Investigation of electrostatic discharge characteristics on low temperature polycrystalline silicon thin film transistors

In this paper theoretical and experimental examinations have been performed for exploring electrostatic discharge (ESD) characteristics in low temperature polycrystalline silicon (LTPS) thin film transistors (TFTs). It is found that LTPS TFT is greatly damaged during ESD current. The damage is quite different from those devices that fabricated on single crystalline silicon films. A short circuit characteristic is found for single crystalline silicon devices; however, an open circuit behavior for polycrystalline transistors is observed. The difference may due to effects of grain boundaries and poor thermal conductivity. In this paper, authors have found that the electro-migration plays an important role for designing ESD protection circuits by LTPS TFTs. Reduction on electro-migration effect will play an effective way to improve ESD robustness for LTPS TFT protection circuits. Details of modeling and simulation for the aforementioned experimental characteristics will be discussed.