Simulation and mechanism analysis of MOSFET threshold voltage drift induced by manufacturing process

Abstract

Three problems of threshold voltage(Vth) drift of Trench-MOSFET induced by manufacturing process are discussed. From the simulation results, it can be found that the N⁺ source impurity compensation caused by P⁺ ion implantation results in a low concentration N^- region, which significantly increases the threshold voltage, and the width of N^- region can cause the drift rate to reach 53.3%. The channeling effect of P⁺ ion implantation also contributes to the threshold voltage drift up to 16.7% due to the increasing of doping concentration in p-body area. The temperature of the rapid-thermal-annealing (RTA) process of the source metal Ti/TiN layer influences the source electrode parasitic resistance, which makes the threshold voltage slightly drift up to 6.7%.