复合钝化多晶硅纳米膜应力分布仿真分析

Simulatiom Analysis of Stress Distribution in Polysilicon Nanofilms of Compound Passivation

多晶硅纳米薄膜具有优良的压阻特性,为提高其在传感器应用中的稳定性和可靠性,对这种薄膜的钝化层结构进行了研究。基于压力传感芯片的结构特点,建立了钝化层结构的有限元分析分析模型,给出了应力分布与SiO_2和Si_3N_4钝化层结构之间关系。结果表明:采用Si_3N_4-SiO_2-Si_3N_4复合钝化结构,适当控制各结构层厚度可有效降低热失配引起的内应力。从而给出了降低薄膜内应力的钝化方法,为多晶硅纳米薄膜在压阻式传感器上的应用提供了必要的技术支持。

In order to improve stability and reliability of polysilicon nanofilms with favourable piezoresistive properties applied in some sensors, the passivation structure of the nanofilms were studied. Based on the structure of general press sensor chips, the models of finite element analysis were set up for the passivation structure, and then the influence of SiO2 and Si3N4 passivation structure was shown on the stress distribution. The conclusion was indicated that using Si3N4 -SiO2 -Si3 N4 compound passivation structure, the internal stress caused by thermal dilation mismatch could be reduced availably in virtue of reasonable manipulation of passivation thickness. Consequently, the passivation method of polysilicon nano-film were given to reduce stress within the film, which provided necessary technical support for the application of the nanofilms in strain sensors.