Estimarea duratei de viață a circuitelor integrate de putere în aplicații / Application-Aware Lifetime Estimation of Power Devices

Power devices are widely used in many fields nowadays. In the characterization stage of power devices, it is necessary to estimate the lifetime on different operating conditions and estimate the spread of the lifetime more accurately. For manufacturers, the main technical challenge is the small amount of reliability data available. The thesis introduces a two-step approach for application-aware estimation of power devices average lifetime. First, the thesis proposes a methodology for the estimation of the main stress-factor of the lifetime (the maximum junction temperature swing) on different operating conditions, based on electro-thermal simulation. Then, the classical lifetime model is assessed and extended so that it can be applied over a wide range of application operating conditions and for a predefined failure criterion (instead of total destruction of devices). The resulting model is robust and simple, with only three coefficients, which are fitted from experimental data. The thesis also proposes a methodology for estimation of the lifetime spread of power devices (caused by the manufacturing process variation), which overcomes the problem of limited available reliability data, by using data from different stages of product development and tests. It is mainly based on the variations of the most relevant electrical parameters (measured before the stress-test) which correlate with the lifetime spread. The presented approach significantly improves the conservative methodology currently used for lifetime characterization of the power devices.