Abstract
A Ge-stabilized tetragonal ZrO 2 (t- ZrO 2 ) film formed by incorporating Ge atoms thermally driven from an underlying Ge layer into a ZrO 2 film was investigated as the gate dielectric for Ge metal-oxide-semiconductor (MOS) capacitors fabricated on a Si substrate. A sole t- ZrO 2 film on Ge is not eligible for the gate dielectric because of the poor interface quality. By using a thermally-grown ultrathin GeO 2 film as an interfacial layer, the t-ZrO 2 / GeO 2 /Ge stack shows improved interface characteristics and a permittivity (κ) value of 36.6 for the t-ZrO 2 . In addition, the stack also demonstrates good leakage current since the amorphous GeO 2 layer terminates grain boundary channels in the crystalline ZrO 2 . Further leakage current suppression can be achieved by a H 2 annealing of the t-ZrO 2 / GeO 2 /Ge stack since the defects at grain boundaries can be effectively passivated, which makes a leakage current of 1.08× 10 -6 A/ cm 2 at V FB -1 V for effective oxide thickness of 1.66 nm and paves an alternative avenue to develop a high-performance crystalline gate dielectric for Ge MOS devices. © 2010 American Institute of Physics.