The prospect of EUVL (Extreme Ultraviolet Lithography) insertion into HVM (High Volume Manufacturing) has never been this promising. As technology is prepared for "lab to fab" transition, it becomes important to comprehend challenges associated with integrating EUVL infrastructure within existing high volume chip fabrication processes in a foundry fab. The existing 193nm optical lithography process flow for reticle handling and storage in a fab atmosphere is well established and in-fab reticle contamination concerns are mitigated with the reticle pellicle. However EUVL reticle pellicle is still under development and if available, may only provide protection against particles but not molecular contamination. HVM fab atmosphere is known to be contaminated with trace amounts of AMC’s (Atmospheric Molecular Contamination). If such contaminants are organic in nature and get absorbed on the reticle surface, EUV photon cause photo-dissociation resulting into carbon generation which is known to reduce multilayer reflectivity and also degrades exposure uniformity. Chemical diffusion and aggregation of other ions is also reported under the e-beam exposure of a EUV reticle which is known to cause haze issues in optical lithography. Therefore it becomes paramount to mitigate absorbed molecular contaminant concerns on EUVL reticle surface. In this paper, we have studied types of molecular contaminants that are absorbed on an EUVL reticle surface under HVM fab storage and handling conditions. Effect of storage conditions (gas purged vs atmospheric) in different storage pods (Dual pods, Reticle Clamshells) is evaluated. Absorption analysis is done both on ruthenium capping layer as well as TaBN absorber. Ru surface chemistry change as a result of storage is also studied. The efficacy of different reticle cleaning processes to remove absorbed contaminant is evaluated as well.
In this work, the SEMI specification for reticle and pod management (E109) with internal reticle library support has been
integrated for the first time on KLA-Tencor’s TeronTM and TeraScanTM reticle inspection tools. Manufacturing
Execution System scheduling reticle jobs and Automated Material Handling System scheduling to transfer pods
simultaneously have also been integrated and tested. GLOBALFOUNDRIES collaboratively worked with KLA-Tencor
to successfully implement these capabilities. Both library and non-library scenarios have been demonstrated for
comparison in a real production environment resulting in productivity increase of approximately 29% by making use of
the library. Reticle re-qualification test cases were used for the comparison in this work.
Requalifying semiconductor photomasks remains critically important and is increasingly challenging
for 20nm and 14nm node logic reticles. Patterns are becoming more complex on the photomask,
and defect sensitivity requirements are more stringent than ever before. Reticle inspection tools
are equally important for effective process development and the successful ramp and sustained
yield for high volume manufacturing. The inspection stages considered were: incoming inspection
to match with Mask Shop Outgoing result and to detect defects generated during transport;
requalification by routine cycle inspection to detect Haze and any other defects; and inspection by
in-house or Mask shop at the post cleaning. There are many critical capability and capacity factors
for the decision for best inspection tool and strategy for high volume manufacturing, especially
objective Lens NA, wavelength, power, pixel size, throughput, full-automation inspection linked
with Overhead Transport, algorithm application, engineering application function, and inspection
of PSM and OMOG . These tools are expensive but deliver differentiated value in terms of
performance and throughput as well as extendibility. Performing a thorough evaluation and
making a technically sound choice which explores these many factors is critical for success of a
fab. This paper examines the methodology for evaluating two different photomask inspection
tools. The focus is on ensuring production worthiness on real and advanced product photomasks
requiring accurate evaluation of sensitivity, throughput, data analysis function and engineering
work function on those product photomasks. Photomasks used for data collection are production
reticles, PDM(Program defect Mask), SiN spray defect Reticle which is described that evaluates
how the tools would perform on a contaminated plate.
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