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We have investigated the thermal stability and interfacial reactions of a Ru/HfSiON gate stack structure, annealed in a nitrogen ambient, using synchrotron-radiation photoelectron spectroscopy. We find that in HfSiON films with Ru metal, competition between catalyst-induced oxidation and oxygen or SiO desorption arises upon high-temperature annealing, unlike in the same films without Ru. The desorption reaction during high-temperature annealing at 1050 °C could be caused by the decomposition of an unstable Si oxide component, formed by catalytic oxidation at the interface between the HfSiON layer and the Si substrate after annealing below 850 °C. [ABSTRACT FROM AUTHOR]

We have investigated the mechanism of Hf silicidation from HfO2 gate insulators on Si by high-resolution core-level photoemission spectroscopy with detailed annealing-temperature controlling. We have found that the silicidation temperature depends on the difference of the chemical states at the interfacial layer. The Hf-silicate layer which is more stable than the SiO2 layer prevents the silicidation. In addition, silicidation processes also promote the formation of SiO2. Chemical shifts in core-level photoemission spectra depend on the interfacial-layer thickness and SiO2 concentration in the HfO2 top layer, which are tunable by detailed annealing temperature. [ABSTRACT FROM AUTHOR]

Abstract: Annealing-temperature dependence of the thermal stability and chemical bonding states of AlO x N y /SiO2/Si gate stacks grown by metalorganic chemical vapor deposition (MOCVD) using new chemistry was investigated by synchrotron radiation photoemission spectroscopy (SRPES). Results have confirmed the formation of the AlN and AlNO compounds in the as-deposited samples. Annealing the AlO x N y samples in N2 ambient in 600–800°C promotes the formation of SiO2 component. Meanwhile, there is no formation of Al–O–Si and Al–Si binding states, suggesting no interdiffusion of Al with the Si substrate. A thermally induced reaction between Si and AlO x N y to form volatile SiO and Al2O is suggested to be responsible for the full disappearance of the Al component that accompanies annealing at annealing temperature of 1000°C. The released N due to the breakage of the Al–N bonding will react with the SiO2 interfacial layer and lead to the formation of the Si3–N–O/Si2–N–O components at the top of Si substrate. These results indicate high temperature processing induced evolution of the interfacial chemistry and application range of AlO x N y /Si gate stacks in future CMOS devices. [ABSTRACT FROM AUTHOR]

We have demonstrated the determining factor of effective work function in TiN/HfO2/Al2O3/SiO2 gate stack structures by photoemission spectroscopy with synchrotron radiation. Difference in depth profiles indicate that the Si layer inserted at the HfO2/Al2O3 interface suppresses diffusion of Al atoms into the HfO2 layer after annealing, resulting in keeping magnitude of the high-k/SiO2 interface dipole. However, it is found that the increase of the effective work function cannot be explained only by the interface dipole model. We suggest that oxidation of the TiN metal electrode due to oxygen diffusion from the HfO2 layer is one of the most important factors. [ABSTRACT FROM AUTHOR]

We have investigated the thermal stability of TiN/HfSiON gate stack structures using synchrotron-radiation photoemission spectroscopy. Spectral intensities of the Si-oxide components in Si 2p core-level spectra systematically increase with annealing temperature, which strongly depends on the thickness of the TiN metal gate layer. Changes brought by annealing procedures in depth profiles of atomic concentration indicate segregation of Si-atoms at the TiN surface. Furthermore, chemical-state-resolved depth analyses by angle-resolved photoemission spectroscopy suggest formation of TiSix and HfNy components due to chemical bond breaking in the HfSiON layer during TiN film growth. This can be related to the degradation of thermal stability. [ABSTRACT FROM AUTHOR]

We have investigated annealing effects on in-depth profile and band discontinuity for a metal gate/high-k gate stack structure on a Si substrate using backside angle-resolved photoemission spectroscopy with synchrotron radiation. In-depth profiles analyzed from angle-resolved photoemission spectroscopy show that La atoms diffuse through the HfSiO layer and reach interfacial SiO2 layers by rapid thermal annealing. Chemical shift of Si 2p core-level spectra suggests that there are changes in the band discontinuity at the high-k/SiO2 interface, which is well related to the Vth shift based on the interface dipole model. [ABSTRACT FROM AUTHOR]

Using synchrotron-radiation photoemission spectroscopy, we have investigated oxidation and reduction reactions of HfSiO(N)/Si gate stack structures annealed in a N2 or O2 atmosphere. It is found that both oxidation and reduction reactions can be suppressed by using nitrogen-incorporated HfSiO films in the annealing process at proper partial pressure of N2 gas (PN2∼100 Torr). The detailed analysis of “SiO2 equivalent thicknesses” for annealed HfSiO and HfSiON films reveals that ambient N2 gas suppresses only the reduction reaction, while nitrogen atoms incorporated in dielectrics suppress both oxidation and reduction reactions. [ABSTRACT FROM AUTHOR]

Thermal stability of the ZrO2/Zr–silicate/Si structure and the Zr–silicide formation were investigated by photoemission spectroscopy depending on the annealing temperature in ultrahigh vacuum. By the annealing below 860 °C, the interfacial layer thickness of the Zr–silicate decreased although the ZrO2 top layer was not affected. The annealing at 860 °C caused the interfacial Zr–silicate layer to disappear. By the annealing above 860 °C, the metallic Zr components appeared and the metallic clusters were formed. High-resolution photoemission spectra have revealed that the clusters consist of a ZrSi2 layer. Valence-band spectra depending on the annealing temperature provide us with the information about the crystallization in the ZrO2 layer. [ABSTRACT FROM AUTHOR]