Impact of Surface Hydrophilicization prior to Atomic Layer Deposition for HfO₂/Si Direct-Contact Gate Stacks

Abstract

We developed a novel technique of surface hydrophilicization that changes the nature of hydrogen- (H-) terminated surfaces from hydrophobic to hydrophilic prior to the formation of high-k gate stacks by atomic layer deposition (ALD). We confirmed that the poor electrical film quality in ALD-grown HfO2/Si direct-contact gate stacks fabricated on H-terminated surfaces can be improved by changing the initial chemical nature of the surface to be hydrophilicized. By using this method, the equivalent oxide thicknesses of the HfO2/Si direct-contact gate stacks fabricated on hydrophilicized surfaces were reduced to 0.56 nm, and a leakage current of 0.74 A/cm2 at a gate voltage of VFB-1 V was obtained.