Particle-in-cell and Monte Carlo simulation of the hydrogen plasma immersion ion implantation process

Abstract

Hydrogen plasma immersion ion implantation into a 200-mm-diam silicon wafer placed on top of a cylindrical stage has been numerically simulated by the particle-in-cell (PIC) and transport-and-mixing-from-ion-irradiation (TAMIX) methods. The PIC simulation is conducted based on the plasma comprising three hydrogen species H+, H2+, and H3+ in a ratio determined by secondary ion mass spectrometry. The local sputtering losses and retained doses are calculated by the Monte Carlo code TAMIX. The combined effect of the three species results in a maximum retained dose variation of 11.6% along the radial direction of the wafer, although the implanted dose variation derived by PIC is higher at 21.5%. Our results suggest that the retained dose variations due to off-normal incident ions can partially compensate for variations in incident dose dictated by plasma sheath conditions. The depth profile becomes shallower toward the edge of the wafer. Our results indicate that it is about 34% shallower at the edge, but within a radius of 6.375 cm, the depth of the peak only varies by about 5%. For plasma implantation process design, a combination of PIC and TAMIX is better than the traditional practice of using PIC alone.