New repair of clear defects on half-tone PSM using Ga implantation

The new repair of the clear defects on the half-tone PSM (EAPSM) was proposed. The Ga (gallium) ions were implanted by the FIB on the area adjacent to the carbon films formed on the clear defects. The Ga ion implanted area on the SiO2 substrate showed the semi-transparency at the KrF and ArF wavelengths. The lithography simulations of the layouts designed for the defect-repaired area endorsed the concept of the new repair. The Ga ion implantation was optimized to the new repair by using the AIMS and AFM measurements for the transmittance and etched depth of the SiO2 surface. The authors applied this method to the clear defects programmed on the KrF and ArF EAPSMs. The AIMS analysis showed that the deviation of the CD (critical dimension) of the defect-repaired regions on the wafer was within +/-5% to the non-defective reference at every defocused point. The new repair moderated the specification of the edge placement accuracy of the FIB processing compared to the conventional carbon film deposition.