Interface layer in hafnia/Si films as a function of ALD cycles
ARXPS data (dots) and fits (lines) for the 15 cycles sample for the (a) Si 2p, (b) Hf 4f, and (c) O 1s core levels. The insets show the area of the peaks composing the spectra (symbols) as a function of electron take-off angle. The lines correspond to the calculated intensities under the assumptions described below.
Spectra for the 3, 5, 10, 15, and 20 cycle samples acquired at 85° for (a) Si 2p (normalized), (b) Hf 4f, and (c) O 1s. The Si 2p spectrum for the clean substrate is also shown in (a). The insets show the binding energy of the peaks as a function of the number of ALD cycles.
Peak intensity as a function of the electron take-off angle for the following components: (a) Si 2p for silicon substrate, (b) Si 2p for hafnium silicate, (c) Hf 4f for hafnia, (d) Hf 4f for hafnium silicate, (e) O 1s for hafnia, (f) O 1s for hafnium silicate, and (g) C 1s for adventitious carbon. The uncertainties of the areas are only shown for carbon since they are relatively the largest. (h) The thickness of the film (silicate + hafnia) of the 10 cycles sample obtained from the HRTEM micrograph is consistent with that obtained from the ARXPS analysis (∼8.7 Å).
(a) Thickness of the silicate and hafnia layers as a function of the number of ALD cycles. (b) The cation composition of the interfacial hafnium silicate layer is quantified through the stoichiometric coefficient x in Hf x Si1- x Oy. The hafnium contribution to the layer increases with the number of cycles. The inset indicates the effective attenuation length values used for the electron transport through the interface layer; it complements the information displayed in Table II . (c) Individual contribution of hafnium and silicon to the silicate quantified in ML. There is a hint of a plateau of the amount of Si between 9 and 25 cycles; it is always smaller than 1 ML.
Peak parameters employed in the fitting of the XPS spectra.
Parameters employed in the calculations of the film structure under the multilayer model. The effective attenuation lengths corresponding to the silicate layer are plotted in the inset of Fig. 4(b) .
Article metrics loading...
Full text loading...