Device and method for measuring thickness and refractive index of multilayer thin film by using angle-resolved spectral reflectometry
View Patent ↗The present disclosure relates to an apparatus and method for measuring the thickness and refractive index of a multilayer thin film by measuring angle-resolved spectral reflectance according to light polarization. According to an exemplary embodiment of the present disclosure, the apparatus and method for measuring the thickness and refractive index of a multilayer structure using angle-resolved spectroscopic reflectometry is capable of measuring and analyzing thickness and refractive index of each layer of a structure having a multilayer thin film through an s-polarized imaging and a p-polarized imaging of the reflective light located in a back focal plane of an objective lens which are acquired through an angle-resolved spectral imaging acquisition part.
1. A method for measuring a thickness and refractive index of measurement object coated with a multilayer thin film, wherein
the method for measuring thickness and refractive index of a multilayer structure using angle-resolved spectroscopic reflectometry comprises steps of:
emitting light from a broad band light source of an illuminant optical module, wherein the illuminant optical module comprises:
the broad band light source emitting light; and
an illuminant optical system emitting light having an even light intensity distribution through the objective lens from light which is emitted from the broad band light source;
reflecting part of the light which is emitted from the illuminant optical module by a first beam splitter;
allowing the light reflected in the first beam splitter to be incident on the measurement object composed of a multilayer thin film through an objective lens;
reflecting part of the reflective light of the light incident on the measurement object by a third beam splitter, followed by allowing a reflective light reflected in the third beam splitter to be incident on an imaging acquisition part, so as to acquire an imaging of the measurement object;
allowing a reflective light transmitted through the third beam splitter to be incident on an image-rotating prism, followed by rotating an input reflective light according to rotation of the image-rotating prism about an optical axis, so as to emit an output reflective light; and
acquiring a first polarized angle-resolved spectral imaging or a second polarized angle-resolved spectral imaging by polarizing an output reflective light transmitted through the image-rotating prism;
wherein the acquiring the first polarized angle-resolved spectral imaging or the second polarized angle-resolved spectral imaging by polarizing the output reflective light transmitted through the image-rotating prism comprises:
imaging, to a first slit, the reflective light reflected in the second beam splitter and located in the back focal plane of the objective lens;
transmitting, by the first slit, only first polarized light in the reflective light in the back focal plane in the first imaging optical system; and
acquiring, by a first imaging spectrometer, the first polarized angle-resolved spectral imaging or the second polarized angle-resolved spectral imaging.
2. The method for measuring a thickness and refractive index of measurement object coated with a multilayer thin film of claim 1 ,
an analysis means measures and analyzes thickness and refractive index of the measurement object from the imaging acquired from the imaging acquisition part, the first polarized angle-resolved spectral imaging and the second polarized angle-resolved spectral imaging.