Focused ion beam (FIB) etching of quartz and carbon for Levenson mask repair

The Etch-back and laser-explosion process was proposed and reported for Levenson mask rep air before. If convex defects and leveling film were etched by physical sputtering and remaining leveling film was removed by laser explosion in the etch-back and laser-explosion process, quartz (Qz) substrate was over-etched because the Ga implanted layer of Qz substrate was also removed. by the laser explosion due to the transmittance decrease of the Ga implanted layer, In this paper, gas assisted etching with the mixture of XeF2 and O2 was applied to the etch-back and laser-explosion process. The coincident etching rate of Qz (phase shifter) with C film was obtained, which is an indispensable requirement for the etch-back process, The optical transmittance of Qz substrate after the repair was 95% for the light of 250nm wavelength. The transmittance was sufficient to avoid over-etching of Qz substrate.