Effect Of Hydrogen Peroxide On Chemical Mechanical Planarization Of Cu/Ni Heterogeneous Microstructure Surface

It has the advantages of miniaturization,integration and high reliability.In essence,the high efficiency,low cost and batch manufacturing of MEMS,which is composed of complex three-dimensional microstructure,has been paid more and more attention by the academic and industrial circles worldwide.EFAB(electrochemical fabrication)technology based on electrochemical deposition is a kind of three-dimensional metal microstructure manufacturing technology that has been proven to be effective in producing MEMS devices.The copper sacrificial layer/nickel structure layer formed an ideal material system and was widely used.Planarization,as a key part of EFAB technology,has a great influence on the manufacturing accuracy and service life of MEMS.However,the traditional mechanical planarization technology will inevitably lead to various forms of surface/subsurface damage,which will reduce the reliability of products.Based on this,Chemical Mechanical Polishing(CMP)is introduced into the planarization of Cu/Ni heterogeneous microstructure.The main research contents and results are as follows:(1)The effects of mechanical action and chemical action on the removal rate of nickel were investigatedIn terms of mechanical effect,the effects of downforce,rotational speed,abrasive concentration and flow rate on the removal rate of nickel were compared by orthogonal experiment and variance analysis.In the aspect of chemical action,with the increase of oxalic acid concentration,the material removal rate of nickel gradually increased and tended to be flat.In addition,hydrogen peroxide concentration has a significant effect on the material removal rate of nickel.(2)Simultaneous and high-quality removal of copper and nickel heterogeneous materialsBy adjusting the concentration of hydrogen peroxide to control the selective ratio of copper and nickel removal rate,the simultaneous removal of copper and nickel heterogeneous materials was realized.At the same time,by adding corrosion inhibitor and adjusting the composition concentration of slurry,the corrosion potential difference between copper and nickel can be reduced,and the optimal composition of polishing solution can be obtained.Using the optimal component polishing,the material removal rates of copper and nickel are75 nm/min and 79 nm/min,respectively,and the surface roughness Ra is 6.1 nm and 2.2 nm,respectively.(3)The planarization process of"First mechanical grinding and then chemical mechanical planarization"was proposed and preliminarily verifiedThe planarization process of"First mechanical grinding and then chemical mechanical planarization"was put forward.A one-inch monolayer Cu/Ni heterogeneous microstructure was used to preliminarily verify the above planarization process.The planarization time is 36min,of which the first 13 min is used for grinding,and the last 23 min is used for chemical mechanical planarization.The polished microstructure has good surface quality(the surface roughness R_a of both copper and nickel is 1.6 nm).In addition,after planarization,the redundancy height h of A,B and C on the surface of Cu/Ni heterogeneous microstructure is-1120 nm,-1186 nm and-1260 nm,which absolute value is about 1/200 of the original structure.