The impact of TiSi2 on shallow junctions

Abstract

properties of shallow n+ and p t junctions (0.17-0.20 um) in Si.We have examined the impact of TiSi2 formation on the The deposited Ti thickness was varied from 300A to 1000A. The p+ junctions developed high leakage currents after reaction junctions were not degraded. In these studies LOCOS isolation with Ti of initial thickness greater than 700A while the n+ was used and the TiSi2 was formed away from the island edges. Additional experiments were performed on n+ diodes using SWAMI isolation with the TiSi2 formed right upto the edges rlf the isolation. From step-height, spreadln resistance and RDS measurements it was found that the tzickness of TiSi2 formed on n+ Si was less than on p+ Si for a given initial Ti thickness. The amount of electrically active dopant remaining in the substrates was seen to decrease with increasing Ti thickness. This was supported by SIMS measurements which also showed an accumulation of atomic fluorine at the TiSi2 interface. Cross-sectional transmission electron microscopy was used to examine the silicide morphology and interface planarity.

Study of contact and shallow junction characteristics in submicron CMOS with self-aligned titanium silicide

“…This saturates the TiSi^ with n-or p-type dopants so that a thin layer diffuses out during the subsequent anneal to keep the interface doping concentration high and, therefore, the contact resistance low. Furthermore, a serious concern in a conventional TiSij process is the possibility of silicide-induced source-drain leakage [8] at the isolation edge shown in Figure 1. The leakage may occur as a result of over-etching the field oxide after source-drain implants and before titanium deposition.…”