Anisotropic etching of n+ polycrystalline silicon with high selectivity using a chlorine and nitrogen plasma in an ultraclean electron cyclotron resonance etcher

Hiroaki Uetake, Takashi Matsuura, Tadahiro Ohmi, Junichi Murota, Koichi Fukuda, Nobuo Mikoshiba

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)

Abstract

Heavily phosphorus-doped polycrystalline silicon films (n+ poly-Si) were etched in a pure chlorine plasma using an ultraclean electron cyclotron resonance etcher. Compared against undoped polycrystalline etching, horizontal etch rates were too high to allow anisotropic etching of n + poly-Si. With the addition of more than about 10% N2, highly anisotropic etches of n+ poly-Si can be obtained simultaneously with selectivities as high as 160 to SiO2 in a 4 mTorr plasma. These results are significant to lower submicron fabrication. X-ray photoelectron spectroscopy studies show that Si - N bonds are formed on the n+ poly-Si surface during etching and it is proposed that this layer protects the sidewall against Cl radicals in a N2/Cl2 plasma. The suppression of SiO2 etching by O2 addition to a N2/Cl2 plasma has also been demonstrated.

Original languageEnglish
Pages (from-to)596-598
Number of pages3
JournalApplied Physics Letters
Volume57
Issue number6
DOIs
Publication statusPublished - 1990 Dec 1

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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