Levelers Effect On Residual Stress Of Electrodeposited Copper Used In TSV Filling

Through Silicon via(TSV) is a novel technology of 3D chip interconnection. It can realize the interconnection by making through-silicon vias between chips and wafers. Using electrodeposited copper to fill TSV has become a trend for its low cost, high efficiency and perfect filling. Residual stress in TSV caused by copper electrodeposition will influence subsequent process and cause electronic products failure. So the study on copper residual stress is of vital importance. In this paper, we studied the effect of levelers effect on the residual stress of electrodeposited copper.In this study, we choose levelers 2-MP(2-mercaptopyridine), JGB(Janus green B) and 2-ABT(2-aminobenzothiazole) to study the mechanism of how levelers influence the residual stress of electrodeposited copper film. To find the cause, leveler’s effect on film texture, surface morphology, impurity content, grain size and the electrochemical behavior are studied. The result show that when useing 2-MP,JGB and 2-ABT as levelers, residual stress decreases in the order of 2-MP,JGB,2-ABT. Levelers effect on residual stress is decided by its nhibitory ability and adsorbability at the cathode. The higher the nhibitory ability and adsorbability, the smaller grain size and higher impurity content, this produce a larger tensile stress. vice versa.We also studied the film stress evolution during self-annealing. The driving force is the decrease of the total energy of the film. When self-annealing procedure is finished, the grain size increases about 10 times, texture evolution is thought to be depended on the leveler type: when 2-MP is used as leveler, the film texture change is not obvious; when use JGB,(220) will grow preferentially during self-annealing; when use 2-ABT,(200) will become the prefered orientation; How the residual stess evolve depend on the competetion of tensile stress and compressive stress induced during self-annealing.