Thin film characterization ellipsometry

Gas barrier properties of polymeric membranes are strongly dependent on thickness, making it critical to verify thickness measurement with multiple methods. Several techniques for obtaining film thickness were reviewed here to demonstrate the benefits and challenges associated with each. Although ellipsometry is a common technique for non-contact and non-destructive thin film characterization, the other methods are necessary to confirm the measured thickness. 

In the case of Langmuir monolayers, film thickness and index of refraction have not been given much attention. While several groups have measured A versus a, [143-145], calculations by Knoll and co-workers [146] call into question the ability of ellipsometry to unambiguously determine thickness and refractive index of a Langmuir monolayer. A small error in the chosen index of refraction produces a large error in thickness. A new microscopic imaging technique described in section IV-3E uses ellipsometric contrast but does not require absolute determination of thickness and refractive index. Ellipsometry is routinely used to successfully characterize thin films on solid supports as described in Sections X-7, XI-2, and XV-7. 

In the example shown in Fig. 7, a thin film of plasma-polymerized trimethylsilane had been deposited on cold-rolled steel as a pretreatment for improved adhesion and corrosion [30]. The film thickness was determined by ellipsometry to be 500 A. The composition was characterized by AES, XPS, and TOFSIMS. AES gave information on the bulk composition, surface enrichment, and interfacial oxide (Fig. 7b). Note that the C/Si ratio of the bulk of the film, after equilibrium sputtering conditions have been reached, is approximately 3, i.e., identical to that of the monomer from which the film was... 

Ellipsometry was originally developed specifically for the optical characterization of thin films. In principal therefore it is an ideal technique for charac-... 

Commonly used spectroscopic or analytical techniques for characterizing surfaces and coating layers on porous silicon are Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy, energy dispersive X-ray spectrometry, fluorescence spectroscopy, UV-Vis absorption/reflectance spectroscopy, thin film optical interference spectroscopy, impedance spectroscopy, optical microscopy, scanning electron microscopy, transmission electron microscopy, atomic force microscopy, ellipsometry, nitrogen adsorption/desorp-tion analysis, and water contact angle. 

Marsillac S, Sestak MN, Li J, Collins RW (2011) Spectroscopic ellipsometry. In Abou-Ras D, Kirchartz T, Rau U (eds) Advanced characterization techniques for thin film solar cells. Wiley-VCH, Weinheim, Chap 6, p 125... 

Ellipsometry is a high-precision optical characterization technique, the potential of which has not yet been sufficiently exploited in polymer science. It is a rapid and nondestructive experimental method for the analysis of surfaces and thin films. Besides the determination of film thickness with high sensitivity ( 0.1 nm), optical parameters related to material properties can also be evaluated [1]. The facts that ellipsometric measurements can be performed under any ambient conditions, and require no special sample preparation procedures, provide a definite advantage over other surface science techniques [2—4]. 

Hilfiker, J.N. (2011) In situ spectroscopic ellipsometry (SE) for characterization of thin film growth, in In Situ Characterization of Thin Film Growth (eds G. Koster and G. Rijnders), Woodhead Publishers, Cambridge, pp. 99-151. 

Other techniques that are used for surface characterization of polymer/HAp nanomaterials include ellipsometry which enables measurement of the thicknesses and composition of the layers in a multilayer thin film, especially if the experiment is performed over a range of wavelengths of the incident beam or a range of angles of incidence. In addition, ellipsometry is frequently applied to characterization of the thickness of proteins adsorbed on gradient surfaces [309],... 

One of the reports of dielectric functions of ZnO is that by Ashkenov et al. [135] who characterized thin films grown by pulsed laser deposition on c-plane sapphire and a single-crystalline sample grown by seeded chemical vapor transport method. The static dielectric constant was obtained from infrared spectroscopic ellipsometry measurements. The high-frequency dielectric constant was calculated through the Lyddane-Sachs-Teller (LST) relation, (Equation 1.31), using the static constant and the TO- and LO-phonon mode frequencies. The results are compared with the data from some of the previous studies in Table 3.8. 

Thin films on substrates provide a characterization challenge the whole system must be measured at once and substrate properties can easily mask those of the thin film. Other techniques have been employed to study these complex systems. Fryer et al. used local thermal analysis to probe polystyrene (PS) and PMMA on two different substrates. These results were comparable to ellipsometry values establishing local thermal analysis as an effective technique. Again, PS did not have a favorable interaction with the polar or nonpolar silicon surface and both PS systems showed a decrease in Tg with decreasing film thickness. PMMA showed similar behavior on the nonpolar surface. However, on the polar substrate the Tg increased as the PMMA films became thinner. Porter saw similar effects measuring PMMA on silica with a differential scanning... 

FIGURE 12.20 Standard silicon solar cell cross section. A, cover glass B, antireflective coating with contacts C, N-type silicon D, P-type silicon E, back contact. (From Characterization of Photovoltaic Devices by Spectroscopic Ellipsometry Using Equipment From Horiba Scientific, Horiba Scientific—Thin Films Division, Date Added April 20, 2007 I Updated June 11, 2013.)... 

Characterization of Photovoltaic Devices by Spectroscopic Ellipsometry Using Equipment From Horiba Scientific, Horiba Scientific— Thin Films Division, Date Added April 20, 2007 I Updated June 11, 2013. 

Rapid advances in computer technolc during the past decades have made possible the automation of ellipsometry instruments and data analysis [5]. Developments in spectroscopic ellipsometry, based on rapid data collection, can offer the real-time characterization of dynamic behavior of thin layers [33,34], including the evaluation of structural changes, phase separation, or the swelling of polymer films [17]. 

Laviron, T. Noguchi, Infrared spectroscopac ellipsometry applied to the characterization of ultra shallow junction on silicon and SOI, Thin Solid Films, 455-456 (2004) 150-156. 

Baker, E.A., Rittigstein, P., Torkelson, J.M., Roth, C.B. Streamlined ellipsometry procedure for characterizing physical aging rates of thin polymer films. J. Polym. Sci. Part B Polym. Phys. 47, 2509 (2009)... 

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