<title>Lithographic performance at 0.3- to 0.35-um patterns by using i-line stepper with off-axis illumination technology</title>

Abstract

The process performance of i-line annular and quadruple off-axis illumination apertures with various opening sizes for pattern feature in the range of 0.4micrometers to 0.3micrometers were addressed in this paper. The process performance was theoretically and experimentally studied in terms of DOF performance and proximity effect. For L/S features, imaging resolution on wafer can only be improved to 0.35micrometers for annular aperture and to 0.30micrometers for quadruple aperture by using stepper with NA equals 0.48 and coherent factor of 0.62. In terms of opening ring size, smaller sized holes for quadruple or ring for annular leads to larger DOF. But for single line feature, DOF performance is much better by using quadruple apertures than by using annular aperture and DOF performance is not strongly dependent on the opening size of aperture stops. Comparing the process performance of single and dense line features, quadruple aperture can benefit in process control in 0.30 to 0.35micrometers patterning. However, proximity effect between L/S and single line becomes worse as the imaging feature gets down to 0.3micrometers . This large proximity effect is also related to the opening size of ring or hole in aperture stop. Therefore optical proximity correction is needed in 0.3-0.35micrometers feature patterning.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.