Argon cluster size-dependence of sputtering yields of polymers: molecular weights and the universal equation

Seah, M. P.

doi:10.1002/sia.5656

Cited by 10 publications

(19 citation statements)

References 15 publications

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“…This is most readily seen in the data of Cristaudo et al [20], and Seah [21], where the yield rises as the molecular weight and, hence, T M , both fall. In Figure 4b, the sputtering transition temperature, T T , is plotted as a function of T M where these temperatures are in Kelvin.…”

Section: Sputtering Yieldsmentioning

confidence: 82%

“…Residual gas analysis showed enhanced methylmethacrylate monomer present [19] that more or less correlated with the enhanced sputtering rate. Recent studies of the effect of the reduction in molecular weight on sputter yields confirm, in detail, that strong enhancement [20,21] of the sputtering yield will occur for the monomer. In a similar manner, Möllers et al [22], in a study of PMMA sputtered by 10 keV C 60 + , find that the depth resolution for 200 nm thick films was better at elevated and reduced temperatures and, again, worst at 20°C.…”

Section: Introductionmentioning

confidence: 93%

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Systematic Temperature Effects in the Argon Cluster Ion Sputter Depth Profiling of Organic Materials Using Secondary Ion Mass Spectrometry

Seah

Havelund

Gilmore

2016

J. Am. Soc. Mass Spectrom.

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Abstract. A study is presented of the effects of sample temperature on the sputter depth profiling of two organic materials, NPB (N,N′-Di(1-naphthyl)-N,N′-diphenyl-(1,1′-biphenyl)-4,4′-diamine) and Irganox 1010, using a 5 keV Ar 2000 + cluster ion beam and analysis by secondary ion mass spectrometry. It is shown that at low temperatures, the yields increase slowly with temperature in accordance with the Universal Sputtering Yield equation where the energy term is now modified by Trouton's rule. This occurs up to a transition temperature, T T , which is, in turn, approximately 0.8T M , where T M is the sample melting temperature in Kelvin. For NPB and Irganox 1010, these transition temperatures are close to 15°C and 0°C, respectively. Above this temperature, the rate of increase of the sputtering yield rises by an order of magnitude. During sputtering, the depth resolution also changes with temperature with a very small change occurring below T T . At higher temperatures, the depth resolution improves but then rapidly degrades, possibly as a result first of local crater surface diffusion and then of bulk inter-diffusion. The secondary ion spectra also change with temperature with the intensities of the molecular entities increasing least. This agrees with a model in which the molecular entities arise near the crater rim. It is recommended that for consistent results, measurements for organic materials are always made at temperatures significantly below T T or 0.8 T M , and this is generally below room temperature.

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Section: Sputtering Yieldsmentioning

confidence: 82%

Section: Introductionmentioning

confidence: 93%

Systematic Temperature Effects in the Argon Cluster Ion Sputter Depth Profiling of Organic Materials Using Secondary Ion Mass Spectrometry

Seah

Havelund

Gilmore

2016

J. Am. Soc. Mass Spectrom.

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“…5 During these studies, an interesting observation was made that the scatter in data points in the dependence of the sputtering yield Y against the incident kinetic cluster energy E for different clusters sizes can be reduced to nearly a curve, if the variables Y and E are presented in quantities scaled by the number of cluster atoms n, that is, Y/n vs E/n. 6 This observation was then confirmed by numerous studies, both experimental 7,8 and computational, [9][10][11] for various solids (Ag, Si, SiO 2 , Irganox, and polystyrene) and the cluster beams (C 60 , Ar n ). The results for atomic and molecular solids, however, separate into two distinct regions on a Y/n vs E/n plot.…”

Section: Introductionmentioning

confidence: 57%

“…The results for atomic and molecular solids, however, separate into two distinct regions on a Y/n vs E/n plot. 8 The observed feature suggests that a universal description of the cluster sputtering process might be possible if appropriate scaling of the variables is used, although the physical basis of this phenomenon was not clear.…”

Section: Introductionmentioning

confidence: 99%

Physical basis of energy per cluster atom in the universal concept of sputtering

Paruch

Postawa

Garrison

2016

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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High-energy ions and atoms sputtered and reflected from a magnetron source for deposition of magnetic thin films J.The interpretation of the variables, scaled by the number of projectile cluster atoms n, in the universal relation of the sputtering yield Y versus incident energy E, that is, Y/n vs E/n, is not necessarily obvious. Following on previous works, the objective of this study is to elucidate the physical basis of the energy per atom variable E/n. The authors employ molecular dynamics simulations of Ar n cluster bombardment of Ag(111) metal samples for this study. The authors find that the energy per cluster atom quantity E/n is responsible for the fraction of the initial energy that is deposited in the solid, rather than energy per cluster mass E/m. The results show that even though there is an average loss of the energy for a cluster, each cluster atom loses a different fraction of its initial energy, thus yielding a distribution of energy loss by individual atoms. The analysis of these distributions indicates that the energy deposition process is more effective for clusters with higher E/n when compared to the clusters with lower E/n. This conclusion is supported by a visual analysis of the cluster bombardment event. The cluster atoms that lose most of their initial energy are those which split off from the cluster and penetrate into the bulk of the solid. Conversely, the atoms of the clusters with low E/n keep together during the interaction with the solid, and eventually reflect into the vacuum taking away a portion of the initial kinetic energy. In addition, the simulations indicate that the clusters of different sizes have the same distribution of energy loss for individual atoms if they have the same E/n, in other words, if the initial energy E is proportional to the cluster size n.

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“…14 These involved energies from 2.5 to 40 keV and cluster sizes from 100 to 10000 atoms. 16 Cholesterol is one of the most easily detectable biomolecules in tissue by SIMS. It was found that A was related to U, the energy per atom, excluding hydrogen, to remove the fragment from the solid.…”

Section: Introductionmentioning

confidence: 99%

Determination of the sputtering yield of cholesterol using Ar_n⁺and C₆₀⁺⁽⁺⁾cluster ions

Rakowska

Seah

Vorng

et al. 2016

Analyst

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The sputtering yield of cholesterol films on silicon wafers is measured using Arn(+) and C60(+(+)) ions in popular energy (E) and cluster size (n) ranges. It is shown that the C60(+(+)) ions form a surface layer that stabilizes the film so that a well-behaved profile is obtained. On the other hand, the Arn(+) gas clusters leave the material very clean but, at room temperature, the layer readily restructures into molecular bilayers, so that, although a useful measure may be made of the sputtering yield, the profiles become much more complex. This restructuring does not occur at room temperature normally but results from the actions of the beams in the sputtering process for profiling in secondary ion mass spectrometry. Better profiles may be made by reducing the sample temperature to -100 °C. This is likely to be necessary for many lower molecular weight materials (below 1000 Da) to avoid the movement of molecules. Measurements for cholesterol films on 37 nm of amiodarone on silicon are even better behaved and show the same sputtering yields at room temperature as those films directly on silicon at -100 °C. The yields for both C60(+(+)) and Arn(+) fit the Universal Equation to a standard deviation of 11%.

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Argon cluster size-dependence of sputtering yields of polymers: molecular weights and the universal equation

Cited by 10 publications

References 15 publications

Systematic Temperature Effects in the Argon Cluster Ion Sputter Depth Profiling of Organic Materials Using Secondary Ion Mass Spectrometry

Systematic Temperature Effects in the Argon Cluster Ion Sputter Depth Profiling of Organic Materials Using Secondary Ion Mass Spectrometry

Physical basis of energy per cluster atom in the universal concept of sputtering

Determination of the sputtering yield of cholesterol using Ar_n⁺and C₆₀⁺⁽⁺⁾cluster ions

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Argon cluster size-dependence of sputtering yields of polymers: molecular weights and the universal equation

Cited by 10 publications

References 15 publications

Systematic Temperature Effects in the Argon Cluster Ion Sputter Depth Profiling of Organic Materials Using Secondary Ion Mass Spectrometry

Systematic Temperature Effects in the Argon Cluster Ion Sputter Depth Profiling of Organic Materials Using Secondary Ion Mass Spectrometry

Physical basis of energy per cluster atom in the universal concept of sputtering

Determination of the sputtering yield of cholesterol using Arn+and C60+(+)cluster ions

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Product

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Determination of the sputtering yield of cholesterol using Ar_n⁺and C₆₀⁺⁽⁺⁾cluster ions