Capillary-Based Liquid Micro/Nano Deposition

Micro/Nanolithography is a creation of micro/nano features on the substrate. Several lithography techniques have been recently developed, including dip-pen nanolithography, nano-imprint lithography, electron-beam lithography, and photolithography. However, all these techniques possess some limitations because of a direct contact with the substrate. This paper proposes a new method that is non-invasive both to the substrate and to the writing tip. The method is based on hollow capillary filled with liquid to be deposited. The application of pressure from one side of capillary causes the liquid meniscus to form at the capillary outlet. Touching the substrate with the meniscus only leads to the liquid bridge formation between the capillary and the substrate. Withdrawing the capillary away from the substrate causes deposition of liquid droplet on the substrate. Theoretical modeling reveals two possible regimes of the liquid bridge formation: stable — “good” bridge and unstable — “bad” bridge. Liquid bridge stability map was created based on two parameters: liquid pressure and the capillary-substrate distance. It was found that the main parameter responsible for the deposition process is the applied pressure. Three pressure ranges were identified with different deposition scenarios. The influence of liquid-capillary and liquid-substrate equilibrium contact angles along with the capillary wall thickness on the liquid bridge stability is discussed.