A unified predictive TFT model with capability for statistical simulation

An accurate polysilicon Thin-Film-Transistor (TFT) model is important for the development of TFT circuits in AMLCD and 3D integrations. The desire to have large polysilicon grain for TFT fabrications has lead to the development of grain enhancement processes (such as MILC, laser annealing). These technologies result in significant variation in TFT characteristics from technology to technology, and create difficulty in the modeling of TFT circuits. In this paper, we have developed a physical based TFTs model by considering the grain structure in the channel region. The formulation is inherent from the BSIM industrial standard model for MOSFETs, and thus all MOS related physics are incorporated automatically and it can be easily implemented in SPICE. The performance variations due to different polysilicon grain size resulting from the fabrication technology have been incorporated. The model can be used to predict the device-to-device variation of a given. The model has been applied to 3 different technologies and excellent agreement with the experimental result is observed.