We investigated the reaction of HfCl4 molecules with a H2O terminated Si (001)-2×1 surface using density functional theory to understand the initial stage of atomic layer deposition (ALD) of HfO2. Half monolayer of H2O molecules were adsorbed on the buckled-down Si atoms of the Si dimers of the Si (001)-2×1 surface below the dissociation temperature of H2O and were dissociated into H and OH at room temperature. This process could make uniform and well-aligned −H and −OH’s on the Si (001) substrate. The reaction of a HfCl4 molecule was more favorable with -OH than -H. The reaction of the HfCl4 molecule with the -OH generated a HCl molecule, and the remaining HfCl3 was attached to the O atom. The first reaction of the HfCl4 molecule with −OH produced 0.21 eV energy benefit. The reaction of the second HfCl4 molecule with the most adjacent −OH of the first one produced 0.28 eV energy benefit. The third and fourth molecules showed same tendency with the first and second ones. The energy differences of the fifth and sixth HfCl4 reactions were -0.01 eV, 0.06 eV, respectively. Therefore, we found that the saturation Hf coverage was approximately 5/8 of the available −OH's, which was 2.08 × 1014 Hf/cm2. The result was well-matched with the experimental study of other group.

We present analysis of thermal stability of thin GdScO3 films grown on silicon and InAlN/GaN substrates. The GdScO3 films were prepared by liquid injection metal organic chemical vapor deposition at 600 °C. The films were processed after deposition by rapid thermal annealing in nitrogen ambient at 900, 1000 and 1100 °C during 10 s. In addition, annealing of the GdScO3 films on InAlN/GaN substrate at 700 °C during 3 hours was performed. The samples were analyzed by grazing incidence X-ray diffraction (GIXRD), X-ray reflectivity (XRR) and time-of-flight secondary ion mass spectroscopy (ToF SIMS). GIXRD confirmed that the as-deposited GdScO3 films were amorphous. Recrystallization of the films on both substrates occurred at 1100 °C. ToF SIMS depth profile of the films annealed at 1000 °C indicated strong reaction of the GdScO3 film with the Si substrate. For the InAlN/GaN substrate rapid thermal annealing at 900 °C induced diffusion of the In and Al atoms into the top GdScO3 layer. Thermal treatment at 700 °C for 3 hours presents upper limit of the acceptable thermal budget for the GdScO3/InAlN interface.

HfO2 is a promising dielectric for alternative high-k gate dielectrics and DRAM capacitor applications because of its high dielectric constant, excellent thermal stability and compatibility with Si processing. Particularly atomic layer deposition (ALD) is suitable as a deposition tool for gate dielectrics as well as capacitor dielectrics due to its excellent conformity and precise thickness control. In order to achieve ideal ALD performance, it is critical to have appropriate precursors. In order to achieve ideal ALD performance, it is critical to use appropriate enabling precursors. So far, Tetrakisethylmethylamidohafnium (TEMAHf) has been considered as one of the most promising precursors due to its good physical properties. However, this precursor has relatively low thermal stability, which has often become a drawback to ALD process for HfO2. To circumvent the decomposition issues of TEMAHf during ALD deposition, often low process temperatures have been used that lead to less dense films and high level of carbon contamination. In order to overcome these challenges, the novel hafnium formamidinate (Hf-FAMD) precursor is developed as an alternate Hf source at Dow Electronic Materials. Following our success with formamidinate platform in previously reported novel lanthanum formamidinate (La-FAMD) source, this new precursor also exhibits high thermal stability and high reactivity towards water and ozone. In this work, we report, for the first time, comparative studies with TEMAHf and novel Hf-FAMD source, e.g. Hf-FAMD exhibits acceptable vapor pressure (> 0.1 Torr at 100 °C) similar to that of TEMAHf, and higher thermal stability than TEMAHf, thus leading to high quality ALD films. We also present the crystal structure of La-FAMD, elucidated by X-Ray Crystallography, and physical properties of novel Hf-FAMD relevant to ALD.

High-resolution synchrotron radiation X-ray photoelectron spectroscopy (HRXPS) is used to study the chemical bonding at the Al2O3/Si(001) and Al2O3/Si(111) interfaces. In both cases, the Si2p spectra recorded at 180 eV photon energy provides evidence a thin interfacial layer rich in Si-O bonding. On the other hand, conventional AlKα X-ray source angular measurements clearly indicate that there are two in-plane orientations for Al2O3/Si(111) : [11-2]Al2O3(111)//[11-2]Si(111) and [-1-12] Al2O3(111)//[11-2]Si(111) but four in-plane orientations for Al2O3/Si(001) : [11-2] Al2O3(111)//[100]Si(001), [11-2]Al2O3(111)//[010]Si(001), [11-2]Al2O3(111)//[-100]Si(001), and [11-2]Al2O3(111)//[0-10]Si(001).

X-ray photoelectron spectroscopy (XPS) technique is employed in situ to quantify changes in the electric dipole formed at the metal/dielectric interface. The proposed method is valid in the particular case of discontinuous metal overlayer in contact with dielectric, and allows one to model metal gate effective work function evolution of metal-oxide-semiconductor (MOS) stack following its treatments in different environments. The obtained results on Au / dielectric (dielectric=HfO2, LaAlO3) corroborate the model that the oxygen vacancies generated in dielectric contribute to the effective work function changes.