Effects of ramp-up rates on the salicide process

Increases in the sheet resistance of TiSi2 with a decreasing linewidth has been attributed to incomplete transformation from high resistance C49–TiSi2 phase to the desired low resistance C54–TiSi2 phase. In this article, we investigate the effects of increasing the ramp up rate of the first rapid thermal anneal (RTA1) in the salicide process. Electrical testing and micro-Raman spectroscopy were used to investigate the C49-to-C54 phase transformation on poly lines with different linewidths. Samples were annealed with two different ramp-up rates in RTA1. From micro-Raman spectra, it is observed that increased ramp-up rate during RTA1 results in more C54–TiSi2 formed during the second rapid thermal anneal (RTA2). It is also shown that higher ramp-up rates result in lower sheet resistance for deep submicron poly lines.