Topographical variations

Among numerous planarization technologies, CMP provides a global planarization of topography with a low post-planarization slope [97,98]. It can also dramatically reduce topographical variations to a degree not possible with any other planarizing process [97,99,100]. 

Oxidizer concentration is also one of the important factors in determining material removal rate, and it was found to increase with the oxidizer concentration [43,106]. With the increase of oxidizer concentration, both Wa and Ra decrease at first and then increase, the optimum concentration is 1 wt %, and relative low oxidizer concentration helps to get lower Wa and Ra values as shown in Figs. 36(a) and 36(b). High concentration of oxidizer may result in excessive corrosive wear, which will lead to the increasing of topographical variations. 

FIGURE 2.4. Left 8x8 pm AFM image of 2-D patterned F8 F8BT blend film. Right Line scan of part of the film shown left. The topographical variations at the edges of the patterned regions can clearly be seen. 

Rademacher J, Caviness VS, Steinmetz H, Galaburda AM. 1993. Topographical variation of the human primary cortices Implications for neuroimaging, brain mapping and neurobiology. Cerebral Cortex 3 313-329. 

Fig. 4 shows two STM images of the surface structure of a carbon black. The sample exhibits a specific surface area, determined by N2 adsorption at 77 K, of 15.3 m g, which is almost coincident with its geometric area (16.9 m g ). Therefore, this is a nonporous carbon and its STM images should be expected to differ from those of the ACFs. As a matter of fact, this is what can be observed in Fig. 4. First, it is noted that the carbon black does not display any mesoporosity (Fig. 4a) such as that of the AFCs (Fig. 2). Second, at the micropore scale the carbon black porosity is also very poorly developed (Fig. 4b) in comparison with the pore development of ACFs (e.g.. Fig. 3a). In the former case (Fig. 4b), altough some trenches are also present, they are very shallow and, consequently, are simple topographic variations of a smooth surface and cannot be considered as pores penetrating deeply into the material as in Fig. 3a. Also, pores of the type shown in Fig. 3b for the ACFs were not normally seen on the carbon black surface. Hence, all these observations agree with the lack of adsorption capabilities of this material.

Macroroughness is a measure of the surface topographic variations at a scale much larger than the atomic scale. The macroroughness of a silicon surface treated in a solution can be determined by numerous factors associated with the initial surface condition (cleanness and roughness), the crystal orientation, solution composition, treadnent procedure, and time. 

C6. Christophers, E., and Petzoldt, V., Epidermal cell replacement Topographical variations in albino guinea pig skin. Brit. J. Dermatol. 81, 598-602 (1969). 

There is topographic variation in the density of scleral emissaries, with the temporal sclera being most free of these vascular conduits (20). The landscape of scleral thickness is quite varied. The mean thickness of human sclera is 0.53 mm at the limbus, 0.39 mm at the equator, and 0.9-1.0mm near the optic nerve (21). However, even these figures are subject to great variation, with equatorial thickness frequently below 0.1 mm. These factors would be important considerations in the placement of a transscleral drug delivery device. With a mean total surface area of 16.3 cm2, the sclera is an inviting portal for intraocular drug delivery. 

During glaciation the much higher glacially induced regional flow in both sections overshadows the local flow that is due to topographic variations. 

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