無電解ニッケルめっきによるアルミニウム上へのマイクロバンプ形成

抄録

Chip bumping for flip chip and tape automated bonding (TAB) assembly has become increasingly important in microelectronic devices. Several methods using vapor deposition followed by electrolytic deposition to form bumps on a spattered aluminum electrode have been reported. The metallization process can be simplified by use of the electroless plating process. Generally the zincate process is used for electroless nickel plating on aluminum substrate. However, the process can not be applied to the metallization of fine circuits, pads or microbumps with photoresists because photoresist are attacked by the highly alkaline zincate solution. Accordingly, electroless nickel plating on aluminum substrate by methods other than the zincate process have been investigated. As a result, straight-walled bumps of up to approximately 20μm in height and between 20μm to 80μm in cubic area can be formed without damege to the photoresist by nickel displacement followed by electroless plating. In addition, nickel bumps can be more uniformly fabricated on an aluminum substrate initially accelerated with DMAB and followed by electroless nickel plating.