Thickness Measurements of Thin Perfluoropolyether Polymer Films on Silicon and Amorphous-Hydrogenated Carbon with X-Ray Reflectivity, ESCA and Optical Ellipsometry

Toney, Michael F.; Mate, C. Mathew; Leach, K. Amanda; Pocker, D. J.

doi:10.1006/jcis.2000.6752

Cited by 46 publications

(39 citation statements)

References 33 publications

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“…Thickness measurements of 5-35 Å thin dip-coated perfluoropolyether ͑PFPE͒ polymer films on silicon substrate and silicon substrates with 120 Å a-C:H coating were carried out by Toney et al using XRR and SE. 8 A linear least-squares fit with a slope of around 1.0 was found for PFPE films irrespective of the substrate. However, the value of the intercept for the least-squares fit line was found to be 5.3± 0.9 Å and 2.7± 1 Å for films deposited on silicon substrates and a-C : H, respectively.…”

Section: Introductionmentioning

confidence: 85%

“…They had attributed the nonzero intercepts to the adsorption of hydrocarbon contaminants on the native silicon oxide layer of the silicon substrates for the a-C : H surfaces. 8 In a recent attempt at metrological characterization of nanometer film thickness standards for XRR and SE applications using 6-1000 nm SiO 2 layer on Si substrate, Hasche et al 9 had reported higher values of thickness measured using SE than XRR. They had a͒ Author to whom correspondence should be addressed; electronic mail: skohli@lamar.colostate.edu also found that the XRR measurements were consistent with the thickness estimation by scanning force microscopy.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of nanometer-thick films by x-ray reflectivity and spectroscopic ellipsometry

Kohli

Rithner

Dorhout

et al. 2005

Review of Scientific Instruments

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Films of tantalum pentoxide ͑Ta 2 O 5 ͒ with thickness of 10-100 nm were deposited on Si wafers and have been compared using spectroscopic ellipsometry ͑SE͒ and x-ray reflectivity ͑XRR͒. ͑Ta 2 O 5 ͒ was chosen for comparison work based on various criterions for material selection outlined in this article. Measurements were performed at six positions across the sample area to take into consideration thickness and composition inhomogeneity. SE and XRR fitted curves required the incorporation of a linearly graded interface layer. SE systematically measured higher values of film thickness as compared to XRR. A linear equation was established between the thickness measurements using SE and XRR. The slope of the linear equation established was found to be 1.02± 0.01. However, the intercepts were found to be 1.7± 0.2 and 2.6± 0.3 when the interface was excluded and included, respectively. These differences in the values of intercepts were attributed to the uncertainties in the determination of the interface layer.

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Section: Introductionmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

Comparison of nanometer-thick films by x-ray reflectivity and spectroscopic ellipsometry

Kohli

Rithner

Dorhout

et al. 2005

Review of Scientific Instruments

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“…As most of the experimental details of our X-ray reflectivity results and sample preparation have been discussed in earlier papers [4], [6], we describe them only briefly: In specular X-ray reflectivity, the reflected X-ray intensity is measured as a function of incidence angle and analyzed using a multilayer model incorporating several parameters-thickness and density of the lubricant film and roughness of the lubricant-air and the substrate-lubricant interfaces-that are varied to produce the best fit to the data. From this modeling, the functional form that best fits the density profile of the lubricant-air interface is an error function, implying a Gaussian distribution of surface heights.…”

Section: Resultsmentioning

confidence: 99%

“…1 shows an example of the density profiles fitted to the X-ray reflectivity data for Zdol on a carbon overcoat. The Zdol profile exhibits a dip in density at the Zdol-carbon interface due to the adsorption of a hydrocarbon layer between the Zdol film and the carbon overcoat [6]. The Zdol-air interface is narrower than for the bare carbon surface, due to the surface tension trying to pull the liquid surface flat, but still has a finite width due to roughening by capillary waves.…”

Section: Resultsmentioning

confidence: 99%

Roughness of thin perfluoropolyether lubricant films: influence on disk drive technology

2001

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Abstract-In disk drive technology, lubricant thickness and roughness are important, but often overlooked, contributors to slider-disk spacing. In this paper, we use X-ray reflectivity to measure the thickness and lubricant-air roughness of a perfluoropolyether lubricant (Fomblin Zdol) on silicon wafers and carbon overcoats. For Zdol on smooth silicon, the roughness increases with increasing lubricant thickness consistent with capillary wave roughening. For Zdol on the rougher surface of amorphous hydrogenated carbon, the lubricant smoothes to a value limited by the capillary wave roughening. We show that the lubricant density above the surface does not reach the density of air until approximately 3 away from the average lubricant thickness. This lubricant-air interface width contributes substantially to current and future slider-disk spacings.

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“…In comparison with the bonded layer of the PFPE by dip-coating, the bonded layer made by the vacuum vapor deposition will be similar to the PFPE of monolayer. Based on the results of the XPS measurements, the thicknesses, h, of the PFPE film fixed on the DLC surface were calculated using the following equation 12) : where λ is the mean free path of the carbon atom, and I PFPE and I DLC are the area intensities of the PFPE and DLC peaks determined from the XPS measurements, respectively. We must note that when the film thickness is less than a monolayer thickness, h max , the ratio of the surface coverage, θ, related to the PFPE molecules covering with the DLC surface can be denoted, h/h max because the XPS measurement is an optical analysis and the results indicate the mean value that depended on the X-ray spot area.…”

Section: Xps Measurementsmentioning

confidence: 99%

Effect of Heat Treatment Temperature on PFPE Molecules Bonded on DLC Surface

et al. 2008

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Based on the demand of extremely increased area density for magnetic data storage, the contact recording systems have been proposed, in which stronger and thinner hard coatings and lubricant films for the head disk interface (HDI) are desired. In this study, two lubrication methods, i.e., the vacuum vapor deposition and dip-coating methods are evaluated and compared in order to satisfy the demands from the HDI development. Perfluoropolyether (PFPE) is applied to the diamond-like carbon (DLC) surface. The advantage of the vacuum vapor deposition is to prevent contamination of the DLC surface from the atmosphere because of no exposed samples to the atmosphere. In contrast, the advantage of dip-coating method is to thicken the bonded layer of the PFPE by heat treatment. We discuss the adsorption mechanism between the PFPE molecules and DLC surface for each method. In addition, a simple reaction model based on the Arrhenius equation is developed and compared to the experimental results. We concluded that the reaction will be dominated by covalent bonds and hydrogen bonding. Furthermore, the reaction model can well express the experimental results. The remarkable destruction of the DLC film by the heat treatment are not seen in the samples heat treated at a temperature from 353 to 423 K while the remarkable destruction are seen in the samples treated from 423 to 473 K.

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Thickness Measurements of Thin Perfluoropolyether Polymer Films on Silicon and Amorphous-Hydrogenated Carbon with X-Ray Reflectivity, ESCA and Optical Ellipsometry

Cited by 46 publications

References 33 publications

Comparison of nanometer-thick films by x-ray reflectivity and spectroscopic ellipsometry

Comparison of nanometer-thick films by x-ray reflectivity and spectroscopic ellipsometry

Roughness of thin perfluoropolyether lubricant films: influence on disk drive technology

Effect of Heat Treatment Temperature on PFPE Molecules Bonded on DLC Surface

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