Articles you may be interested inFocused helium and neon ion beam induced etching for advanced extreme ultraviolet lithography mask repair Testing new chemistries for mask repair with focused ion beam gas assisted etching Hard mask fabrication for magnetic random access memory elements using focused ion beam assisted selective chemical vapor depositionThe key challenge in extreme ultraviolet ͑EUV͒ mask defect repair is to avoid or limit the damage to the sensitive reflective multilayer ͑ML͒ stacks on the mask substrate and repair Ͻ55 nm mask defects. Our EUV mask design employs an oxide buffer layer between the ML and the absorber to protect the ML during repair. We have developed both opaque and clear EUV mask defect repair processes using focus ion beam ͑FIB͒ based gas-assisted etching ͑GAE͒ and ion-induced deposition. The process has been successfully demonstrated on our TiN baseline mask by 10ϫ EUV print tests of 100 nm resist lines/spaces. More importantly we have assessed the current FIB tool performance capability and compared it with the general requirements for repairing the EUV mask for the 70 nm lithography node. The characterization includes minimum ''effective'' beam size, etch selectivity, and edge placement precision. We discussed the required improvements and future directions in repair tool research and development in order for the mask repair technology to keep pace with lithography scaling in future generations.
In extreme ultraviolet lithography (EUVL), the multilayer (ML) damage-free mask patterning processes and damage-free usage cycle are the keys in obtaining a successful, functional EUVL mask. A robust ML capping layer design will enable a long mask lifetime. In this article detailed investigation on the viability of ruthenium (Ru) thin films as capping layer for EUVL ML mask blanks is presented. The study is focused on Ru capping layer design for high reflectivity and its properties relevant to EUVL mask applications, such as microstructure, stress, optical properties at EUV wavelength, and chemical durability. The authors found that Ru thin films with a crystalline structure present a very high compressive stress which is insensitive to the primary ion deposition source energy. The Ru∕Si interdiffusion layer, however, presents a much lower stress than the of Ru-only film. Amorphization of the Ru film is via atomic composition modification, which the authors believe could be one of the keys in reducing Ru film stress. The ruthenium cap, under a piranha chemical clean, was found to be more durable than Si capped ML blanks, indicating the advantages of using Ru as the EUVL ML mask blank capping layer.
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.
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