EN 15042-1:2006
(Main)Thickness measurement of coatings and characterization of surfaces with surface waves - Part 1: Guide to the determination of elastic constants, density and thickness of films by laser induced surface acoustic waves
Thickness measurement of coatings and characterization of surfaces with surface waves - Part 1: Guide to the determination of elastic constants, density and thickness of films by laser induced surface acoustic waves
This document gives guidance on methods of determining the elastic constants, density and thickness of thin films by laser-induced surface acoustic waves.
It defines terms and described procedures.
Schichtdickenmessung und Charakterisierung von Oberflächen mittels Oberflächenwellen - Teil 1: Leitfaden zur Bestimmung von elastischen Konstanten, Dichte und Dicke von Schichten mittels laserinduzierten Ultraschall-Oberflächenwellen
Dieses Dokument legt einen Leitfaden fest für die mechanische Charakterisierung von Oberflächen mit laserinduzierten Ultraschall-Oberflächenwellen zur Bestimmung von elastischen Konstanten, der Dichte sowie der Dicke von dünnen Schichten.
Es legt Messverfahren und Begriffe fest.
Mesure de l'épaisseur des revêtements et caractérisation des surfaces à l'aide d'ondes de surface - Partie 1 : Guide pour la détermination des constantes élastiques, de la masse volumique et de l'épaisseur des films à l'aide d'ondes acoustiques de surface générées par laser
Le présent document constitue un guide relatif aux méthodes de détermination des constantes élastiques, de
la masse volumique et de l’épaisseur de films fins à l’aide d’ondes acoustiques de surface générées par laser.
Le mode opératoire de mesurage et les termes employés y sont définis.
Merjenje debeline nanosa prevlek in karakterizacija valovitih površin – 1. del: Vodilo za ugotavljanje prožnosti, specifične teže in debeline prevlek z laserjem, ki povzroča valovito akustično površino
General Information
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Thickness measurement of coatings and characterization of surfaces with surface waves - Part 1: Guide to the determination of elastic constants, density and thickness of films by laser induced surface acoustic wavesMesure de l'épaisseur des revetements et caractérisation des surfaces a l'aide d'ondes de surface - Partie 1 : Guide pour la détermination des constantes élastiques, de la masse volumique et de l'épaisseur des films a l'aide d'ondes acoustiques de surface générées par laserSchichtdickenmessung und Charakterisierung von Oberflächen mittels Oberflächenwellen - Teil 1: Leitfaden zur Bestimmung von elastischen Konstanten, Dichte und Dicke von Schichten mittels laserinduzierten Ultraschall-OberflächenwellenTa slovenski standard je istoveten z:EN 15042-1:2006SIST EN 15042-1:2006en17.040.20ICS:SLOVENSKI
STANDARDSIST EN 15042-1:200601-september-2006
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 15042-1April 2006ICS 17.040.20 English VersionThickness measurement of coatings and characterization ofsurfaces with surface waves - Part 1: Guide to the determinationof elastic constants, density and thickness of films by laserinduced surface acoustic wavesMesure de l'épaisseur des revêtements et caractérisationdes surfaces à l'aide d'ondes de surface - Partie 1 : Guidepour la détermination des constantes élastiques, de lamasse volumique et de l'épaisseur des films à l'aided'ondes acoustiques de surface générées par laserSchichtdickenmessung und Charakterisierung vonOberflächen mittels Oberflächenwellen - Teil 1: Leitfadenzur Bestimmung von elastischen Konstanten, Dichte undDicke von Schichten mittels laserinduzierten Ultraschall-OberflächenwellenThis European Standard was approved by CEN on 2 March 2006.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2006 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 15042-1:2006: E
Material data.21 Annex B (informative)
Other methods for determining Young's modulus of film materials.23 Bibliography.26
According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
3.1 surface acoustic waves ultrasonic wave propagating along the surface of the material NOTE An important property of this wave is the penetration depth into the material, which depends on frequency. 3.2 phase velocity velocity at which the phase of the wave propagates 3.3 group velocity
velocity at which the surface acoustic wave impulse induced by the laser propagates 3.4 dispersion dependence of the phase velocity on the frequency of the wave 3.5 dispersion relation ratio of angular frequency to the amount of the wave vector (wave number) 3.6 dispersion degree difference between phase and group velocity NOTE The dispersion degree is expressed as a percentage. 3.7 bandwidth
frequency range of the amplitude spectrum
c phase velocity of the surface acoustic wave; c(E', E, ν', ν, ρ ', ρ, d, fk) theoretical values of the phase velocity (calculated for example according [2]); c(fk) phase velocity of the measured dispersion curve; C1, C2 constants (functions of the Poisson’s ratio ν); d
film thickness; dS substrate thickness; dN
nitriding depth; δ
indentation depth;
∆f frequency shift;
∆d uncertainty of the film thickness; ∆E uncertainty of Young’s modulus of the film;
∆ν
uncertainty of Poisson’s ratio of the film;
∆ρ
uncertainty of the density of the film; ∆E’
uncertainty of Young’s modulus of the substrate; ∆ν’ uncertainty of Poisson’s ratio of the substrate; ∆ρ’ uncertainty of the density of the substrate; E*
Young’s modulus; E Young’s modulus of the film; E' Young’s modulus of the substrate; Eo Young’s modulus of the indenter;
EI Young’s modulus determined by indenter test; ELA Young’s modulus determined by the laser-acoustic method; fk frequency values of the measured dispersion curve; f frequency; f0 resonance frequency of the resonance test method; F force;
h deflection of membrane deflection technique;
hp plastic indentation depth of the indenter test; k magnitude of the wave vector; light wavelength of the light of Brillouin-scattering technique; p pressure of the membrane deflection technique;
ν* Poisson’s ratio;
ν’ Poisson’s ratio of the substrate; νo Poisson’s ratio of the indenter;
scattering angle of the Brillouin-scattering method; ρ* density; ρ density of the film;
ρ’ density of the substrate; σE residual stress; ω
angular frequency; TA annealing temperature; U voltage amplitude. 5 Description of the method 5.1 General principles The elastic modulus (Young's modulus) of the film essentially determines the mechanical behaviour of the coated material, the development of residual stresses, the mechanical energy induced by externally loading the coated surface, influencing creation and growth of cracks in the film and, therefore, influencing essentially the failure behaviour of the coated material. Especially for hard coatings, Young's modulus correlates with hardness that can be measured only with increasing error for reducing film thickness. The structure of coatings can vary within a wide range, depending on the deposition process. This accompanies a Young's modulus of the film which varies considerably. The value tabulated for the bulk material therefore is only a very rough estimation for the material deposited as film. They are given for some selected materials in Annex A. Consequently, measuring the film modulus is a method for controlling the film quality and monitoring the technological process. For measuring Young's modulus of the film, several static and dynamic techniques are used, such as the membrane deflection test, indentation test, Brillouin-scattering, ultrasonic microscopy and resonance vibration test. An overview of the principles of these alternatives is given in Annex B.
These methods are characterised to require special sample preparation, to be time-consuming, or to fail for films of sub-micrometer and nano-meter thickness. The laser-acoustic technique is a practicable method for reproducibly determining Young's modulus of films with thickness down to less than 10 nm without special sample preparation. The technique also enables the film thickness to be measured and provides access to the film density. The method can also be used to characterise layers with gradually varying properties perpendicular to the surface as created by transition hardening and nitriding steels or machining the surface of semiconductor materials. The applicability of the method can be limited by the ultrasonic attenuation of the test material. 5.2 Surface acoustic waves 5.2.1 Properties The test method is based on measuring the dispersion of surface acoustic waves that have a vibration component perpendicular to the surface.
Surface acoustic waves propagate along the surface of the test sample. For isotropic media, their penetration depth is defined to be the distance to the surface where the wave amplitude is decreased to 1/e of the amplitude at the surface A (Figure 1). Approximately, the penetration depth can be equated with the
fc=λ (1) where c
is the
phase velocity,
in m/s; f
is the
frequency, in Hz. The phase velocity depends on the elastic constants and the density of the material.
For a homogeneous isotropic half-space, the following approximation is used ()∗∗∗∗∗+++=vEvvc1112,187,0ρ (2) where v∗ is the
Poisson's ratio; E∗ is the Young's modulus, in N/m2; ∗ is the density, in kg/m3. Equation (2) does not apply to anisotropic materials which are more complex as described in [2]. Key 1
film 2
substrate 3
amplitude within the material A
amplitude at the surface AλA/e = 0,37A123λ123AA/e = 0,37A 1a) — Low frequency: long wavelength, high penetration depth, little effect of the film 1b) — High frequency: short wavelength, low penetration depth, large effect of the film Figure 1 — Properties of the surface acoustic waves
()λρρω/,,,,,,dvEvEckc′′′== (3) where c is the phase velocity, in m/s;
is the circular frequency, in Hz; k is the magnitude of wave vector, in 1/m; E' is the Young's modulus of the substrate, in N/m2; v'
is the Poisson's ratio of the substrate; '
is the density of the substrate, in kg/m3; E is the Young's modulus of the film, in N/m2; v is the
Poisson's ratio of the film;
is the density of the film, in kg/m3; d is the thickness of the film in m;
is the wavelength, in m. Equation (3) is the dispersion relation for the surface wave propagating in coated materials. The implicit form of this relation is deduced from the boundary conditions of stress and displacement components at the surface and the interface between film and substrate [2].
For anisotropic film and substrate materials, the elastic constants Cij are used instead of Young's modulus and Poisson ratio.
The effect of the film on the wave propagation increases with increasing frequency of the wave due to its reducing penetration depth. This makes the wave velocity dependent on frequency. Figure 2 shows three characteristic cases.
E = 3,8 GPa ρ = 1,4 g/cm3
d = 1,85 µm
Measured Calculated
Figure 2 — Two cases of dispersion of the surface acoustic wave in coated material compared to the case of non-coated material
The film properties in Figure 2 (Young's modulus, density, film thickness) were deduced from the measured curve by the inverse solution of
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