The Study Of Copper Deposition And Hole Metallization In Blind Vias For Electronic Interconnections

Recently,multifunctional and portable electronic products have become part of the mainstream of consumer electronics products.Printed circuit boards are required to achieve the production and interconnection of miniaturized multi-function microelectronic devices.Copper plating is one of the most important processes in the manufacture of multilayer printed circuit boards.Microvia filling is a major copper electroplating technique used to achieve the electronic interconnection of multilayer printed circuit boards.Obviously,the quality of electrodeposited copper determines the stability and reliability of the printed circuit boards.This thesis starts from two aspects of pretreatment technology and electroplating additives.Firstly,electrochemical testing,Haring cell plating blind hole filling experiment and scanning electron microscopy tests were used to study the reeaction mechanism and the optimal concentration of the tetrazolium violet and myclobutanil as corrosion inhibitors in the new electroplating pretreatment solution.Galvanostatic measurement,cyclic voltammetry tests,electrochemical impedance spectroscopy tests,chronoamperometry,and thermodynamic analysis were applied to study the four new nitrogen-containing agents L1,L2,L3 and L4 as levelers.This thesis evaluated the corrosion inhibitory effect of tetrazolium violet and myclobutanil for copper in 0.5 mol/L H₂SO₄ solution by polarization curve and electrochemical impedance spectroscopy tests.The results showed that tetrazolium violet and myclobutanil have excellent corrosion inhibition performance for copper in0.5 mol/L H₂SO₄.The inhibition efficiency of 3.2×10^-4 mol/L tetrazolium violet at 298K is 98.3%,and the inhibition efficiency of 3.2×10^-4 mol/L myclobutanil is 92.2%.A scanning electron microscope was applied to characterize the inhibition performance on the copper surface.The results of thermodynamic analysis show that the adsorption of tetrazolium violet and myclobutanil on the copper surface is a spontaneous reaction,and is the result of the combined effect of physical adsorption and chemical adsorption.This thesis mainly starts with four new nitrogen-containing heterocyclic small molecule compounds as levelers.A high copper and low acid system was used as the electroplating system.The composition of the basic plating solution is 0.88 mol/L Cu SO₄·5H₂O and 0.54 mol/L H₂SO₄.The composition of the virgin make-up solution is0.88 mol/L Cu SO₄·5H₂O and 0.54 mol/L H₂SO₄,the remaining additives are SPS as accelerator,PEP as suppressor,Cl^-and tested leveler.The electrochemical test methods such as galvanostatic measurements and cyclic voltammetry tests were used to optimize the composition of each additive in the electroplating solution for filling blind holes.The electrochemical test results proved that Cl^-can significantly enhance the inhibitory effect of PEP,and the adsorption of SPS on the copper surface is a mixed type.The result of chronoamperometry proved that nucleation of Cu electrodeposition is instantaneous nucleation mechanism in the first few seconds.The blind hole filling experiments were applied with the optimized electroplating formula,and the filling performance can be effectively improved after good pretreatment.The optimized electroplating formula was used,and the current density was 2 A/dm² at a temperature of 298 K.The results of the metallographic section after electroplating for 45 minutes showed four new leveler have good filling effects for blind holes with the diameter of0.13 mm and depth of 0.08 mm.Scanning electron microscope test and surface roughness test were used to characterize the surface morphology after electroplating.The results show that the surface of the coating was bright and flat,and the roughness is only 0.16μm.