Assessment of EUV reticle blank availability enabling the use of EUV tools today and in the future

Abstract

With first full-field exposure tools for extreme ultraviolet lithography (EUVL) materializing, the present paper intends to review the status of the EUV mask infrastructure to assure timely availability of reticles, first for the alpha demo tool (ADT), but also in preparation for future use of EUV lithography in production. First, the major requirements such as low thermal expansion substrates, multilayer reflectivity control, flatness requirements and absorber related requirements are reviewed and motivated. In a second part the status of the infrastructure is reviewed, and it is shown that both for mask blank suppliers and mask shops full-field EUV reticles bring new challenges. Because the mask blank infrastructure is critical to the success of EUV lithography, IMEC has addressed blanks vendors (together with ASML) and mask shops, to get first feedback on the challenges recognized for production tool masks, exploring key parameters that impact overlay and imaging. IMEC has prepared to obtain reticles with an identical layout from multiple mask shops. The present paper gives a snapshot of the available EUV mask infrastructure, with a focus on blank related aspects, in an anonymous way. It is a report of work in progress. Figure 1: Photograph of the ADT installed in the IMEC cleanroom. The tool is interfaced with a TEL ACT12 track, as shown in front of the ADT.