A method and system for fabricating an array of electronic devices, typically a display or sensor is described. In the method, a droplet source ejects droplets of a masking material for deposit on a thin film or substrate surface to mask an element of the array of electronic devices. The temperature of the thin-film or substrate surface is controlled such that the droplets rapidly freeze upon contact with the thin-film or substrate surface. The thin-film or substrate is then etched. After etching the masking material is removed.