Miloslav Ohlídal

• Prof.
• Principal Investigator at Brno University of Technology

Angle-resolved scattering was measured for four samples of silicon exhibiting different surface roughnesses. The measurements were performed for three wavelengths: 457.9 nm, 514.5 nm, and 647.1 nm. Three approaches were used to evaluate the experimental data. The first approach corresponds to the exact formula derived using the scalar diffraction t...

Amorphous hydrogenated silicon carbide (a-CSi:H) thin films were deposited by plasma-enhanced chemical vapor deposition using tetravinylsilane as organosilicon precursor. The mechanical properties of the thin films, namely the modulus of elasticity, hardness, and elastic recovery parameter, were determined by nanoindentation, as well as the interna...

The roughness of four samples of silicon single-crystal surfaces roughened by anodic oxidation is studied using atomic force microscopy (AFM) and angle-resolved scattering of light. The power spectral density functions (PSDFs) are determined on the basis of the measured values of the intensity of the scattered light. This is done on the basis of th...

The method of variable angle spectroscopic ellipsometry usable for the complete optical characterization of inhomogeneous thin films exhibiting complicated thickness non-uniformity together with transition layers at their lower boundaries is presented in this paper. The inhomogeneity of these films is described by means of the multiple-beam interfe...

The study was devoted to optical characterization of non-stoichiometric silicon nitride films prepared by reactive magnetron sputtering in argon-nitrogen atmosphere onto cold (unheated) substrates. It was found that these films exhibit the combination of three defects: optical inhomogeneity (refractive index profile across the films), uniaxial anis...

This chapter focuses on optical characterization of thin films by means of non-microscopic imaging spectroscopic reflectometry. This technique is primarily intended for characterization of thin films with an area non-uniformity in their optical properties. An advantage of the technique is the possibility to measure along a relatively large area of...

The paper deals with the analysis of one of the technological factors (machining process parameters – tool feed rate) in relation to the topography of the surface created by machining technology (turning). The influence of the tool feed rate on the character of the resulting sample profile of wood-filled plastics was evaluated experimentally. Infor...

This book is an up-to-date survey of the major optical characterization techniques for thin solid films. Emphasis is placed on practicability of the various approaches. Relevant fundamentals are briefly reviewed before demonstrating the application of these techniques to practically relevant research and development topics. The book is written by i...

In this paper an imaging spectroscopic reflectometer with enhanced spatial resolution is presented. Main features of its design, experimental data acquisition, i.e. maps of thin film spectral dependencies of local reflectance and the local thickness map determination are described. The ability of this instrument to characterize thin film thickness...

This work presents a new application of imaging spectroscopic reflectometry to determine a distribution of metallic gold in a layer of an organogold precursor which was treated by a plasma jet. Gold layers were prepared by spin coating from a solution of the precursor containing a small amount of polyvinylpyrrolidone on a microscopy glass, then the...

A rough non-uniform ZnSe thin film on a GaAs substrate is optically characterised using imaging spectroscopic reflectometry (ISR) in the visible, UV and near IR region, applied as a standalone technique. A global-local data processing algorithm is used to fit spectra from all pixels together and simultaneously determine maps of the local film thick...

It is possible to encounter thin films exhibiting various defects in practice. One of these defects is area non-uniformity in optical parameters (e.g. in thickness). Therefore it is necessary to have methods for an optical characterization of nonuniform thin films. Imaging spectroscopic reflectometry provides methods enabling us to perform an effic...

Scattermeter II is the second generation device designed and built at The Institute of Physical Engineering, Faculty of Mechanical Engineering, Brno University of Technology. This device has been designed for measuring the angular distribution of the intensity of electromagnetic radiation scattered from a surface of a solid. In this paper, the basi...

Imaging spectroscopic reflectometry is a technique suitable for measurements of local optical parameters (thickness, refraction index and index of extinction) of non-uniform thin films along their surface. It is usually assumed that gradients of these non-uniformities are reasonably small. A new design of an imaging spectroscopic reflectometer prov...

A least-squares data fitting procedure is developed for the analysis of measurements of thin films non-uniform in thickness by imaging spectroscopic reflectometry. It solves the problem of simultaneous least-squares fitting of film thicknesses in all image pixels together with shared dispersion model parameters. Since the huge number of mutually co...

A least-squares data fitting procedure is developed for the analysis of measurements of thin films non-uniform in thickness by imaging spectroscopic reflectometry. It solves the problem of simultaneous least-squares fitting of film thicknesses in all image pixels together with shared dispersion model parameters. Since the huge number of mutually co...

The construction of a normal-incidence imaging spectrophotometer for mapping of thin film properties is described. It is based on an on-axis reflective imaging system, utilising a telescope-like arrangement. A charge-coupled device camera is used as the detector, permitting measurements in the spectral range of 275–1100 nm with resolution of 37 µm....

Epitaxial ZnSe thin films exhibiting two important defects, i.e., boundary roughness and thickness nonuniformity, prepared on GaAs substrates, are optically characterized using a combination of variable-angle spectroscopic ellipsometry, spectroscopic near-normal reflectometry, and imaging spectroscopic reflectometry (ISR). The influence of boundary...

A multi-pixel modification of the data fitting procedure for imaging spectroscopic reflectometry is used for the optical characterisation of thin films non-uniform in thickness. It is shown that this procedure allows a more precise and reliable determination of the optical parameters compared to the standard application of the imaging spectroscopic...

This paper compares Chromatic white light (CWL) and stylus profilometer measurements. Standard samples with vacuum deposited aluminum films of different thicknesses in the range of 50-300 nm were prepared and measured by both methods. It was found that the CWL technique is proper for a measurement of thin organic films with higher than 40-50 nm fil...

This paper compares chromatic white light (CWL) and interference microscope measurements aiming to find a proper non-contact method for a thickness determination of thin soft organic films. Standard samples with vacuum deposited aluminum films of different thicknesses in the range of 50-1000 nm were prepared and measured by both methods. It was fou...

Abasic study of a surface topography generated by an abrasive waterjet cutting is performed by means of the spectral analysis of these surfaces. The initial data were acquired by using an optical profilometer MicroProf FRTin the form of 2D maps of the surfaces' heights. The basic notions of the spectral analysis applied to the surface topography ar...

Experimental study of a titan grade 2 surface topography prepared by abrasive waterjet cutting is performed using methods of the spectral analysis. Topographic data are acquired by means of the optical profilometr MicroProf (R) FRT. Estimation of the areal power spectral density of the studied surface is carried out using the periodogram method com...

In this paper, an original method for the complete optical characterization of thin films exhibiting area thickness non-uniformity is presented. This method is based on interpreting experimental data obtained using an original imaging spectroscopic photometer operating in the reflection mode at normal incidence of light. A CCD camera is employed as...

The combined optical method enabling us to perform the complete optical characterisation of weakly absorbing non-uniform thin films is described. This method is based on the combination of standard variable angle spectroscopic ellipsometry, standard spectroscopic reflectometry at near normal incidence and spectroscopic imaging reflectometry applied...

In this article we present results of rough surface scattering calculations using a graphical processing unit implementation of the Finite Difference in Time Domain algorithm. Numerical results are compared to real measurements and computational performance is compared to computer processor implementation of the same algorithm. As a basis for compu...

The optical characterisation of the As33Se67 and Ge2Sb2Te5 chalcogenide thin films is carried out using the combined method of VASE and SR. This method permits to determine both structural and dispersion parameters describing the thin films exhibiting various defects. The structural model is based on including roughness, overlayers and thickness no...

Complete optical characterization of SiOx films non-uniform in thickness is performed using imaging spectroscopic reflectometry. It is shown that by using this technique it is possible to determine the area distribution of the local thickness (area map) of these films with arbitrary shape of this thickness non-uniformity. Furthermore, it is shown t...

Complete optical characterization of diamond-like carbon (DLC) films non-uniform in thickness is performed using spectroscopic imaging reflectometry (SIR). It is shown that by using this technique it is possible to determine the area distribution (area map) of the local thickness of these films with arbitrary shape of this thickness non-uniformity....

A new method of imaging spectroscopic photometry enabling us to perform the complete optical characterization of thin films exhibiting area non-uniformity in optical parameters is presented. An original imaging spectroscopic photometer operating in the reflection mode at normal incidence is used to apply this method. A CCD camera serves as a detect...

Two formulae expressing the reflectance of non-uniform thin films are presented. The first of them corresponds to the arbitrary shapes of this non-uniformity and illuminated light spot under the assumption that this non-uniformity is sufficiently slight. The second formula corresponds to the wedge-shaped non-uniformity of arbitrary magnitude within...

Experimental study of the surface quality produced by abrasive waterjet (AWJ) on metallic materials has been performed. The surface roughness/waviness was quantitatively evaluated by using the contactless optical measurement. In order to characterize the cut surface qualities, a single-parameter criterion has been proposed. Based on root mean squar...

The paper deals with results obtained by means of contactless optical shadow method and by commercial methods, namely by using an optical commercial profilometer MicroProf (FRT) and a contact profilometer HOMMEL TESTER T8000. The main emphasis is put on the analysis of results for defining the process of creation of a new surface generated by the s...

In this paper we describe the principle of a new method for the optical measurement of surfaces generated by abrasive waterjets. There measured parameters are defined and we determined the way of creating a database of the measured values, and the method for statistical and analytical processing of data for optimising the technology, improving the...

The aim of the present contribution is the study of the influence of the annealing on the mechanical and optical properties of the plasma deposited diamond-like carbon (DLC) films. The DLC films were prepared for different values of hydrogen content from the mixture of methane and hydrogen in capacitively coupled PECVD reactor. Thermal stability of...

In this paper the influences of the technological conditions, i.e. the influences of the hydrogen flow rate and deposition time, on the values of the intrinsic mechanical stresses inside the diamond-like carbon (DLC) thin films prepared by plasma enhanced chemical vapor deposition onto silicon substrates are studied. These stresses are measured by...

In this paper the method of imaging spectrophotometry enabling us to characterize non-absorbing thin films non-uniform in the optical parameters is described. This method is based on interpreting the spectral dependences of the local absolute reflectances measured at the normal incidence of light. It is shown how to determine the area distribution...

A new approach to surface roughness measurement based on the digital two-wavelength holographic interference microscopy with the synthetic wavelength is presented. Two holograms of a randomly rough surface are recorded step by step at two wavelengths by means of a CCD camera. Both holograms are numerically reconstructed. Two reconstructed waves obt...

Principle, parameters and selected applications of the optical profilometer MicroProf FRT (Fries Research & Technology GmbH) in determining surface quality are presented in this contribution.

In this paper the mechanical stresses taking place in diamond like thin films prepared by the plasma enhanced chemical vapor deposition onto silicon single crystal substrates are studied. For determination of the stress values the Stoney's formula is used. The values of the film thicknesses are determined using the combined method of variable angle...

In this paper the quantitative dependence of the mechanical stress inside diamond-like carbon films containing Si and O atoms on a flow rate ratio of methane CH4 and hexamethyldisiloxane C6H18Si2O in the deposition mixture is determined. For this purpose the modified Stoney's formula is employed. The important quantities taking place in this formul...

In this paper the results of optical and atomic force microscopy characterization of oxide thin films prepared by thermal oxidation of GaAs single crystal wafers at a temperature of 500°C in air are presented. The optical characterization is performed using multi-sample modification of the method based on combining variable angle spectroscopic elli...

In this paper, a new optical method for characterizing nonuniform thin films is employed. For applying this method the special experimental arrangement containing CCD camera as a detector is used. Using this experimental arrangement the spectral dependencies of the local reflectances are obtained. After treating these experimental data of the distr...

Laser speckle field can be generated as the result of interaction of a laser wave with randomly rough surface. Information on statistical properties of the surface is encoded in statistical properties of the light intensity distribution of the scattered wave. We can get this information from the degree of correlation of two laser speckle fields obt...

Correlation of laser speckle fields generated by light of two different wavelengths, which illuminates a randomly rough surface, is solved within the framework of the scalar Kirchhoff theory of wave scattering from random rough surfaces. The Fresnel approximation is used in description of the scattered wave. The solution obtained is applied to surf...

Correlation of laser speckle fields generated by light of two different wavelengths, which illuminates successively a randomly rough surface, is solved theoretically within the framework of the scalar Kirchhoff theory of wave scattering from random rough surfaces. The Fresnel approximation is used in description of the scattered wave. The solution...

Correlation of laser speckle fields generated by light of two different wavelengths, which illuminates successively a randomly rough surface, is solved theoretically within the framework of the scalar Kirchhoff theory of wave scattering from random rough surfaces. The Fresnel approximation is used in description of the scattered wave. The solution...

In this paper, a new optical method for characterizing thin films exhibiting area nonuniformity in optical parameters is described. This method is based on interpreting the spectral dependences of the reflectance measured using the special experimental arrangement described in detail. Using this method, the distribution of both the optical paramete...

An original method enabling us to characterize the non-uniformity of thin-film thickness is described. This method employs the interpretation of data obtained by multiple-wavelength reflectometry (MWR). Within this MWR method the values of the reflectance are measured for several wavelengths in many points lying along the area of the film. The spec...

In this contribution a new efficient modification of a method that enables us to perform the optical characterization of nonabsorbing and weakly absorbing thin films without using the absolute values of the reflectances measured is presented. Namely, this modification is based on determining the values of the wavelengths corresponding to touching t...

In this paper results concerning the complete optical analysis of inhomogeneous ZrO2 films are introduced. The optical analysis of these films is carried out using the combined optical method based on interpreting experimental data corresponding to variable angle of incidence spectroscopic ellipsometry (VASE) and near-normal incidence spectroscopic...

The topic of this paper is theoretical consideration on utilization of light scattering for measurement of surface roughness. We use correlation of laser speckle fields generated by light of two different wavelengths, which illuminates investigated randomly rough surface. We present the solution of the problem within the framework of the scalar Kir...

In this paper results concerning optical analysis of the SiO2/Si system performed by the combined ellipsometric and reflectometric method used in multiple-sample modification will be presented. This method is based on combining both the single-wavelength method and the dispersion method. Three models of the system mentioned, i.e. the model of the s...

In this contribution examples of the optical characterization of multilayer systems with randomly rough boundaries are presented. The method based on measuring and interpreting the spectral dependences of the coherent reflectance is used to determine the values of the optical and statistical parameters of samples of three-layer and thirteen-layer s...

The values of the basic characteristics of surface roughness measured by means of optical and non-optical methods often differ mutually. So far a systematic comparison of the results obtained by those methods has not been done. The results we have achieved comparing optical and non-optical methods of the surface roughness measurement for selected s...

A method of determination of the basic morphology parameters of rough metal surfaces with periodic and random components of surface roughness by means of laser light scattering is presented. The method is based on interpreting the angular distribution of the laser light intensity scattered from such surfaces. The theory of the method is based on th...

A method of shearing interferometry for evaluating the basic statistical quantities of randomly flat and randomly rough curved surfaces of solids is presented. Using this method the root-mean-square (RMS) values of heights and slopes, the values of autocorrelation lengths, autocorrelation coefficients and one-dimensional height distribution functio...

In this paper a method of shearing interferometry enabling us to perform a characterization of the basic statistical properties of non-gaussian randomly rough surfaces of solids will be described. This method is based on a statistical analysis of the form of dark fringe centers taking place in interferograms obtained by using a suitable interferenc...

This chapter discusses the scattering of light from multilayer systems with rough boundaries. Multilayer systems are employed in various branches of applied optics and the optics industry. The chapter reviews the important theoretical and experimental results concerning the optics of rough multilayer systems. The physical models of rough boundaries...

In our previous paper, part I, analytical terms for normalized mean intensity and the contrast of mean-intensity Young's fringes in the Fourier plane of the photographic random surface roughness record have been derived in the case of the Fraunhofer and the Fresnel approximations. In this paper the experimental verification of these theoretical con...

Optical analysis of rough single and double layers is performed by interpreting the spectral dependences of the measured coherent reflectance. Formulas for the coherent reflectance of these systems derived within the scalar theory of diffraction of light are used for this interpretation. Possibilities and limitations of the method utilized are illu...

A new shearing-interferometry method is used to characterize the basic statistical properties of very rough surfaces of transparent solids. The mean level of these rough surfaces can be curved or flat. Using this method, one evaluates the root-mean-square values (standard deviations) of the heights and slopes of the surface irregularities. Moreover...

A characteristic surface structure is observed on the samples prepared by plasma polymerization of n-hexane and n-heptane microwave discharge. This typical structure depends on the deposition conditions. The interpretation of the structural changes was based on the nature of the plasma polymer, one result of which is the frost effect that we observ...

In this paper we discuss some new theoretical results which we reached in the analysis of a random surface roughness in the framework of the two-dimensional (2D) Fresnel approximation. A comparison with 2D Fraunhofer approximation results is made. It is shown for experimentally reasonable values of the geometrical arrangement parameters of the meth...

An angle speckle correlation was proposed for a measuring of surface roughness parameters first in [1) . In this paper we present some new results of the method which we reached for a case of randomly rough surfaces in 2D Fresnel approximation. W made a comparison with 2D Fraunhofer approximation results.

The optical constants of mechanically polished silicon surfaces were determined at λ = 546.1 nm applying the least squares method to the ellipsometric parameters ψ and Δ studied as functions of angle of incidence in the interval 〈70°, 80°〉. These optical constants differ considerably from those of Si single crystal. For all polished samples studied...

This paper deals with the preparation technique of thin foils (below 5000 Å) for the transmission electron microscopy from silicon implanted by N+ ions. Mechanical and chemical thinning and anodic oxidation techniques are discussed and selective etching of the surface of silicon for the purposes of the replica technique is noted. Compositions of et...

Surface roughness is a very important parameter of machining, especially the machining of metals. Tools based on the contact measuring by vibrating diamond tip drawn along the surface are used commonly up-to-date. Nevertheless, few optical methods seem to yield the same information as mechanical measuring tools. The possibility of the recurrence of...

The knowledge of the surface roughness is a very important parameter for machining techniques. The direct detection of surface quality is a problem of abrasive water jet technology, especially if used for turning, milling or grinding, where the surface is opened for detection. The topic of the paper is a theoretical and experimental investigation o...

Přehl. lit Rozmn. datum schválení: 19890927 ČVO: 11-22-9 Kand. dis. autoreferát - datum: 1989 autoreferát - rozsah: 21 s. datum obhajoby: 19890915