Paper
30 September 2003 Rapid photo-lithographic technique for high-resolution micro-optics
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Abstract
An interesting alternative to the former use of HEBS glass (suitable e-beam exposed to give a “true” variable transmission contact mask) is the “simulated” variable transmission gray-tone projection reticle. It is simply obtained from a film generated on a 4000 dpi laser writer and then 10x reduced on a Cr.-glass plate. This projection gray-tone reticle, having sub-resolution pixel elements, is able to modulate light intensity in a thick positive resist to give arbitrary 3-D shapes. A tremendous enhancement in resolution, both for horizontal and vertical direction, was obtained by applying an original combination of binary masking technique (N powered by M levels for M reticles having each N gray-tones) with a proper focusing depth of the projection objective (just at the middle of the exposed resist layer). So, it was possible to structure a thick resist in very complex smooth 3-D shapes, which are very useful for micro-optics, by using M exposing steps. Interesting applications for micro-optics are given.
© (2003) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Niculae Dumbravescu "Rapid photo-lithographic technique for high-resolution micro-optics", Proc. SPIE 5227, Advanced Topics in Optoelectronics, Microelectronics, and Nanotechnologies, (30 September 2003); https://doi.org/10.1117/12.520096
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KEYWORDS
Reticles

Lithography

Photomasks

Micro optics

Binary data

Diffraction

Modulation

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