**10 nm**

Fig. 1. Cross-sectional views of HfO2 films obtained by using a high-resolution TEM: (a) a HfO2 film fired at 450 oC and (b) a HfO2 film fired at 700 oC (Shimizu et al., 2004).

Fig. 2. XPS spectra of sol-gel-derived HfO2 films. Solid lines are observed spectra and those fitted by the nonlinear least-squares algorithm. Dashed lines for O 1s spectra have two Gaussian peaks corresponding to Hf-OH (531.8 eV) and Hf-O (530.1 eV) (Shimizu et al., 2007).

Characterization of Sol-Gel-Derived and Crystallized

crystallized.

HfO2, ZrO2, ZrO2-Y2O3 Thin Films on Si(001) Wafers with High Dielectric Constant 319

One large peak at 530.2 eV (designated as the low-binding-energy component: LBC) was from Zr-O bonds and the other low peak at 532.0 eV (designated as the high-binding-energy component: HBC) was from Zr-OH bonds near the bulk at the surface area. However, since the binding energy of H2O was slightly higher (533.2 eV) than that of OH, the peak due to physisorbed H2O may [have been included in HBC?] in the present XPS measurements.

The XRD patterns for HfO2 films on Si(001) wafers fired at 450, 550 and 700 oC were found to be in good agreement with previously reported results (Nishide et al., 2000) by using a spectrometer (Rigaku RAD-2 XRD) with CuKαradiation (Figure 4). Specifically, the film was still amorphous at 450 oC, and at 550 oC, new peaks appeared at 2θ = 28.4 and 31.8°, as well as small peaks in the region from 18 to 41°; these have been assigned to monoclinic crystalline HfO2 components (Nishide et al., 2000). At 700 oC, the HfO2 film was completely

Fig. 4. XRD patterns obtained for HfO2 films on Si(001) wafers fired at 450, 550 and 700 oC.

In the electron beam (EB) nanodiffraction pattern for a cross section of the HfO2 film fired at 550 oC, the Debye ring indicates the beginning of crystallization [Figure 5(a) and 5(b)].

Open circles indicate monoclinic HfO2 (Shimizu et al., 2004).

**4. Crystallinity of sol-gel-derived HfO2 thin films on Si(001) wafers** 

from the sol-gel-derived HfO2 film fired at 450 °C indicated that the HfO2 film was amorphous. The Hf 4f 7/2 line was determined to be at 16.2±0.1 eV, which is in good agreement with that of the bulk HfO2 (Chiou et al., 2007, Moulder et al., 1995).

Crystallized HfO2 films fired at temperatures of 550 and 700 °C showed similar XPS spectra regardless of whether they were amorphous or crystalline. The crystallization of sol-gelderived HfO2 films will be discussed later. The O 1s spectrum at 450 °C [Figure 2(b)] was separated into two Gaussian-Lorentzian features corresponding to two chemical states by using the nonlinear least-squares method. One large peak at 530.1 eV (designated as the low-binding-energy component: LBC) was from Hf-O bonds and the other low peak at 531.8 eV (designated as the high-binding-energy component: HBC) was from Hf-OH bonds near the bulk at the surface area. However, since the binding energy of H2O was slightly larger (533.2 eV) than that of OH, the peak due to physisorbed H2O may have been included in HBC in the present XPS measurements.
