Development of an electrochemical micromachining instrument for the confined etching techniques.

This study proposes an electrochemical micromachining instrument for two confined etching techniques, namely, confined etchant layer technique (CELT) and electrochemical wet stamping (E-WETS). The proposed instrument consists of a granite bridge base, a Z-axis coarse/fine dual stage, and a force sensor. The Z-axis coarse/fine dual stage controls the vertical movement of the substrate with nanometer accuracy. The force sensor measures the contact force between the mold and the substrate. A contact detection method based on a digital lock-in amplifier is developed to make the mold-substrate contact within a five-nanometer range in CELT, and a force feedback controller is implemented to keep the contact force in E-WETS at a constant value with a noise of less than 0.2 mN. With the use of the confined etching techniques, a microlens array and a curvilinear ridge microstructure are successfully fabricated with high accuracy, thus demonstrating the promising performance of the proposed micromachining instrument.