Interface states and P_b defects at the Si(100)/HfO₂ interface

Defects present at the Si(100)/HfO₂ interface are analyzed using a combination of electron spin resonance (ESR) and frequency-dependent impedance analysis. The 3.4 nm HfO₂ layers were formed by injection metalorganic chemical vapor deposition on boron-doped silicon (100) substrates. ESR spectra indicate the presence of P_b0, defects ((5.0 ± 0.4) × 10¹² cm^-2), while analysis of the low-frequency (20 Hz) capacitance-voltage (CV) response indicates a defect density of (5.8 ± 1.1) × 10¹² cm^-2, between 0.1 and 0.56 eV above the valence bandedge (E_v), with the peak density located at E_v + 0.28 eV. Analysis of conductance data reveals an interface state density of (8.4 ± 2.1) × 10¹² cm^-2, with a peak density observed at E_v + 0.27 eV. These results provide a link between the density of P_b centers measured by ESR, and the electrical active defects measured from CV and conductance analysis. This provides an explanation for the nonideal, frequency-dependent features in the region between accumulation and strong inversion for high-k MOS structures.