Design And Manufacturing Of Bionic Polishing Pad And Research On Flow Field Based On Sunflower Seed Pattern

The paper, on the basis of the bionic, a new kind of bionic polishing pad with sunflower seed pattern is proposed, the polishing pad surface is made of independent grain blocks, and create polishing pad similar to the distribution of sunflower seed pattern. The trench on the polishing pad is opened can improve the performance of the polishing pad, slurry flows along the counterclockwise and clockwise spiral grooves of phyllotaxis pattern, it not only makes fluid flow divergence around and litter exclusion, but also help supplying slurry from the center of the bionic pad to the radial, so that chemical and mechanical action can get a reasonable match in CMP, solve the the problems of geometric errors which is brought by the uneven fluid flow during the chemical mechanical polishing.First of all, this paper have introduced Fibonacci array phenomena in the sunflower pad, and descirbes mathematical model of the growth of sunflower which is proposed by F.R.Yeatts, using the F.R.Yeatts equation to simulate the seeds arrangement according to different plants disperse angel, different parameters of phyllotatic k and different seeds radius. Base on the result of simulation, UG software is used to establish the 3D model of the polish pad sunflower seed pattern according to the simulation results.And then this paper describes the basic theory of liquid-solid two phase flow and knowledge of computational fluid dynamics, and make a brief overview for computational fluid dynamics CFD and Fluent software. Derived the flow motion equations of fluid during the Chemical Mechanical Polishing, the calculation domain, mesh divison and boundary conditions are given, by using computational fluid dynamics software (Fluent), the flow state of the polishing slurry are simulated and the effects of the phyllotaxis parameters of polishing pad on the flow field of polishing slurry are analyzed. After that, making method of fixed abrasive bionic polishing pad is proposed, screen printing method is adopted as making fixed abrasive bionic polishing pad, introduces the basic principles of screen printing, determines the three major elements of screen printing process, that is:printing frame, scraper, distance between printing frame and bearing objects. Materials and making process of fixed abrasive bionic polishing pad are given, fixed abrasive bionic polishing pad in kind is obtained.Finally, through the polishing experiments of the silicon wafer, parameters of polishing pad, the speed of polishing platen, slurry flow and pressure impact on the material removal rate are researched, by adding fluorescence to slurry in order to observe the slurry flow state and uniformity under different speed of polishing platen on the polishing pad.