Thermochemical reaction of ZrO_x(N_y) interfaces on Ge and Si substrates

We have studied the thermochemical characteristics of ZrO _x(N_y)/Ge and Si interfaces by employing postdeposition annealing. We found that Ge oxide species severely desorbed from the inherent interfacial layer, which was speculated to retard the formation of Zr germanate during high-temperature processing. These unique features enable ZrO _x(N_y)/Ge gate stack to show a better equivalent-oxide-thickness scalability as compared to ZrO_x(N _y)/Si gate stack. However, the volatilization of GeO _x-contained interfacial layer also caused the formation of small pits and/or holes in the overlying ZrO_x(N_y) gate dielectrics, which was expected to cause deterioration in the electrical properties of fabricated high-k/Ge devices.