结构,尽量简化对测试仪器的要求。本文使用Intellisuite仿真软件以及Matlab软件优化,同时采用对称式的结构增加了测试精度。最后本文还给出了应力梯度的测试方法。

Residual stress on the beams of MEMS switches has an important effect to its mechanical properties.The coefficient of elasticity k of the beam is determined by the beam shape and material properties,such as Young ’ s modulus and residual stress.The stress gradient will bend cantilever beams,and will also affect the coefficient of elasticity k.The length variation of the beam caused by residual stress is in the micrometer-level,and difficult to measure with general experimental apparatus.Residual stress of devices based on GaAs and Si is different,and thus the test structure based on these two materials is different and need to redesign.In order to solve such problems,this paper uses and optimizes micro-rotating structure of the residual stress measurement,which will simplify the requirements for test instruments.Matlab and simulation software Intellisuite is used for design.And this structure is a symmetric structure,which can double precision of test results.This paper also gives test method of the stress gradient.