IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Semiconductors Tuesday Sessions
       Session SC-TuM

Paper SC-TuM6
Formation of Co Silicides on Si@sub 0.7@Ge@sub 0.3@ Layer in the Presence of Thin Interposing Au Layer and Capping Ti Layer

Tuesday, October 30, 2001, 10:00 am, Room 124

Session: Semiconductor Interfaces and Thin Films
Presenter: W.W. Wu, National Tsing Hua University, Taiwan, R.O.C.
Authors: W.W. Wu, National Tsing Hua University, Taiwan, R.O.C.
T.F. Chiang, National Tsing Hua University, Taiwan, R.O.C.
S.L. Cheng, National Tsing Hua University, Taiwan, R.O.C.
H.H. Lin, National Tsing Hua University, Taiwan, R.O.C.
L.J. Chen, National Tsing Hua University, Taiwan, R.O.C.
H.H. Cheng, National Taiwan University, Taiwan, R.O.C.
Y.H. Peng, National Taiwan University, Taiwan, R.O.C.
Correspondent: Click to Email
Strained SiGe alloys offer the possibility of bandgap engineering for silicon-base devices. Due to their high mobility, SiGe/Si heterostructures have been investigated for use as SiGe channels in MOSFET@super '@s as well as high speed and high transconductance MODFET@super '@s, elevated source-drain contacts and gate material in CMOS technologies. Silicide/Si@sub 1-x@Ge@sub x@/Si(001) heterostructures are promising structures for use in devices such as the heterojunction bipolar transistor and infrared detectors with high cutoff wavelength. Due to its low resistivity, low Schottky barrier, good thermal stability, and possibility of self-aligned formation at relatively low temperatures, CoSi@sub 2@ is an attractive contact material for submicron Si devices. However, in the Co/Si@sub 0.7@Ge@sub 0.3@ system, the CoSi@sub 2@ tended to agglomerate at relatively low temperatures. The formation of Co silicides on Si@sub 0.7@Ge@sub 0.3@ alloys with a thin interposing Au layer and capping Ti layer has been investigated. CoSi@sub 2@ was observed to be the only silicide phase in Si@sub 0.7@Ge@sub 0.3@ samples annealed at 650-950 °C with a thin interposing Au layer and capping Ti layer. The sequence of phase formation is the same as the reaction of Co with single-crystal Si. The presence of Au was found to decrease the formation temperature of CoSi@sub 2@ by about 300 °C compared to that of Co(30nm)/Si@sub 0.7@Ge@sub 0.3@ samples. In addition, a thin capping Ti layer improves the uniformity and thermal stability of CoSi@sub 2@ layer. For Ti(5nm)/Co(30nm)/Au(1nm)/Si@sub 0.7@Ge@sub 0.3@ system, the process window of CoSi@sub 2@ was extended to 650-950 °C. SIMS analysis indicated that a large amount of Au diffused from the Co/Si@sub 0.7@Ge@sub 0.3@ interface to disperse in CoSi@sub 2@ layer during annealing.