| 摘要 |
Methods and reticles are provided for performing charged-particle-beam microlithography in which degradations in transfer accuracy arising from the space-charge effect and/or resist heating are reduced. A reticle is divided into multiple exposure units (e.g., subfields) each having at least one pattern feature, and each exposure unit is divided into multiple subunits. Certain features include non-exposed regions having dimensions larger than the resolution limit of the projection-optical system used to project the reticle pattern onto the substrate. Also, the non-exposed regions are desirably smaller than the dimensional limit at which resolution is impossible due to the proximity effect. With stencil reticles, the non-exposed regions are preferably provided at boundaries between complimentary pairs of large-dimension features inside exposure units having different feature densities. The non-exposed regions absorb backscattered electrons from the exposure doses received by surrounding portions of the feature. The dose represented by the backscattered electrons is typically above a threshold value for developing the resist. Such features reduce the feature-density variation of the pattern as defined on the reticle.
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