Papers by Keyword: Fixed Abrasive Pad

Abstract: The choice of abrasive particle size is crucial to improve the lapping efficiency and surface quality in lapping of sapphire wafer by fixed abrasive (FA) pad. A model for the penetration depth of a single abrasive is developed with fixed abrasive pad. A serious of lapping tests were carried out using FA pads embedded with different size of diamond particles to verify the validity of the developed model. Results show that the penetration depth of abrasive is related not only to the particle size, but to the hardness ratio of the work-piece to the pad as well. The material removal rate of sapphire is proportional to the square of abrasive particle size, while the average surface roughness is proportional to the abrasive particle size.

Abstract: Fixed abrasive technology which has many advantages is one of the future machining directions. Free and fixed abrasive lapping of BK7 glass was investigated and different material removal modes and surface damage categories by lapping were discussed. The results show that material removal rate is larger for free abrasive lapping than that of fixed abrasive lapping with four abrasive sizes and decreases with diamond size decreasing in two lapping processes. Surface quality is better for fixed abrasive lapping than that of free abrasive lapping at the same diamond size and gets better with the decreasing of diamond size. Fixed abrasive lapping can achieve simultaneously high MRR and good surface quality.

Abstract: The process parameters affect the lapping efficiency and the surface quality of work pieces. The fixed abrasive pad of w3-5 diamond abrasive was used for lapping magnesium aluminate spinel wafers in orthogonal experiment. The affection of lapping pressure, plate speed and slurry type on material removal rate (MRR) and surface roughness Ra were investigated. Finally, the process parameters were optimized. The results showed that lapping efficiencies were higher and the surface quality was better on the conditions of Zhongjing slurry, lapping pressure 10.37Kpa and plate speed 100rpm.

Abstract: The processing technology of sapphire with a high material removal rate a good surface quality is critical for its applications. The experiment of sapphire lapping and polishing was carried out by using three different fixed abrasive pad (FAP). Their material removal rate (MRR) and surface roughness (Ra) were measured and analyzed. Results indicate that a MRR of 5.6μm/min reaches in rough lapping and a MRR of 0.4μm/min in fine lapping. The average surface roughness Ra of rough lapping and fine lapping is 142nm and 1.2nm respectively. The processing efficiency of sapphire wafer is effectively improved and a good surface quality is obtained when FAP adopted.

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 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.