Study On Pad Properties & Effects On Processing In CMP

With the development of Ultra Large-Scale Integration (ULSI), the dimension of silicon substrate become more and more bigger and the characteristic dimension go diminishing. Therefore the demand of the wafer's quality becomes higher too. Now, chemical mechanical polishing (CMP) is widely used in the flatness process of polishing substrate and multilevel interconnections. However, some problems still exist in actual- CMP such as: low-level polishing efficiency, poor repetition of polishing wafer, low ratio of end product, etc. Therefore, the influence parameters aiming at CMP process and their effects to polishing result need to be researched deeply. The pads as one of crucial consumptions play an important role in polishing silicon substrate, which influences directly the process of CMP and polishing effect..In this paper, firstly, according to the respective characteristic of pad's parameters, the experiment scheme is ensured, the major parameters are detected and evaluated, such as thickness, density, hardness, compressibility, porosity, rebound resilience, groove, roughness and holding capacity to slurry, etc. All these parameters provide important foundation for building up model between the polishing quality and the characteristic of pads.Based on this, with the CP-4 desktop CMP test-bed, quadrature experiments are used. The range of the process parameters, such as the pressure on the wafer, the velocity of platen, the flow rate of slurry and the sweeping range and velocity etc is confirmed. The effects of process parameters and material remove rate along with the average roughness of wafer are discussed by one element experiment method, and corresponding curve relationship is achieved.According as these results, the effect of the characteristic of pads aimed at the same kinds of pads to material remove rate along with the average roughness of wafer is systemically analyzed in immobile process parameters by large numbers of polishing experiments. The ideal characteristic of pad in this experiment condition is summarized. The effects of characteristic of pads to the quality of polishing are summarizedIn the end, by the validating experiment, the effects of validating velocity and validating time to the pad's rebound resilience, roughness. The technology method improving the chrematistic of pad is explored based on validating method.