Best metal mask for BOE/HF etching?

[Yinxiao Li]

I am thinking about using a metal mask for BOE or HF etching because I realize that for normal photoresist, it will gradually peel off and affect my results. I don't know which metal is the best--so far, I see people use Cr/Au, Al, and Ni. Anybody knows which metal will give the best result?

 

[Hyo X]

I am thinking about using a metal mask for BOE or HF etching because I realize that for normal photoresist, it will gradually peel off and affect my results. I don't know which metal is the best--so far, I see people use Cr/Au, Al, and Ni. Anybody knows which metal will give the best result?

what about using photoresist?

 

[leright]

I think the reason it peels is because of underetching (the HF etches underneath the resist as well, since it is an isotropic etchant). See this document for tips.

http://www.microchemicals.com/technical_information/hf_etching.pdf

 

[Yinxiao Li]

I think the reason it peels is because of underetching (the HF etches underneath the resist as well, since it is an isotropic etchant). See this document for tips.

http://www.microchemicals.com/technical_information/hf_etching.pdf

Thanks. I am still looking for the best mask that prevents this underetching...