Selection Guide
Choosing an Etchant: Metal Type & Selectivity Matter
Etchants are metal-specific — Ti, Mo, Ru and W each need their own system; mixing causes attack or loss of control.
1Match the metal system
Ti uses oxidation+complexation or low-fluoride (ET-Ti/SE); Mo uses classic PAN (ET-Mo); Ru is at R&D stage in alkaline media (ET-Ru); W/TiW uses ammoniacal oxidation (ET-W). Never mix: the Mo main system attacks aluminum.
2Watch selectivity
Semiconductor-grade etch needs >100:1 selectivity to SiO₂/glass, no resist attack, and controlled undercut. Confirm geometry precision to pick the right grade.