Interlayer-related paramagnetic defects in stacks of ultrathin layers of SiOx, Al2O3, ZrO2, and HfO2 on (100)Si -: art. no. 033510

An electron spin resonance (ESR) study has been carried out of the influence of postdeposition heating on stacks of (100)Si with nanometer-thick dielectric layers of SiOx and atomic-layer-deposited Al2O3, ZrO2, and HfO2. This reveals upon postdeposition oxidation (PDO) in the range 650-800 degreesC the appearance of various SiO2-characteristic defects, including E-', EX, and a 95-G doublet, in different intensities with increasing anneal temperature, attesting to significant modification and/or additional SiOx interlayer growth. The revealed defects enable probing of the quality of the interlayer on atomic level. In terms of the E-' criterion, it is found that the SiOx interlayer formed in (100)Si/SiOx/ZrO2 is drastically inferior to standard thermal (100)Si/SiO2, exhibiting over one order of magnitude more O-deficiency (E-') centers. The (100)Si/Al2O3 and (100)Si/HfO2 systems appear more robust with better interlayer properties. Particularly in the (100)Si/HfO2 structure, both the E-' and EX densities remain small (<1.6x10(11) cm(-2)) after PDO, which comes as one more favorable property for the application of HfO2 as an alternative gate dielectric. Yet, the Si/Al2O3 entity exhibits the largest EX density, and there appears evidence for an additional Si/dielectric interface defect. No obvious ESR-active defect inherent to the metal oxide layers could be detected. (C) 2004 American Institute of Physics.