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 (<inline-formula> <tex-math notation="LaTeX">${n}{(}{y}{)}{)}$ </tex-math></inline-formula> in the a-IGZO film along the channel length direction (<inline-formula> <tex-math notation="LaTeX">${y}{)}$ </tex-math></inline-formula>, the lateral diffusion coefficient (<inline-formula> <tex-math notation="LaTeX">${D}_{y}{)}$ </tex-math></inline-formula> according to the post-annealing temperature (<inline-formula> <tex-math notation="LaTeX">${T}_{\text {post}}{)}$ </tex-math></inline-formula> is extracted. Consistency of the measured and simulated <inline-formula> <tex-math notation="LaTeX">${V}_{\text {T}}$ </tex-math></inline-formula> of a-IGZO TFTs is confirmed for <inline-formula> <tex-math notation="LaTeX">${T}_{\text {post}}$ </tex-math></inline-formula> from 353 K to 573 K, indicating that <inline-formula> <tex-math notation="LaTeX">${n}{(}{y}{)}$ </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">${V}_{\text {T}}$ </tex-math></inline-formula> changes during annealing are predictable. The results can become a cornerstone of a-IGZO TFT process simulation and suggest the possibility of precise modulation of <inline-formula> <tex-math notation="LaTeX">${V}_{\text {T}}$ </tex-math></inline-formula> of a-IGZO TFTs by controlling the annealing conditions.