By Eulitha AG
What is DTL? Displacement Talbot Lithography (DTL) prints periodic nanostructures down to ~60 nm in a non-contact configuration, using the light diffracted by a periodic mask. The substrate moves through the interference pattern during the exposure, which gives a depth of focus orders of magnitude larger than projection tools of the same resolution. Patterning works on topography, on curved surfaces and on substrates that do not lie flat. Eulitha builds i-line and DUV tools on this process, from manual R&D systems to fully automated high-volume platforms. How DTL works Eulitha's Displacement Talbot Lithography (DTL) is a new paradigm in optical lithography. It leverages the properties of light diffracted by a periodic pattern on a mask to print periodic nanostructures with unparalleled resolution and precision in a non-contact configuration. In a DTL exposure, a periodic mask is illuminated by a coherent light source, such as a laser. This illumination produces an intricate interference pattern between the mask and substrate planes. During exposure, a substrate with photosensitive material displaces, or moves through the interference pattern, patterning the desired nanostructures with exceptional accuracy. The process of integration by the substrate movement creates an extremely large effective depth of focus which is many orders of magnitude larger than projection tools with comparable resolution. This is particularly useful when patterning on topography, curved surfaces, or substrates that struggle with flatness. Eulitha offers a variety of optical lithography tools purpose-built to take advantage of the DTL concept. The range of tools includes different wavelength choices such as i-line and DUV wavelengths depending on resolution needs of the application, manual R&D systems and fully automated high volume manufacturing systems. Advantages DTL patterns down to a ~60 nm minimum critical dimension at low cost, with reliable, repeatable results. Three properties of the process make that possible: Large exposure fields - 140 mm x 140 mm imageable area (with 6 in standard mask) - Seamless device printing - No complex reduction/magnification optics Very large depth of focus - Patterning on surfaces that are non-planar, topography, curved, etc. - Up to millimeters of depth of focus (DOF) Mask-locked design - Tight pitch control (down to 2 pm) - Single-exposure design can have different patterns, pitches, duty cycles, and orientations
