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Versailles, France

Kociniewski T.,University of Versailles | Khatir Z.,Laboratory of New Technologies
IEEE International Reliability Physics Symposium Proceedings

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. © 2015 IEEE. Source

Ousten J.P.,Laboratory of New Technologies | Khatir Z.,Laboratory of New Technologies
Microelectronics Reliability

This paper presents new investigations on the aging of Thermal Interface Materials (TIMs) subjected to thermal cycling conditions. The challenge was to design a specific and original set-up in order to not only undergo avionic temperature mission profile (-50 °C/+150 °C) but also to perform standardized thermal characterization at always same conditions. Thermal conductivity is used as aging indicator. Several TIM materials (change phase, graphite and polymer based) have undergone more than 1500 of such cycles. As a result, only the phase change material thermal interface has been affected with a 30% increase of initial thermal resistance. © 2011 Elsevier Ltd. All rights reserved. Source

Ibrahim A.,Laboratory of New Technologies | Khatir Z.,Laboratory of New Technologies
2013 15th European Conference on Power Electronics and Applications, EPE 2013

The reliability of power electronic modules is of utmost importance all the more so since they would be exposed to high ambient temperatures and frequent power cycling. Aging tests at 200°C have been done using power cycling in order to study some packaging materials for high temperature power electronics. Junction temperature swings were performed between 196°C and 245°C and tests have concerned the die attach, wire bond and die metallization materials. Experimental results have shown that AuGe solder material is highly resistant comparatively to a high leaded material. Furthermore, for die top-metal/wire couple, gold material exhibits a better performance compared to Aluminum. © 2013 IEEE. Source

Moussodji J.,Laboratory of New Technologies | Kociniewski T.,Laboratory of New Technologies | Kociniewski T.,University of Versailles | Khatir Z.,Laboratory of New Technologies
Microelectronics Reliability

A new distributed electro-thermal model has been developed in order to analyze electrical and thermal mappings of power devices during critical operations. The model is based on dividing power device into a vertical multilayer structure, with each layer discretized into multiple slab volumes. This model has been used to evaluate the effects of chip metallization ageing on temperature distributions and current sharing between cells within an IGBT chip during short-circuits operations. Dynamic latch-up failures during short-circuit operations has been investigated. © 2013 Elsevier Ltd. All rights reserved. Source

Kociniewski T.,University of Versailles | Kociniewski T.,Laboratory of New Technologies | Moussodji J.,Laboratory of New Technologies | Khatir Z.,Laboratory of New Technologies
Microelectronics Reliability

It has been demonstrated that high power devices like power diodes and IGBTs (Insulated Gate Bipolar Transistors) could remain functional after cross section. This has opened a field of possibilities for the characterization of distribution of physical quantities over vertical cross-sections of power semiconductor devices. In this paper, we used the Raman spectroscopy technique to perform the mapping of temperature distribution over the cross section area of a forward biased power PIN diode. As the mechanical stresses lead to shift the Raman peak, for accurate measurements in strained structures, it is necessary to deconvolute the influence of stress and temperature on Raman shift to measure temperature. Another solution consists in measuring the Full Width at Half Maximum (FWHM) of the silicon related Raman peak. This parameter depends only on the temperature and the crystalline quality of material. By this way, it is possible to measure the temperature accurately without any artifact due to the stress. Using this method, we have measured the temperature distribution over a vertical cross section of a power diode in forward bias conditions and strained by its packaging. The residual stress in the chip cross section was also estimated at room temperature in order to validate the FWHM choice for temperature calibration. © 2015 Elsevier Ltd. All rights reserved. Source

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