Simultaneous dose modification for balanced E-beam proximity correction minimizing CD error

Abstract

Many proximity effect correction schemes employ certain iterative procedures and often correct circuit features sequentially within each iteration for faster convergence. Such sequential correction procedures, whether dose or shape modification, tend to lead to unbalanced results due to the recursive effect especially for high-density fine-feature circuit patterns. In this paper, a dose modification scheme which performs correction non-recursively within each iteration is proposed in order to obtain spatially well-balanced correction results, minimizing CD error. A common drawback of such a non-recursive or simultaneous scheme is its long computation time required for convergence of the solution (correction result). In the proposed scheme, a scaling factor is used between successive iterations to avoid oscillation of the solution. Also, it partitions each rectangular feature into regions judiciously such that the total number of regions, on which correction time mainly depends, is not too large. Performance of the scheme has been analyzed through an extensive computer simulation.