Novel and high-yield fabrication of electroplated 3D microcoils for MEMS and microelectronics

A novel and high-yield process is presented to fabricate electroplated 3D micro-coils for MEMS and microelectronics. The 3D Solenoid-type Integrated Inductor (SI2) is decomposed into two parts, bottom conductor lines and air bridges. The bridges are formed by only one electroplating step. This single-step fabrication of the electroplated air bridges is possible by forming the 3D photoresist mold with a Multi-Exposure and Single Development method (MESD). We have successfully demonstrated 3D micro-coils with or without a core. This method is so easy and simple that we can dramatically improve the fabrication yield, which is the hardest obstacle in the various 3D micro-coil fabrication methods. Also, this method has good IC process compatibility owing to low process temperature and the monolithic feature.