Mechanical and thermal stresses characterization maps on cross-sections of forward biased electronic power devices

Characterization of mechanical and thermal stresses inside the power devices crystal is required for physics of failure analyses of power electronic devices. Recent results have shown the capability to keep this power device functional after cross section. The use of Raman spectroscopy to map mechanical stress and temperature distributions on cross-sections of IGBT (Insulated Gate Bipolar Transistor) devices in forward bias conditions is reported. Mechanical and thermal stresses maps were made in unbiased and forward biased using μ-Raman technique with spatial resolution up to 500nm. Temperature and stress contributions on Raman diffusion were deconvoluted fitting Full Width at Half Maximum (FWHM) and position of the Stokes peak. For the first time, it was possible to quantify experimentally mechanical stress and temperature evolution during operation. These results give experimental data on thermo-mechanical coupling in power devices and are compared with numerical models made with finite elements under ANSYS with a focus on IGBT elementary cell areas.