(Invited) Epitaxial HfO2 Thin Films on Si Substrates: Strategy for Sub-1 nm EOT Technology

Equivalent oxide thickness (EOT) of gate dielectric films was scaled to sub-1 nm by epitaxial growth of HfO2 films on Si substrates. The process consists of two parts; deposition of amorphous HfO2 films on Si substrates and crystallization in a solid-phase epitaxy manner. Conventional productions tools of atomic-layer deposition and rapid thermal anneal were applied to construct this technique. Epitaxial growth of HfO2 films was confirmed on both Si (100) and Si (111) substrates. Metal-oxide-semiconductor capacitors and field-effect transistors were fabricated, and electrical properties were measured. The thinnest EOT accomplished by this technique was 0.5 nm, and the gate leakage current was about 6 times smaller than the SiO2 case at the same EOT. Potential of crystalline high-k films in future gate stack technology is discussed on the basis of their crystal growth behaviors.