Thermal Process and Dopant Diffusion Model of a-InGaZnO TFTs for VT Prediction Using Lateral Carrier Density Profiling Technique

To establish a thermal process and corresponding dopant diffusion model to predict the properties of a-InGaZnO (a-IGZO) TFTs, the dopant distribution along the a-IGZO channel after thermal process is analyzed and modeled in detail. Considering that the thermal process induces diffusion of the dopants and changes carrier density (n(y))in the a-IGZO film along the channel length direction (y), the lateral diffusion coefficient (Dy)according to the post-annealing temperature (Tₚₒₛₜ)is extracted. Consistency of the measured and simulatedVTof a-IGZO TFTs is confirmed forTₚₒₛₜfrom 353 K to 573 K, indicating thatn(y)andVTchanges during annealing are predictable. The results can become a cornerstone of a-IGZO TFT process simulation and suggest the possibility of precise modulation ofVTof a-IGZO TFTs by controlling the annealing conditions.