Papers by Author: Yang Liang Pai

Abstract: Diamond disks are indispensable for dressing CMP pads in the manufacture of semiconductors. Conventional diamond disks contain one type of diamond grits, with the aim to achieve two different functions, viz. glaze shaving and asperities grooving. Cocktail diamond disks are made by assembling brazed diamond pallets that contain different types of diamond crystals. Thus, the pad can be dressed clean, and at the same time, asperities may polish wafers fast without damaging.

Abstract: The primary consumables in chemical mechanical polishing (CMP) are the polishing pad and slurry. The polishing pad significantly influences the stability of the polishing process and the cost of consumables (CoC). Usually a diamond pad conditioner is used to scrap off the polishing debris from the pad top. Recently, an alternative planarization process can be achieved by polishing with a "fixed abrasive pad" (FAP). In order to dress bumps on FAP, this paper use an amorphous diamond, a diamond-like carbon deposited by cathode arc system as the dresser for FAP. The amorphous diamond can produce a surface relief that ranges from a few nanometers to about 200 nanometers. With the addition of this dressing step on a rotary platform, FAP can renew its polishing surface 10 to 100 times before the bumps are used up. The pad cost for polishing can be reduced by at least ten folds and make FAP more desirable than slurry pad for silicon wafer manufacturer due to its intrinsic capabilities to produce flatter wafers with high polishing rate.

Abstract: The fundamental characteristics of dressing action on the polyurethane pad are investigated via dressing by single diamond of different orientations, dressing parameters and dressing path in this study. Experimental results show that a groove with pile-up on both side walls forms as the diamond moves over the pad with a specific dressing depth. The resulting asperities on the pad are strongly affected by the diamond orientation. Plowing is found to be the major mechanism responsible for this surface topology if dressing is conducted by the face of a diamond. On the contrary, cutting action dominates when the point of a diamond is responsible for dressing. It is also found that dressing velocity has an insignificant effect on the groove and ridges created on the pad. The depth of the groove is smaller than the dressing depth due to the spring back of the pad. When the groove created is repeatedly dressed over the same track, the ridge height and groove depth increases for each additional dressing. When two grooves cross each other, the ridges at the four corners of the intersection grow while the depth of the overlapped area decreases. These ridges will become the pressure enhancer of the abrasives to polish the wafer.