Study On Super - Electroless Nickel Plating In

Iron, cobalt, nickel and related alloys have favorable property, such as magnetism, abrasive resistance, corrosion resistance and therefore are widely used in the automotive and electronics industries. At present, S. K. Kim completed bottom-up filling on electro nickel deposition. And then C. H. Lee completed bottom-up filling used the synergy effect of MB on electro nickel deposition. But with the increase of people demand, electronics began develop to the aspect of thin, intelligent, multi-function and so on, thus will be more and more requirements are put forward on the circuit board, hierarchical, high density circuit layout is the trend of its development, therefore the higher and higher demands about the fabrication of metal interconnect are proposed in ultra large-scale integration circuit, but when a conductive layer by filling in nickel plating technology have some problem, and therefore will be replaced by bottom-up nickel filling with the electroless nicke plating solution.In this paper, the effects accelerator and inhibitors additives on the bottom-up filling in the electroless plating were investigated, and bottom-up nickel filling was obtained using sodium hypophosphite as a reducing agent. The formation mechanism of bottom-up nickel filling in the electroless nickel plating bath included of various additions were investigated by electrochemistry method.The content of this thesis is as follows:First of all, This article choose in lactic acid as complexing agent sodium hypophosphite as the reducing agent of electroless plating nickel solution, with a large number of screening choose the suitable accelerating and inhibitor Additives, MPS,2-mercaptobenzothiazole, sodium thiosulfate as accelerator, soluble chitosan, polyethylene imine5000as inhibitor, and choice of additives for further mix. Then the effect of the additives on the deposition rate, deposited nickel microstructure and surface morphology were researched, further to choose the appropriate mixed additives MPS and PEI-5000. The study found that with the increase of concentration of MPS the nickel deposition rate was increased, until concentrations reach5.0mg/L, deposition rate from5.12to6.92μm/h, and decreases with the concentration of PEI-5000, until concentrations reach2.0mg/L, the final deposition rate reduce to2.33μm/h, but when these two kinds of additives are added together, namely5.0mg/L MPS and2.0mg/L PEI-5000, the average deposition rate down to1.31μm/h, appear the synergistic inhibition effect.And then the effects of additives on the polarization behaviors of the electroless nickel plating bath were investigated by the linear sweep voltammetry method, and for the cause of the additive effect on deposition rate was reasonabled explanation.Finally, when choose5.0mg/L MPS and2.0mg/LPEI-5000was added in electroless nickel bath, the bottom-up filling behaviors of electroless nickel bath with200nm widths and500nm depths trenches were not achievemented. It is the reason of in the later period of the bottom-up filling appear caking phenomenon, it is bad for the filling. So the surface active agent was continued add in the plating solution, to improve the particle size of nickel layer and to achievement the bottom-up filling. When surface active agent was added, the bottom-up filling behaviors of electroless nickel bath with200nm widths and500nm depths trenches were achievemented, and the cross-section SEM observation indicated the trenches with different widths ranging were all filled by electroless nickel, but the filling effect is not very satisfactory.