The isothermal annealing of boron implanted silicon

Abstract

Isothermal annealing studies of boron implanted silicon have been made at temperatures above 600°C for boron doses in the range of 10¹⁴ to 10¹⁵ ions/cm². A 5 eV activation energy is obtained in the temperaturè range 600°C to 900°C. This value is the same as that associated with the generation and subsequent migration of vacancies in silicon. This indicates that the mechanism responsible for the increase in electrical activity of the implanted boron is due to the thermal generation of vacancies and the diffusion of these vacancies or vacancy complexes to interstitial boron atoms, which then become substitutional. The characteristic annealing times are dose dependent. No simple integral-order kinetic process will explain all the data. Good agreement between the data and a calculation is obtained if it is assumed that the characteristic annealing times are position dependent. Detailed data are presented which provide the time and temperature necessary to obtain complete electrical activity of boron implanted silicon over several orders of magnitude of incident dose.