EFFECTS OF RAPID THERMAL ANNEALING ON THE FORMATION OF SHALLOW P+N JUNCTION BY IMPLANTING BF2+ IONS INTO THIN METAL-FILMS ON SI SUBSTRATE .1. THIN TITANIUM FILMS

Abstract

High-quality Ti-silicided shallow p+ n junctions have been fabricated by implanting BF2+ ions into thin Ti films on Si substrate and subsequent silicidation/drive-in by rapid thermal annealing (RTA) or conventional furnace annealing (CFA) under proper implant and anneal conditions. For both the RTA and CFA techniques, annealing temperatures higher than 800-degrees-C degrade the junction formation because of more severe dopant confinement within the silicides and more serious diffusion of knock-on Ti into junction regions. The high-dose implant greatly enhanced the dopant activation and thus improved the junctions. The high heating rate for RTA caused an immediate formation of Ti-B compounds at high temperatures, while CFA considerably promoted the drive-in efficiency because of its low heating rates and long annealing times. Hence, CFA yielded better low-bias rectifying characteristics than RTA due to larger dopant activation. However, CFA caused much worse high reverse-bias characteristics. A rapid increase of reverse currents with bias voltage was observed for the CFA-treated samples, indicating a severe Ti penetration due to long annealing times.