Authors: H-Y Lin, Y. Li, J-W Lee, C-M Chiu and S.M. Sze
Affilation: Natl Nano Device Labs & Natl Chiao Tung Univ, Taiwan
Pages: 13 - 16
Keywords: thin film transistors, simulation, mobility model, excimer laser annealed, complementary TFTs, low temperature polycrystalline silicon
Excimer laser annealing technique has been proposed in the fabrication of low temperature polycrystalline silicon (LTPS) in the recent years, in particular for the applications to active-matrix liquid crystal display (AMLCD) . In comparing with the traditional thin film transistors (TFTs), the most attractive property of the laser annealed polycrystalline silicon is due to its relatively larger grain size and higher electron-hole mobility. Therefore, the embedded driving circuit could be easily achieved for replacing the additional driving integration circuits (IC) in LCD. It is known that circuit models play important role in the design of the embedded driving circuit using laser annealed LTPS TFTs. Unfortunately, most of mobility models are valid only for some conventional TFTs and can not be applied to the simulation of the laser annealed LTPS TFTs  accurately. In this work, we propose a unified mobility model which is suitable for the simulation of both the n- and p-type laser annealed LTPS TFTs. By considering the channel mobility degraded by the vertical electric field, this empirical model is similar to the BISM4-liked MOSFET mobility model. With the well-known RPI TFT model, this mobility model can be directly incorporated into SPICE circuit simulator without any convergence problems. Comparisons among the conventional RPI TFT mobility model, and measurement data, this new mobility model demonstrated very good accuracy in the simulation of laser annealed LTPS TFTs.