The influence of high dose and elevated-temperature implantation on pn-junction leakage current during rapid thermal annealing

Abstract

The electrical properties of the pn junction formed by As implantation and rapid thermal annealing (RTA) have been studied in this article. It is found that the behavior of the pn junction formed by As implantation at elevated temperature (573 K) after RTA is better than that of room-temperature (RT) implantation. The changes of density of residual defects and motion of the defects for different annealing time were observed by TEM. The results of implanting at 5 × 10 15 or 1.0 × 10 16 cm −2 show that the density of residual defects for elevated-temperature (ET) implantation is lower than that of RT implantation. The carrier concentration profiles for different annealing times were measured by a spreading resistance probe (SRP). It is shown that the carrier concentration profile of elevated-temperature implantation is broader than that of RT implantation. The leakage current decreases with increasing RTA time and temperature. The depth of the pn junction (0.6 μm) for elevated-temperature implantation is larger than that of RT implantation (0.4 μm). The pn-junction leakage current of elevated-temperature implantation is several times lower than that of RT implantation. The influence of change of defect density on the leakage current of the pn junction was analyzed using these results. If the dose is as high as 5 × 10 16 cm −2 for implantation, the result is different from that for a dose of 5 × 10 15 cm −2, except for elevated-temperature implantation. The results from channeling measurements show that the lattice stress increases with increasing RTA time. Therefore the leakage current of the pn junction also increases with increasing RTA time. The minimum leakage current is obtained for RTA during 5 s.