In-Situ Aberration Metrology Using Phase Wheel Targets

Aberration metrology and monitoring of lithography projection systems in the semiconductor industry are becoming more important as today’s ICs are printed at sub-100 nm resolution. All lenses suffer from lens aberrations and it is important that the lithographer knows which aberration and the magnitude of the aberration in order to understand its impact on the process window and resolution limitations. A technique and process to recognize and measure lens aberrations in-situ has been developed using a phase wheel target at 157nm and 193nm lithography. This project will use the phase wheel target technique to extend aberration monitoring into i-line lithography using RIT’s Canon exposure tool. Test reticle design, layout and fabrication, as well as the exposure process optimization will be carried out for the technique to work at 365nm. First order aberrations from the Canon exposure tool will be identified using this system