Highly uniform ion implants into GaAs by wafer rotation

The influence of wafer rotation on implanted dose uniformity was investigated using thermal-wave measurement to realize highly uniform ion implants into a (001) wafer. It was found that conically rotating ion implantation is an effective way to scramble the scanning ion beam during implantation by using an electrostatic-scan implantation system with a specially designed wafer station. Furthermore, two-fold ion implantation was employed to correct the dose inhomogeneity caused by the variation of the tilt angle across a wafer. Based on these considerations, a high dose uniformity of less than 1% across a wafer was achieved.