Measuring the tensor nature of stress in silicon using polarized off-axis Raman spectroscopy

Polarized off-axis Raman spectroscopy is a technique for measuring the complete tensor nature of stress fields in semiconductors. By combining incident light tilted away from the normal axis with polarization of the incident and scattered beams, any Raman-active optical phonon mode can be selectively studied. Once the frequencies and intensities of these phonons are measured, the complete stress tensor can be uniquely determined. This technique has been applied macroscopically to mechanically deformed silicon wafers under biaxial tension. The results of this approach compare favorably with the stress calculated by means of the theory of elasticity.