Highly phosphorus-doped crystalline Si layers grown by pulse-magnetron sputter deposition

Abstract

The electrical properties of highly phosphorus-doped crystalline silicon films deposited by pulse-magnetron sputtering were studied. The films were grown, 450 nm thick, on Si(100) and Si(111) wafers at low substrate temperatures Ts of 450–550 °C and post-treated by rapid thermal annealing (RTA) and plasma hydrogenation (PH). In the case of films grown on Si(100), at all values of Ts postgrowth treatment by RTA resulted in an increase in the dopant activation up to 100% and of the Hall mobility to about bulklike values of 50 cm2 V−1 s−1. This result suggests high structural quality of the films on Si(100). The Si(111) films, which are typically more defective, exhibit a completely different behavior with a strong dependence of the electrical dopant activation and the Hall mobility on Ts. By post-treatment a maximum P donor activation level of 22% could be obtained. The variation in the post-treatment procedure (RTA+PH and PH+RTA) for the films deposited at high Ts showed that PH results only in minor changes in the film properties. The different influence of RTA and PH is discussed in terms of the different defect structure of the films. These investigations reveal that high Ts and after-treatment by RTA are the main preconditions for optimal electrical film properties.