Toward a Better Understanding of Ni-Based Ohmic Contacts on SiC

Satoshi Tanimoto,Masanori Miyabe,Shinichi Nakashima,Tatsuhiro Suzuki,Takamitsu Shiiyama,Hiroshi Yamaguchi,Hajime Okumura

doi:10.4028/www.scientific.net/msf.679-680.465

Satoshi Tanimoto, Masanori Miyabe + Show 5 more

Open Access

https://doi.org/10.4028/www.scientific.net/msf.679-680.465

Copy DOI

Abstract

There is still little consensus regarding why low contact resistivity is achieved when Ni on n-type 4H- and 6H-SiC is annealed at temperatures of more than above 950°C. The objective of this paper is to provide an answer concerning to this question. It is has been reported that even Ni-based contacts formed in the n++ region exhibited a steep reduction of contact resistivity in an annealing temperature range > 900°C. This effect reduction cannot be explained by the carbon vacancy induced donor model (Vc model) proposed by Han and his coworkers [Appl. Phys. Lett., Vol. 79, p. 1816 (2001)]. And, it is clarified that It was observed that the surface of substrates annealed at 1000°C was not covered with not Ni2Si but with a thin layer of NiSi. Finally, a plausible model is proposed that as the result of annealing at higher temperatures, results in the formation of the a NiSi/SiC system is builtat the substrate interface, resulting in significant reduction in low causing contact resistivity to be reduced significantly.

Highlights

Ni is annealed at temperatures above 950°C
Ni-based contacts, fabricated by thin Ni film deposition followed by rapid thermal annealing (RTA) at 950°C-1050°C, have become the mainstream contacts to the n-type region on SiC power devices
The transmission line model (TLM) contacts, having a Ta/TaN/Al-Si overlayer, were formed in phosphorus ion hot-implanted and activated n++ regions (ND = 2.5×1020 cm-3, Xj = 250 nm), which were electrically isolated from the substrate and the surrounding area by p-well (Al+)

Summary

Introduction

Ni is annealed at temperatures above 950°C. The objective of this paper is to present some experimental results that provide an answer to this question. Ni-based contacts, fabricated by thin Ni film deposition followed by rapid thermal annealing (RTA) at 950°C-1050°C, have become the mainstream contacts to the n-type region on SiC power devices.

Objectives

Results

Conclusion