Surface Passivation of Crystalline Silicon by Heat Treatment in Liquid Water and its Application to Improve the Interface Properties of Metal-Oxide-Semiconductor Structures

Heat treatment in liquid water at 80°C well passivated the surfaces of 20-Ωcm p-type crystalline silicon substrate and a high photo-induced minority carrier lifetime, τeff of 4.0×10⁻⁵ s was obtained. 100-nm-thick SiO2 layers were formed on the liquid water passivated surfaces at 300°C by the plasma chemical vapor deposition method to form the metal-oxide-semiconductor (MOS) structure. The MOS samples were subsequently annealed at 300°C for 1 h. The high frequency capacitance response with the bias voltage (C-V) measurement resulted in a threshold voltage, a density of interface defects, and a density of fixed charge as −0.35 V, 2.2×10¹¹ cm⁻²eV⁻¹, and 1.1×10¹¹ cm⁻², respectively, while they were −9.7 V, 1.4×10¹² cm⁻²eV⁻¹, and 2.3×10¹² cm⁻² in the case of no liquid water heat treatment.