Characteristics of La₂O₃-and Al₂O ₃-capped HfO₂ dielectric metal-oxide-semiconductor field-effect transistors fabricated on (110)-oriented silicon substrates

The influence of the crystal orientation difference between (100) and (110) silicon substrates on characteristics of La2O3-and Al2O3-capped HfO2 dielectric metal-oxide-semiconductor field-effect transistors has been investigated. We observed that the equivalent oxide thickness of the capped devices varies according to the crystal orientation, indicating that the two substrates are not equal in the gate stack scalability within a subnanometer regime. We found that the mobility dependency on the crystal orientation is reduced by additional scattering associated with the capping films, suggesting the difficulty to derive maximum benefit from an inherent difference in the mobility depending on the crystal orientation. © 2011 The Japan Society of Applied Physics.