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Gao C.,Zhejiang University | Wang Z.,Zhejiang University | Liang X.,Ningbo QL Electronics Co. | Tian D.,Ningbo QL Electronics Co. | And 3 more authors.
Journal of Physics Condensed Matter | Year: 2012

The effect of heavy phosphorus (P) doping on oxygen diffusion in Czochralski (Cz) silicon has been experimentally and theoretically investigated. It is experimentally found that the oxygen diffusion in heavily P-doped Cz silicon is retarded, with a diffusion activation energy which is ∼0.12 eV larger than that of its lightly P-doped counterpart. First-principles calculations suggest that the P-O complexes in the -P-Si-O-Si- configuration can form in heavily P-doped Cz silicon, leading to the trapping of interstitial oxygen (Oi) atoms at the twelve equivalent second-nearest neighbors of the P atoms. Furthermore, the calculated increase of the oxygen diffusion activation energy, taking account of the trapping effect of such P-O complexes, is in accordance with the experimental result. This indicates that the retarded oxygen diffusion in the heavily P-doped Cz silicon can be ascribed to the trapping of Oi atoms associated with the formation of the aforementioned P-O complexes. © 2012 IOP Publishing Ltd. Source


Dong P.,Zhejiang University | Liang X.B.,Ningbo QL Electronics Co. | Tian D.X.,Ningbo QL Electronics Co. | Ma X.Y.,Zhejiang University | Yang D.R.,Zhejiang University
Solid State Phenomena | Year: 2016

We report a strategy feasible for improving the internal gettering (IG) capability of iron (Fe) for n/n+ epitaxial silicon wafers using the heavily arsenic (As)-doped Czochralski (CZ) silicon wafers as the substrates. The n/n+ epitaxial silicon wafers were subjected to the two-step anneal of 650 °C/16 h + 1000 °C/16 h following the rapid thermal processing (RTP) at 1250 °C in argon (Ar) or nitrogen (N2) atmosphere. It is found that the prior RTP in N2 atmosphere exhibits much stronger enhancement effect on oxygen precipitation (OP) in the substrates than that in Ar atmosphere, thereby leading to a better IG capability of Fe contamination on the epitaxial wafer. In comparison with the RTP in Ar atmosphere, the one in N2 atmosphere injects not only vacancies but also nitrogen atoms of high concentration into the heavily As-doped silicon substrate. The co-action of vacancy and nitrogen leads to the enhanced OP in the substrate and therefore the better IG capability for the n/n+ epitaxial silicon wafer. © (2016) Trans Tech Publications, Switzerland. Source


Zeng Y.,Zhejiang University | Zeng Y.,Ningbo Institute of Materials Technology and Engineering | Ma X.,Zhejiang University | Chen J.,Zhejiang University | And 5 more authors.
Journal of Applied Physics | Year: 2012

Through comparing the oxygen precipitation in the heavily and lightly phosphorus (P)-doped Czochralski silicon (CZ Si) specimens subjected to the simulated cooling processes of silicon ingot, we researched the influences of heavily P doping on grown-in precipitates by preferential etching and transmission electron microscopy (TEM). It was found that grown-in precipitates were more significant in heavily P-doped CZ Si than in lightly one. Most grown-in precipitates in heavily P-doped CZ Si were generated at (800-600) C. The significant grown-in oxygen precipitates in the heavily P-doped CZ Si would change the density and morphology of oxygen precipitation. TEM examination revealed that the grown-in precipitates in heavily P-doped CZ Si were amorphous oxygen precipitates composed of tiny precipitates in essential. Although more or less phosphorus may be incorporated in the grown-in precipitates, however, phosphorus cannot be detected so far. We further confirmed that extending annealing at 550 C produced significant silicon phosphide (SiP) precipitation in heavily P-doped CZ Si. Summarily, enhancement of grown-in oxygen precipitates was attributed to SiP precipitation and high-concentration vacancy, tentatively. Nonetheless, further investigation on the essential of grown-in precipitates in heavily P-doped CZ Si is worthy. © 2012 American Institute of Physics. Source


Dong P.,Zhejiang University | Liang X.,Ningbo QL Electronics Co. | Tian D.,Zhejiang University | Zhao J.,Zhejiang University | And 3 more authors.
Journal of Materials Science: Materials in Electronics | Year: 2014

The effects of the prior rapid thermal processing (RTP) at 1,250 °C in argon (Ar) and nitrogen (N2) atmosphere on oxygen precipitation (OP) and associated internal gettering (IG) in the heavily arsenic (As)-doped Czochralski (CZ) silicon substrates of n/n+ 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 °C/16 h + 1,000 °C/16 h can be significantly enhanced by the prior RTP in either Ar or N2 atmosphere. By comparison, the prior RTP in N2 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 °C in N 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 N2 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+ epitaxial silicon wafers. © 2014 Springer Science+Business Media New York. Source


Dong P.,Zhejiang University | Zhao J.,Zhejiang University | Liang X.,Ningbo QL Electronics Co. | Tian D.,Zhejiang University | And 5 more authors.
Journal of Applied Physics | Year: 2015

We have investigated the effects of germanium (Ge)-doping at the level of 1020 cm-3 on oxygen precipitation (OP) behaviors in Czochralski (CZ) silicon subjected to different low-high two-step anneals without or with prior high temperature rapid thermal processing (RTP). It is found that Ge-doping remarkably suppresses OP in CZ silicon without prior RTP. However, Ge-doping significantly enhances OP in CZ silicon with prior RTP. The suppressed OP in the case of the absence of prior RTP is primarily due to the fact that the 1020 cm-3 Ge-doping introduces compressive strain into silicon crystal lattice, which increases the critical size of oxygen precipitate nuclei for a given nucleation temperature. Moreover, it is revealed that the 1020 cm-3 Ge-doping facilitates the formation of vacancy-oxygen (V-O) complexes and may introduce Ge-V-O complexes in CZ silicon during high temperature RTP. More vacancy-related complexes in CZ silicon not only reduce the critical size of oxygen precipitate nuclei but also provide more precursors for oxygen precipitate nucleation. Therefore, the 1020 cm-3 Ge-doping enhances OP in CZ silicon subjected to the two-step anneals following high temperature RTP. © 2015 AIP Publishing LLC. Source

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