Abstract
A new illumination system for mask aligner lithography is presented. The illumination system uses two subsequent microlens-based Köhler integrators. The second Köhler integrator is located in the Fourier plane of the first. The new illumination system uncouples the illumination light from the light source and provides excellent uniformity of the light irradiance and the angular spectrum. Spatial filtering allows to freely shape the angular spectrum to minimize diffraction effects in contact and proximity lithography. Telecentric illumination and ability to precisely control the illumination light allows to introduce resolution enhancement technologies (RET) like customized illumination, optical proximity correction (OPC) and source-mask optimization (SMO) in mask aligner lithography.
Highlights
Microlithography in mask aligners is widely used for transferring a geometric pattern of microstructures from a photomask to a light-sensitive photoresist coated on a wafer or substrate by exposing both with ultraviolet light, where the mask and the wafer are in close contact or proximity
Proximity lithography, where the photomask and the wafer are separated by a proximity gap of typically 30 to 200 microns is well suited for mass production, diffraction effects limit the resolution and fidelity of the pattern generated or printed in the photoresist
The presented new illumination system [1] provides excellent uniformity of the light irradiance, telecentric illumination and the possibility to freely shape the angular spectrum of the mask illuminating light to minimize diffraction effects in contact and proximity lithography
Summary
Microlithography in mask aligners is widely used for transferring a geometric pattern of microstructures from a photomask to a light-sensitive photoresist coated on a wafer or substrate by exposing both with ultraviolet light, where the mask and the wafer are in close contact or proximity. Proximity lithography, where the photomask and the wafer are separated by a proximity gap of typically 30 to 200 microns is well suited for mass production, diffraction effects limit the resolution and fidelity of the pattern generated or printed in the photoresist. These diffraction effects are related to the mask pattern and the angular spectrum of the illumination light. The presented new illumination system [1] provides excellent uniformity of the light irradiance, telecentric illumination and the possibility to freely shape the angular spectrum of the mask illuminating light to minimize diffraction effects in contact and proximity lithography
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
