Papers by Keyword: Diamond Conditioner

Abstract: This paper presents a combined diamond disk that is designed and manufactured to markedly improve the leveling of diamond tips, thereby reducing the amount of diamond grit. First, a small brazed diamond disk was manufactured. Second, 12-or 24-disk brazed diamond disks were mounted onto a substrate with a diameter of 108 mm for completing the combined diamond disk. Four types of disks were fabricated, and their performances were compared with that of a conventional diamond disk. The experimental results showed that the combined diamond disk has more complete diamond crystal shapes and distribution with better leveling, which increases the effectiveness of the working diamond grits. Compared to a conventional diamond disk, the combined diamond disk achieved a higher wafer removal rate and better uniformity while consuming less pad material. The number of diamond grits required was significantly lower. Roughly, 7,600 and 12,000 diamond grits were used for the 24-and 12-disk brazed diamond disks, respectively, in the new disk, whereas 20,000 diamond grits were used in a conventional diamond disk. In the case of the conventional diamond disk, the diamond tips are leveled to more than 50 μm. However, in the case of the combined diamond disk, the diamond tips can be leveled to less than 30 μm because the diamond tips are already leveled. These results contribute to the understanding of conditioning techniques and further improvement of the chemical mechanical polishing process.

Abstract: A pad conditioner or diamond disk is needed to regenerate the asperity structure of the pad and recover its designated role in the chemical mechanical polishing process. In this paper, the effect of dressing load and speed on removal rate of oxidized wafers were investigated using a polycrystalline diamond disk and brazed diamond disk. It was found that polycrystalline diamond disk enable the manufacturer to tightly control diamond leveling and the cutter’s shape by comparison with a brazed diamond disk that contains discrete diamond grits of random orientation. Experimental results revealed that for polycrystalline diamond disk, the removal rate of oxidized wafer displayed an almost unchanged curve when the load was less than 4kg, but the removal rate of oxidized wafer for brazed diamond disk initially increased with the dressing load, reaching a maximum value at a dressing load of approximately 4 kg. Then, it decreased slowly with further increases of the dressing load. The removal rate of oxidized wafer remains unchanged with dressing speed.

Abstract: The friction phenomenon was investigated to explore the relationship between the diamond conditioner, polishing pad and wafer of oxide film in the chemical mechanical polishing (CMP) process. Two kinds of diamond conditioners (disk-A and disk-B) were used. Diamond disk-A used was traditional diamond conditioner containing random shaped diamond grits. Diamond disk-B used was made by sculpturing a sintered polycrystalline diamond to form identically shaped cutting tips. Experimental results reveal that friction force between disk and pad increases with dressing load. But friction force decreases with sliding speed due to increase of sliding speeds resulting in an increase of interface temperature. The coefficient of friction between wafer and pad initially increases with the dressing load, and then it starts to drop slowly with further increases of the dressing load. It was found that removal rate of the oxide film correlates well with the variation of the coefficient of force. In addition disk-B can produce a higher wafer removal rate under a low dressing load.

Abstract: A diamond conditioner or dresser is needed to regenerate the asperity structure of the pad and recover its designed ability in chemical mechanical polishing (CMP) process. In this paper a new design of diamond conditioner is made by shaping a sintered matrix of polycrystalline diamond (PCD) to form teethed blades. These blades are arranged and embedded in epoxy resin to make a designed penetration angle, called the blade diamond disk. The dressing characteristics of pad surface textures are studied by comparison with conventional diamond conditioner. It is found that the height variation of the diamond tip of blade diamond disk is significantly smaller than the conventional diamond disk. The dressing rate of blade diamond disk is lower than that of the conventional diamond disk, and hence the pad life is prolonged. As a result, reduction of the cost CMP is expected. In addition the pad surface roughness Ra of about 3.79μm is less than Ra of about 4.15μm obtained after dressing using a conventional diamond disk.

Abstract: Diamond pad conditioner or dresser can determine the efficiency of chemical mechanical polishing (CMP) processes and the quality of polished wafers. Conventional diamond pad conditioners are made by adhering discrete diamond grits on a flat substrate. The size distribution of diamond grits coupled with the deformation of the substrate often make the tips of diamond grits lying at different heights. Instead of attaching individual diamond grits to a metal substrate, a revolutionary design of pad conditioners is based on carving a structure out of sintered polycrystalline diamond (PCD) matrix. The PCD dresser is manufactured by wire electro discharge machining to form cutting pyramids of a specific size with a designed shape. The dressing characteristics of pad surface textures are studied by comparison with conventional diamond pad conditioner. Experimental results indicate that the PCD dresser can dress asperities of the pad more uniformly than the conventional diamond dresser due to PCD dresser having identically shaped tip and the same height diamond. In addition the cutting rate of PCD dresser for IC1000 pad not only is reduced by about 30% but also it can dress pad more effectively than conventional diamond dresser.

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.