Robust Performance Under Ball Drop on Coplanar Oxide TFT by Organic Passivation Layer on Top

We report the effect of the ball drop on coplanar oxide thin-film transistors (TFTs) on polyimide (PI) substrate. The ball drop tests were carried out on the TFTs without and with an organic passivation layer (OPL) as a function of drop number. The oxide TFTs without an OPL show electrical degradation by ball drop impact. However, the performance of the TFTs with an OPL changes a little even after 10 times of ball drops on top. It is also found that the splitting of the active layer is more robust under the ball drop test. The performance degradation is mainly due to the O vacancy increase in the channel and the crack formation on the TFTs after the ball drop. It is concluded that splitting the active layer of the coplanar TFT with OPL on top TFT shows no change in electrical performance after many times of ball drops.