Masks for electron projection lithography ͑EPL͒ require the use of thin membranes for either stencil or all membrane scattering masks. The processes of forming the printable patterns before or after the membrane etch step are compared for EPL stencil masks. Image size uniformity and image placement distortions are characterized and indicate, with appropriate process optimization, either process flow is viable for EPL mask manufacture. Image size uniformity within individual membranes has achieved Ͻ10 nm ͑3͒ with the membrane flow process, and the magnitude of process induced image placement distortions is similar for both process flows. Stencil masks have also been fabricated with support rings. The masks with support rings show more repeatable absolute image placement, but the image placement distortion due to patterning is nearly identical for masks with or without a support ring.

Articles you may be interested inProximity and heating effects during electron-beam patterning of ultraviolet lithography masks Electron projection lithography mask format layer stress measurement and simulation of pattern transfer distortion J.Proximity effect correction using pattern shape modification and area density map for electron-beam projection lithography J.The development of a low-distortion mask is critical to the success of the sub-0.1 m lithography technologies. Electron-beam projection lithography ͑EPL͒ is one of the potential candidates for next-generation lithography. In order to minimize mask image placement ͑IP͒ errors, it is important to understand the factors that induce pattern distortions during mask fabrication and pattern transfer. The fabrication process flows for two EPL mask formats were numerically simulated and experimentally assessed for IP. This study included continuous membranes and stencil membranes for 1 mm ϫ1 mm and 1 mm ϫ12 mm window sizes on a 4 in. wafer. Both intramembrane ͑i.e., within a single window͒ and intermembrane ͑i.e., cross-mask͒ results are reported with excellent correlation between the finite element ͑FE͒ data and the experimental measurements. In this article details of the FE simulations are presented; an article by ͑M. Lercel et al., J. Vac. Sci. Technol. B, these proceedings͒ describes the corresponding experimental work.

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