Weichelt, T.T.WeicheltVogler, U.U.VoglerStuerzebecher, L.L.StuerzebecherVoelkel, R.R.VoelkelZeitner, U.D.U.D.Zeitner2022-03-042022-03-042014https://publica.fraunhofer.de/handle/publica/23655410.1364/OE.22.016310The application of the phase-shift method allows a significant resolution enhancement for proximity lithography in mask aligners. Typically a resolution of 3 mu m (half-pitch) at a proximity distance of 30 mu m is achieved utilizing binary photomasks. By using an alternating aperture phase shift photomask (AAPSM), a resolution of 1.5 mu m (half-pitch) for non-periodic lines and spaces pattern was demonstrated at 30 mu m proximity gap. In a second attempt a diffractive photomask design for an elbow pattern having a half-pitch of 2 mu m was developed with an iterative design algorithm. The photomask was fabricated by electron-beam lithography and consists of binary amplitude and phase levels.en621journal article