Fabrication of three-dimensional inductor coil using excimer laser micromachining

Abstract

Conventional lithographic techniques are typically used for the fabrication of three-dimensional multilayer structures such as micro-inductors and microactuators. In this work a novel approach based exclusively on laser micromachining of dry film resists and electroplating is presented. The process involves seed layer deposition, lamination of dry film resist, laser micromachining and electroplating to mould the resist patterns. The process is then repeated, using intermediate plating seed layers if necessary, to realize the three-dimensional coil structure. The steps for sacrificial material removal involve laser patterning and chemical removal of resist and plating seed layers. The major advantages with this process are that it has fewer steps compared to conventional UV-based processing technology, and it utilizes the benefits of dry film resist processing using the laser. A three-layer micro-inductor coil was designed and fabricated using the new laser micromachining-based processing technology. The problems encountered during fabrication and possible actions to address them are discussed. This work reports the first multilayer structure that has been fabricated exclusively using laser ablation for the patterning of resist. Furthermore, this work reports the first structural layer that has been fabricated using laser ablation of resist to expose an underlying intermediate plating seed layer.