Optical microscopic pattern

Fig. 14. A sample of a lamellar liquid crystal between crosses polarized in an optical microscope gives a pattern of "oily streaks" and Maltese crosses (a) while the Hquid crystal consisting of an array of cylinders shows the characteristic sectional pattern (b).

An optical microscope photograph taken at 200 X magnification using polarizing filters is shown in Fig. 21. The spherulites show a characteristic Maltese cross pattern produced by the interaction of the polarized light with the... 

Etch times were investigated for aluminum and SU8 sacrificial cores patterned on silicon. Samples were periodically removed from the acid etch solution, and the amount of sacrificial core that was removed was measured using an optical microscope. We found that the etch length as a function of time follows the equation... 

When the step separation is wide enough, typical spiral step patterns observable by optical microscopy may appear, but if the separation becomes narrower than the resolution power of the optical microscope, the spirals appear in the forms of polygonal pyramids or conical growth hillocks. Even if spiral patterns are not directly observable, we may assume that these growth hillocks are formed by the spiral growth mechanism. Examples representing the two cases are compared in Fig. 5.8. 

Fig. 10.33. Registered PDMS/Mylar stamp on Substrate using lock and key mechanism A, B, C and D are optical microscope images of matched relief features of stamp on photoresist patterns of substrate a, b, c, and d are optical microscope images of matched keys of stamp on to locks on substrate.

Figure 9.13 shows examples of ablation patterns taken in a single shot and observed by (a) an optical microscope and (b) an atomic force microscope (AFM). The diameter of the circular hole is approximately 2 pm, which agrees well with the Ce YAG scintillator experiment. 

Fig. 4.11. Left (a) Optical microscope image of an OLED working at a luminance of 100 cd/m2 under water vapor atmosphere. Non-emitting dark spots can be seen clearly, (b) SEM image of the bubbles formed on the aluminum cathode in the dark spot area, (c) Correlation between dark spot growths (taken from the increase in diameter) and total current density [110]. Right (a) Shown here is the random pattern of carbonized areas on the surface of the cathode after operation, shown in wide field, (b) At higher resolution, the structure of one of these areas becomes more apparent, (c) and (d) show nanoscale views of carbonized areas with the extrusion of the polymer through the cathode and the resulting void underneath [111].

Optical Microscopy The resist pattern was examined under an optical microscope normally at the stage shortly after the development. The Nikon Optiphot microscope was supplied by Nikon Instrument Division of Garden City, New York. 

FIGURE 12.21 Optical microscope picture of wafer surface with a patterned nitride overcoat after planarization and nitride strip. Notice the complete elimination of dishing (color uniformity in the green isolation area). 

An optical microscope is a very useful tool for defect observation [64]. The resolution is limited to about 180 nm with a normal white light or down to about 80 nm with a deep UV (DUV) light source and a DUV camera. Therefore, optical microscopes are clearly inferior compared to electron microscopes in resolving the small features printed on the patterned wafers. This is a significant limitation. However, it is important to point out that, in many cases, what matters most is to see the defects not the features where the defects are located. In addition, optical microscopes can observe certain things that SEM cannot Indeed, an optical microscope allows the observation of color variation that qualitatively indicates thickness variation. It also has the... 

The major feature of polymers that have been bulk crystallized under quiescent conditions are polycrystalline structures called sphemlites. These are roughly spherical supercrystalline structures which exhibit Maltese cross-extinction patterns when examined under polarized light in an optical microscope. Spheruliies are characteristic of semicrystalline polymers and are also observed in low-molecular-weight materials that have been crystallized from viscous media. Sphemlites are aggregates of lamellar crystallites. They are not single crystals and include some... 

Sanidine is monoclinic (space group C2/m), and there is complete disorder in the occupation of the tetrahedral (T) sites by the A1 and Si atoms. Over geological time, ordering takes place. In low (or maximum) micro-cline, the ordering is complete (all A1 in TiO sites), and the symmetry is reduced to triclinic (CT). There are four main orientational variants in this structure two orientations related by the albite twin law (rotation of 180° about b ) and two orientations related by the pericline twin law (rotation of 180° about b). The composition planes of these two twins are, respectively, (010) and the rhombic section which is parallel to b and approximately normal to (001). Thus, the characteristic cross-hatched pattern observed in (001) sections between crossed-polarizers in the optical microscope has, for many years, been simply interpreted as intersecting sets of albite and pericline twin lamellae formed at the monoclinic-to-triclinic transformation. However, TEM observations indicate that this model is too simple. Because these observations, collectively, also constitute an excellent example of the application of the principal modes of operation of TEM to a specific mineralogical problem, we discuss them in some detail. 

Fig. lla and b. Cholesteric liquid crystalline structure of PBLG in m-cresol a, striation patterns observed under a polarizing microscope b, optical diffraction pattern with a beam from the He—Ne gas laser. Concentration is 17% volume fraction of polymer, and cell thickness is 2 mm... 

The question at this stage is How does one derive the atomic arrangement in a crystal, such as that of sodium chloride or potassium chloride, from the intensities in their respective diffraction patterns The answer is that the diffracted X-ray beams, which have amplitudes represented by the square roots of their measured intensities, must be recombined in a manner similar to that achieved by a lens in an optical microscope. This recombination is done by a mathematical calculation called a Fourier synthesis. The recombination cannot be done directly because the phase relations among the different diffracted X-ray beams usually cannot be measured. If the phases, however, can be estimated by one of the methods described in Chapter 8, an approximate image of the arrangement of atoms in the crystal can be obtained. 

---