Chemical attack defects

The fluorescence pattern that grew from one metallization line to the next under low frequency excitation is believed to represent an aqueous pathway. Although the formation mechanism has not been identified, in light of the AC experiment, a chemical attack of the polymer leading to delamination at the interface may create an area for water to aggregate. The observed growth from one metallization line to another of opposite bias is consistent with chemical attack related to a local extreme in pH arising from an electrochemical reaction at a metallization defect. 

Graphite may be the thermodynamically most stable modification of carbon. StUl it is chemically attacked more easily than diamond due to its layered structure and the comparatively weak interaction between the graphene sheets. Altogether the graphite s reactivity toward many chemicals is rather low nevertheless. With chlorine, for example, it does not react at all under usual conditions, and even with fluorine reaction occurs only at more than -400 °C. Suitable performance yields the transparent, colorless carbon monofluoride CF (up to CF1.12 due to additional fluorine atoms at marginal positions and defects), a chemically very resistant... 

In fact, the rate of chemical attack and the rate of abrasive polishing of the colloidal silica need to be well matched, if the chemical attack is so fast compared to the abrasive character that the abrasive action cannot level the high spots left on the etched surface then pits will be left in the polished surface. If these cannot be smoothed out in the final polish, then they will represent defects in the finished wafer surface. 

Other types of defects related to chemical attack are Cu nodules or dendrites (DE) as exhibited in Figure 17.15(e). Previous works identify the DE as CuOx particulates formed after certain queue time post-CMP [19—21]. Galvanic corrosion is responsible for the formation of DE as shown in Figure 17.16 [19]. In the presence of wet slurry or... 

In most cases, the chemical properties of vitreous carbon are similar to those of the graphite crystal, reviewed in Ch. 3, Sec. 7. Since the material has low permeability, is essentially non-porous and free of surface defects, and can be made with very low impurities, its resistance to chemical attack is generally excellent and is one of its outstanding characteristics. In many instances, it is far more chemically resistant than other forms of carbon, such as molded or pyrolytic graphites. 

Yield tests have shown, on the one hand, the mechanism of surface degradation caused by the chemical attack or internal pressure and, on the other hand, the sweating defect that appears before failure [8, 9]. 

Enamel coatings usually consist of several layers in which the prime coating is applied for adhesion but does not have the chemical stability of the outer layers. With cathodic polarization at holidays, attack on the exposed prime coating is possible as the cathodically produced alkali causes the defects to increase in size. This particularly cannot be excluded in salt-rich media. 

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