A Novel Three-dimensional Microstructure Fabrication Method Based on Multilevel Imprint Lithography

A 3D layered fabrication process based onMultilevel imprint lithography (MIL) is proposed and thecritical issues involving template fabrication and overlayaccuracy were investigated. A fast and low-cost templatefabrication process based on glass wet etching is introduced, in which, the etching mask of Cr metal film is partially remained on top of the template pattern protrusionafter etching, which facilitates the residual resist removaland pattern quality improvement. An imprint tool withan alignment subsystem based on computer micro-visionis developed and the experimental results show an averageoverlay accuracy within 1.5μm with a standard deviationwithin 0.33μm. Finally, as an instance of the proposedmethod, the process based on MIL, electroplating and liftoff was investigated and tri-layer metallic structures with apattern feature size of 20μm were fabricated using the optimized process, which demonstrates the feasibility of thelayered fabrication method.