Thermal Stability Concern of Metal-Insulator-Semiconductor Contact: A Case Study of Ti/TiO2/n-Si Contact

This work discusses the thermal stability of metal-insulator-semiconductor (MIS) contacts. A case study is performed on a typical low-Schottky barrier height (qφb) MIS contact: Ti/TiO
₂
/n-Si. By incorporating different levels of donor concentration in n-Si, we perform a systematic Ti/TiO
₂
/n-Si thermal stability study under different electron conduction mechanisms. We find that both qφ
_b
and contact resistivity (ρ
_c
) of the Ti/TiO
₂
/n-Si MIS contacts vary dramatically after mere 300°C-500°C 1-min rapid thermal treatments. The variations in qφ
_b
and ρ
_c
are related to the thermally driven TiO
₂
decomposition. This thermal stability study of Ti/TiO
₂
/n-Si reveals a general concern for the MIS contact application: since the MIS contacts on n-type semiconductor generally utilize a reactive lowwork function metal and an ultrathin insulator, it is difficult to maintain their interface quality considering the thermal budget in standard manufacturing of integrated circuits. Possible solutions to this MIS thermal stability issue are discussed.