Electrical activation in boron doped polycrystalline Si formed by sequential lateral solidification

Abstract

We have investigated the electrical activation in boron doped poly-Si using Hall measurement, 4-point probe, and secondary ion mass spectroscopy. Through doping was conducted using a mass-separated ion implanter with acceleration energies from 20 to 35 keV at doses ranging from 1 x 10(15)/cm(2) to 4 x 10(15)/cm(2), followed by isothermal rapid-thermal-annealing at temperatures ranging from 550 to 650 degrees C. The substrates used were poly-Si, produced by two-shot sequential lateral solidification. Reverse annealing, in which a continuous loss of charge carriers occurs, was observed in boron doped poly-Si. We found that implantation conditions play a critical role on dopant activation as well as annealing conditions. We observed that a certain implantation condition does exist where the sheet resistance is not changed upon activation annealing. Damage recovery encountered in activation annealing seems to be closely related to a reverse-annealing phenomenon. We assume that the defect-concentration profile would be more important to activation behavior of poly-Si than integrated defect-density accumulated in the silicon layer. (C) 2011 Elsevier B.V. All rights reserved.