We have used an ultrahigh powered, 100-kW vortex cooled arc lamp to anneal 75-mm-diam 〈100〉 silicon wafers implanted with various doses of 50-keV B+ and BF+2 ions. Sheet resistivity measurements, secondary ion mass spectrometry, and transmission electron microscopy have been used to characterize the annealed wafers. Standard diffusion coefficients predict little dopant movement in the temperature (∼1200 °C) and time (∼1 s) region we studied. However, boron atoms which have been channeled relatively deep into the silicon and left in interstitial positions move ∼100 nm in ∼1 s at low temperatures, then stop. We presume that they encounter a vacancy and become substitutional. The dopant diffusion rate then is close to equilibrium values, and there is little measurable movement between 900 and 1250 °C. A 3-s lamp cycle with maximum wafer temperature 1230 °C is sufficient to fully activate a 1014 cm−2 BF+2 implant and leave the material with no extended defects. The dopant half-width and junction depth are 50 and 250 nm for the as-implanted sample, and 90 and 340 nm for the annealed sample.

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Gas flow engineering involves gas dynamics optimization for effective ambient change before heating and for homogeneous convective cooling of the wafers during the heating steps. Multiple gas buffle system, dynamical gas handling, low pressure operation, low temperature edge guard ring and independent top and bottom heater bank control are the proper tools for this optimization. Silicon surface or interface damage during inert gas anneal can be avoided by addition of a small amount of oxygen.

The continuous scaling of electron devices places strong demands on device design and simulation. The currently prevailing bulk transistors as well as future designs based on thin silicon layers all require a tight control of the dopant distribution. For process simulation, especially the correct prediction of boron diffusion and activation was always a problem. The paper describes the model developed for boron implanted into crystalline silicon and shows applications to hot-shield annealing and flash-assisted rapid thermal processing.

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