| Popis: |
CD metrology requirements have increased dramatically within the last years. For the coming technology generations, it is not clear which CD measurement method will be standard for mask manufacturing. An interesting approach is to use the diffracted signal of periodic mask patterns for determination of CD. For wafer CD measurement, CD scatterometry tools using visible or UV wavelengths are already commercially available. For this experiment, diffracted EUV light was used. Dense lines of pitches 1:1, 2:1 and 5 :1 and nominal CDs of 150 nm, 200 nm, 300 nm, 400 nm and 500nm have been illuminated with EUV light of ?= 13.35 nm at the BESSY II storage ring in Berlin. The reflected signal has been collected with a movable detector in a range of -1 ° to 200 relative to the specular reflection. With the angular position of the peak, the pitch can be calculated. The CD, however, is related to the intensity of the peaks. Several effects as mask topography and measurement uncertainties are discussed. The results are compared to CD-SEM measurements of the same patterns. |
