Formation of CoTi barrier and increased thermal stability of CoSi2 film in Ti capped Co/Si(100) system

Abstract

We investigated the formation of CoSi2 for Ti capped Co on (100) Si substrate with emphasis on the Co–Ti interaction and its effect on thermal stability. A 15 nm thick Ti capping layer is shown to improve the interfacial roughness and thermal stability of CoSi2 film grown on Si substrate compared with TiN capping. The increased uniformity of silicide/Si(100) interface is speculated to result from retarded Co–Si reaction by the formation of CoTi binary phase. And the high thermal stability can be explained by the fact that the amount of Ti atoms in CoSi2 film for Ti capping is much higher than what is in TiN capping. It is likely that the surface Ti diffuses rapidly into CoSi2 grain boundaries and slows down the agglomeration process, thereby increasing thermal stability while Ti in TiN capping did not.

Growth behavior and thermal stability of epitaxial CoSi2 layer from cobalt–carbon films on (100) Si substrate

“…Thin capping layers of TiN or Ti generally have been used to avoid the oxidation of Co during annealing and to improve the uniformity of CoSi 2 layers. 13,14 The capping-layer deposition process was omitted to simplify the SALICIDE process, on the expectation that Co is less oxidized in cobalt-carbon film during annealing than pure cobalt film. Subsequent ex situ rapid thermal annealing ͑RTA͒ was carried out in N 2 ambient at temperatures between 500 and 800°C for 1 -5 min.…”

Suppression of Arsenic Loss by Phosphorus Co-Implantation in n+/p Shallow Junction Diffused from a CoSi2 Layer

“…Without breaking the vacuum, 15 nm-thick Ti films were sequentially sputtered to serve as capping layers. 9) The wafers were first annealed at 600 • C for 60 s in an N 2 ambient and then the unreacted metals were selectively etched in NH 4 OH+H 2 O 2 +H 2 O solution followed by HCl+H 2 O 2 +H 2 O solution. Additional annealing was carried out at 750 • C for 30 s in an N 2 ambient.…”

Abnormal junction leakage characteristics in titanium-capped cobalt disilicide

“…These results are contrary to the other studies. 6,7 According to previous investigations, the Ticapping process has an advantage of uniformity of the silicide/Si interface and its thermal stability. This suggests that junction leakage can be improved by the Ti-capping process.…”

“…6 In addition, other researchers addressed differences in silicide/Si interface morphology and thermal stability between Ti-and TiN-capped CoSi 2 . 7 This study was mainly focused on the roles of Ti capping for protection against O 2 contamination, silicide/Si interface morphology, and thermal stability on polycrystalline Si.…”