Inductively coupled plasma etching of bulk tungsten for MEMS applications

Tungsten based MEMS devices have the potential to be used for many applications, such as tools for micro electrical discharge machining and ultrasonic machining, or mold for inject molding. For the first time, bulk tungsten inductively coupled plasma (ICP) etching was developed and characterized, which is capable of producing high aspect ratio (>13) structures with feature size below 3μm. Etching depth of 230μm has been achieved at an etch rate up to 2.2μm/min. This technology offers big opportunities for MEMS applications.