Process control issues for ion implantation using large tilt angles

Abstract

Using large tilt angles (7°–60°) and wafer rotational repositioning during ion implantation results in several effects which can compromise process control. These effects include: (1) tilt-related nonuniformity, (2) effective dose reduction from decreased ion flux density, (3) effective ion energy decrease, (4) effective dose reduction from dopant loss by surface scattering, and (5) effective surface film thickness increase. In this paper we characterize these effects and explain their physical basis.