Electron spin resonance observation of Si dangling-bond-type defects at the interface of (100) Si with ultrathin layers of SiOx, Al2O3and ZrO2

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Abstract
Paramagnetic point defects were probed by electron spin resonance in stacks of (100) Si with nm-thin SiOx, ZrO2 and Al2O3 layers. After photodesorption of passivating hydrogen (300 K; 8.48 eV), the Si dangling bond type interface centres Pbo, Pb1 appear as prominent defects at all (100) Si/dielectric interfaces, with Pbo densities up to ~6×1012 cm-2. This Pbo, Pb1 fingerprint, generally unique for the thermal (100) Si/SiO2 interface, indicates that, while reassuring for the Si/SiOx/ZrO2 case, the as-deposited (100)Si/Al2O3 interface is basically Si/SiO2-like. As probed by the Pb-type defects, the interfaces are under substantially enhanced stress, characteristic for low-temperature Si/SiO2 growth. Standard quality thermal Si/SiO2 interface properties, as exposed by the Pb-type defects (density ~1×1012 cm-2), may be approached by appropriate mild annealing (~650 °C). This fact of a naturally present or possibility to establish a high quality (100) Si/SiO2-type interface, with ultrathin SiO2 interlayer, may be basic to successful application of high-κ metal oxides in Si-based devices.