Statistical Analysis of Degradation and Failure of Flexible LTPS TFTs under Dynamic Mechanical Stress

For flexible low-temperature poly-Si (LTPS) thin-film transistors (TFTs), statistical analysis of their degradation under dynamic bending stress and failure under dynamic stretch stress are investigated. Under dynamic bending stress, statistic shows that on-state current degradation follows the gamma distribution. From dependence of gamma distribution parameters on bending cycles, TFTs operation lifetime can be evaluated. Under dynamic stretch stress, three failure modes of TFTs are identified: GI damage, channel traps generation, and microcracks in the source/drain metal wires. Failure statistic shows that the first mode follows the exponential distribution, and the other two modes follow the limited failure population (LFP) model, from which TFTs operation lifetime can be estimated.