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

Defects present at the Si(100)/HfO 2 interface are analyzed using a combination of electron spin resonance (ESR) and frequency-dependent impedance analysis. The 3.4 nm HfO 2 layers were formed by injection metalorganic chemical vapor deposition on boron-doped silicon (100) substrates. ESR spectra indicate the presence of P b 0 defects ((5.0 ′ 0.4) × 10 1 2 cm - 2 ), while analysis of the low-frequency (20 Hz) capacitance-voltage (CV) response indicates a defect density of (5.8 ′ 1.1) X 10 1 2 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) X 10 1 2 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.

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