UTBOX SOI Structures with High-k Stacks of Hafnia and Alumina

PEALD grown hafnia and alumina buried oxide (BOX) stacks in silicon-on-insulator (SOI) structures were produced and characterized by XTEM and pseudo-MOSFET techniques. The ferroelectric phases of hafnia were observed by XTEM and SAED. It was shown that the minimal density of interface states (IFS) < 10
¹²
cm
⁻²
and the maximal one with a memory window MW ~ 1 V could be obtained by the right choice of a high-k dielectric layer sequence and thermal processing.