Ellipsometry film thickness

Ellipsometry — Film thickness — Polarized light Sample transparent 88, 91... 

Spectroscopic ellipsometry Film thickness, homogeneity, refractive index... 

Smith [113] studied the adsorption of n-pentane on mercury, determining both the surface tension change and the ellipsometric film thickness as a function of the equilibrium pentane pressure. F could then be calculated from the Gibbs equation in the form of Eq. ni-106, and from t. The agreement was excellent. Ellipsometry has also been used to determine the surface compositions of solutions [114,115], as well polymer adsorption at the solution-air interface [116]. 

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. 

Electrolyte adsorption on metals is important in electrochemistry [167,168]. One study reports the adsorption of various anions an Ag, Au, Rh, and Ni electrodes using ellipsometry. Adsorbed film thicknesses now also depend on applied potential. 

Dielectric constants of metals, semiconductors and insulators can be detennined from ellipsometry measurements [38, 39]. Since the dielectric constant can vary depending on the way in which a fihn is grown, the measurement of accurate film thicknesses relies on having accurate values of the dielectric constant. One connnon procedure for detennining dielectric constants is by using a Kramers-Kronig analysis of spectroscopic reflectance data [39]. This method suffers from the series-tennination error as well as the difficulty of making corrections for the presence of overlayer contaminants. The ellipsometry method is for the most part free of both these sources of error and thus yields the most accurate values to date [39]. 

Early work in ellipsometry focused on improving the technique, whereas attention now emphasizes applications to materials analysis. New uses continue to be found however, ellipsometry traditionally has been used to determine film thicknesses (in the rang 1-1000 nm), as well as optical constants. " Common systems are oxide and nitride films on silicon v ers, dielectric films deposited on optical sur ces, and multilayer semiconductor strucmres. 

Ellipsometry is a very powerfiil, simple, and totally nondestructive technique for determining optical constants, film thicknesses in multilayered systems, sur ce and... 

Ellipsometry is a method of measuring the film thickness, refractive index, and extinction coefficient of single films, layer stacks, and substrate materials with very high sensitivity. Rough surfaces, interfaces, material gradients and mixtures of different materials can be analyzed. 

The film thickness and retractive index were calculated using spectroscopic ellipsometry. X-ray photoelectron spectroscopy (XPS) was used for composition analysis. Auger electron spectroscopy (AES) and secondary ion mass spectroscopy (SIMS) was used to investigate the depth profiles of the film. 

Ellipsometry is used to study film growth on electrode surfaces. It is possible to study films at the partial monolayer level and all the way up to coverage of thicknesses of thousands of angstroms while doing electrochemical measnrements. To get nseful data it is important to determine A and j/ for the bare electrode snrface and the surface with a film. These data are processed to derive the film thickness, d, and the refractive index, h, which consists of a real (n) and imaginary part (k), h = n- ik. So ellipsometry gives information on the thickness and refractive index of snrface hlms. 

Thus, ellipsometry gives direct evidence for a model of the initial stages of polythiophene growth, disproving the conclusions based purely on coulo-metry. In the same paper, Hamnett and Hillman were able to obtain valuable and complementary information not just on the initial stages of the polymerisation but also on the mechanism of the subsequent nucleation and growth. The unique piece of information that the ellipsometer was able to extract, the changes in film thickness (in real time), when combined with coulometric data allowed a wealth of information to be deduced, e.g. with respect to the film composition, and ably showed the power of the technique. 

We report here, for the first time, that hydrodynamic forces can dramatically Increase the rate of desorption in polymer systems which are otherwise irreversibly adsorbed under no-flow conditions. Indeed, at high enough shear stresses, complete removal of the polymer is possible. The technique of ellipsometry is well suited for this problem as simultaneous measurements of both film thickness and adsorbance are possible during the flow process. 

Unlike the dependence of Aeff on film thickness alone (dNc /dd) that is sometimes used as a figure of merit for guided mode molecular sensors, 5m0d captures both the index and thickness dependence of the sensor response in a single parameter. While Dopt does not uniquely determine the film response for other optical techniques such as ellipsometry and reflectance difference, once d and n of the film are known, the optical thickness can be evaluated and comparisons are made between guided mode sensors and other techniques. 

Optical Exposure. Multicomponent LB films were prepared from solutions of novolac/PAC varying in concentration from 5-50 wt% PAC, and transferred at 2.5 -10 dyn/cm. The films were composed of 15 - 20 monolayers, with an average film thickness of 30 nm, as measured by ellipsometry. Exposures were performed with a Canon FP-141 4 1 stepper (primarily g-line exposure) at an exposure setting of 5.2 and with a fine line test reticle that contains line/space patterns from 20 to 1 pm (40 to 2 pm pitch). They then were then developed in 0.1 - 0.2 M KOH, depending on the PAC content The wafers received a 20 min 120°C post development bake to improve adhesion to the Cr. Finally, the Cr was etched in Cyantek CR-14 chromium etchant, and the resist and Cr images were examined by SEM. 

The monotonic increase of immobilized material vith the number of deposition cycles in the LbL technique is vhat allo vs control over film thickness on the nanometric scale. Eilm growth in LbL has been very well characterized by several complementary experimental techniques such as UV-visible spectroscopy [66, 67], quartz crystal microbalance (QCM) [68-70], X-ray [63] and neutron reflectometry [3], Fourier transform infrared spectroscopy (ETIR) [71], ellipsometry [68-70], cyclic voltammetry (CV) [67, 72], electrochemical impedance spectroscopy (EIS) [73], -potential [74] and so on. The complement of these techniques can be appreciated, for example, in the integrated charge in cyclic voltammetry experiments or the redox capacitance in EIS for redox PEMs The charge or redox capacitance is not necessarily that expected for the complete oxidation/reduction of all the redox-active groups that can be estimated by other techniques because of the experimental timescale and charge-transport limitations. 

Indirect evidence for solvent exchange can also be gained by in-situ ellipsometry. This technique can provide information of film thickness and optical properties as a function of the electrode potential. Figure 2.19 shows that the film swells during oxidation and shrinks during reduction, in agreement with EQCM measurements. A decrease in the refractive index from 1.42 to 1.38 during oxidation also supports the uptake of water, which has a refractive index of 1.33. 

Another real-time study of the reaction of M-FA films with H2S utilized ellip-sometry to monitor changes in film thickness concurrent with metal sulfide formation (53). The reactions appeared to reach equilibrium within the same period of time (within 2 h), with a change per monolayer of 0.2 nm for CdBe and 0.9 nm for both CuBe and ZnBe. Their ellipsometry results, in agreement with Peng et al. (66), also show a dependence of the reaction rate on the H2S pressure and the surface pressure at which the films were deposited. 

Fig. 21. Film thickness, determined by ellipsometry, vs layer number, measured on eight different multilayer samples [194]...

The absorption parameter, k, and the refractive index, n, were measured using variable angle spectrophotometric ellipsometry. The bottom antireflective coating of test solutions were spin coated onto primed silicon wafers and baked to get selected film thickness. The coated wafers were then measured using an ellipsometer to obtain and n values. 

Table 1 Values of interplanar spacing (d 100 ), film thickness (h), refractive index at 550 nm (n and n ), porosity (Vp), areal density of atoms ( 5 %), obtained for as-prepared and treated films by XRD, ellipsometry and RBS. (A as-prepared coating, B washed in ethanol at 298 K, C thermally treated at 430 K in air for 1 h, D thermally treated at 400 K in air for 1 h + sohxlet extraction in hot ethanol for lh, E thermally treated at 400 K for 1 h + ultrasonic extraction in ethanol for 30 min, F calcined at 620 K in air for 1 h (ramp at 10 K/ min)).

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