压敏电阻的热应力分析及结构优化

Thermal Stress Analysis and Structure Optimization of Piezoresistor

为解决SOI压阻式压力传感器敏感芯片上电阻条因热应力堆积导致的断裂问题,通过在电阻条上容易堆积应力的弯折处建立平滑倒角的方式来降低热应力堆积,提高电阻条的热稳定性。利用多物理场耦合分析软件对有无倒角的2种结构进行仿真分析,仿真结果表明:在常压450℃条件下,倒角的存在使得电阻条弯折处的应力比无倒角的结构降低了50%。在300℃测试环境下无倒角电阻发生断裂,而有倒角电阻在300℃测试以及之后的温度测试中结构完好,电压输出正常,表明倒角的设计有助于提高敏感芯片的耐温性,从而提高传感器的热稳定性。

In order to solve the fracture problem of the resistance strip on the sensitive chip of SOI piezoresistive pressure sensor due to thermal stress accumulation,a smooth chamfer was established at the bend of the resistance strip that is easy to accumulate stress to reduce the thermal stress accumulation and improve the thermal stability of the resistance strip.The multi physical field coupling analysis software was used to simulate the two structures with and without chamfering.The simulation results show that the stress at the bending point of the resistance bar is reduced by 50%compared with the structure without chamfering under normal pressure and 450℃.Under the test environment of 300℃,the non chamfered resistance breaks,while the chamfered resistance has intact structure and normal voltage output in the test at 300℃and the subsequent temperature test,which indicates that the chamfered design is helpful to improve the temperature resistance of the sensitive chip,thus improving the thermal stability of the sensor.