Stress relaxation of a patterned thin film on diaphragms of different material and thickness was investigated through experimental study and numerical simulation. The diaphragm deflections, caused by relaxation of the residual stress in a patterned thin film residing on top, were measured using a Twyman–Green laser interferometer. The first diaphragm used was a Si3N4(top)/SiO2/Si composite diaphragm and the second a 0.5-μm-thick Si3N4 membrane. Custom-written simulation software, which uses a novel numerical algorithm named Nonlinear Sequential Analysis (N-LISA), was utilized to calculate the stress distribution in the patterned thin film and the diaphragm substrate. Agreement between the model and the experimental results was satisfactory. Simulation of the system balance between a tensile-stressed circular Ti film and a stress-free Si substrate of different thickness clearly shows a transition in the substrate behavior from a pure plate to a pure membrane. Interestingly, the deflection of the Si substrate caused by the residual stress in the Ti film reaches its maximum at a certain substrate thickness where plate and membrane characteristics coexist. This study addresses some basic mechanics issues involved in modern devices dealing with thin diaphragms.
通过实验研究和数值模拟,研究了不同材料和厚度的膜片上图案化薄膜的应力松弛。使用 Twyman-Green 激光干涉仪测量了由顶部图案化薄膜的残余应力松弛引起的膜片偏移。第一个膜片使用的是 Si3N4(顶部)/SiO2/Si 复合膜片,第二个膜片使用的是 0.5μm 厚的 Si3N4 薄膜。定制编写的模拟软件采用了一种名为非线性序列分析 (N-LISA) 的新型数值算法,用于计算图案化薄膜和隔膜基底的应力分布。模型与实验结果的一致性令人满意。拉伸应力圆形 Ti 薄膜和不同厚度的无应力 Si 基底之间的系统平衡模拟清楚地显示了基底行为从纯板到纯膜的过渡。有趣的是,钛膜中的残余应力引起的硅基板挠度在一定的基板厚度下达到最大,此时板和膜的特性并存。这项研究解决了处理薄膜片的现代设备所涉及的一些基本力学问题。