Thermal imprint process of parylene for MEMS applications

This study investigated a thermal imprint technique to pattern parylene microstructures over an area of 25×25 mm². A nickel mold having arrays of 25 μm-high, 10 μm-wide and 1 mm-long lines with 10 μm spacing was fabricated using the deep RIE silicon etching followed by the electroplating process. Imprint tests were then carried out under different conditions of temperature, imprint-hold time and applied pressure to investigate a thermal imprint condition for the complete filling of parylene. Good release results without damage or deformation in parylene microstructures were achieved by the help of a release agent in the imprint temperature range of 160°C to 250°C. With increasing temperature, the depths of imprinted structures increased and their distribution came to be homogeneous. Complete filling was obtained under the imprint temperature of 250°C, applied load of 195 kgf (3 MPa) and imprint hold time of 1800 s.