Raman spectroscopy as a stress sensor in packaging: correct formulae for different sample surfaces

In the paper, RS (Raman Spectroscopy) is discussed as a stress sensor in packaging. This paper discusses the measurement of thermo-mechanical stress introduced in the Si chip by packaging. Examples are shown for Si on Cu substrate, flip-chip and PSGA samples. It is shown that the relation between the Raman shift and the stress tensor components depends on the crystallographic orientation of the surface of the sample, i.e. Raman measurements on a [001] surface of a chip give different results than measurements on a cross-section ((1-10) surface). The Raman data are compared with finite element calculations.