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Electron projection lithography (EPL) is one of the leading candidates for next-generation lithography at the 65-nm lithography node, particularly for contact levels. EPL has traditionally employed either an open stencil mask with a single patterned (perforated) scattering layer or a continuous membrane mask with a patterned scattering layer supported by an un-perforated membrane. This article reports on an experimental study of a type of EPL mask developed by Team Nanotec that employs a continuous ultrathin membrane (UTM) comprised of a trilayer of carbon, silicon nitride, and carbon. These UTM masks combine all of the benefits of continuous membrane masks with the higher energy throughput (and the smaller chromatic aberration) of an open stencil mask.

Electron projection lithography (EPL) is a promising candidate for the next generation lithography choice. There are several advantages to EPL, such as a large depth of focus and a lower relative mask cost. Significant challenges also face this technology, including the limitation of the membrane format of the mask. One of the obstacles with the membrane format is image placement distortions, which can be very sensitive to the stress of the membrane as well as the pattern density. This paper studies how the stress of various types of films effects image placement distortions, as well as examines the effect of final mask cleans on image placement distortions.

Electron projection lithography ͑EPL͒ is one of the leading candidates for next-generation lithography at the 65 nm lithography node, particularly for contact levels. This article describes the results of an experimental effort to benchmark the current state of EPL stencil mask making. In this article, we report on the current status of the data handling software needed to pattern an EPL stencil reticle, EPL stencil reticle repair techniques, and EPL stencil mask stability following prolonged electron-beam irradiation.