Post-annealing effects on the shallow-junction characteristics caused by high-fluence 77 keV BSi molecular ion implantations at room and liquid nitrogen temperatures

摘要

In this study, n-type <100> silicon specimens were liquid nitrogen temperature (LT) and room temperature (RT) implanted with 2 × 10~(15) cm~(-2) 77 keV BSi molecular ions to produce shallow junctions. Post-annealing methods under investigation included furnace annealing (FA) at 550 ℃ for 0.5, 1, 2, 3 and 5 h and rapid thermal annealing (RTA) at 1050 ℃ for 25 s. Post-annealing effects on the shallow-junction characteristics were examined using one-step (FA) and two-step (FA + RTA) post-annealing treatments. Secondary ion mass spectrometry (SIMS), cross-sectional transmission electron microscopy (XTEM), a four-point probe and Raman scattering spectroscopy (RSS) were employed to analyze junction depths (Xj), damage microstructures, sheet resistance (Rs) and damage characteristics, respectively. The results revealed that the shallow-junction characteristics of the LT implant are better than those of the RT one when post-annealing time in FA exceeds 1 h. A post-annealing time of 3 h in FA is needed in order to obtain the optimal one- or two-step post-annealing effects on the shallow-junction characteristics in both the LT and RT implants.