Electroplating Copper Mask for Glass Deep Wet Etching in MEMS Relay

This paper reports an electroplated copper mask technology which consists of sputtered chromium and copper seed layer with electroplated copper and gold layer, in combination with hard baked thick AZ4620 photoresist based on MEMS technology. The etching depth attains to 680μm after more than 3 hours’ immerging in the concentrated HF 48% etching solution with smooth generated surface without pinholes. In addition, undercut ratio of 0.87 could be achieved. Compared with other masks in the literature, this electroplating mask technology is characterized by lithography compatibility, simple, low cost, short time consumption, large undercut ratio as well as smooth generated surface. Thus, it can be used in MEMS fields such as: precisely assignment of permanent magnet for the electromagnetic microrelay.