Effects of the substrate on the determination of hardness of thin films by the nanoscratch and nanoindentation techniques: A comparative study for the cases of soft film on hard substrate and hard film on soft substrate.

2003 ◽  
Vol 795 ◽  
Author(s):  
Noureddine Tayebi ◽  
Andreas A. Polycarpou ◽  
Thomas F. Conry
Keyword(s):  
Thin Films ◽  
Elastic Recovery ◽  
Hard Substrate ◽  
Substrate Effect ◽  
Soft Substrate ◽  
Substrate Interaction ◽  
Pile Up ◽  
Fused Quartz ◽  
Hardness Values

ABSTRACTHardness values of Au/Fused Quartz and SiO2/Al systems, which correspond to the cases of soft film on hard substrate and hard film on soft substrate, were measured using both the nanoindentation and nanoscratch techniques. The effect of substrate interaction on the measurement of hardness using the nanoscratch technique is found to be much less pronounced compared to that of the nanoindentation technique. Such reduction in substrate effect is attributed to the features used in the nanoscratch analysis: (a) direct imaging of residual profile allows for the effect of pile-up/sink-in to be considered, (b) lower normal loads applied as compared to the nanoindentation, (c) effect of elastic recovery of the plastically deformed surfaces is included in the nanoscratch analysis, whereas the nanoindentation analysis is based solely on the load-displacement data. Moreover, experiments with residual scratch depths as shallow as 3 nm are used to estimate hardness of thin films; a promising indication for the use of such technique in the measurements of ultra-thin films.

Effects of substrate on determination of hardness of thin films by nanoscratch and nanoindentation techniques

2004 ◽  
Vol 19 (6) ◽  
pp. 1791-1802 ◽  
Author(s):  
Noureddine Tayebi ◽  
Andreas A. Polycarpou ◽  
Thomas F. Conry
Keyword(s):  
Thin Films ◽  
Film Thickness ◽  
Elastic Recovery ◽  
Empirical Relationship ◽  
Residual Deformation ◽  
Substrate Effect ◽  
Nanoindentation Technique ◽  
Film Substrate ◽  
Composite Hardness

A comparative study on the effects of the substrate on the determination of hardness of thin films by the use of the nanoscratch and nanoindentation techniques was conducted. Gold films deposited on fused quartz substrates and silicon dioxide films deposited on aluminum substrates with variant film thicknesses were investigated. These two systems correspond to a soft film on a hard substrate and a hard film on a soft substrate, respectively. The effect of substrate interaction on the measurement of hardness using the nanoscratch technique was found to be less pronounced compared to that of the nanoindentation technique due to: (i) the lower normal loads applied to achieve the penetration depths that occur at higher loads when using the nanoindentation method; (ii) the direct imaging of the residual deformation profile that is used in the nanoscratch technique, which allows for the effects of pileup or sink-in to be taken into account, whereas in the nanoindentation technique the contact area is estimated from the load-displacement data, which does not include such effects; and (iii) the account of elastic recovery of the plastically deformed surfaces from scratch tests. The film thickness did not appear to have any effect on the hardness of Au and SiO2 films obtained from nanoscratch data. This observation allowed, for the case of SiO2 films, the determination of the “free substrate effect region” and the derivation of an empirical relationship that relates the composite hardness of the film/substrate system to the contact-depth-to-film-thickness ratio, even when the indenter penetrates into the substrate. Such findings can allow for the determination of the intrinsic hardness of ultrathin hard films (∼1–5 nm thick), where the substrate effect is unavoidable.

Effects of dynamic indentation on the mechanical response of materials

2008 ◽  
Vol 23 (6) ◽  
pp. 1604-1613 ◽  
Author(s):  
M.J. Cordill ◽  
N.R. Moody ◽  
W.W. Gerberich
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Mechanical Response ◽  
Length Scale ◽  
Polycrystalline Nickel ◽  
Dynamic Indentation ◽  
Crystalline Materials ◽  
Fused Quartz ◽  
Hardness Values ◽  
Measured Hardness

Dynamic indentation techniques are often used to determine mechanical properties as a function of depth by continuously measuring the stiffness of a material. The dynamics are used by superimposing an oscillation on top of the monotonic loading. Of interest was how the oscillation affects the measured mechanical properties when compared to a quasi-static indent run at the same loading conditions as a dynamic. Single crystals of nickel and NaCl as well as a polycrystalline nickel sample and amorphous fused quartz and polycarbonate have all been studied. With respect to dynamic oscillations, the result is a decrease of the load at the same displacement and thus lower measured hardness values of the ductile crystalline materials. It has also been found that the first 100 nm of displacement are the most affected by the oscillating tip, an important length scale for testing thin films, nanopillars, and nanoparticles.

A Finite Element Study on the Nanoindentation of Thin Films

2000 ◽  
Vol 649 ◽  
Author(s):  
Xi Chen ◽  
Joost J. Vlassak
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Finite Element ◽  
Film Thickness ◽  
Substrate Effect ◽  
The Finite Element Method ◽  
Effect Factor ◽  
Pile Up ◽  
Key Factor ◽  
Elastic Mismatch

ABSTRACTNanoindentation is a technique commonly used for measuring thin film mechanical properties such as hardness and stiffness. Typically, shallow indentations with contact depths less than 10-20% of the film thickness are used to ensure that measurements are not affected by the presence of the substrate. In this study, we have used the finite element method to investigate the effect of substrate and pile-up on hardness and stiffness measurements of thin film systems. We find that: i) for soft films on hard substrates, the hardness is independent of the substrate as long as the indentation depth is less than 50% of the film thickness; ii) as soon as the hardness exceeds that of the substrate, the substrate effect becomes significant, even for indentations as shallow as 5% of the film thickness; iii) if the film is at least 40 times harder than the substrate, the plastic zone is mostly confined to the substrate while the film conforms to the deformed substrate by bending. We define a substrate effect factor and construct a map that may be useful in the interpretation of indentation measurements on thin films. It is found that the yield stress mismatch is a key factor characterizing the hardness of thin film system, and the elastic mismatch is important when making stiffness measurements. The results obtained in this study are very useful when it is difficult to avoid the influence of the substrate on the measurements.

Experimental Study on the Nanoindentation of Thin Copper Films from Deep Submicron to Nano-Scale

2012 ◽  
Vol 28 (3) ◽  
pp. 507-511 ◽  
Author(s):  
Y.-R. Jeng ◽  
C.-M. Tan ◽  
C. C. Su ◽  
S.-C. Cheng ◽  
C.-Y. Cheng
Keyword(s):  
Thin Films ◽  
Composite System ◽  
Indentation Size Effect ◽  
Single Crystal Silicon ◽  
Deep Submicron ◽  
Substrate Effect ◽  
Copper Films ◽  
Pmma Substrate ◽  
Soft Substrate ◽  
Crystal Silicon

AbstractThis study uses the nanoindentation technique to evaluate the mechanical properties of thin copper films at indentation depths measured in the order of nanometers. Copper films with various thicknesses are deposited on a single crystal silicon wafer with a (100) orientation and on a polymethylmethacrylate (PMMA) substrate, respectively. The experimental results show that for soft thin films on a hard substrate, the substrate effect is negligible when the indentation depth is less than 20% of the film thickness. However, the results suggest that hard films on a soft substrate should be treated as a composite system in indentation because the substrate effect is significant. Finally, the results reveal that a significant indentation size effect exists for thin films with a thickness of less than 100nm. A number of possible reasons for the depth dependence of the hardness properties at ultra-shallow indentation depths are proposed and discussed.

Indentation at the Nanometer Scale on Ultra Thin Films of Diamond-Like Carbon

1994 ◽  
Vol 356 ◽  
Author(s):  
Sandrine Bec ◽  
André Tonck ◽  
Jean-Luc Loubet
Keyword(s):  
Thin Films ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Elastic Recovery ◽  
Contact Stiffness ◽  
Natural Diamond ◽  
Tangential Displacement ◽  
Diamond Like Carbon ◽  
New Instrument

AbstractUltra thin films (50 nm and 180 nm) of amorphous diamond-like carbon on a silicon substrate produced by laser ablation are tested by nanoindentation with a new instrument deriving from a Surface Force Apparatus. Quasi-static measurements of the load and dynamic measurements of the contact stiffness are continuously and simultaneously recorded versus the penetration depth. Scanning lines on the tested surface before and after indentation are made by means of tangential displacement of the diamond indenter on the surface.The tests are conducted with maximum loads from 50 μN to 2500 μN, which correspond to maximum indentation depths between 7 nm and 70 nm. The indentation curves show near elastic recovery but scanning lines and/or topographic images on the surfaces show detectable plastic prints. Despite the extremely small residual indentation depths for these ultra thin films, we show how the hardness value we calculate from the indentation curves with an elastoplastic theory is in good agreement with the hardness value we calculate from the indentation print profile. The determination of the Young's modulus, even at the smallest indentation depths, must take into account the mechanical properties of the substrate. The determination of both values, hardness and elastic modulus, also requires a calibration procedure for the geometry of the tip and knowledge of the piling-up effect.We find that the apparent hardness and the apparent Young's modulus of the tested diamondlike films are high. They are underestimated in comparison with the real values. A rough correction which overestimates the Young’s modulus gives higher values than those of natural diamond.

scholarly journals Conical Nanoindentation Allows Azimuthally Independent Hardness Determination in Geological and Biogenic Minerals

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1630 ◽  
Author(s):  
Corinna F. Böhm ◽  
Patrick Feldner ◽  
Benoit Merle ◽  
Stephan E. Wolf
Keyword(s):  
Standard Deviation ◽  
Mechanical Performance ◽  
Azimuthal Dependence ◽  
Azimuthal Variation ◽  
Conical Indenter ◽  
Pile Up ◽  
Hardness Values

The remarkable mechanical performance of biominerals often relies on distinct crystallographic textures, which complicate the determination of the nanohardness from indentations with the standard non-rotational-symmetrical Berkovich punch. Due to the anisotropy of the biomineral to be probed, an azimuthal dependence of the hardness arises. This typically increases the standard deviation of the reported hardness values of biominerals and impedes comparison of hardness values across the literature and, as a result, across species. In this paper, we demonstrate that an azimuthally independent nanohardness determination can be achieved by using a conical indenter. It is also found that conical and Berkovich indentations yield slightly different hardness values because they result in different pile-up behaviors and because of technical limitations on the fabrication of perfectly equivalent geometries. For biogenic crystals, this deviation of hardness values between indenters is much lower than the azimuthal variation in non-rotational-symmetrical Berkovich indentations.

INVESTIGATION OF INDENTATION METHODS FOR PROPERTIES DETERMINATION IN HARD FILM – SOFT SUBSTRATE SYSTEMS

2004 ◽  
Vol 841 ◽  
Author(s):  
M. S. Kennedy ◽  
N. R. Moody ◽  
D. F. Bahr
Keyword(s):  
Thin Films ◽  
Residual Stress ◽  
Elastic Modulus ◽  
Loading Frequency ◽  
Soft Substrate ◽  
Dynamic Motion ◽  
Pile Up ◽  
Unloading Rate ◽  
Indentation Methods ◽  
Cr Film

ABSTRACTElastic modulus values of the thin films utilized in three different hard film- soft substrate systems were measured using a combination of traditional and continuous stiffness indentation. These systems were chosen to represent typical systems currently utilized in MEMS and included Si/SU8/W, Si/SiO2/Ti/Pt/PZT, and Si/SiO2/Ti/Pt. The last system was coated with either a compressive or nonstressed Cr film. By taking into account ratio between the creep due to the polymer substrate, SU8, to the unloading rate, the modulus of W was measured to be 400 GPa. The modulus of the SU8 was also determined to be 6 GPa. Comparing both the CSM and traditional indentation for the Si/SiO2/Ti/Pt/PZT system showed that the dynamic motion of the indenter caused pile-up in the PZT and resulting in the overestimation of the PZT modulus. This pile-up is a function of the sinusoidal loading frequency. Instead, the modulus of the PZT was measured by shallow depths of traditional indentation that resulted in the PZT modulus of 100 GPa. The hard film-soft substrate systems were show to follow the same trend as stressed soft-film hard-substrate systems with residual stress. The modulus was over estimated for compressively stressed Cr films.

A method for interpreting the data from depth-sensing indentation instruments

1986 ◽  
Vol 1 (4) ◽  
pp. 601-609 ◽  
Author(s):  
M.F. Doerner ◽  
W.D. Nix
Keyword(s):  
Thin Films ◽  
Elastic Modulus ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Depth Sensing ◽  
Plastic Properties ◽  
Total Displacement ◽  
Exact Shape ◽  
Hardness Values

Depth-sensing indentation instruments provide a means for studying the elastic and plastic properties of thin films. A method for obtaining hardness and Young's modulus from the data obtained from these types of instruments is described. Elastic displacements are determined from the data obtained during unloading of the indentation. Young's modulus can be calculated from these measurements. In addition, the elastic contribution to the total displacement can be removed in order to calculate hardness. Determination of the exact shape of the indenter at the tip is critical to the measurement of both hardness and elastic modulus for indentation depths less than a micron. Hardness is shown to depend on strain rate, especially when the hardness values are calculated from the data along the loading curves.

MEASUREMENT OF THE HARDNESS OF ULTRA-THIN FILMS BY THE FIRST DERIVATIVE OF LOAD-DISPLACEMENT CURVE FROM NANOINDENTATION DATA

2010 ◽  
Vol 24 (01n02) ◽  
pp. 256-266 ◽  
Author(s):  
AMIT KUMAR ◽  
KAIYANG ZENG
Keyword(s):  
Thin Films ◽  
Indentation Depth ◽  
Displacement Curve ◽  
Bulk Materials ◽  
Alternative Analysis ◽  
Soft Substrate ◽  
Substrate Effects ◽  
Film Substrate ◽  
Hardness Values ◽  
Measured Hardness

The commonly-used nanoindentation experiments for measuring hardness of thin films may not give the accurate results when the thickness of the film is in the range of few hundred nanometers or less due to the unavoidable substrate effects. The available analysis methods usually work well when the indentation depth is less than one tenth of the total thickness of the film; otherwise, it is very difficult to determine the film-only properties without substrate effects. This work proposes an alternative analysis to measure the hardness of ultra-thin film from nanoindentation data. This method is tested for numbers of bulk materials and the results agreed well with literature reported values; the method is then applied to thin films. It is found that this analysis can give very accurate results for different kind of film-substrate systems such as soft-films on hard-substrate and hard-film on soft-substrate. As the proposed method is based on the measurement of hardness at each indentation step therefore, it is also capable to show at what indentation depth the substrate starts affecting the indentation-measured hardness values.

Determination of hardness from nanoscratch experiments: Corrections for interfacial shear stress and elastic recovery

2003 ◽  
Vol 18 (9) ◽  
pp. 2150-2162 ◽  
Author(s):  
Noureddine Tayebi ◽  
Thomas F. Conry ◽  
Andreas A. Polycarpou
Keyword(s):  
Shear Stress ◽  
Elastic Recovery ◽  
Interfacial Shear Stress ◽  
Interfacial Shear ◽  
Material Behavior ◽  
Extended Model ◽  
Air Exposure ◽  
Model Based ◽  
Fused Quartz

A frequent application of the nanoscratch technique is to estimate hardness of ultrathin films when substrate effects are encountered with the nanoindentation technique. A model based on the work of Goddard and Wilman, which assumes a rigid-plastic behavior of the deformed surfaces, is commonly used for the determination of hardness from scratch tests, yet it overestimates the hardness of materials by as much as a factor of three at very shallow indentation depths on the order of 1–10 nm. The Goddard and Wilman model was extended in this paper to include the effects of the component of the shear stress tangential to the meridianal plane and the elastic recovery of the plastically deformed surfaces assuming elastic-perfectly-plastic material behavior. The proposed model was subsequently verified by performing nanoscratch experiments on fused quartz, which is homogeneous and isotropic with no known surface layers and with known hardness. The hardness was calculated using both the model based on the work of Goddard and Wilman and the extended model. The hardness calculated using the extended model was in very close agreement with the accepted value of bulk hardness of fused quartz over the range of scratch depths tested, showing the importance of the effects of elastic recovery and interfacial shear stress. The model was further verified for the case of a pure aluminum sample and the native thin film coating of alumina that forms on the surface upon air exposure.

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