Performance enhancement of strained-Si MOSFETs fabricated on a chemical-mechanical-polished SiGe substrate

Nobuyuki Sugii, Digh Hisamoto, Katsuyoshi Washio, Natsuki Yokoyama, Shin'ichiro Kimura

Research output: Contribution to journalArticlepeer-review

69 Citations (Scopus)

Abstract

Chemical-mechanical-polishing (CMP) was used to smooth the surface of a SiGe substrate, on which strained-Si n- and p-MOSFETs were fabricated. By applying CMP after growing the SiGe buffer layer, the surface roughness was considerably reduced, namely, to 0.4 nm (rms). A strained-Si layer was then successfully grown on the CMP-treated SiGe substrate. The fabricated strained-Si MOSFETs showed good turn-off characteristics, (i.e., equivalent to those of Si control devices). Moreover, capacitance-voltage (CV) measurements revealed that the quality of the gate oxide of the strained-Si devices was the same as that of the Si control devices. Flat-band and threshold voltages of the strained-Si devices were different from those of the Si control devices mainly due to band discontinuity. Electron and hole mobilities of strained-Si MOSFETs under a vertical field up to 1.5 MV/cm increased by 120% and 42%, respectively, compared to the universal mobility. Furthermore, current drive of the n- and p-MOSFETs (Leff ≥ 0.3 μm) was increased roughly by 70% and 50%, respectively. These improvements in characteristics indicate that CMP of the SiGe substrate is a critical technique for developing high-performance strained-Si CMOS.

Original languageEnglish
Pages (from-to)2237-2243
Number of pages7
JournalIEEE Transactions on Electron Devices
Volume49
Issue number12
DOIs
Publication statusPublished - 2002 Dec 1
Externally publishedYes

Keywords

  • Epitaxial layers
  • MOSFETs
  • Semiconductor heterojunctions
  • Strain

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering

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