The existing studies, concerning the dressing process, focus on the major influence of the dressing conditions on the grinding response variables. However, the choice of the dressing conditions is often made, based on...The existing studies, concerning the dressing process, focus on the major influence of the dressing conditions on the grinding response variables. However, the choice of the dressing conditions is often made, based on the experience of the qualified staff or using data from reference books. The optimal dressing parameters, which are only valid for the particular methods and dressing and grinding conditions, are also used. The paper presents a methodology for optimization of the dressing parameters in cylindrical grinding. The generalized utility function has been chosen as an optimization parameter. It is a complex indicator determining the economic, dynamic and manufacturing characteristics of the grinding process. The developed methodology is implemented for the dressing of aluminium oxide grinding wheels by using experimental diamond roller dressers with different grit sizes made of medium- and high-strength synthetic diamonds type AC32 and AC80. To solve the optimization problem, a model of the generalized utility function is created which reflects the complex impact of dressing parameters. The model is built based on the results from the conducted complex study and modeling of the grinding wheel lifetime, cutting ability, production rate and cutting forces during grinding. They are closely related to the dressing conditions （dressing speed ratio, radial in-feed of the diamond roller dresser and dress-out time）, the diamond roller dresser grit size/grinding wheel grit size ratio, the type of synthetic diamonds and the direction of dressing. Some dressing parameters are determined for which the generalized utility fimction has a maximum and which guarantee an optimum combination of the following： the lifetime and cutting ability of the abrasive wheels, the tangential cutting force magnitude and the production rate of the grinding process. The results obtained prove the possibility of control and optimization of grinding by selecting particular dressing parameters.展开更多
Diamond grits held in metal matrix(sintered or electroplated) are retained primary by mechanical locking.Because of this weak attachment,the pullouts of diamond from matrix are inevitable during the cutting process.Mo...Diamond grits held in metal matrix(sintered or electroplated) are retained primary by mechanical locking.Because of this weak attachment,the pullouts of diamond from matrix are inevitable during the cutting process.Moreover,the working grits have low protrusion heights,so the cutting speed of the tool is limited. Furthermore,the rubbing of metal matrix and the work object can cause thermal damages of diamond and other materials,and power increase for the operation. Diamond can be firmly held in a metal matrix by brazing.Because of the presence of strong chemical bonding,diamond grits can protrude twice as high without being knocked off from the matrix.As a result,the cutting speed of the tool may be doubled. When the braze melts,the carbide formers will migrate toward diamond to form carbide at the interface. This reaction may be excessive as to degrade diamond significantly.In this case,a coating on diamond may be needed to moderate the reaction. When diamond is brazed on the surface of a substrate,the melt tends to pull the grits closer together that may thicken the braze layer locally.The clustering of grits can reduce the cutting effectiveness of the diamond tool.A diamond grid design is necessary to maintain the uniform thickness of the braze layer.Moreover,the controlled melting of braze alloy can form a gentle slope around each diamond grit.Such a massive support can allow aggressive cutting of the diamond tool with a low power consumption.展开更多
Diamond pad conditioners can determine the efficiency of CMP processes and the quality of polished wafers.The polishing rate of a wafer is dependent on the amplitude(height) of pad asperities.The polishing uniformity ...Diamond pad conditioners can determine the efficiency of CMP processes and the quality of polished wafers.The polishing rate of a wafer is dependent on the amplitude(height) of pad asperities.The polishing uniformity is controlled by the frequency(density) of such asperities.Current diamond pad conditioners cannot dress the pad to produce microns sized asperities at high density.This is because the tips of diamond grits cannot be leveled to the same height so the grooved pad top is uneven with excessive asperities that may ruin the wafer and under sized asperities that is easily glazed. New designs of diamond pad conditioners have markedly improved the leveling of diamond tips.Organic diamond disks(ODD) are manufactured by reverse casting of polymers.Due to the uniform spacing of diamond grits and their controlled tip heights,none of the diamond grits will be overly stressed.Moreover,all diamond grits are sharing the dressing work.Consequently,the number of working grits of ODD is significantly higher than conventional designs.Moreover,because no diamond will cut pad unecessarily,the pad life is greatly lengthened.Furthermore,due to the uniform distribution of pad asperities,the slurry will be held efficiently so the run off is avoided.As a result,the slurry usage is reduced.ODD is therefore a significant savor of CMP consumables for semiconductor manufacture.展开更多
Low stress polishing is required for the manufacture of advanced integrated circuits(IC) with node sizes of 45 nm and smaller.However,the CMP community achieved the low stress by reducing the down force that press the...Low stress polishing is required for the manufacture of advanced integrated circuits(IC) with node sizes of 45 nm and smaller.However,the CMP community achieved the low stress by reducing the down force that press the wafer against a rotating pad.The reduced down force also decrease the removal rate of the wafer. As a result,the productivity suffers.In order to cope with this problem,an electrical potential is applied to the copper layer during polishing,in this case,the chemical oxidation is accelearated and hence the removal rate. Alternatively,the rotating pad must be softened to minimize the defects of wafers caused by CMP. In this research,we report a simpler solution to achieve low stress polishing without investing in new equipment and in developing new pad materials.The conventional CMP is proceeded by dressing the pad with a PCD dresser that can form 10×more asperities on the pad surface.The fluffy surface can then polish delicate IC without using the brutal force.As a result,the removal rate of wafers can be maintained without causing defectivity on the IC layer.展开更多
文摘The existing studies, concerning the dressing process, focus on the major influence of the dressing conditions on the grinding response variables. However, the choice of the dressing conditions is often made, based on the experience of the qualified staff or using data from reference books. The optimal dressing parameters, which are only valid for the particular methods and dressing and grinding conditions, are also used. The paper presents a methodology for optimization of the dressing parameters in cylindrical grinding. The generalized utility function has been chosen as an optimization parameter. It is a complex indicator determining the economic, dynamic and manufacturing characteristics of the grinding process. The developed methodology is implemented for the dressing of aluminium oxide grinding wheels by using experimental diamond roller dressers with different grit sizes made of medium- and high-strength synthetic diamonds type AC32 and AC80. To solve the optimization problem, a model of the generalized utility function is created which reflects the complex impact of dressing parameters. The model is built based on the results from the conducted complex study and modeling of the grinding wheel lifetime, cutting ability, production rate and cutting forces during grinding. They are closely related to the dressing conditions （dressing speed ratio, radial in-feed of the diamond roller dresser and dress-out time）, the diamond roller dresser grit size/grinding wheel grit size ratio, the type of synthetic diamonds and the direction of dressing. Some dressing parameters are determined for which the generalized utility fimction has a maximum and which guarantee an optimum combination of the following： the lifetime and cutting ability of the abrasive wheels, the tangential cutting force magnitude and the production rate of the grinding process. The results obtained prove the possibility of control and optimization of grinding by selecting particular dressing parameters.
文摘Diamond grits held in metal matrix(sintered or electroplated) are retained primary by mechanical locking.Because of this weak attachment,the pullouts of diamond from matrix are inevitable during the cutting process.Moreover,the working grits have low protrusion heights,so the cutting speed of the tool is limited. Furthermore,the rubbing of metal matrix and the work object can cause thermal damages of diamond and other materials,and power increase for the operation. Diamond can be firmly held in a metal matrix by brazing.Because of the presence of strong chemical bonding,diamond grits can protrude twice as high without being knocked off from the matrix.As a result,the cutting speed of the tool may be doubled. When the braze melts,the carbide formers will migrate toward diamond to form carbide at the interface. This reaction may be excessive as to degrade diamond significantly.In this case,a coating on diamond may be needed to moderate the reaction. When diamond is brazed on the surface of a substrate,the melt tends to pull the grits closer together that may thicken the braze layer locally.The clustering of grits can reduce the cutting effectiveness of the diamond tool.A diamond grid design is necessary to maintain the uniform thickness of the braze layer.Moreover,the controlled melting of braze alloy can form a gentle slope around each diamond grit.Such a massive support can allow aggressive cutting of the diamond tool with a low power consumption.
文摘Diamond pad conditioners can determine the efficiency of CMP processes and the quality of polished wafers.The polishing rate of a wafer is dependent on the amplitude(height) of pad asperities.The polishing uniformity is controlled by the frequency(density) of such asperities.Current diamond pad conditioners cannot dress the pad to produce microns sized asperities at high density.This is because the tips of diamond grits cannot be leveled to the same height so the grooved pad top is uneven with excessive asperities that may ruin the wafer and under sized asperities that is easily glazed. New designs of diamond pad conditioners have markedly improved the leveling of diamond tips.Organic diamond disks(ODD) are manufactured by reverse casting of polymers.Due to the uniform spacing of diamond grits and their controlled tip heights,none of the diamond grits will be overly stressed.Moreover,all diamond grits are sharing the dressing work.Consequently,the number of working grits of ODD is significantly higher than conventional designs.Moreover,because no diamond will cut pad unecessarily,the pad life is greatly lengthened.Furthermore,due to the uniform distribution of pad asperities,the slurry will be held efficiently so the run off is avoided.As a result,the slurry usage is reduced.ODD is therefore a significant savor of CMP consumables for semiconductor manufacture.
文摘Low stress polishing is required for the manufacture of advanced integrated circuits(IC) with node sizes of 45 nm and smaller.However,the CMP community achieved the low stress by reducing the down force that press the wafer against a rotating pad.The reduced down force also decrease the removal rate of the wafer. As a result,the productivity suffers.In order to cope with this problem,an electrical potential is applied to the copper layer during polishing,in this case,the chemical oxidation is accelearated and hence the removal rate. Alternatively,the rotating pad must be softened to minimize the defects of wafers caused by CMP. In this research,we report a simpler solution to achieve low stress polishing without investing in new equipment and in developing new pad materials.The conventional CMP is proceeded by dressing the pad with a PCD dresser that can form 10×more asperities on the pad surface.The fluffy surface can then polish delicate IC without using the brutal force.As a result,the removal rate of wafers can be maintained without causing defectivity on the IC layer.
