HI,

very recently, i singly spin coat Su-8 2025 at 2k rpm, the thickness is
about 40 um. to remove edge bead, after coat the PR (before soft bake),
i spin the wafer at about 500 rpm (no rationale, can be faster or
slower), at the same time, manually use a dropper to drop acetone at the
edge. then the bumping edge can be removed.

zeta
ucla

Jiang Ziling wrote:

>Dear all,
>  We have Su-8 2025, which is 25um thick at 4000rpm. We want to gain
>thickness of 40um so we tried double-spin. We found that edge bead is very
>serious and the surface is not so smooth as single spin. Anyone knows any
>method to enhance its performance, such as, whether we should bake it after
>each spin, and remove edge bead after each spin? What is the usual solvent
>used to remove Su8 edge bead? And how?
>  cheers
>  Jiang Ziling
>