Characterization and simulation studies on high tilt ion implantation for precision halo implant applications

Precision dopant placement at high tilt angles for halo applications is required in the fabrication of advanced devices to achieve better transistor characteristics, such as suppression of short channel effects, Vt control and drive current. However, monitoring high tilt implants is not popular in semiconductor fabs, even though most have started monitoring zero-tilt implants in the recent couple of years. In this paper, the authors explore the possibilities of using high tilt angles with higher Miller Index channels. As an example, axial channeling along the 〈112〉 direction is used to evaluate the angle control performance of the VIISta 810EHP medium current ion implanter. Crystal-TRIM (a Monte Carlo simulation code) calculations are compared with experimental SIMS (Secondary Ion Mass Spectrometry) profiles. In addition, the effects of wafer orientation on the platen and wafer mis-cut on the dopant profiles are discussed. Metrology characterization, such as ThermaWaveTM and SIMS, of the 〈112〉 ion channeling is presented.