Benefits of Considering More than Temperature Acceleration for GaN HEMT Life Testing

Abstract

Abstract:The purpose of this work was to investigate the validity of Arrhenius accelerated-life testing when applied to gallium nitride (GaN) high electron mobility transistors (HEMT) lifetime assessments, where the standard assumption is that only critical stressor is temperature, which is derived from operating power, device channel-case, thermal resistance, and baseplate temperature. We found that power or temperature alone could not explain difference in observed degradation, and that accelerated life tests employed by industry can benefit by considering the impact of accelerating factors besides temperature. Specifically, we found that the voltage used to reach a desired power dissipation is important, and also that temperature acceleration alone or voltage alone (without much power dissipation) is insufficient to assess lifetime at operating conditions.

Applications and Impacts of Nanoscale Thermal Transport in Electronics Packaging

“…The Arrhenius extrapolations reported in the literature [157,169] show extremely long predicted median times that significantly overpredict the actual device lifetime in field applications. This is a major concern in industry because such false prediction may lead to catastrophic events in reliability critical applications [157,168,169]. The overprediction of device lifetime stems from inaccurate estimation of the device peak temperature at the site of degradation/failure during the accelerated high power testing.…”

“…Such failure mechanisms include mechanical damage in the AlGaN barrier due to induction of thermo-elastic stress [159] and thermally assisted interdiffusion at the semiconductor/metal interface [165]. Although GaN HEMTs have been commercialized for small-scale applications (e.g., laptop chargers), questions regarding GaN device thermal reliability remain unanswered [166,167], as evidenced by the continued research into their life expectancies [157,168,169].…”

“…The industry-standard method to estimate GaN HEMT lifetime is the temperature-accelerated direct current operational-life test [170]. The Arrhenius extrapolations reported in the literature [157,169] show extremely long predicted median times that significantly overpredict the actual device lifetime in field applications. This is a major concern in industry because such false prediction may lead to catastrophic events in reliability critical applications [157,168,169].…”

Temperature-Sensitivity of Two Microwave HEMT Devices: AlGaAs/GaAs vs. AlGaN/GaN Heterostructures

“…Hence, the reported comparative analysis has not aimed at distinguishing each contribution but at assessing the overall impact of the ambient temperature on the DC and microwave characteristics of the two tested technologies. Nevertheless, for the sake of completeness, it should be underlined that the channel temperature is higher than the ambient temperature because of the heat generated by the self-heating effects, which are strongly dependent not only on the dissipated power level but also on the thickness and thermal conductivity of the materials [13,[29][30][31][32][33][34][35][36]. Furthermore, it is worth mentioning that the extraction of the equivalent-circuit elements may be inevitable affected by the uncertainty inherent in measurements and that, in addition, the model topology itself is an approximation of the device physics [37][38][39][40][41][42][43], which in turn may impact on the achieved temperature-dependent findings.…”

Dynamic Temperature Measurements of a GaN DC–DC Boost Converter at MHz Frequencies

“…The acceleration factor (AF), expressed in (1), determines the device lifetime projections and calculates the time acceleration value, that results from operating a device at an elevated temperature. By definition, the AF is the device time to failure at low temperature divided by the time to failure at higher temperature [13],…”