2D mesh grid effect of SILVACO TCAD tools for NMOS structure

Process of developing the NMOS structure is performed in 2D SILVACO Athena and Atlas Simulation tools. Mesh grid effects are obtained by varying the grid in x-axis and yaxis. Simulation results compared will have the same parameters in its doping concentration, same time and temperature during wet oxidation and go through the same geometrical etching process. Simulation results show that mesh grid has major effect on net doping and wet oxidation process in NMOS structure. Doping concentration will affect junction depth formation due to mesh grid where the difference of net doping can be seen at the surface of the substrate. Change injunction depth formation will then gave an effect to the value of threshold voltage. Observation using sheet resistance of Athena tool shows that having high density mesh in y-axis will results in high concentration at the highly doped region (n++) but low concentration in the lightly doped region (LDD). Effect due to x-axis variation occurs during wet oxidation process while variations in yaxis affect the ion implantation process. Geometrical etching process was also being investigated but shows that mesh grid has no effect on it. It is not necessary to have fine mesh for better process simulation results. By focusing on important processes, less time use to complete simulation.