22.3. Processing After Lithography

After the resist pattern is in place, wafers can experience several different process steps, which have their own specific requirements for resists. And after wafer processing, resist removal is affected by the processes which the resist underwent.

Wet-etching quality depends critically on resist adhesion. Wet etchants do not etch resist in most cases, but liquid penetration between substrate and resist leads to adhesion loss. Resists have been tailored specifically for wet etching, with low molecular weight and good adhesion. The same applies to electroplating and electroless plating.

Wet-etching processes are mostly immersion processes where the etchant attacks both sides of the wafer. In many MEMS applications, ...

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