Single Diallylamine Type Copolymer Additive which Perfectly Fills Cu Electrodeposition with only 1ppm

Cu via-filling is an essential technology for fabricating signal lines both on chips and on printed circuit boards and also through silicon via in 3-D wafer lever packaging for electrical devices. Generally, four additives, such as suppressors, accelerators, levelers and chloride ions, are added to a Cu electrodeposition bath in order to achieve bottom-up filling. The selection of additives and the control of additive concentrations are complicated and cause cost increase and complicated quality control. In order to solve these problems, we succeeded in developing bottom-up filling by only one additive, which has four kinds of functions. This additive is a diallylmethylamine copolymer, and it has cationic nitrogen and chloride ions and sulfur dioxide in its structure. The counter ion of diallylmethylamine copolymer was chloride ion and bromide ion. They were synthesized from the monomer with anions in aqueous solution from radical polymerization. Surface morphology and cross section of electrodeposits were observed by scanning electron microscopy (SEM) and optical microscopy (OM). Linear sweep voltammetry (LSV) and quarts crystal microbalance (QCM) were conducted.