Analysis of layered samples with XRF
AssigneeMalvern Panalytical Limited
InventorsArmand Jonkers, Justyna Wiedemair
Life of this patent
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Abstract
A method of making X-ray fluorescence, XRF, measurements of a layered sample is described. At least two measurements are made, one through one surface of the sample and another through the opposite surface. This may be conveniently done by inverting the sample between the measurements. The data from the additional measurements may be used to calculate multiple parameters of the sample, such as the concentration, density or thickness of each of the layers.
Claims15
A method of making X-ray fluorescence, XRF, measurements of a layered sample comprising a first major surface, a second major surface, and at least two layers between the first and second major surfaces, the method comprising:
- carrying out a first X-ray measurement through the first major surface to obtain a first X-ray intensity value (I1) of a first XRF line corresponding to a first element;
- carrying out a second X-ray measurement through the second major surface to obtain a second X-ray intensity value (I2) of the first XRF line corresponding to the first element;
- and
- calculating from the first X-ray intensity value (I1) and second X-ray intensity value (I2) at least two analysis parameters selected from the layer parameters, the layer parameters including:
- the concentration (C1) of a first element in the first layer;
- the concentration (C2) of the first element in the second layer;
- the density (d1) of the first layer;
- the density (d2) of the second layer;
- the thickness (t1) of the first layer;
- and
- the thickness (t2) of the second layer.
A computer program product comprising a tangible non-transitory computer readable medium in which program instructions are stored, arranged to carry out an analysis of X-ray fluorescence measurements on a layered sample comprising a first major surface, a second major surface, and at least two layers between the first and second major surfaces, the measurements including a first X-ray measurement through the first major surface to obtain a first X-ray intensity value (I1) of a first XRF line corresponding to a first element and a second X-ray measurement through the second major surface to obtain a second X-ray intensity value (I2) of the first XRF line corresponding to the first element,
- wherein the sample is characterised by layer parameters including:
- the concentration (C1) of the first element in the first layer;
- the concentration (C2) of the first element in the second layer;
- the density (d1) of the first layer;
- the density (d2) of the second layer;
- the thickness (t1) of the first layer;
- and the thickness (t2) of the second layer;
- wherein the computer program product is arranged to carry out the steps, when run on a computer, of
- (i) taking known values for each of the layer parameters apart from a plurality of analysis parameters;
- (ii) assuming the values of the analysis parameters apart from at least one analysis parameter, and calculating an analysed value of the at least one analysis parameter from the first X-ray intensity value (I1) and the assumed and known values;
- and
- (iii) assuming the values of the analysis parameters apart from at least one analysis parameter, and calculating an analysed value of the at least one analysis parameter from the second X-ray intensity value (I2) and the assumed and known values;
- repeating steps (ii) and (iii) for each of the analysis parameters, and intensity values, replacing the assumed values of the analysis parameters with previously obtained calculated values of the analysis parameters, until the calculated values converge, and
- outputting the converged calculated values of the analysis parameters.
Dependencies are inferred from the claim text.