Etchants

NBT has designed etching chemicals for the removal or patterning of metals, sacrificial layers or seed layers for electroplating. The requirements on the solutions depend on the plating sequence. The difference is whether the seed needs to be removed after plating with selectivity to all other materials and least dimension loss, or if the seed needs to be patterned before plating, which requires compatibility with masking resists.

Etchant	Application	Features
Au etch 200	Seed patterning/removal	Non-toxic, cyanide-free, very small undercut, resist compatible, selectivity to many metals and materials like Ni, Cr, Ti, Al, Ta, Pt; (Cu is etched); 50°C
Cr etch 200	Adhesion layer etching	Alkaline solution, RT, good selectivity to many metals like Au, Pt, Ta, Ti, Ni, Cu; (Ag is etched)
Cr etch 210	Adhesion layer patterning (resist mask)	Alkaline solution, compatible with resist for patterning, 40°C, good selectivity to many metals like Au, Pt, Ta, Ti, Ni, Cu; (Ag is etched)
TiW etch 100	Barrier layer removal	Compatible with resist, low undercut, contains fluoride, RT, selectivity to many metals and materials like Au, Ni, Cr, Sn; (Al and Cu with limitation)
TiW etch 200	Barrier layer patterning (resist mask)	Compatible with resist, low undercut, RT, selectivity to many metals and materials like Au, Cr, Ni; (Cu is etched)
Cu etch 100	Sacrifical layer removal	Alkaline etchant, compatible with resist for patterning or etching thick Cu layers, high undercut, RT, selective to Ni, Au, Ag, Al, Sn, Ti, Ta, Cr, Si, Si2N4, SiO2
Cu etch 150	Seed patterning/removal	Alkaline etchant, compatible with resist (e.g. Cu seed layers), selective to Ni, Au, Ag, Al, Sn, Ti, Ta, Cr, Si, Si2N4, SiO2
Cu etch 200 UBM	Seed patterning (resist mask)	Patterning of thin Cu layers, low undercut, compatible with resist, RT, selective to Au, Ni, Cr, Ti, Ta, Sn, Al, Pt)
AX 100	Activator for plating of nickel on nickel	Acidic pre-dip solution, 40°C application, improves significantly adhesion, where nickel is plated on nickel Etching