(Color online) (a) Processing flow for the fabrication of HfO2/SiOx based MIS capacitors. (b) Schematic of the Si surface having variable Si-OH bond densities after H2O2 treatment. (c) Schematic of the final MIS capacitor structure.
(Color online) Physical thickness and atomic surface roughness of ultrathin SiOx films grown on p-type Si(100) substrates after immersion in hot H2O2. The inset shows some typical SiOx surface roughness after AFM measurements (the vertical axis is 100 nm per line). The lowest Rrms is obtained after 2–8 min of immersion time in H2O2.
(Color online) FTIR spectrum (in absorbance mode) of the absorption coefficient for ultrathin SiOx grown on p-Si(100) after immersion in hot H2O2. The peaks at ∼3652 cm−1 are correlated to different Si-OH bond densities. The inset shows the result of integrating the area under the curve for each Si-OH bond peak at its highest intensity. After 2 min of immersion in H2O2, an HF-last silicon surface develops a larger Si-OH bond density.
(Color online) Gate leakage current density vs gate voltage characteristics for gate injection conditions. Similar carrier conduction mechanisms are observed for all samples except for the 2 min condition and the breakdown samples. After chemical oxidation, almost all samples are able to minimize Jg for the same Vg applied while increasing the necessary electric field for breakdown Ebd to larger values.
(Color online) Gate leakage current density vs gate electric field characteristics for gate injection conditions. All samples reach breakdown for Ebd = 6–7 MV/cm. With the exception of the sample oxidized for only 2min, the same conduction mechanism can be observed before all samples reach breakdown.
(Color online) Simultaneous comparison of Jg at |Vfb − 1| and Vfb characteristics to each H2O2 immersion-time condition. The lowest Jg at |Vfb − 1| is obtained between 4 and 16 min of immersion time while the Vfb is kept almost constant between −0.9 and −1.0 V for the same conditions.
(Color online) Normalized capacitance vs gate voltage characteristics for all studied samples. Compared to our reference sample, all silicon surfaces being chemically oxidized in H2O2 present a shift to the left side of the C–V plot, which is characteristic of an increase in positive charge.
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