Using Double-EPI Structure to Solve the Problems Caused by High Process Temperature Requirements

In some BCD processes, if the annealing temperature of NBL and DNW processes is too high, it will cause the upward and downward diffusion of NBL, and the p-type layer of sub will also expand upward. Due to this, it will bring many problems, such as the need for deepe substrate layers, and upper silicon layers. This article uses a double-epi structure and inject additional DNW between two epi processes, thereby reducing the temperature required for thermal and avoiding the above situation. This article improves the thermal process and ion implantation of a specific BCD process. Satisfactory results were obtained through TCAD simulation, which matched the inherent properties and reduced the thermal diffusion temperature and ion diffusion.