Reliability Analysis for Flexible Electronics: Case Study of Integrated a-Si:H TFT Scan Driver

Flexible electronics fabricated with thin-film and bendable substrates (e.g., plastic) have great potential for novel applications in consumer electronics such as flexible displays, e-paper, and smart labels; however, the key elements - namely thin-film transistors (TFTs) - often suffer from electrical instability. Therefore, thorough reliability analysis is critical for flexible circuit design to ensure that the circuit would operate reliably throughout its lifetime. In this paper, we propose a methodology for a-Si:H TFT circuits´ reliability simulation. We show that: (1) the threshold voltage (V_TH) shift of a single TFT can be modeled by analyzing its operating conditions and (2) the circuit lifetime can be predicted accordingly using SPICE. We also propose an algorithm to reduce the simulation time by orders of magnitude with negligible accuracy loss. To validate our analytical model and simulation methodology, we compare the SPICE simulation results with the actual measurements of our integrated a-Si:H TFT scan driver fabricated on the glass substrate and demonstrate very high consistency in the overall results.