Photolithography on micromachined 3D surfaces using electrodeposited photoresists

Photolithography on micromachined 3D surfaces is becoming a key process for the fabrication of a wide range of novel micromechanical devices. Due to the surface tension, photoresists deposited as a liquid cause problems at sharp corners, which occur commonly in micromachined silicon devices. This paper describes the application of an electrodepositable ultraviolet sensitive photoresist, which is commercially available and which is already used in printed circuit board production. Process considerations are discussed to apply this technology successfully to silicon substrates. The results show the feasibility of photolithography on surfaces with anisotropically etched 200 mu m deep cavities in (100) silicon.