Reaction of Excess Silicon Interstitals in the Presence of Arsenic and Germanium
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REACTION OF EXCESS SILICON INTERSTITALS IN THE PRESENCE OF ARSENIC AND GERMANIUM R. Brindos a, P. H. Keys a, M. Griglione b, K. S. Jones a, M. E. Law b, Aditya Agarwal c, Ebrahim Andideh d a) Department of Materials Science and Engineering, Swamp Center, 525 Engineering Bldg. #33 University of Florida, Gainesville, FL 32611-6130 b) Department of Electrical and Computer Engineering, Swamp Center, 525 Engineering Bldg. #33 University of Florida, Gainesville, FL 32611-6130 c) Eaton Corporation, Beverly, MA 01915 d) Intel Corporation, Hillsboro, OR 97124-6497
ABSTRACT CVD grown boron marker layers were used to monitor the release of silicon interstitials from an arsenic doped surface region that was subsequently implanted with silicon. These structures were annealed for various times at 750°C under a nitrogen gas flow. A comparison of boron spike enhancement and defect dissolution is made. It is shown that enhancement values from the Si+ implant were reduced at short times for samples containing arsenic compared to samples implanted with Si+ alone or As+ alone. The TEM results showed that defect densities were dramatically reduced for the samples containing As. These results imply that the previously reported reduction in {311} formation observed in As doped wells is most likely not a Fermi level effect and is consistent with the formation of As interstitial clusters (AsIC's). The data shows that AsIC's form and control extended defect formation and slow the enhanced diffusion. INTRODUCTION Arsenic is the most common n-type dopant used in silicon based microelectronic device fabrication. High Mass, high solubility, high electrical activation, and low diffusivity are all properties that make arsenic an attractive dopant to the device industry. Although arsenic displays all these desired qualities, transient enhanced diffusion (TED) and electrical activation are still concerns. TED and electrical activation studies of arsenic implanted samples have lead to the conclusion that there is both an electrical solubility limit and solid solubility limit associated with arsenic. Nobili et al. [1] has suggested that electrical inactive clusters are responsible for the difference between the two limits. The electrical solubility limit was been shown to be dependent on the equilibrium carrier densities and have an exponential dependence on the annealing temperature given by [2]: −0.47 ne ( As ) = 2.2 x10 22 exp (1) kT where kT is in eV. From this conclusion, it is realized that there are distinct regimes of concentration when dealing with arsenic in terms of TED, activation, and point defects. At low concentrations (below electrical solubility limit), but above amorphization, TED is
B8.4.1
As Grown (A) RTA (B, D) As+RTA (C)
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EXPERIMENTAL
B o r o n C o n c e n t r a t i o n ( c m)
dominated by end of range damage and surface effects. Increasing the arsenic concentration above the electrical solubility limit, leads to arsenic clustering at which point deactivation of the arsenic begins [2]. The clustering reaction is
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