Rule-based methods for proximity-effect correction of charged-particle-beam lithography pattern using subregion-approximation for determining pattern element bias

Abstract

Methods are provided for determining bias of pattern elements of a pattern to be defined on a reticle for use in charged-particle-beam microlithography. The pattern elements, as defined on the reticle, are biased as required to reconfigure the pattern elements sufficiently to offset the proximity effect when the reconfigured pattern elements are projected onto and imprinted in a layer of resist on a lithographic substrate. The subject methods involve subregion-approximation to reduce calculation time while producing bias data that achieves pattern-transfer results that are sufficiently similar to as-designed ideal results of pattern-transfer accuracy and fidelity. For example, within a first subregion of the pattern the backscatter is different at each pattern-element location than in a second subregion. Within the first subregion on the reticle, all pattern element(s) are biased identically, and within the second subregion, all pattern element(s) are biased identically, but not necessarily at the same bias magnitude as in the first subregion position. Calculation of respective biases is made at the subregion level rather than the conventional element-by-element level, thereby reducing calculation complexity and hence calculation time.

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