Systematic Investigation of Interface Properties in 4H-SiC MOS Structures Prepared by Over-Oxidation of Ion-Implanted Substrates

Abstract

A change in the interface state density in 4H-SiC metal–oxide–semiconductor (MOS) structures by incorporation of various elements was systematically investigated. B, N, F, Al, P, and Cl ions were implanted prior to the oxidation and introduced at the SiO2/SiC interface by subsequent thermal oxidation. Interface state density near the conduction band edge for Al-, B-, F-, and Cl-implanted MOS capacitors increased with implantation dose. On the other hand, a strong reduction of the interface state density was observed for N- and P-implanted samples when the implantation dose was larger than 5.0 × 1012 cm−2. It was found that the interface state density can be reduced by P as well as N.

Investigation on the Mechanisms of Nitrogen Shallow Implantation Influence on Trap Properties of SiO2/n-Type 4H-SiC Interface

“…A completely dierent behavior of trap density was observed by Okamoto et al [14]. This group observed the decrease of trap density within energy range near the conduction band with increasing dose of implanted nitrogen.…”

“…This resulted in a wide variety of nitrogen concentration prole. On the other hand, Okamoto et al [14] has applied low energy and low implantation dose using the same set of energy and dierent doses from a relatively small range (Table III). All researchers used fast decaying as a function of depth implantation proles similar to that used by authors (except sample #4 from [13] where double implantation resulted in an extended prole).…”

“…The third process with moderate parameters has only slight inuence on trap density in this region. The observation of Okamoto et al [14] was made at one order of magnitude smaller dose and much thicker oxide. This resulted in consumption of highly damaged substrate layer and the damage near the interface.…”

“…Nevertheless by using low energy implantation with constant energy, Okamoto et al [14] resulted in decrease of D it as a function of dose. This result is in opposite to ndings reported by our team here and in [17].…”

Tailoring Oxide/Silicon Carbide Interfaces: NO Annealing and Beyond

“…As mentioned in the previous section, implantation of nitrogen in SiC prior to oxidation has proved to be a beneficial nitridation technique. Hence, Prof. Yano and his group cleverly extended this logic to a screening method for various potential passivating species [87]. This is how phosphorus caught their attention as oxidation of P-implanted SiC also showed a lower density of electrically active defects than as-oxidized un-implanted interfaces.…”