Strong chemical polishing

Although abrasive polishing is the most common metal polishing operation, other forms of polishing and chemical brightening are used ia iadustrial operations. Aluminum tmck trailers often are cleaned and brightened by treatments with strong acids or alkaHes, which chemically remove oxides. Chemical methods can also remove tarnish from other metals (55,56). 

In order to make a FPI chemical sensor, the FP cavity needs to be made accessible by the analyte molecules. One way to achieve this is to use a holey sleeve to host the cavity. Xiao et al.7 reported such a fiber FPI gas sensor formed by bonding two endface-polished fibers in a holey sleeve using epoxy. The holey sleeve allows gas to freely enter and leave the cavity. A resolution of 10 5 was estimated in monitoring the changes in the refractive index caused by varying the gas composition. However, the sensor assembly was complicated and required the use of epoxy. In addition, the various components used in sensor construction were made of different materials. As a result, the device had a strong dependence on temperature. 

Reexamination of bulk and wafer-level modeling in the context of copper CMP is also underway. Due to the strong interaction between chemical and mechanical processes in copper polishing, consideration of the removal mechanisms as well as proper Preston-equation like modeling is being pursued [37,65]. More work is needed to produce effective and efficient wafer-level, feature-level, and die-level models for copper CMP, particularly as the industry moves to copper interconnect systems. 

Experimental evidence strongly suggests that material removal in chemical-mechanical polishing (CMP) processes is a result of one or more chemical steps that alter the wafer surface combined with a mechanical step that removes the altered material. Chemical action by itself also removes material by static etching, but generally at a much lower rate than is observed when mechanical action is also present. Similarly, polishing rates observed when a minimally reactive fluid such as water is used instead of slurry are also low. Both chemical and mechanical processes are therefore involved in material removal at commercially practical rates, and the model we describe reflects this dual nature of the process. 

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