Chemical mechanical planarization behavior

Merrick D, Santora B, Her B, Frink S. An Investigation of ceria-based slurries exhibiting reverse-prestonian behavior. Proceedings 11th International Symposium on Chemical Mechanical Planarization 2006. 

Li, J., Chai, Z., Liu, Y., et al., 2013a. Tribo-chemical behavior of copper in chemical mechanical planarization. Tribology Lett. 50, 177—184. 

Kim, S.K., Lee, S., Paik, U., Katoh, T., Park, J.G., 2003. Influence of the electrokinetic behaviors of abrasive ceria particles and the deposited plasma-enhanced tetraethylorthosiU-cate and chemically vapor deposited S13N4 films in an aqueous medium on chemical mechanical planarization for shallow trench isolation. J. Mater. Res. 18, 2163—2169. 

In single step voltammetry, the existence of chemical reactions coupled to the charge transfer can affect the half-wave potential Ey2 and the limiting current l. For an in-depth characterization of these processes, we will study them more extensively under planar diffusion and, then, under spherical diffusion and so their characteristic steady state current potential curves. These are applicable to any electrochemical technique as previously discussed (see Sect. 2.7). In order to distinguish the different behavior of catalytic, CE, and EC mechanisms (the ECE process will be analyzed later), the boundary conditions of the three processes will be given first in a comparative way to facilitate the understanding of their similarities and differences, and then they will be analyzed and solved one by one. The first-order catalytic mechanism will be described first, because its particular reaction scheme makes it easier to study. 

This different behavior can be explained by considering that for a CE mechanism (the reasoning is similar for an EC one), C species is required by the chemical reaction whose equilibrium is distorted in the reaction layer (whose thickness in the simplified dkss treatment is <5r = jDj(k + 2)) and by the electrochemical reaction, which is limited by the diffusion layer (of thickness 8 = yfnDt). For a catalytic mechanism, C species is also required for both the chemical and the electrochemical reactions, but this last stage gives the same species B, which is demanded by the chemical reaction such that only in the reaction layer do the concentrations of species B and C take values significantly different from those of the bulk of the solution. In summary, the catalytic mechanism can reach a true steady-state current-potential response under planar diffusion because its perturbed zone is restricted to the reaction layer <5r, which is independent of time, whereas the distortion of CE (or EC) mechanism is extended until the diffusion layer 8, which depends on time, and a stationary current-potential response will not be reached under these conditions. 

Figure 7.36a-c shows the forward and reverse components of the square wave current. When the chemical kinetics is fast enough to achieve kinetic steady-state conditions (xsw > 1.5 and i + k2 > (D/rf), see [58,59]), the forward and reverse responses at discs are sigmoidal in shape and are separated by 2 sw. This behavior is independent of the electrode geometry and can also be found for spheres and even for planar electrodes. It is likewise observed for a reversible single charge transfer at microdiscs and microspheres, or for the catalytic mechanism when rci -C JDf(k + k2) (microgeometrical steady state) [59, 60]. 

Film Microstructure Microstructure provides a surface (to be polished) composed of differently oriented surfaces with different chemical and mechanical behaviors and grain boundaries that are prone to enhanced chemical activity. Thus a relationship between the film microstructure and planarization should be carefully monitored. 

There are, in fact, no well-authenticated examples of nonphoto-chemical reactions of square-planar complexes of the heavier elements in which a tetrahedral geometry is attained. Despite this, a few intramolecular geometry changes have, tentatively, been assigned to this mechanism. The fluxional behavior of [RhHlPPhsls], a molecule obviously related to the [NiHLa] cations already met, has been so ex-... 

On the other hand, adsorbents A and B modified with ODS and adsorbent C unmodified or modified with ODS as well as with ODS+HMDS exhibit higher adsorption capacity. Benzene shows similar adsorption behavior [68]. The above facts are due to the specific structure of adsorption sites which is formed after the chemical modification of the adsorbents. Adsorption energy sites constitute of spacially arranged CH, CH2 and CH3 groups of the octadecyl radical, chemically bonded to the surface of the silica gel and, in the case of carbosils of components of the carbon deposit (i.e. CH, CH2, CH3) planary distributed on the surface of the supporting material. There is an essential difference in the mechanism of the molecular adsorption on chemically modified and unmodified adsorbents [30]. The surface of chemically unmodified adsorbents can be considered as planar, i.e. two-dimensional, while that of the modified sorbents as three-dimensional. 

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