Fabrication of Micro Bump Using Electroless Plating

近年来，微电极在集成电路芯片和高密度线路板上的形成已变得十分重要。首先，研究了化学镀镍在铝电极上形成的微凸点。用镍置换法代替锌酸盐法在铝表面形成了宽20 μ m、高15 μ m的微镍凸起。在凸起形成过程中，控制沉积反应的早期行为是很重要的。用二甲基胺硼烷（DMAB）溶液代替镍置换溶液活化电极，在电极上形成扁平凸起。我们检查了高密度布线的电镀作为IC安装所需的下一个研究。在铜表面化学镀镍过程中，通常采用钯催化剂作为前处理。而使用DMAB和镍的混合溶液代替钯催化剂溶液时，没有发生外源沉积。在化学镀镍液中加入DMAB可在铜衬底上获得化学镀镍膜。通过控制还原剂的氧化和化学镀镍的早期阶段，形成了选择性镍沉积。

Recently, the formation of microelectrode on the IC chip and the high density wiring board have become important. First, a microbump formation on the aluminum electrode using the electroless nickel plating was investigated. The micro nickel bumps of 20 mum wide and 15 mum high were formed by applying the nickel displacement process instead of the zincate process on the aluminum. It is important to control the behavior of the early stage of deposition reaction in the bump formation. The flat bumps were formed on the electrode by activating with the dimethyl amine borane (DMAB) solution in place of the nickel displacement solution. We examined the plating of the high density wiring as the next research that is required to IC mounting. Generally, the palladium catalyst has been used as the pretreatment to initiate the electroless nickel plating on copper. However, the extraneous deposition did not occured using the mixed solution of DMAB and nickel instead of the palladium catalyst solution. The electroless nickel films can be obtained on the copper substrate adding DMAB into the electroless nickel plating bath. Furthermore, the selective nickel deposition was formed by the control of the oxidation of reducing agent and early stage of electroless nickel plating.