Probing/Manipulating the Interfacial Atomic Bonding between High k Dielectrics and InGaAs for Ultimate CMOS

The MOS technology using high-k dielectrics on high carrier mobility semiconductors of InGaAs leading to a faster speed at lower power is now at the International Technology Roadmap for Semiconductors (ITRS). Great efforts have been dedicated to understand the high k/InGaAs interface. This project involves an examination of interfacial electronic structure of in-situ HfO2 on In0.53Ga0.47As\(001)-4x2 probed by synchrotron radiation photoemission. The dielectric film was prepared by atomic layer deposition (ALD) with the precursors as tetrakis[ethylmethylamino] Hafnium (TEMAHf) and water. Samples were kept under ultra-high-vacuum (UHV) throughout from MBE/ALD preparation to data-acquisition photoemission chambers in the synchrotronradiation facility. The high-resolution work with a short inelastic mean-free path allowed for the first time identification of atom-toatom interaction at this interface. This work has elucidated the mechanism and nature of the bonding between the Hf atom in TEMAHf and In/As atoms of the reconstructed In0.53Ga0.47As(001)-4x2 surface. The TEMAHf precursor is either intact, or loses one ethylmethylamino ligand to become tri-EMAHf. The initial purge of the TEMAHf precursors effectively passivates all the edge As atoms in the top row. As a result, no oxygen bonding was found at either surface As or In atoms. The subsequent water purge reacts with tri-EMAHf to facilitate the growth of hafnium oxides there. The interface obtained by ALD in the present study found no evidence of oxygen bonding to any atom in the trough. The unpassivated surface In atoms may contribute to the frequency dispersion in the accumulation region of n-In0.53Ga0.47As MOSCAP.