A novel method for utilizing AIMS™ to evaluate mask repair and quantify over-repair or under-repair condition

摘要

The ZEISS AIMS™ platform is well established as the industry standard for qualifying the printability of mask features based on the aerial image. Typically the critical dimension (CD) and intensity at a certain through-focus range are the parameters which are monitored in order to verify printability or to ensure a successful repair. This information is essential in determining if a feature will pass printability, but in the case that the feature does fail, other metrology is often required in order to isolate the reason why the failure occurred, e.g., quartz level deviates from nominal. Photronics-nanoFab, in collaboration with Carl Zeiss, demonstrate the ability to use AIMS™ to provide quantitative feedback on a given repair process; beyond simple pass/fail of the repair. This technique is used in lieu of Atomic Force Microscopy (AFM) to determine if failing post-repair regions are "under-repaired" (too little material removed) or "over-repaired" (too much material removed). Using the ZEISS MeRiT® E-beam repair tool as the test platform, the AIMS™ technique is used to characterize a series of opaque repairs with differing repair times for each. The AIMS™ technique provides a means to determine the etch depth based on through-focus response of the Bossung plot and further to predict the amount of MeRiT® recipe change required in order to bring out of spec repairs to a passing state.