Temperature and strain mappings over forward biased power IGBT cross-section area by μ-Raman spectroscopy

Thermal characterizations inside power device crystal are required for failure analyses physic of power electronic devices. We have succeeded to keep power devices functional after cross section. We use Raman spectroscopy to map temperature and mechanical stress distributions on cross-sections of IGBT (Insulated Gate Bipolar Transistor) devices in forward bias conditions 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 temperature and stress evolutions in the Si bulk during operation. These results give experimental data on thermo-mechanical coupling in power devices. We have also compared stress measurements in unbiased condition with numerical models made with finite elements under ANSYS with a focus on IGBT elementary cell areas.