AVS 57th International Symposium & Exhibition
    Surface Science Monday Sessions
       Session SS2+EM-MoM

Paper SS2+EM-MoM11
Interfacial Effects of Near-surface Dopant Diffusion and Electrical Activation in Silicon

Monday, October 18, 2010, 11:40 am, Room Santa Ana

Session: Semiconductor Surfaces and Interfaces
Presenter: P. Gorai, University of Illinois at Urbana-Champaign
Authors: P. Gorai, University of Illinois at Urbana-Champaign
Y. Kondratenko, University of Illinois at Urbana-Champaign
E.G. Seebauer, University of Illinois at Urbana-Champaign
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Defect behavior in silicon can be controlled by manipulating the chemical state of nearby surfaces and solid-solid interfaces, with important implications for transistor fabrication by ion implantation and annealing. Silicon interstitials formed during the ion implantation step are responsible for unwanted transient enhanced diffusion (TED) of dopants, and affect the degree of dopant activation as well. Earlier work in our laboratory has shown that certain chemical treatments of surfaces and interfaces changes its ability to act as sinks for interstitials. The fundamental kinetic quantity describing “sink” behavior can be described by an annihilation probability (S). Yet surfaces and interfaces also support electrically charged defects, which create local strong electric fields that influence the local motion of interstitials that are charged. The degree of charge buildup can be quantified by an electric potential (Vi). The combined effects of S and Vi not only influence the annihilation of interstitials, but lead under some conditions to the pile up of electrically active dopant near the surface or interface. However, up to now, the precise nature of the interplay, including the most relevant time scales during annealing, has never been quantified. Through continuum modeling on the nanometer length scale, the present work provides such quantification. Differential equations describing the diffusion and reaction of silicon and boron interstitials are solved to yield the time evolution of boron profiles that are compared in important cases to experiment.