InGaAs MOSFET performance and reliability improvement by simultaneous reduction of oxide and interface charge in ALD (La)AlOx/ZrO2 gate stack

The performance and reliability of ZrO₂/In_0.53Ga_0.47As MOSFETs are shown to be improved by simultaneous reduction of dielectric and interface charges. An amorphous (La)AlO_x interlayer at the ZrO₂/In_0.53Ga_0.47As interface is a key to reduce border traps, interface traps and move ZrO₂ fixed charge away from the In_0.53Ga_0.47As. Border traps are reduced ~3x, effective fixed charges are reduced ~3x and interface trap density is reduced ~1.5x. The net effect of the improved stack is 50% normalized I_d improvement and 75% normalized G_m improvement. P/NBTI cyclic stress results indicate Al₂O₃/ZrO₂ is more reliable than ZrO₂ only. ¿V_th of the bilayer show excellent repeatability; conversely, ¿V_th of ZrO₂ shows permanent (not recoverable) interface degradation during relaxation (NBTI stress). La incorporation in Al₂O₃ increases the ¿-value while providing improved reliability over both the ZrO₂ and Al₂O₃/ZrO₂ stack.