Simulations of deposition of dip-pen nanolithography and annealing characterizations of patterns

摘要

The pattern transfer mechanism of an alkanethiol self-assembled monolayer(SAM) during the dip-pen nanolithography(DPN) process and pattern characterizations after annealing process are studied using molecular dynamics(MD) simulations.The mechanisms of molecular transference, meniscus characteristics, contact angle, surface adsorbed energy, and pattern formation are evaluated during the DPN process at different deposition temperatures.The simulated results clearly show that the molecular transfer ability in DPN is strongly dependent on the deposition temperature.The transfer ratio in the high deposition temperature of 500 K is about eight times more than in the low deposition temperature of 100 K.When the molecules are deposited at low temperatures of 100?300 K, the meniscus area on the substrate is smaller and the meniscus length can be pulled longer by the atomic force microscope(AFM) tip, and the whole transfer process is relatively stable.However, at the high temperature deposition, both gasification number and transfer number of HDT molecules increase, and the deposited structure is looser.A high temperature can also easily cause non-specific deposition on the substrate surface.In the annealing process, when the highest temperature is below 500 K, the nanodot contours have become smoother and have both a highly concentrated and highly packed structure as the annealing temperature increases.