The width of tilted line patterns, such as are needed when drawing circular structures, is found to vary with the oblique angle when it falls into the sub-50-nm scale in Gaussian e-beam lithography. The authors' analysis shows that this orientation dependence of linewidth variation originates from the nonuniformity of discrete primitive filling in Cartesian coordinates. Two correction schemes based on pattern segmentation are proposed. Test exposures of high resolution zone plate patterns show that both two schemes work well; a double-insert scheme is superior in terms of dose distribution uniformity. (c) 2006 American Vacuum Society.