Local stress measurements in packaging by Raman spectroscopy

This paper discusses the application of micro-Raman spectroscopy to measure mechanical stress in microelectronic packages. Examples are given for local stress induced in the silicon chip by solder bumps, stress induced in the chip by bonding to a Cu substrate, and stress induced during thinning of wafers by polishing. Both 1D and 2D results from stress measurements are shown. It is demonstrated that micro-Raman spectroscopy is a very useful tool for the study of packaging induced local mechanical stress and offers a means for verification of finite element simulation results.