Thermal stress analysis in die-attached β-Ga2O3 using Raman spectroscopy

Abstract We determine the stress deformation potentials using micro-Raman spectroscopy and evaluate thermal stress in a (−201) plane β -Ga 2 O 3 mounted on a Cu plate with a Pb-free solder. We conduct four-point bending tests and thermomechanical experiments to experimentally determine the stress deformation potentials of A g (4), A g (5) and A g (6) modes. Based on experimental results, we estimate the suitable phonon modes for evaluating the stress, and we apply confocal Raman measurements to a β -Ga 2 O 3 chip mounted on a Cu plate with a Pb-free solder. In accordance with the theoretical relation between the phonon frequency shifts and the stress, we obtain the stress components in the (−201) plane β -Ga 2 O 3 using the peak frequency shift of A g (4) and A g (5) modes. The stress components in the (−201) plane is almost same, regardless of the thermal expansion anisotropy of β -Ga 2 O 3 , and the results are consistent with those of the finite element method.