Polish mechanism

Using impedance data of TBN+ adsorption and back-integration,259,588 a more reliable value of <7 0 was found for a pc-Cu electrode574,576 (Table 11). Therefore, differences between the various EffM) values are caused by the different chemical states and surface structures of pc-Cu electrodes prepared by different methods (electrochemical or chemical polishing, mechanical cutting). Naumov etal,585 have observed these differences in the pzc of electroplated Cu films prepared in different ways. 

Metal polishing mechanisms appear to be considerably different from silica polishing. The critical event that determines the polishing process in metal CMP appears not only to be influenced by the crystallographic/microstructure deformation process but also to relate to more complex components of slurry [18]. To better understand the removal mechanism in metal CMP, tungsten is chosen, since both industrial and laboratory CMP data are available for this metal, and its abrasion behavior as a metal is similar to that of other ductile metals which have been studied quite extensively under two- and three-body abrasion [66]. 

Solid metal electrodes are usually polished mechanically and are sometimes etched with nitric acid or aqua regia. Purification of platinum group metal electrodes is effectively achieved also by means of high-frequency plasma treatment. However, electrochemical preparation of the electrode immediately prior to the measurement is generally most effective. The simplest procedure is to polarize the electrode with a series of cyclic voltammetric pulses in the potential range from the formation of the oxide layer (or from the evolution of molecular oxygen) to the potential of hydrogen evolution (Fig. 5.18F). 

Those trying to imitate the polishing mechanisms of TBT-SPC through hydrolysable acrylate binders. 

The expected impact of the material properties reviewed in Table II on the polishing mechanisms reviewed in the previous section is summarized in Table IV. As might be expected from previous discussion on structure vs properties, a high degree of interaction between properties and process effects is evident. Publicly available evidence to support materials properties effects on the CMP process is relatively limited. This is reviewed in Section IV. 

Material property Impact on polishing mechanism CMP process impact... 

Consider the main features of the process of dissolution of some transition metals in liquid aluminium as an example.169,303,304"30S Cylindrical specimens of a transition metal, 11.28 0.01mm diameter and 5-6 mm high, were machined from 12-13 mm diameter rods produced by arc melting the metal under investigation. The disc surface was then ground flat and polished mechanically. 

The reflection characteristics for the copper surface polished mechanically and the copper surface polished both mechanically and electrochemically12 are shown in Fig. 9a. 

Figure 9. The dependence of the degrees of reflection on the wavelength of visible light for a) the ideal reflectance of copper ( ) and the total reflections of the copper surface polished mechanically (o), the copper surface polished both mechanically and electrochemically (A), b) mirror (+) and diffuse (x) reflections of the copper surface polished mechanically mirror ( ) and diffuse (-) reflections of the copper surface polished both mechanically and electrochemically. (Reprinted from Ref.

Figure 10. 3D STM images of a) the copper surface polished mechanically, b) the copper surface polished both mechanically and electrochemically. Scan size (880 x 880) nm. (Reprinted from Ref.12 with permission from Elsevier.)...

The line sections analysis of the flat parts of the copper surfaces is shown in Fig. 12. The roughness of the flat parts of the copper surface, polished both mechanically and electrochemically, is very small and less than the atomic diameter of copper. For this reason, it can be said that these flat parts of the surface are smooth on the atomic level. The roughness of the flat parts of the copper surface, only polished mechanically, is less than 2 atomic diameters of copper.12... 

The degrees of development of a surface, determined by the STM analysis as the surface area diff., for the silver mirror surface, the copper surface polished mechanically only and the mirror-bright copper coating obtained from solution Cu II of 25 pm thickness, calculated from an area (880 x 880) nm2, are given in Table 2.12... 

Analyses of Stribeck curves, Preston s coefficient, COF, and tribological mechanism indicator correlating with each other help to understand the polishing mechanisms. Such an analysis not only helps in the process development but also provides useful feedback to the pad development manufacturers. 

FIGURE 11.7 An illustration of ECMP polishing mechanism in relation to a conventional electropolishing process (from Ref. 25). 

Film Hardness Polish rate is inversely proportional to the hardness of the surface of the film being polished.Mechanical damage on the film surface is also related to film hardness. Creep and work hardening of the film during CMP will alter the hardness from values measured prior to CMP. 

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