Thermal stability of cobalt and nickel silicides in amorphous and crystalline silicon

Metal silicides have been widely used in microelectronic industries, especially as contact material to reduce the series resistance of source, drain and gate regions in MOSFETs. Among all silicides, cobalt-disilicide (CoSi₂) and nickel-monosilicide (NiSi) have been demonstrated to be two of the most promising silicide materials for future ULSI, thin film transistor (TFT) and novel devices. They have the advantages of having the lowest resistivities (~14 μohm-cm), good thermal stability (up to 700-900°C), low formation temperature (~400-600 °C) and little or no resistivity degradation on narrow lines/gates. Moreover, for CoSi₂, it can have low film stress (lattice mismatch with silicon (Si) is only 1.2%), less lateral gate-source/drain silicide overgrowth, good resistance to HF and plasma etching, and do not react with oxide below 900°C. For NiSi, it has the advantages of less Si consumption, no reaction with N₂ and a simple single step annealing. This paper aims to provide a first study to explore and compare the thermal stability and process windows of NiSi and CoSi₂ in amorphous Si (a-Si) and single-crystalline Si (c-Si) substrates after 30 minutes long time annealing