氮化硅薄膜的应力与性能控制

The Residual Stress Adjustment and the Properties Optimization of a-SiNx Films

提出一种通过构建特殊的多层膜结构的方法,降低SiNx薄膜的残余应力。曲率和拉曼两种测量结果都表明,通过引入一层240nmSiO2薄膜,可以使SiNx薄膜的残余应力从高的张应力(+358MPa)明显地降低到低的压应力(-57MPa)。重要的是,这种应力的改变能够使薄膜在光学带隙保持不变的情况下,SiNx薄膜的折射率发生增大,取得常规方法难以达到的效果。遗憾的是,该过程同时使SiNx薄膜的杨氏模量和硬度等力学性能减弱。此外,还把相关结果与常规方法调控SiNx薄膜应力的结果相比较。证明了通过改变SiN薄膜的应力可以调控薄膜的其它物理性能。

This article presents an approach for the adjustment of residual stress in silicon nitride （SiNx） films by constructing a composite multilayer structure.Curvature and Raman measurement results indicate that with the introduction of a 240-nm-thick SiO2 sublayer,the residual stress in a 110-nm-thick SiNx film varies dramatically from high tensile stress （＋358 MPa） to low compressive stress （-57 MPa）.The adjustment of film stress leads to the improvement of film quality and the increase of refractive index.However,it also leads to the decreases of Young’s modulus and film hardness of SiNx.Particularly,the optical band gap of SiNx remains almost unchanged during the process.This work demonstrates the practical feasibility of modifying the physical properties of SiNx with the film stress,and suggests a new physical route to stress engineering of SiNx films for microelectronic and optoelectronic applications.