University of Durham

University of Sheffield

Nicholas Luke Seed

Alan Purvis

Richard Peter McWilliam

Peter Anthony Ivey

Gavin Lewis Williams

Andrew Maiden

Simon Johnson

Richard Ian Curry

Jose Juan De Jesus Toriz-Garcia

A light beam collimated by illumination optics () from a radiation source () illuminates the surface of a wave front modulator () such as an Spatial Light Modulator (SLM) or Computer Generated Hologram photomask (CGH). The resulting wave travels via projection optics () to the substrate (), passing through a projection lens assembly (). The SLM () is programmed or CGH configured with a modulation pattern that is determined by the substrate () topography and desired pattern. The substrate topography is provided by Digital Holography (DH) surface profilometery performed by a DH microscope (), which provides geometrical or topographical input to the CGH calculation routines (). An arrangement for vertical or sloping surface patterning has a grating () superimposed onto the CGH pattern () to generate +1 and &#x2212;1 orders. The SLM or CGH may be configured: using Fresnel patterns to provide an extended depth of field of the projected wave front; by encoding line segments of the desired pattern as cylindrical lines; by calculating inverse propagation between non-planar topography of the substrate and the SLM or CGH (using a Rayleigh-Sommerfield diffraction formula); and/or using iteration to determine a restricted encoding in the configuration of the SLM or CGH.

Exposure apparatus and methods

A method of generating a holographic diffraction pattern and a holographic lithography system. The method involves defining at least one geometrical shape; generating at least one line segment to represent the at least one geometrical shape; calculating a line diffraction pattern on a hologram plane, including calculating the Fresnel diffraction equation for an impulse representing the at least one line segment with a line width control term and a line length control term; and adding vectorially, where there are two or more line segments, the line diffraction patterns to form the holographic diffraction pattern. The method and system enables holographic masks to be generated without creating a physical object to record. The required shapes or patterns are defined in terms of a three-dimensional coordinate space and a holographic pattern is generated at a defined distance from the shapes in the coordinate space.

Generation of holographic diffraction patterns

Growing community of inventors

Sheffield, United Kingdom

Nicholas Luke Seed