Two-dimensional simulation and modeling for dynamic sheath expansion during plasma immersion ion implantation

Abstract

Summary form only given. Plasma immersion ion implantation (PIII) has been utilized as a low cost, low energy doping method for large area targets with applications to semiconductor manufacturing. They include doping, shallow junction formation, hydrogenation for poly-Si thin film transistors, and SIMOX (Separated by IMplant of OXygen) structure formation. The characteristics of the dynamic sheath expansion during PIII process is very important for the optimum PIII configuration design and process control in order to obtain more accurate doping results such as the implant dose and impurity profile. For example, the sheath thickness is critical to chamber design and monoenergic ion implant for a more accurate control of as-implanted impurity profile of shallow junction and SIMOX structures. A PDP2 simulation code has been used to simulate PIII processes which aid in the understanding of the physics of PIII processes and obtain the optimum process parameters. PDP2 code is a two-dimensional planar bounded plasma simulator. The Particle-in-Cell method is implemented to solve for the particles and field parameters self-consistently. The code also uses a Monte Carlo scheme to model charged and neutral particle collisions. In order to minimize the simulation time, a pseudo two-dimensional analytical dynamic sheath model has also been developed. It is simple and has an acceptable accuracy but in a very small fraction of the computing time by PDP2 simulations. This model was verified by comparing with the PDP2 computer simulations and the experimental results of the PIII doping processes.