Passivation and Comparison of Interface Defects in HfO2/Si0.7Ge0.3 Gate Stacks via Al2O3 and TMA Pre-Treatments

The passivation and comparison of interface defects in Al 2 O 3 and trimethylaluminum (TMA) pre-treated HfO 2 /Si 0.7 Ge 0.3 gate stacks are investigated under various post-deposition annealing (PDA) temperatures. GeO is confirmed to be the primary contributor to the interface trap density (D it ) and the main component of GeO x in interfacial layer (IL). For Al 2 O 3 pre-treated samples, as the PDA temperature increases from 300 °C to 500 °C, SiO x in IL increases while GeO x decreases accordingly. As PDA temperature increases to 600 °C, the crystallization of HfO 2 leads to a significant increase in D it . For TMA pre-treated samples, compared with PDA of 300 °C, the formation of SiO x and GeO x in IL is more effectively suppressed under PDA of 400 °C, achieving the lowest D it of 8 × 10 11 eV −1 ·cm −2 . When the PDA temperature increases to 500 °C and 600 °C, the formation of Al-O bonds in HfO 2 leads to an increase in D it . The superior passivation effect of TMA pre-treatment offers a promising technology for SiGe-based 3D devices.