Stiction problems in releasing of 3D microstructures and its solution

Micro-stereolithography (μSL) is capable of fabrication of highly complex three-dimensional (3D) microstructures by selectively photo-induced polymerization from the monomer resin. However, during the evaporative drying of structures from liquid resin, the 3D microstructures often collapse due to the capillary force. In this work, a theoretical model is developed to analyze the deflection and adhesion between thin polymer beams under capillary force. The detachment length of the test structures and adhesion energy of a typical μSL polymer (HDDA) are obtained experimentally which are important for MEMS structure design. Finally, we successfully developed a sublimation process to release the 3D microstructures without the adhesion.