Enhanced internal gettering in n/n super(+) epitaxial silicon wafer: coaction of nitrogen impurity and vacancy on oxygen precipitation in substrate

• Published in: Journal of materials science. Materials in electronics Vol. 25; no. 8; pp. 3486 - 3491
• Main Authors: Dong, Peng, Liang, Xingbo, Tian, Daxi, Zhao, Jianjiang, Gao, Chao, Ma, Xiangyang, Yang, Deren
• Format: Journal Article
• Language: English
• Published: 01.08.2014
• Subjects: Atmospheres; Epitaxy; Gettering; Precipitation; Secondary ion mass spectroscopy; Silicon; Silicon substrates; Wafers
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-014-2043-7

The effects of the prior rapid thermal processing (RTP) at 1,250 degree C in argon (Ar) and nitrogen (N sub(2)) atmosphere on oxygen precipitation (OP) and associated internal gettering (IG) in the heavily arsenic (As)-doped Czochralski (CZ) silicon substrates of n/n super(+) epitaxial silicon wafers have been comparatively investigated. It is found that OP in the heavily As-doped silicon subjected to the two-step anneal of 650 degree C/16 h + 1,000 degree C/16 h can be significantly enhanced by the prior RTP in either Ar or N sub(2) atmosphere. By comparison, the prior RTP in N sub(2) atmosphere exhibits much stronger enhancement effect on OP thus leading to a better IG capability of the epitaxial wafer. Secondary ion mass spectroscopy measurement reveals that nitrogen atoms of high concentration are injected into the heavily As-doped silicon substrate by the RTP at 1,250 degree C in N sub(2) atmosphere. It is believed that the vacancy- and nitrogen-assisted heterogeneous nucleation mechanisms are simultaneously operative for OP in the substrate subjected to the prior RTP in N sub(2) atmosphere, thus leading to the more pronounced OP and therefore the better IG capability. It is expected that the present work offers a strategy feasible for improving the IG capability of n/n super(+) epitaxial silicon wafers.