Improved Anti-adhesive Coating for Nanoimprint Lithography

In nanoimprint lithography (NIL), it is essential to provide stamps with good anti-sticking surface properties. A low surface energy release layer on the stamps helps to improve the imprint quality, and it also increases the stamp lifetime significantly by preventing surface contamination. Low adhesion and friction at structure sidewalls can only be assured if the stamp is fully covered with a durable anti-adhesive layer, which sustains high temperatures and pressures of the NIL process [1]. Fluorinated trichlorosilanes are often used as anti-adhesive layers for Si stamps due to the stable covalent anchoring. They provide in many cases satisfactory results. However, the dense and fully cross-linked film is not easily achieved due to the OSi-O distance not leaving enough space for parallel, upright-standing fluorinated carbon chains [2]. In addition, the trichloro-silanes have some tendency to polymerize to bulk deposits. Therefore, we pursued a new route of the silane coating leading to a lower of surface energy and the absence of the polymerized bulk deposits by co-evaporating fluorinated C8 mono(TFDS) and trichlorosilanes (TFS) in the gas phase.