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Study On Improvement Of Planarization Performance For Rough Polishing In GLSI Multilevel Copper Interconnection

Posted on:2017-07-19Degree:MasterType:Thesis
Country:ChinaCandidate:Y X WangFull Text:PDF
GTID:2428330596456778Subject:Engineering
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With the rapidly development of integrated circuits,chemical mechanical planarization(CMP)is internationally recognized as the only way to provide the global planarization for the wafer surface.The wafer itself is uneven after the double Damascus technology.In order to meet the nano precision requirements of image resolution,focus and photolithography,each layer must be planarized.Rough polishing,as the first step of planarization,is crucial to the entire copper wiring.Because various influences will be generated during this process,which extend the butterfly pit of fine polishing,impact on the subsequent cabling and result in the decline in efficiency of chip and surface planarization performance.It needs to be realized and difficult for the local planarization,global planarization,surface consistency and planarization efficiency in rough polishing process,which relates to materials,methods and technologies.In this paper,a kind of novel alkaline copper slurry was studied for meeting the planarization requirement in copper interconnection structure.Compared with the traditional acid polishing slurry,it has many advantages,for example,low cost,simple composition,environmentally friendly,non-corroding equipments,and no addition of benzotriazole(BTA).Using hydroxy amine chelating agent,which is independent researched and owns higher chemical potential,can solve effectively the difficulties of copper oxidation and hydroxide indissolvable in alkaline environment.The oxidation agent has functions of oxidizing convex and passivating concave,which can effectively avoid using corrosion inhibitor BTA.In this way,the higher removal rate between convex with concave and good planarization are achieved.The nonionic surfactant can reduce the surface tension,accelerate the mass transfer of convex and be adsorbed preferentially in concave.It has a great effect on improving the consistency and planarization efficiency.The abrasive can improve the removal rate of the convex by using the mechanical grinding.The variation tendency of copper removal rate and planarization performance caused by changing the components of slurry and process conditions were acquired through a series single-factor experiments and planarization experiments.Based on the complexation theory,equilibrium theory,mass transfer theory and self-passivation theory,were optimized the slurry components,and certified finally the optimum proportion in terms of the synergistic effect of the components under the process conditions: applied pressure 1psi(1psi=6.895Kpa),polish head/polish plate 87/93 rpm,flow rate 300ml/min.The concentration of colloidal silica,FA/O chelating agent,FA/O I nonionic surfactant and ?oxidizing agent(H2O2)were identified as 5wt%,3Vol%,6Vol% and 3Vol%,respectively.The experimental results performed on 12 inch blanket wafer indicate that the copper removal rate can reach to 6863.80 ?/min,the within wafer non-uniformity(WIWNU)is 3.17% less than the industrialization indexes(5%),and the roughness is only 0.319 nm under the above-mentioned process conditions.After polishing 60 s,the residual step height of 12 inch pattern wafer(M1)is below 562?.This kind of novel alkaline copper rough polishing slurry can realize better removal rate difference between the convex and concave.It can achieve global planarization with a rapid removal rate,improve the planarization performance,and effectively eliminate the height difference.
Keywords/Search Tags:CMP, alkaline rough polishing slurry, WIWNU, planarization performance, residual height difference
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