title: Digital projection photochemical etching defines gray-scale features.
abstract: We demonstrate a maskless photochemical etching method that is capable of performing one-step etching of multi-level structures. This method uses a digital projector to focus an image onto the sample and define the etching pattern. By combining digital projection photochemical etching with diffraction phase microscopy, etch heights can be measured in situ in a non-destructive manner. This method is single shot, eliminating the need for expensive gray-scale masks or laser scanning methods. The etch rate is studied as a function of the wavelength and irradiance of the projected light. A lateral etch resolution of 2 μm is demonstrated by etching selected portions of the USAF-1951 target. Micropillars, multi-level plateaus, and an Archimedean spiral are etched, each in a single processing step, to illustrate the unique capabilities.
authors.affiliation: Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors.forename: Chris
authors.initials: C
authors.lastname: Edwards
authors.forename: Kaiyuan
authors.initials: K
authors.lastname: Wang
authors.forename: Renjie
authors.initials: R
authors.lastname: Zhou
authors.forename: Basanta
authors.initials: B
authors.lastname: Bhaduri
authors.forename: Gabriel
authors.initials: G
authors.lastname: Popescu
authors.forename: Lynford L
authors.initials: LL
authors.lastname: Goddard