Stress characterization of tungsten-filled through silicon via arrays using very high resolution multi-wavelength raman spectroscopy

Abstract

Stress in Si adjacent to W-filled TSVs has been measured by multi-wavelength Raman spectroscopy (probe depth ranging from 290 to 645 nm) and compared to finite element modeling. The stress in Si from the TSVs increases with TSV width and is almost constant at the different depths probed in this study. The Raman signal is mainly due to the sum of the Sx and S y stress components, perpendicular and parallel to the TSV bars. The Sx component is tensile and the Sy component is compressive, with the Sy component dominant in between the TSVs. However, ∼10 μm from the edge of the TSV array, the two components are equal in magnitude so that the stress measured by Raman is zero, even though the individual Sx and Sy stresses are considerable. Hence, it is important to use finite element modeling in conjunction with Raman spectroscopy to characterize stresses in TSVs. ©The Electrochemical Society.