AFM characterization of anti-sticking layers used in nanoimprint

Resist pull-off during mold-substrate separation is one of the major limiting factor for high resolution replication using nanoimprint lithography (NIL). Adhesion properties of anti-sticking layers (ASLs) are generally obtained using contact angle measurements; however, this technique does not take into account mold penetration into the polymer and interactions between the mold and resist that can affect the demolding step. In this paper, we present results on adhesion properties of different ASLs used for NIL, measured using AFM nano-indentation tests. AFM tips were coated with two different ASLs and nano-indentations were performed on three different polymers (NEB22A2, PMMA, and polycarbonate). The total force necessary to remove the AFM tip from the indented resist surface was measured for both ASL-coated and uncoated tips to more quantitatively analyse the importance of adhesion forces in NIL. Results show important influence of both ASL and polymer used on adhesion properties.