Accurate Determination of Quantity of Material in Thin Films by Rutherford Backscattering Spectrometry

Abstract

Ion beam analysis (IBA) is a cluster of techniques including Rutherford and non-Rutherford backscattering spectrometry, and particle-induced X-ray emission (PIXE). Recently, the ability to treat multiple IBA techniques (including PIXE) self-consistently has been demonstrated. The utility of IBA for accurately depth profiling thin films is critically reviewed. As an important example of IBA, three laboratories have independently measured a silicon sample implanted with a fluence of nominally 5.1015As/cm2 at an unprecedented absolute accuracy. Using 1.5 MeV 4He+ Rutherford backscattering spectrometry (RBS), each lab has demonstrated a combined standard uncertainty around 1% (coverage factor k=1) traceable to an Sb-implanted certified reference material through the silicon electronic stopping power. The uncertainty budget shows that this accuracy is dominated by the knowledge of the electronic stopping, but that special care must also be taken to accurately determine the electronic gain of the detection system and other parameters. This RBS method is quite general and can be used routinely, to accurately validate ion implanter charge collection systems, to certify SIMS standards, and for other applications. The generality of application of such methods in IBA is emphasised: if RBS and PIXE data are analysed self-consistently then the resulting depth profile inherits the accuracy and depth resolution of RBS and the sensitivity and elemental discrimination of PIXE

Role of Cl on Diffusion of Cu in In2S3 Layers Prepared by Ion Layer Gas Reaction Method

“…The integral of the respective peaks were used to calculate the areal densities, from which the layer thicknesses were obtained. The number of atoms (Nit) of a given element in a layer is given by [27],…”

“…Rutherford backscattering spectroscopy (RBS) is an absolute method for determination of elemental composition and depth profiling of various materials with high accuracy [27,28]. The diffusion coefficient of Cu in In2S3 can be obtained from Cu concentration profiles by solving the diffusion equation analytically or numerically with appropriate boundary conditions and comparing or fitting the resulting profiles with the experimental data.…”

Accurate electronics calibration for particle backscattering spectrometry

“…This is a multilayer calibration sample discussed at length previously 4,25 and consisting of a thin metallic bilayer on a silica-coated silicon substrate.…”

“…The PHD must be taken into account for properly interpreting the RBS spectra. The non-linearity of the PHD has a dramatic effect on RBS spectra that cannot be accurately fitted for all peaks and edges without properly taking it into account (see Fig.1 in Jeynes et al 4 and Fig.4 in Pascual-Izarra & Barradas 19 ). On the other hand, Figure 3 shows that the non-linearity of the PHD is mainly due to the energy loss in the detector dead layer.…”

Composition measurement of epitaxial ScxGa1−xN films

“…The mass resolution of RBS is high, especially for light elements, and an accuracy of 1% is commonly accepted [40][41][42]. Another direct composition determination method is X-ray photoelectron spectroscopy (XPS), which is very surface sensitive.…”