Planarization Results

While polish rate is an important CMP metric that is relatively simple to monitor on a routine basis, the end goal of 

There are several factors that influence the planarizing ability of a CMP process, the most significant being the material properties of the polishing pad. From the discussion above, it is clear that hard, incompressible pads will achieve the best planarity. 

Normalized (with respect to pre-polish value A,) post-polish amplitude (of the square wave) as a function of the oxide removed. (From Ref. (24), (c) IEEE). 

There are several models discussed in the literature of CMP planarization of oxides. In this section we shall review two of these models that assume different modes of polishing, i.e., Hertzian indentation, by Wamock and fluid based wear, by Runnels. In addition to predicting planarity, these models gives good insight into the planarization mechanisms for CMP. However, these models are not necessarily the most accurate models. Other models include those by Burke et al., Yu et al, and Renteln and Coniff.  

if the shading factor for all points on the surface is calculated, the corresponding acceleration factor for each point may be determined by iteration. 

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Intramolecular heteroatom coordination may also influence the stabilities or structures of catenated tellurium compounds. For example, a rare example of a tritelluride, bis[2-(2-pyridyl)phenyl]tritelluride, is stabilized by a Te N contact of 2.55 The ditelluride (2-MeOCelFtCOTe) has an unusual planar structure. Although the C=0 Te interaction is longer (3.11 A) than the Me 0 contact (2.76 A), ab initio molecular orbital calculations indicate that the planarity results predominantly from the former intramolecular connection. 

The contact wear calculations appear to hold great promise for detailed feature-level simulation. The die-level simulation approaches discussed earlier can be viewed as approximations to the contact-wear approach that focus on the polish or planarization results over large length scales rather than over feature-length scales. 

The x-ray diffraction studies of the crystals of small peptides showed that the peptide bond is planar and trans (anti) (Figure 1.3). The same structure has been found for all peptide bonds in proteins, with a few rare exceptions. This planarity results from a considerable delocalization of the lone pair of electrons of the nitrogen onto the carbonyl oxygen. The C—N bond is consequently shortened, and it has double-bond character (equation 1.2). Twisting of the bond breaks it and loses the 75 to 90 kJ/mol (18 to 21 kcal/mol) of delocalization energy. 

The structure of crystalline PETP has been the subject of a detailed x-ray diffraction study [Daubeny, Bunn, and Brown (45)]. The results of this study are indicated in Fig. 21. The molecules are nearly planar and have a center of symmetry. A slight departure from planarity results from... 

Table S.l. Spheres at separations small compared with radius, Derjaguin transform from Lifshitz planar result, including retardation and all higher-order interactions...

Table C.2. Perpendicular cylinders, Rx = R2 = R, Derjaguin transform from full Lifshitz planar result, including retardation...

However, deviation from full planarity results in a pyramidal geometry which is dissymmetric when the three substituents are different. This is represented in diagrams Vb and Vc, the interconversion of the two forms occurring via the planar transition state Va. 

Fig. 12.17). The additional mask required for OE is a reversed copy of the STI mask with reduced structure size. RIE then removes the oxide in the exposed areas, stopping on the nitride. After RIE of the oxide and resist removal, the remaining nonplanarity at the periphery of the active areas is easily removed with CMP. The planarity results are excellent (Fig. 12.18), and unlike in the case of dummy insertion, planarity improvement is achieved without a negative impact on performance. The main disadvantage of the technique is the increased process complexity due to the additional lithography and RIE steps. 

Which optimization technique do you think gives the best planarity results ... 

The requirement for global planarity results as circuit dimensions are extended into the sub-0.5 pm regime. Lithography tools require high numerical aperture lenses to print the sub-0.5 pm... 

A single crystal X-ray structural analysis of the alkyne-containing product 6.26a revealed that the macrocycle adopts a near-planar conformation in the solid state (Figure 6.3.3). Deviation from planarity results, presumably, from the methyl-methyl steric interactions within the terpyrrolic subunit. The crystallographic data also served to support the contention that the macrocycle does indeed contain a true an alkyne-like (C-C=C-C) fragment. Such a bond isolation, although expected in the present instance, stands in contrast to what is seen in the case of Vogel s stretched porphycene precursor. In this latter instance cumulene-type (C = C = C = C) bond delocalization is observed. 

In previous work, we have formalized the notions of planarization length and planarization response function as key parameters that characterize a given CMP consumable set and process. Once extracted through experiments using carefully designed characterization mask sets, these parameters can be used to predict polish performance in CMP for arbitrary product layouts. The methodology has proven effective at predicting oxide interlevel dielectric planarization results. 

Given the difficulties encountered in the epoxidation of frans-olefins by Mn(salen) complexes, it is intriguing that a wide range of trisubstituted olefins are outstanding substrates for asymmetric epoxidation (Scheme 7) [62,76]. The absolute stereochemistry of the epoxide products is inverted at the benzylic carbon when compared with the sense of induction seen with cfs-disubstituted olefins. A qualitative transition state model has been suggested wherein the trisubstituted substrate reacts with the metal-oxo complex via a skewed side-on approach (Fig. 12). The distortion of trisubstituted olefins from planarity resulting from Aj 2 or Aj 3 interactions may be critical in this context. 

When two more of the bridging groups are the less bulky oxygen atom, near-planarity results, and the concomitant effect on the delocalization... 

Microemulsions are stabilized by a monolayer of amphiphiles at the oil/water interface. Whether the oil disperses in the water phase or water in the oil phase depends primarily on the shape of the amphiphilic molecules, notably on their value for vla pl. For flnj 0 > v//, the amphiphile prefers the curvature to be convex toward the water and for < vH toward the oil. Accordingly, oil in water and water in oil emulsions are formed in which the dispersed phase occurs as spherical (or sometimes cylindrical) particles as illustrated in Figure 11.18a and b. Only for vla l 1 is the interface preferably planar, resulting in the bicontinuous distribution shown in Figure 11.18c. In such bicontinuous systems, the conduits may easily break and form during which the water and the oil may change places. 

The minimum energy conformation of the allyl system is planar. We will ignore the deviations from planarity resulting from vibrational bending of the system. 

Since the highest resonance stabilization may be achieved only when the amide group is planar, any departure from planarity results in a higher polymerizability. On the other hand, the preference for coplanarity may render the lactams less stable, introducing some strain into their rings. Contrary to three-and four-membered lactams, the five-membered 2-pyrrolidone is only slightly strained and shows a nearly planar conformation (Figure 3). The impossibility to adopt a fully planar conformation, as it would impose more strain, results in a lower resonance stabilization. 

The pentamethylallyl cation (see Figure 3) has C symmetry the remarkable distortion of the allyl system out of planarity results in almost eclipsed conformations of the (Z)-methyl groups with the ally system. Figure 3 lists geometry parameters for some allyl cations. 

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