Control of parameters influencing the thermal imprint of parylene/silicon

The study aims to investigate the possible defects that may occur during imprinting of poly(chloro-p-xylyiene) (parylene-C) film (thermal oxidation, delamination, thermal cracking and insufficient filling at the periphery) and to overcome them by modifying the process conditions and mold design. X-ray diffraction (XRD) analyses results for the parylene-C films indicated that higher deposition pressure leads to a lower crystallinity of parylene-C film. By tuning the process conditions and mold design, patterned fields (composed of arrays of 25-mu m-high, 10-mu m-wide and 1-mm-long lines with 10 mu m spacing) in 0.4-mm-thick and 20-mm-sized nickel molds could be successfully replicated on 60-mu m-thick parylene-C films deposited at both 25 and 45 mTorr. Complete filling over the whole imprint area could be achieved at <270 degrees C with the press force at 2 kN and the press hold time of 900 s with the aid of an implemented dummy pattern. Both thermal cracking and delamination could be avoided, even at 270 degrees C, under the established process conditions and mold design with the help of an adhesion promotion treatment of silicon substrates (SF6 plasma etching for 2 min and spin-coating of KBM-503-based solution). Furthermore, the molds used for paryelne imprinting could be cleaned by dipping in chloronaphthalene solution at >175 degrees C, followed by an oxygen plasma etching.