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Proceedings Paper

Strained Si NMOSFET on relaxed Si1-xGex formed by ion implantation of Ge
Author(s): Soji John; Samit K. Ray; Sandeep K. Oswal; Sanjay K. Banerjee
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Paper Abstract

Strained-Si films show considerably higher electron mobility than conventional silicon films which results in increased transconductance and drive current of strained-Si channel NMOSFETs. However, in order to form tensile strained silicon it is necessary to use relaxed Si1-xGex 'substrates,' typically requiring the growth of several microns of a graded Si1-xGex layer, followed by a buffer layer. In this work, we have used ion implantation of Ge followed by high- temperature annealing to form a relaxed substrate, eliminating the growth of graded, relaxed layers, and simplifying the fabrication process. Upon this film, a 1000 angstrom buffer layer of Si0.85Ge0.15 was grown. X-ray analysis indicates that the films formed by this method are 75% relaxed. This was followed by a 200 angstrom thick strained-Si layer. For comparison, unstrained Si epitaxial films and a 2000 angstrom thick film of Si0.85Ge0.15 (on unimplanted Si) followed by 200 angstrom of Si were used. A typical self-aligned MOS process with modifications to achieve low-thermal budget was used to fabricate NMOSFETs with gate lengths ranging from 10 micrometer to 0.8 micrometer. Strained-Si devices show a 17.5% higher peak linear gm than control devices as a result of higher electron mobility in the strained-Si channel.

Paper Details

Date Published: 27 August 1997
PDF: 5 pages
Proc. SPIE 3212, Microelectronic Device Technology, (27 August 1997); doi: 10.1117/12.284584
Show Author Affiliations
Soji John, Univ. of Texas/Austin (United States)
Samit K. Ray, Indian Institute of Technology (India)
Sandeep K. Oswal, Univ. of Texas/Austin (United States)
Sanjay K. Banerjee, Univ. of Texas/Austin (United States)

Published in SPIE Proceedings Vol. 3212:
Microelectronic Device Technology
Mark Rodder; Toshiaki Tsuchiya; David Burnett; Dirk Wristers, Editor(s)

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