MEF studies for attenuated phase shift mask for sub 0.13 um technology using 248nm

Mask error factor (MEF) plays an important role as lithography progresses to sub wavelength patterning. For patterning feature in the sub wavelength region of the illuminating system, namely 0.10 um line and space feature, resolution enhancement techniques (RET) such as optical proximity correction (OPC),and assist features (AF) are applied. A study on the impact of MEF on 248 nm lithography will be investigated. Experimental results for both isolated line and dense lines up to 0.10 um with AF will be obtained and analyzed. A through pitch experimental study shows a decrement in MEF from dense line to semi-isolated line. Experimental studies on varying the placements of the assist features for both isolated will be conducted. Furthermore, the study also included the comparison by conventional and annular illumination for both line and space. Simulation results will also be utilised as a comparison.