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Characterization of Films with Thickness Less than 10 nm by Sensitivity-Enhanced Atomic Force Acoustic Microscopy

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ABSTRACT

We present a method for characterizing ultrathin films using sensitivity-enhanced atomic force acoustic microscopy, where a concentrated-mass cantilever having a flat tip was used as a sensitive oscillator. Evaluation was aimed at 6-nm-thick and 10-nm-thick diamond-like carbon (DLC) films deposited, using different methods, on a hard disk for the effective Young's modulus defined as E/(1 - ν2), where E is the Young's modulus, and ν is the Poisson's ratio. The resonant frequency of the cantilever was affected not only by the film's elasticity but also by the substrate even at an indentation depth of about 0.6 nm. The substrate effect was removed by employing a theoretical formula on the indentation of a layered half-space, together with a hard disk without DLC coating. The moduli of the 6-nm-thick and 10-nm-thick DLC films were 392 and 345 GPa, respectively. The error analysis showed the standard deviation less than 5% in the moduli.

No MeSH data available.


The theoretical curve, which relates the resonant frequency to the effective Young's modulus of a sample, fitted to the experimental data (ο) for the reference. The error bars and the broken curves indicate the 95% confidence regions, namely twice the standard deviations.
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Figure 5: The theoretical curve, which relates the resonant frequency to the effective Young's modulus of a sample, fitted to the experimental data (ο) for the reference. The error bars and the broken curves indicate the 95% confidence regions, namely twice the standard deviations.

Mentions: Fitting Eq. 1 to the relationship between the resonant frequencies measured for reference and the effective Young's moduli listed in Table 1, we determined and , which are hard to measure or estimate directly. Figure 5 shows the least-squares fit obtained for the reference samples, which yielded A = 0.2496 ± 0.0061 (± 2σ) m/kg and = 184.6 ± 8.8 (± 2σ) GPa. The errors for A and correlate, and the error's sign is taken opposite to each other.


Characterization of Films with Thickness Less than 10 nm by Sensitivity-Enhanced Atomic Force Acoustic Microscopy
The theoretical curve, which relates the resonant frequency to the effective Young's modulus of a sample, fitted to the experimental data (ο) for the reference. The error bars and the broken curves indicate the 95% confidence regions, namely twice the standard deviations.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211417&req=5

Figure 5: The theoretical curve, which relates the resonant frequency to the effective Young's modulus of a sample, fitted to the experimental data (ο) for the reference. The error bars and the broken curves indicate the 95% confidence regions, namely twice the standard deviations.
Mentions: Fitting Eq. 1 to the relationship between the resonant frequencies measured for reference and the effective Young's moduli listed in Table 1, we determined and , which are hard to measure or estimate directly. Figure 5 shows the least-squares fit obtained for the reference samples, which yielded A = 0.2496 ± 0.0061 (± 2σ) m/kg and = 184.6 ± 8.8 (± 2σ) GPa. The errors for A and correlate, and the error's sign is taken opposite to each other.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

We present a method for characterizing ultrathin films using sensitivity-enhanced atomic force acoustic microscopy, where a concentrated-mass cantilever having a flat tip was used as a sensitive oscillator. Evaluation was aimed at 6-nm-thick and 10-nm-thick diamond-like carbon (DLC) films deposited, using different methods, on a hard disk for the effective Young's modulus defined as E/(1 - ν2), where E is the Young's modulus, and ν is the Poisson's ratio. The resonant frequency of the cantilever was affected not only by the film's elasticity but also by the substrate even at an indentation depth of about 0.6 nm. The substrate effect was removed by employing a theoretical formula on the indentation of a layered half-space, together with a hard disk without DLC coating. The moduli of the 6-nm-thick and 10-nm-thick DLC films were 392 and 345 GPa, respectively. The error analysis showed the standard deviation less than 5% in the moduli.

No MeSH data available.