| Super-filling copper-plating technology is the key to metallization processes for Printed Circuit Boards(PCB),especially High Density Interconnect(HDI)boards.At present,Super-filling copper-plating is selected from acidic sulfate copper plating systems,and the key to acidic sulfate copper plating is the selection and use of additives.In this paper,the accelerator is taken as the research object.According to the composition and structural characteristics of the molecule,the organic molecules to be studied are divided into two groups:1)linear alkane in the molecule;2)five-membered heterocyclic ring in the molecule.Firstly,the effects of various organic molecules on the copper plating process were studied by electrochemical methods such as cyclic voltammetry and chronopotentiometry.The results show that all organic molecules have an accelerating effect on the copper plating process,but the accelerated response time and acceleration intensity exist differences.Next,the effects of accelerator concentration,convection intensity and chloride ion on accelerator acceleration are revealed in detail.The results show that:1)H1,SH110,TPS and M have critical concentrations,and they all show accelerated copper at low concentration.while inhibiting copper deposition at high concentration;2)The weaker the convection intensity,the more obvious the acceleration effect of the accelerator on the copper plating process;3)The DMPS and TPS accelerate more under chlorine-free conditions,and other accelerators perform.For inhibition.Then,the adsorption-desorption behavior of the accelerator molecules on the electrode surface was revealed by pre-adsorption-desorption experiments.The results showed that chloride ions can enhance the adsorption strength of the accelerator molecules on the electrode surface and prolong the desorption time,but accelerate under chlorine-free conditions.The amount of molecules adsorbed is more.In order to further study the mechanism of the effect of accelerator molecules on the copper plating process,The effect of accelerator molecules on Cu+ production of copper intermediates was studied by means of rotating ring disk electrode(RRDE)technology,and the influence of accelerator molecules on the copper deposition rate-determining step(RDS)was also determined.The results show that the sulfhydryl group and the sodium sulfonate group in the accelerator molecule have nothing to do with the yield of Cu+;while the presence of chloride ions can enhance the oxidation peak of Cu+.Finally,the potential time curve under strong and weak convection is tested by chronopotentiometry,and then the difference between the strong and weak convection potentials is calculated.According to the Convection-Dependent Adsorption(CDA),the microvia filling effect of the accelerator molecules is predicted.The results show that MPS,TPS and M accelerators are most likely to achieve overfilling.Next,the surface morphology,crystal structure and pore filling effect of the copper plating layer obtained by different accelerator molecules were characterized by the actual electroplating copper filling microvia experiment.The results showed that the surface of the three accelerator systems MPS,SH110 and TPS The growth orientation of the copper layer in the[200]direction is enhanced,which improves the flatness and brightness of the surface copper layer.However,the flatness of the copper layer on the surface of the M system is very poor.MPS,TPS and M all have super-filling capabilities.By introducing a level to optimize the DMPS and M systems and verifying whether H1 and TPS can be super-filled as a single additive,the results show that the introduction of JGB can make the DMPS system super-filled,and the introduction of PN can improve the flatness of the copper layer on the surface of the M system;both H1 and TPS can be used as a single additive to achieve super-filling,and the optimal filling concentration is about 2.5 mg/L and 5 mg/L,respectively. |
PDF Full Text Request