Ultra-thin film

Si(Li) detectors without Be windows ("windowless") or with thin metal-coated polymer films (Ultra-Thin Window UTW) have become an important peripheral to modern-day AEMs for the qualitative detection of elements with 5vacuum requirements because the removal of the Be window increases the probability of detector contamination (from the specimen or column environment) and consequent degradation of performance [12]. Windowless and UTW Si(Li) detectors are commonly installed with additional airlock mechanisms and only on instruments with acceptable levels of vacuum cleanliness. Thus, design constraints on modern AEMs preclude placement of the UTW detector close to the sample. In addition, loss of detection efficiency at low energies (light-element K-lines with the L-lines of transition metals all conspire to limit windowless or UTW EDS analysis of minerals to a qualitative basis only. 

The mechanism of rupture depends upon the thickness of the lamella film. Ultra-thin films, with thicknesses in the 1-20 nm range, are believed to rupture due to the amplification of thermally-generated surface waves [28-30]. However, studies by Artavia and Macosko [31] and Akabori and Fujimoto [32] demonstrated that most of the ruptured lamellae in a PU foam are in the 200-1000 nm thickness range. Therefore, it is assumed here that the mechanism of rupture of these thicker films is most important when considering PU foam. 

Base dielectrics Conductor materials Copper-clad laminates Coverlay Adhesive sheets Polyimide films (Kapton K, E, EN, KJ Apical NP, FP Upilex S) Liquid polyimide resin, PEN film, LCP films Ultra-thin copper foils, sputtered copper, copper alloys, stainless steel foil Adhesiveless laminates (cast type, sputtered/plated type, laminated type) Photoimageable coverlay (PIC) (dry film type, liquid ink type) Hot-melt polyimide film... 

Ellipsometry in the vacuum UV (< 190 nm) enables the analysis of materials for the next generation lithography (photoresist, AR coatings) at the latest exposure wavelengths (157 nm and 193 nm). The short wavelengths increase the sensitivity of ellipsometric measurements of ultra thin films (<10 nm). New prospects are expected for the analysis of thin metallic and dielectric layers. 

It will be clear that L-B films are intrinsically linked to self-assembly of molecules, and this has been recognised in the title of a recent overview book (Ulman 1991), An Introduction to Ultra thin Organic Films from Langnmir-Blodgett to Self-Assembly An Overview. 

As discussed above, it is desirable to use large, almost grazing angles of incidence in RAIR spectroscopy in order to maximize the sensitivity of the technique to ultra-thin films. Using such large angles of incidence usually requires the substrates to be at least a few centimeters in length. This severely limits the spatial... 

The study of ultra-thin Fe thin films on Cu(OOl) substrate has attracted a lot of interest in the past. This is due to the abundance of interesting phenomena associated with this system. Due to the small epitaxial misfit a good layer by layer growth is expected stabilizing the film in a structure related to the fee phase of bulk Fe which is otherwise unstable at low temperatures It also become a test system for magnetic measurements. 

Figure 5-19. N(ls) XPS core level spectra of emeraldine base adsorbed on ITO. The top most spectrum corresponds to ultra-thin Him (in the mono layer regime) while the bottom spectrum corresponds to thick film.

Figure 5-21. N(ls) core level spectra of the iiniim model compound PC20X adsorbed on ITO. The upper curve corresponds to a thick film, the central curve to an intermediate thick film, and the lower curve to an ultra thin Him, essentially a mono-layer in thickness. The bold solid lines are the filled curves and the thin solid and dolled lines are the Gaussian peak components lor physisorbed and chemisorbed PC20X, respectively.

Ultra-thin films of polyanilinc may be spin-coaled onto the ITO substrates. By studying thick films, spectra of the polymer itself are obtained. As the thickness of the polymer overlayer is reduced, some of the subtle details of the interface between the very thinnest possible polymer layer (essentially a mono-layer, in the... 

While thin polymer films may be very smooth and homogeneous, the chain conformation may be largely distorted due to the influence of the interfaces. Since the size of the polymer molecules is comparable to the film thickness those effects may play a significant role with ultra-thin polymer films. Several recent theoretical treatments are available [136-144,127,128] based on Monte Carlo [137-141,127, 128], molecular dynamics [142], variable density [143], cooperative motion [144], and bond fluctuation [136] model calculations. The distortion of the chain conformation near the interface, the segment orientation distribution, end distribution etc. are calculated as a function of film thickness and distance from the surface. In the limit of two-dimensional systems chains segregate and specific power laws are predicted [136, 137]. In 2D-blends of polymers a particular microdomain morphology may be expected [139]. Experiments on polymers in this area are presently, however, not available on a molecular level. Indications of order on an... 

Westlake, F. J., "An Interferometric Study of Ultra-Thin Fluid Films," Ph.D. thesis, Univ. of London, 1970. 

Subsequently, a lubrication theory considering the solvation force is deduced accordingly in such ultra-thin film lubrication. 

Pressure between solid walls separated by ultra-thin liquid film is then expressed as follows ... 

Tichy, J. A., Ultra Thin Film Structured Tribology," Proc. 1 st Int. Symp. Tribol. 19-23 Oct, 1993, Beijing, pp. 48-57. 

Wang, H. and Hu, Y. Z., Molecular Dynamics Study on Interfacial Slip Phenomenon of Ultra-thin Lubricating Films," presented 2XITC2000, Nagasaki, Japan, Oct. 2000. 

Meanwhile, study on ultra-thin film gas lubrication problems has become one of the most attractive subjects in the held of tribology during the past three decades. 

Since the middle of the 1990s, another computation method, direct simulation Monte Carlo (DSMC), has been employed in analysis of ultra-thin film gas lubrication problems [13-15]. DSMC is a particle-based simulation scheme suitable to treat rarefied gas flow problems. It was introduced by Bird [16] in the 1970s. It has been proven that a DSMC solution is an equivalent solution of the Boltzmann equation, and the method has been effectively used to solve gas flow problems in aerospace engineering. However, a disadvantageous feature of DSMC is heavy time consumption in computing, compared with the approach by solving the slip-flow or F-K models. This limits its application to two- or three-dimensional gas flow problems in microscale. In the... 

Modified Reynolds Equations for Ultra-Thin Film Gas Lubrication... 

Mitsuya, Y., Modified Reynolds Equation for Ultra-thin Film Gas Lubrication Using 1.5-order Slip-Flow Model and Considering Surface Accommodation Coefficient," ASME J. Tri- [25] fcoZ.,Vol. 115,1993, pp. 289-294. 

Huang, P., Niu, R. J., and Hu, H. H., A New Numerical Method to Solve Modified Reynolds Equation for Magnetic [31] Head/Disk Working in Ultra Thin Gas Films, Sci. China,... 

Wu, J. K. and Chen, H. X., Operator Splitting Method to Calculate Pressure of Ultra-Thin Gas Film of Magnetic Head/ Disk," Tribology, Vol. 23, No. 5, 2003, pp. 402-405 (in Chinese). 

Li, W. L. and Weng, C. I., "Modified Average Reynolds Equation for Ultra-Thin Film Gas Lubrication Considering Roughness Orientations at Arbitrary Knudsen Numbers, Wear, Vol. 209,1997,pp. 292-230. 

This chapter describes a DML model proposed by the authors, based on the expectation that the Reynolds equation at the ultra-thin film limit would yield the same solutions as those from the elastic contact analysis. A unified equation system is therefore applied to the entire domain, which gives rise to a stable and robust numerical procedure, capable of predicting the tribological performance of the system through the entire process of transition from full-film to boundary lubrication. 

The biggest challenge to produce an ultra-thin (about 1 nm) overcoat is to make the coating free of pin-holes while maintaining the durability and tribological properties. In an HDD system, pin-holes can cause much more contaminants from all sources, such as outgas compounds from polymeric foam components, pressure sensitive adhesives, ionic residues from improperly cleaned components and ambient pollutants, which can be detrimental to the tribology and durability of the HDD. Therefore, efforts have been made mainly on the improvement of carbon film [4-7]. 

In ultra-thin films, on the other hand, the mechanism of spreading is dominated by surface diffusion so that the diffusion coefficients can be written as... 

---