Low energy boron and phosphorus implants in silicon (b) doping profiles

Silicon wafers were implanted in 〈111〉-and 〈110〉-direction with boron ions of 6 keV and phosphorus ions of 20 keV at room temperature. Doses of 10¹⁴ ions/cm² were applied. At four different temperatures, 300, 420, 600, and 900°C. a few samples of each type of implant were annealed. Standard electrical techniques combined with successive layer removals were used to determine the depth distribution of electrically active centers. Since the method of using non type inverting implanted layers was applied, the local annealing behavior over the whole penetration region could be measured.

For both Si(B)-and Si(P)-implants the part of the profile beyond approx. 0.15 μm, i.e. the deeper part of the channeling and the whole supertail region, is unaffected by going from 300 to 900°C. All additional annealing, with respect to the electrical yield, takes place in the amorphous range and the adjacent part of the channeling range. After raising the temperature from 600 to 900°C both B-and P-profiles undergo diffusion controlled changes in this latter region.