1X HP EUV reticle inspection with a 193nm inspection system

The current industry plan is for EUV Lithography (EUVL) to enter High Volume Manufacturing (HVM) in the 2019/20 timeframe for the 1X nm half-pitch (HP) node (logic and memory). Reticle quality and reticle defects continue to be a top industry risk. The primary reticle defect quality requirement continues to be “no reticle defects causing 10% or larger CD errors on wafer (CDE)”. In 2013, KLA-Tencor reported on inspection of EUV reticles using a 193nm wavelength inspection system1. The report included both die-to-database (db) and die-to-die (dd) inspection modes. Results showed the capability to detect a wide variety of programmed and native reticle defects judged to be critical. We have developed extensions to the 193nm wavelength (193) inspection system for the typical 2019/20 HVM EUV reticle defect requirements. These improvements include innovations in: defect enhancement methods, database modeling, defect detection, and throughput. In this paper, we report on the latest data and results of this work, focusing on EUV reticle dieto- database inspection. Inspection results are shown using typical next generation EUV programmed defect test reticles and typical full field product-like EUV reticles, all from industry sources. Results show significant defect detection improvements versus the prior generation inspection system. We also report the test results of a high throughput die-todatabase inspection mode that could be used for the typical mask shop outgoing inspection of EUV reticles where particles are the primary defect to be detected and there is no pellicle (or the pellicle transmits 193nm wavelength²).