BS ISO 23131:2021 pdf download.Ellipsometry – Principles.
The ellipsometry measuring method is a phase-sensitive reflection technique using polarized light in the optical far-field. Over a long time, ellipsometry has been established as a non-invasive measuring method in the field of semiconductor technology — especially within the integrated production — in the first instance as a single-wavelength, then as a multiple-wavelength and later as a spectroscopic measuring method.
By means of ellipsometry, optical or dielectric constants of any material as well as the layer thicknesses of at least semi-transparent layers or layer systems can be determined. Ellipsometry is an indirect measuring method, the analysis of which is based on model optimization. The measurands, which differ according to the procedural principle, are converted into the ellipsometric factors t (Psi, amplitude information) and zi (Delta, phase information), based on which the physical target figures of interest (optical or dielectric constants, layer thicknesses) will then be determined by means of a parameterized fit.
Ellipsometry shows a high precision regarding the ellipsometric transfer quantities ‘P and zi, which can be equivalent to a layer thickness sensitivity of 0,1 nm for ideal layer substrate systems. As a result, the measuring method can verify even the slightest discrepancies in the surface characteristics. This is closely linked to the homogeneity and the isotropy of the material surface. In order to achieve high precision, carrying out measurements at the exact same measuring point is a prerequisite for
The following documents are referred to in the text in such a way that some or all of their content constitutes requirements of BS ISO 23131. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in measurement (GUM:1995)
The following experimental boundary conditions with respect to the measurement should be agreed upon in advance and, if relevant, be documented in the test report:
— indication of whether an imaging ellipsometer or a mapping ellipsometer (manual or automatic) is concerned;
— for imaging ellipsometers the following factors are relevant: resulting size of the measuring field/ of the region of integration [FOl (field of illumination: sample surface that is illuminated by the incident light), FOV (field of view: sample surface within the FOl from which the light collected by the detector originates), ROl (region of interest: sample surface within the FOV that is relevant for the measurement)];
— for mapping ellipsometers the following factors are relevant: resulting size of the measuring heidi of the region of integration [FOl (field of illumination: sample surface that is illuminated by the incident light), FOA (field of analysis: sample surface within the FOl from which the light collected by the detector originates)];
— ellipsometer configurations: [P-S-A, P-C-S-A, P-S-C-A or P-C-S-C-A];
The following boundary conditions with respect to the simulation shall be agreed upon in advance and, if relevant, be documented in the test report:
— definition of the ellipsometric model (substrate material, roughness, layer architecture, layer materials, initial layer thicknesses and fit parameters);
— application of database values for optical or dielectric constants or separate experimental determination of these constants for non-fit parameters;
— applied dispersion formulae.BS-ISO-23131-2021