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Interfacial barrier layers (IBLs), such as a thermally grown SiO2using O3, thermally nitrided SiOxNyusing NH3, and an atomic layer deposited (ALD) HfO2layer, were used as an interface layer between a sputtered SrTiO3film and a Si substrate. Sr-silicate phase formation at the interface between the SrTiO3film and Si substrate was suppressed by these IBLs. The ALD HfO2layer was the most effective diffusion/reaction barrier against Si diffusion and the interfacial reactions among the IBLs examined. However, the crystallinity of the SrTiO3layer deteriorated as a result of a chemical reaction with the underlying ALD HfO2layer, which decreased the permittivity of the SrTiO3layer. The SrTiO3film with a SiOxNyIBL showed lower Si diffusion and better crystallinity, which provided the optimum dielectric properties of the film.

The dielectric properties and n-type metal oxide semiconductor field-effect transistor (nMOSFET) positive bias temperature instability (PBTI) characteristics of in situ nitrogen-incorporated plasma-enhanced atomic layer deposited HfOxNygate dielectrics were compared with those of the HfO2films. Although the physical thickness of the HfOxNyand HfO2films were almost identical (∼4.1nm), the capacitance equivalent oxide thickness of HfOxNy(1.43 nm) was much lower than that of HfO2(2.28 nm), suggesting that HfOxNyhas a larger dielectric constant. However, HfOxNyshowed a higher leakage current than HfO2due to a decrease in bandgap. HfOxNyshowed a turnaround effect under a positive gate stress bias in nMOSFET. The threshold voltage (Vth)shifted to the positive direction during the first second due to the trapping of electrons at pre-existing trap sites in Hf-based gate dielectrics. Subsequently, the Vthshifted in the negative direction due to hole trapping, which originated from the generation of electron–hole pairs related to the surface plasmon. HfOxNyshowed a higher initial interface trap density but a lower interface trap generation rate during n-type MOS PBTI stress than HfO2.

This study examined the positive bias temperature instability (PBTI) of n-type metal-oxide-semiconductor field effect transistor (nMOSFET) characteristics and the negative bias temperature instability (NBTI) of p-type metal-oxide-semiconductor field effect transistor (pMOSFET) characteristics of HfO2gate dielectrics with a metal gate. The interface trap charge (ΔNit)and bulk oxide trap charge (ΔNot)densities were separately estimated to determine the defects responsible for the threshold voltage (Vth)shift during the BTI stress. The contribution of ΔNitto the Vthshift for nMOSFET PBTI and pMOSFET NBTI was ∼5and ∼30%, respectively. In addition, the estimated activation energy (Ea)of ΔNitand ΔNotwas 0.10 and 0.03 eV, respectively, for nMOSFET PBTI, and 0.11 and 0.17 eV, respectively, for pMOSFET NBTI. It was confirmed that the main degradation mechanism of nMOSFET PBTI is related to the generation of oxide trap charges. However, the degradation under pMOSFET NBTI stress is due to the generation of both interface states and oxide trap charges. By measuring the stress and recovery characteristics under various bias conditions, it was also found that the electron trapping/detrapping characteristics are dominant in the nMOSFET, whereas the generation of both hole trapping/detrapping and interface states competitively occurs in the pMOSFET.

SrTiO3films were grown by radio-frequency magnetron sputtering and postdeposition annealing (PDA) in N2, O2, or NH3atmospheres. A Sr silicate layer formed at the interface between the SrTiO3film and Si substrate due to Si diffusion into the films during deposition. This resulted in an inhomogeneous composition of SrTiO3films along the vertical direction, which was enhanced by PDA. While the thick SrTiO3film was crystallized after PDA and the permittivity increased (220), the thin SrTiO3films remained amorphous even after PDA due to the diffused Si. TiOxin the amorphous SrTiO3layer was easily nitrided after PDA in an NH3atmosphere but TiOxin the crystalline SrTiO3layer was barely nitrided. The electrical properties of the SrTiO3films were improved by PDA.