Atomic Layer Deposition for CMOS Scaling: High-k Gate Dielectrics on Si, Ge, and III-V Semiconductors

We review the impact of oxide-semiconductor interface chemistry and precursor choice on the quality of novel field-effect transistor gate dielectrics grown by atomic layer deposition (ALD). Focus is on hafnium- and aluminum-based high-permittivity ('high-k') gate dielectrics on silicon and on high carrier mobility (germanium, gallium arsenide) channels. We shed light on the ways processing parameters (choice of materials; surface preparation; high-k dielectric deposition process) determine stack structure (continuity of the high-k layer; interfacial oxide thickness; detrimental channel-dielectric interactions) and hence electrical quality. Trends are rationalized based on thermodynamic properties of the semiconductors, dielectrics, and metal-organic precursors involved. This may serve as a basic guideline for ALD precursor selection.