Ultra shallow junction monitoring

One of the main challenges to the scaling of CMOS devices involves the formation of ultra shallow junctions (USJ) in the source drain extension region of a transistor. This paper describes the response of a Therma-Probe™ metrology tool for the non-destructive measurement of USJ samples. Samples consisted of Boron and BF₂ USJ samples fabricated with low energy implants and rapid thermal spike anneals. These junctions were measured by SIMS analysis, and their junction depths were correlated to the therma-wave signal. The thermawave response was found to be linear. The results demonstrate the ability of the Therma-Probe technique to accurately measure shallow junctions as low as 11.5nm. These types of shallow junctions are targeted around 2007, as outlined in the 2001 ITRS roadmap.