Study On The Factors Influencing The Modulation Of Copper Electrodeposition Layers

As electronic communication technology continues to evolve,electronic interconnects are developing in the direction of high density and high integration.The reliability of copper electrodeposition technology directly determines the stability of signal transmission and electrical interconnects in electronic interconnects.Given the wide range of factors affecting the quality of copper electrodeposition,this work systematically discusses the influence of substrate,virgin make-up solution（VMS）and electrodeposition method on the copper crystallisation process utilizing crystallographic analysis methods,material characterization,combined with electrochemical testing,quantum chemical calculations and molecular dynamics simulations.The main studies and results of this thesis are as follows:（1）The effect of substrate on the morphology of copper electrodeposition.The linear sweep voltammetry（LSV）electrodeposition behavior of Cu²⁺on copper,phosphorated copper and titanium substrates was investigated.The results show that Cu²⁺underwent lattice matching on copper substrates.The reduced copper atoms proceeded within the existing copper lattice of the substrate,accompanied by transient nucleation.The crystallization of the copper film was fine.Due to LSV activation,the nucleation of Cu²⁺took place preferentially on phosphorated copper substrates with"black films"and titanium substrates.The copper nucleation process became dominant due to the sharp reduction of active sites,and the resulting copper layer was composed of large columnar crystals with grain sizes ranging from 40 to 120μm in the X-Y axis.（2）The effect of the electrodeposition method on the morphology of the copper film.This section investigated the effect of potential-controlled and current-controlled electrodeposition methods on the morphology of copper deposits.The results demonstrated that the controlled-current electrodeposition method achieved a high crystalline quality layer compared to the controlled-potential method and that it was easier to control the morphology of the copper film.Temperature,stirring intensity and the surface roughness of substrate indirectly affected the morphology of the copper film by influencing the material transfer efficiency in the bath,the nucleation density of Cu²⁺and the process of copper crystallization.The influence of the VMS was discussed with an orthogonal experimental design.The results showed that the components of VMS were supposed to be maintained at a suitable ratio to ensure the crystalline quality,current efficiency and stability of the plating solution.（3）Effects of plating additives on copper electrodeposition.Six nitrogen-containing heterocyclic levelers had successfully synthesized and characterized by molecular structure design.The results showed that IPIEP was the preferred leveler with a throwing power（TP）value of 84.6%for the acid copper plating solution.The mechanism of the levelers at the substrate/plating solution interface was also constructed by using electrochemical tests,plating experiments,quantum chemical calculations and molecular dynamics simulations.These results indicated that the key to the levelling performance of nitrogen-containing heterocyclic leveler was the inhibition of 3-Mercapto-l-Propanesulfonate（MPS）activity by the electrostatic coupling between their cationic amine functionalities and the sulphonate of MPS.In addition,the modification of hydroxyl（-OH）or carbonyl（-C=O）groups triggered an extra inter-or intra-chain anion-cation pairing between the nitrogen-containing heterocyclic levelers and H₂O-Cu（I）-MPS,further inhibiting the activity of MPS and enhancing the uniformity of copper film.This provides theoretical guidance for the development of subsequent high-performance straight-chain levelers.