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Silicon carbide (SiC) wafers are becoming widely used for making power devices. In order to reduce the wafer cost and the electric power consumed by the SiC power devices, the thickness of SiC wafers are being made thinner and thinner to restrain the R on (On-state resistance). Ion implantation is an essential process for manufacturing SiC devices. We have found a thinner SiC wafer is more likely to be distorted during manufacturing processes. Processes such as thermal process, film coating and ion implantation can change the shape of the wafer. In this study, the wafer distortion (bow, the deformation of the median surface of a free and unclamped wafer at the center point) induced by ion implantation has been investigated and the ion implanter which can handle the distorted thin SiC wafer is explained.

A high temperature ion implanter called as IMPHEAT® for SiC devices and a high temperature ion implanter called EXCEED® are developed by Nissin Ion Equipment Co., Ltd. They are based on the mainstream ion implanter of EXCEED®, a field proven tool for more than 10 years, so they are suitable for the mass production of both SiC devices and Si devices. IMPHEAT® can run 4″ and 6″ SiC devices, including HPSI-SiC based devices with a wafer temperature of 500°C, while high temperature implanter of EXCEED® can do 8″ and 12″ Si wafer implantation with a wafer temperature of 450°C.

We have measured the radiative lifetime of the 1S0 metastable level in Kr2+ using an electrostatic ion trap. The obtained lifetime was 17.4 ± 0.4 ms. Comparing with the previous results, our value is consistent with the theoretical predictions, but inconsistent with the experimental results even considering their errors.