The semiconductor industry recently concluded that EUV lithography is the most promising candidate to replace ArF for the 22nm half-pitch node and beyond. Significant progress was made in EUV scanner and source technology and EUV resists have achieved acceptable performance levels as well. But issues related to EUV mask inspection and defectivity remain for the most part unanswered. This gap positions EUV masks as the leading risk to the entire technology, and requires a robust solution during the introduction phase of EUVL. In this paper we present results from a EUV mask inspection system. We demonstrate optimal pattern image formation by using illumination shaping, and consider detection of various defect types that represent realistic mask defectivity scenarios. These results demonstrate that DUVbased patterned mask inspection tool can meet the requirements of the pre-production EUV phase, at 32nm half-pitch, and has adequate room to extend to production at the 22nm node.

EUV lithography is regarded as the leading technology solution for the post-ArF era. Significant progress was made in recent years in closing the gaps related to scanner technology. This progress rendered EUV mask defectivity and related infrastructure as the primary risk for EUV lithography.The smallness of mask features, the novel defectivity mechanisms associated with the multilayer reflecting coating, and the stringent constraints on both multilayer and pattern imposed by the EUV wavelength -present a major challenge to current inspection technology, which constitutes a predominant gap to EUVL production-worthiness.Here we present results from an evaluation of a DUV mask inspection system and e-beam mask inspection technology on EUV masks. On this 193nm DUV system, we studied sensitivity and contrast enhancements by resolution enhancement techniques. We studied both pattern and blank inspection. Next, we studied image formation and performance of e-beam mask inspection technology for patterned mask defects. We discuss the advantages and roadmap of DUV and EBI mask inspection solutions for blank and patterned masks.

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Ever since the 180nm technology node the semiconductor industry has been battling the sub-wavelength regime in optical lithography. During the same time development for a 13.5nm Extreme Ultraviolet [EUV] solution has been in development, which would take us back from a λ/10 to a >λ regime again -at least for one node. Add to this the potential to increase the wafer size as well, and we are at a major crossroads.The introduction of EUV has been marred by many delays, but we are finally seeing the hardware development efforts converge and multiple customers around the world embarking on this adventure. As it becomes clear that this preproduction phase will occur at or below 20nmHP, it also becomes clear that this will happen at the limiting edge of existing 19x-based patterned mask inspection technology, reaching the practical resolution limits at around 20nm HP mask densities. Resolution is coupled with sensitivity and throughput such that the extended sensitivity may come at an unreasonable throughput. Loss of resolution also badly impacts defect dispositioning, or classification, which becomes impractical. As resolution is especially critical for die to database inspection, single die masks and masks with high flare bias are at risk of not being inspectable with 19xnm based inspectors.E-Beam based mask inspection has been proposed and demonstrated as a viable technology for patterned EUV mask inspection. In this paper, we study the key questions of sensitivity and throughput, in both die-to-die and die-to-database applications. We present new results, based on a new generation of E-Beam inspection technology, which has a higher data rate at smaller spot sizes. We will demonstrate the feasibility of acceptable inspection time with EBMI. We also will discuss die-to-data-base inspection and the advantage of using E-Beam imaging for meeting future requirements of single-die EUV masks. IntroductionThe EUV mask inspection challenge, using 193nm wavelength, becomes harder as nodes are getting smaller, resulting in higher false alarm events and significant scan time increases. This could raise the Cost-of-Ownership [CoO] beyond a reasonable point for the 16/11 nm nodes (see Figure 1,2). On the other hand, E-Beam inspection solutions are already available for wafer inspection. Naturally, the same E-Beam technology was proposed as a cost-effective solution for EUV high volume manufacturing [HVM] in mask shops and fabs, utilizing superior E-Beam resolution and imaging while applying scalable technology..In this study, we focus on the two main gaps for an E-Beam inspection system to be ready for EUV masks at production level requirements as well as reasonable Cost-of-Ownership. The first gap is Throughput : E-Beam inspection systems Extreme Ultraviolet (EUV) Lithography III, edited by Patrick P. Naulleau, Obert R. Wood II, Proc. of SPIE Vol. 8322, 832227 · © 2012 SPIE CCC code: 0277-786X/12/$18 ·