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Lateral Uniformity of Ultra-Shallow Junctions Formed by Rapid Thermal Annealing in Polysilicon-on-Silicon Systems

Published online by Cambridge University Press:  28 February 2011

S. Batra
Affiliation:
The University of Texas at Austin, Austin, TX - 78712
K. Park
Affiliation:
The University of Texas at Austin, Austin, TX - 78712
S. Banerjee
Affiliation:
The University of Texas at Austin, Austin, TX - 78712
T. Smith
Affiliation:
Semiconductor Products Sector, Motorola Inc., Phoenix, AZ - 85202
B. Mulvaney
Affiliation:
CAD Program, MCC, Austin, TX - 78759
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Abstract

Lateral non-uniformities can be expected in the dopant diffusion front in the substrate in polysilicon-on-single crystal Si systems upon Rapid Thermal Annealing (RTA), because the grain boundaries in polysilicon act as fast diffusant pipelines and also possibly inject defects into the substrate, which can locally enhance diffusivities in the substrate due to dopant-point defect interactions. The lateral uniformity of As, B and P ultra-shallow junctions formed in the substrate by indiffusion from as-deposited amorphous or polysilicon films has been studied using concentration dependent etching and transmission electron microscopy. Due to a larger final grain size after annealing in the case of as-deposited amorphous Si films compared to asdeposited polysilicon films, there is significant lateral doping inhomogeneities in the diffusion front. However, the doping inhomogeneities are gradually smeared out as the impurities diffuse deeper into the substrate due to lateral as well as vertical diffusion.

Type
Research Article
Copyright
Copyright © Materials Research Society 1991

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