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Gate Quality Oxides Prepared by Rapid Thermal Chemical Vapor Deposition

Published online by Cambridge University Press:  22 February 2011

R.T. Kuehn
Affiliation:
North Carolina State University, Department of Electrical and Computer Engineering, Raleigh, N.C. 27695
X. Xu
Affiliation:
North Carolina State University, Department of Electrical and Computer Engineering, Raleigh, N.C. 27695
D.J. Holcombe
Affiliation:
North Carolina State University, Department of Electrical and Computer Engineering, Raleigh, N.C. 27695
V. Misra
Affiliation:
North Carolina State University, Department of Electrical and Computer Engineering, Raleigh, N.C. 27695
J.J. Wortman
Affiliation:
North Carolina State University, Department of Electrical and Computer Engineering, Raleigh, N.C. 27695
Q.-F. Wang
Affiliation:
IMEC, Kapeldreef 75, B-3001 Leuven, Belgium
D.M. Maher
Affiliation:
D.M. Maher, North Carolina State University, Department of Electrical and Computer Engineering, Raleigh, N.C. 27695
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Abstract

As the feature size of MOSFET devices shrink, issues such as thermal budget associated with controlling channel doping profiles and oxide growth kinetics raise concerns about using thermally grown furnace oxides for deep-submicron device applications. To address these concerns, we have developed a new RTCVD oxide process using a gas system of silane and nitrous oxide. The RTCVD oxides are deposited in a lamp-heated, cold wall, RTP system. Deposition rates ranging from 55 Å/min. to 624 Å/min. can be achieved at 800°C with silane nitrous oxide flow rate ratio of 2% and total pressure ranging from 3 to 10 Torr. The results indicate that this RTCVD process can be used to deposit both thin gate and thick isolation insulators for single wafer processing. Deposition rates of the RTCVD oxides exhibit a nonlinear dependence on the total deposition pressure. Electrical characterization of the as-deposited RTCVD oxides shows a mid-gap interface trap density of < 5×1010 eV−1 cm−2 and an average breakdown field of 13MV/cm. AES, RBS and TEM analyses have been used to study surface cleaning effects on the silicon-silicon dioxide interface quality and to determine the chemical composition of the RTCVD oxides. The results show that RTCVD oxides with stoichiometric composition and atomic flat silicon-silicon dioxide interface can be achieved using silane nitrous oxide flow rate ratio of <2%. I-V characteristics and transconductance degradation under hot carrier stress for MOSFET's using as-deposited RTCVD gate oxides have been found to be comparable to those of MOSFET's using thermal gate oxides.

Type
Research Article
Copyright
Copyright © Materials Research Society 1994

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References

references

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