An extreme ultraviolet (EUV) lithography tool using 13.4 nm radiation is being developed by a consortium of integrated circuit (IC) manufacturers to support 100 nm imaging for integrated circuit production. The 4×, 0.1 NA alpha tool has a >1 μm depth of focus, all reflective optics, a xenon laser plasma source, and robust reflective masks. The technology is expected to support feature scaling down to 30 nm.
A model is proposed to explain radiation damage and charge trapping in the oxide layer of MOS devices after exposure to ionizing radiation. This model is based upon the close similarity between radiation effects in the silicon dioxide layer and in fused silica. In addition to explaining the production of damage by ionization, the model has an advantage over other models inasmuch as the charge trapping in a relatively impurity-free silicon dioxide layer can be explained. The model explains radiation-induced charge trapping in the oxide and subsequent annealing of the charge as a function of temperature and exposure to ultraviolet radiation. In addition, the model suggests that the sensitivity of MOS devices to ionizing radiation can be reduced by decreasing the amorphous structure of the oxide.
The Engineering Test Stand (ETS) is a developmental lithography tool designed to demonstrate full-field EUV imaging and provide data for commercial-tool development. In the first phase of integration, currently in progress, the ETS is configured using a developmental projection system, while fabrication of an improved projection system proceeds in parallel. The optics in the second projection system have been fabricated to tighter specifications for improved resolution and reduced flare. The projection system is a 4-mirror, 4x-reduction, ring-field design having a numeral aperture of 0.1, which supports 70 nm resolution at a k 1 of 0.52. The illuminator produces 13.4 nm radiation from a laser-produced plasma, directs the radiation onto an arc-shaped field of view, and provides an effective fill factor at the pupil plane of 0.7. The ETS is designed for fullfield images in step-and-scan mode using vacuum-compatible, magnetically levitated, scanning stages. This paper describes system performance observed during the first phase of integration, including static resist images of 100 nm isolated and dense features.
The extreme ultraviolet (EUV) Engineering Test Stand (ETS) is a step-and-scan lithography tool that operates at a wavelength of 13.4 nm. It has been developed to demonstrate full-field EUV imaging and acquire system learning for equipment manufacturers to develop commercial tools. The initial integration of the tool is being carried out using a developmental set of projection optics, while a second, higher-quality, projection optics is being assembled and characterized in a parallel effort. We present here the first lithographic results from the ETS, which include both static and scanned resist images of 100 nm dense and isolated features throughout the ring field of the projection optics. Accurate lithographic models have been developed and compared with the experimental results.
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