Dear all,

I want to deposit Chrome and Gold twice on SiO2 grown
Si wafer by depositing and patterning the first Cr +
Au layer and again depositing Cr + Au on top of
patterned CR + Au and pattern and use as mask for KOH
bulk etching.

 The problem faced in the lab was that while etching
the top Cr layer after etching the top Au layer, the
etchant seeped to the bottom Cr layer through the
intermediate bottom Au layer pores and etches and
washes off the bottom Cr layer from SiO2 surface. This
leads to peeling and washing off of  intermediate Au
layer. Using positive photoresist on top of inner Au
layer also failed as during metallisation the PR chars
off due to high temperature making it difficult to
remove the PR.

 Can any one suggest a method to overcome the problem
please.

                            P K mohan