Fast Fourier transform and multi-Gaussian fitting of XRR data to determine the thickness of ALD grown thin films within the initial growth regime

Abstract

While a linear growth behavior is one of the fingerprints of textbook atomic layer deposition processes, the growth often deviates from that behavior in the initial regime, i.e., the first few cycles of a process. To properly understand the growth behavior in the initial regime is particularly important for applications that rely on the exact thickness of very thin films. The determination of the thicknesses of the initial regime, however, often requires special equipment and techniques that are not always available. We propose a thickness determination method that is based on X-ray reflectivity (XRR) measurements on double layer structures, i.e., substrate/base layer/top layer. XRR is a standard thin film characterization method. Utilizing the inherent properties of fast Fourier transformation in combination with a multi-Gaussian fitting routine permits the determination of thicknesses down to t≈2 nm. We evaluate the boundaries of our model, which are given by the separation and full width at half maximum of the individual Gaussians. Finally, we compare our results with data from x-ray fluorescence spectroscopy, which is a standard method for measuring ultra-thin films.

Mechanical force-driven multi-state memory in WO3–δ thin films

“…1a). 29 The synchrotron radiation-based out-of-plane θ –2 θ XRD only shows the (001) and (002) diffraction peaks of the WO 3– δ , LSMO thin film, and STO substrate, without any other impurity peaks (Fig. 1b).…”

Thermal Atomic Layer Etching of MoS2 Using MoF6 and H2O

“…After etching, the samples were characterized using SE and XRR measurements to determine the MoS 2 thickness values (SE and XRR data are provided in Section S4 of the Supporting Information). The XRR thickness values were determined using a fast Fourier transform of the fringes 49 generated by the MoS 2 films. Figure 5 shows the MoS 2 thickness values versus number of MoS 2 ALE cycles from the SE (orange squares) and XRR (blue triangles) measurements.…”

The Hump Phenomenon and Instability of Oxide TFT Were Eliminated by Interfacial Passivation and UV + Thermal Annealing Treatment

“…The number of periods is positively correlated with the film thickness. In addition, if the surface or internal interface of the film is very rough, the scattering will consume more light intensity, resulting in the decline of X-ray reflection intensity and the weakening or disappearance of interference patterns, from which the roughness of the film surface or internal interface can also be determined. − …”