A finite element analysis(FEA)model is developed for the chemical-mechanical polishing(CMP)process on the basis of a 12-in five-zone polishing head.The proposed FEA model shows that the contact stress non-uniformity i...A finite element analysis(FEA)model is developed for the chemical-mechanical polishing(CMP)process on the basis of a 12-in five-zone polishing head.The proposed FEA model shows that the contact stress non-uniformity is less dependent on the material property of the membrane and the geometry of the retaining ring.The larger the elastic modulus of the pad,the larger contact stress non-uniformity of the wafer.The applied loads on retaining ring and zone of the polishing head significantly affect the contact stress distribution.The stress adjustment ability of a zone depends on its position.In particular,the inner-side zone has a high stress adjustment ability,whereas the outer-side zone has a low stress adjustment ability.The predicted results by the model are shown to be consistent with the experimental data.Analysis results have revealed some insights regarding the performance of the multi-zone CMP.展开更多
As an important optical component in laser system,silicon mirror surface is required to have micron-level flatness and subnanometer-level roughness.The research concentrates on how to improve roughness as far as possi...As an important optical component in laser system,silicon mirror surface is required to have micron-level flatness and subnanometer-level roughness.The research concentrates on how to improve roughness as far as possible while maintaining flatness of silicon mirror surface during chemical mechanical polishing(CMP)process.A polishing edge effect model is established to explain the reason of flatness deterioration,and a roughness theoretical model is set up to get the limit of perfect surface roughness.Based on the models above,a polishing device is designed to maintain the surface flatness,and the optimized polishing process parameters are obtained by orthogonal tests to get a near-perfect surface roughness.Finally the maintenance of flatness and the improvement of roughness can be achieved at the same time in one step of CMP process.This work can be a guide for silicon mirror manufacture to improve optical reflection performance significantly.展开更多
Nanoparticle movement near a surface is greatly influenced by electrostatic and Van der Waals forces between the particle and the surface,as well as by Brownian motion.In this paper,several precise equations are deriv...Nanoparticle movement near a surface is greatly influenced by electrostatic and Van der Waals forces between the particle and the surface,as well as by Brownian motion.In this paper,several precise equations are derived to describe the Van der Waals and electrostatic forces between a particle and a surface when the particle is removed from the surface.These include an equation for particle displacement under the electrostatic force,and a numerical calculation for particle displacement under the Van der Waals force.Finally,a kinematic model is constructed to describe the particle distribution under the effects of the electrostatic and Van der Waals forces,as well as the particle’s Brownian motion.The results show that increasing the multiply of the particle and surface zeta potential values and decreasing the ionic strength of the detergent can prevent a particle from redepositing onto a surface.展开更多
基金supported by the Science Fund for Creative Research Groups (Grant No. 51021064)the National Natural Science Foundation of China (Grant No. 51205226)the China Postdoctoral Science Foundation (Grant No. 2012M510420)
文摘A finite element analysis(FEA)model is developed for the chemical-mechanical polishing(CMP)process on the basis of a 12-in five-zone polishing head.The proposed FEA model shows that the contact stress non-uniformity is less dependent on the material property of the membrane and the geometry of the retaining ring.The larger the elastic modulus of the pad,the larger contact stress non-uniformity of the wafer.The applied loads on retaining ring and zone of the polishing head significantly affect the contact stress distribution.The stress adjustment ability of a zone depends on its position.In particular,the inner-side zone has a high stress adjustment ability,whereas the outer-side zone has a low stress adjustment ability.The predicted results by the model are shown to be consistent with the experimental data.Analysis results have revealed some insights regarding the performance of the multi-zone CMP.
基金supported by the National Basic Research Program of China(Grant No.2015CB057203)the National Natural Science Foundation of China(Grant No.91323302)
文摘As an important optical component in laser system,silicon mirror surface is required to have micron-level flatness and subnanometer-level roughness.The research concentrates on how to improve roughness as far as possible while maintaining flatness of silicon mirror surface during chemical mechanical polishing(CMP)process.A polishing edge effect model is established to explain the reason of flatness deterioration,and a roughness theoretical model is set up to get the limit of perfect surface roughness.Based on the models above,a polishing device is designed to maintain the surface flatness,and the optimized polishing process parameters are obtained by orthogonal tests to get a near-perfect surface roughness.Finally the maintenance of flatness and the improvement of roughness can be achieved at the same time in one step of CMP process.This work can be a guide for silicon mirror manufacture to improve optical reflection performance significantly.
基金supported by the National Natural Science Foundation of China(Grant Nos.91323302 and 51205226)the Science Fund for Creative Research Groups(Grant No.51321092)
文摘Nanoparticle movement near a surface is greatly influenced by electrostatic and Van der Waals forces between the particle and the surface,as well as by Brownian motion.In this paper,several precise equations are derived to describe the Van der Waals and electrostatic forces between a particle and a surface when the particle is removed from the surface.These include an equation for particle displacement under the electrostatic force,and a numerical calculation for particle displacement under the Van der Waals force.Finally,a kinematic model is constructed to describe the particle distribution under the effects of the electrostatic and Van der Waals forces,as well as the particle’s Brownian motion.The results show that increasing the multiply of the particle and surface zeta potential values and decreasing the ionic strength of the detergent can prevent a particle from redepositing onto a surface.
