Kunio Ohtsuki

Non-Destructive Quantitative Measurement Method for Normal and Shear Stresses on Single-Crystalline Silicon Structures for Reliability of Silicon-MEMS

This paper describes an experimental analysis method for evaluating surface stress distribution in single-crystalline silicon (SCS) microstructures using laser Raman spectroscope. A biaxial tensile tester designed for film specimens was employed to apply uni/biaxial stresses to SCS specimen having 270-nm-high, 4-¿m-square SCS convex structures in the gauge section. As reported in Transducers 2007 [1], two-curve fitting of Raman spectrum was useful for analyzing stress magnitude at the edge of convex structures. In this study, the partial least-square (PLS) method was adopted for the obtained Raman spectra at the convex edge in order to determine stress components as well as their magnitudes. By using the PLS method, the shear stress component was able to be measured in addition to the normal stress components. The stress magnitude in respective stress components was in very good agreement with that estimated by finite element analysis (FEA).

In-Situ Raman Spectroscopic Surface Stress Measurement of Single Crystal Silicon Microstructures Subjected to Uniaxial Tensile Loading

This paper describes Raman spectroscopic stress analysis of single crystal silicon (SCS) microstructures for development of reliability evaluation technique utilized for silicon-based microelectromechanical systems (MEMS). An in-house tensile tester was employed to apply a uniaxial tensile stress to the SCS specimen with a 270 nm-height, 4 mum-square SCS boss in the gauge section. Raman spectra on the boss were obtained under a constant tensile stress applied. The stress distribution obtained from two-curve fitting of Raman spectrum was in good agreement with that estimated by finite element analysis (FEA). The Raman spectroscopic stress evaluation method would be effective for nondestructive reliability testing for silicon-MEMS.