Abstract
Center humped bump is ideal shape for high density interconnection. This is because of smaller interconnection area and less lateral expansion in thermal compression. Coumarin additive was found to show inhibition effect and diffusion control from current-potential curves with rotation disk electrode. The two layered photo resist structure was newly introduced. With two layered resist structure and Coumarin, we succeeded in forming center humped bumps. The center humped bump has aspect ratio of 0.6 having 12μm height and 20μm diameter.
