Modeling of dopant diffusion during rapid thermal annealing

Observations of enhanced dopant diffusion during rapid thermal annealing (RTA) have been made and correlated with the existence of the following phenomena: (1) amorphization of the ion implanted layer; (2) damage-induced dislocation formation; (3) damage annealing; (4) selfinterstitial trapping; or (5) dopant solubility enhancement. Thus, modeling the diffusion of As, B, P, and Sb during RTA presents a unique challenge, since point-defect generation, damage annealing, and solid solubility levels are occurring or changing during the short diffusion intervals. The base line modeling environment for studying transient diffusion must include normal, thermally assisted diffusion processes such as electric field effects, concentrationdependent diffusion, clustering or precipitation, dopant misfit strain, etc. In addition, transient phenomena must be introduced. We have handled transient modeling by overlaying the timedependent effects on steady-state thermally assisted diffusion calculations. Temperature and point-defect transients are calculated by performing calculations over small time intervals in which average parameter values are determined. Calculations and measurements have been performed for As, P, B, and BF2 implants into crystalline and preamorphized Si. Atomic level models are proposed and activation energies have been determined for each substrate-dopant combination. © 1986, American Vacuum Society. All rights reserved.

Duke Scholars

Author Richard B. Fair Electrical and Computer Engineering