Formation of Ultra-Shallow and Low-Reverse-Bias-Current Tantalum-Silicided Junctions Using a Si-Encapsulated Silicidation Technique and Low-Temperature Furnace Annealing below 550°C

Low-temperature processing, below 550°C, has been developed to form ultra-shallow, low-leakage, and low-contact-resistance junctions with tantalum silicide. We have experimentally demonstrated that the amount of residual defects after ion implantation and subsequent low-temperature annealing is strongly dependent on the substrate dopant concentration for both n+p and p+n junctions. It is also confirmed that ion implantation through Ta is not the main factor inducing larger leakage due to metal-knock-on. As a result, ultra-low leakage current (7.8×10-10 A/cm2 and 6.6×10-10 A/cm2 for n+p and p+n junctions at reverse-bias of 5 V) and ultra-shallow junction depth (70 nm and 40 nm for n+p and p+n junctions) have been achieved in Ta-silicided junctions at an annealing temperature of as low as ~550°C, by employing an ultraclean ion implanter, Si-encapsulated silicidation, and low-dopant-concentration substrate.