TK

I assume you need the Cr for adhesion. If so, and your contaminant is brownish
in colour, try Ti instead if it fits your chemistry. The contaminant likely will
disappear as I am just guessing it is a form of chromium hydroxide that can be
formed by the presence of humidity and in my case, excess electrical current.
I'm wondering if your e-beam litho could have a similar effect.

Rick Williston