2004 年 7 巻 2 号 p. 176-178
We have succeeded in forming high aspect ratio nickel bumps. The high aspect ratio of 0.66 nickel bumps have been obtained with additive of Coumarin in Watt-type bath and with 0.5μm thin photo resist. This 0.66 aspect ratio is more than twice as high as previous results. The outer surrounding diffusion of Coumarin inhibits the outer surroundings of bump forming cathodes and forms hump at the center. This inhibition effect depends on the thickness of photo resist. The thinner the photo resist the higher the aspect ratio of bumps. The obtained high aspect ratio bump is suited for flip chip interconnection and also for probers.