Papers by Author: Cheng Yi Shih

Abstract: Current polishing pads cannot polish a workpiece without using slurry with free abrasive. The new slurry is required to be continually poured into the working area, so more than half of the slurry may be lost from the table without contacting the wafer surface; this leads to economic and environmental problems. In the current work, the fixed abrasive pad was used, where nano-sized diamond abrasives were embedded in the polishing pad; distilled water, rather than slurry, was used. The effect of various fixed abrasive pad designs on polishing characteristics during silicon wafer polishing was investigated. Moreover, the primary function of fixed abrasive was to remove the rough parts of silicon wafer as they were being polished. Consequently, it needed to disperse the nano-sized abrasives into the pad material with high hardness value; this way, working abrasives are not pressed into the pad material. Furthermore, with the use of a pad conditioner, the interior working abrasives were exposed to the pad surface. As a result, the best outcome of using the fixed abrasive pad with a nano-sized diamond was a surface roughness of Ra 0.47 nm.

Abstract: A mechanical polishing process was used to reduce surface roughness through mechanical fracturing and removal of the substrate’s roughened regions. It was thus necessary to understand the effect of grain size and morphology on the material removal mechanisms of silicon wafers by stepwise polishing using a fixed abrasive pad. A hybrid process combining the optimized silicon polishing recipe for rapid roughness reduction with a micro-sized diamond, and then polishing using a nano-sized diamond to produce a final finished surface, may be the optimum approach. The best result using the hybrid polishing process was the surface roughness (Ra) value of 3.32 nm.

Abstract: The primary consumables in chemical mechanical polishing (CMP) are the polishing pad and the slurry. The polishing pad significantly influences the stability of the polishing process and the cost of consumables (CoC). During the polishing process, a diamond dresser must be frequently employed to remove the debris to prevent accumulation, a process known as pad conditioning. In this paper, we investigated the physical properties of the CMP pad such as compressibility, thickness, and surface roughness. The difference between new and used pads has been studied. Conclusively, conditioning via a diamond dresser will extend pad life and reduce CoC.