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Mask inspection

About: Mask inspection is a research topic. Over the lifetime, 1072 publications have been published within this topic receiving 8696 citations.


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Proceedings ArticleDOI
28 Jun 2005
TL;DR: In this paper, a new generation of growing defects is introduced: crystals that grow on the half-tone (MoSi) film or on the chrome film, on the pattern side of the mask.
Abstract: Progressive mask defect problems such as crystal growth or haze are key yield limiters at DUV lithography, especially in 300mm fabs. With the high energy photons involved in DUV lithography and large wafer size requiring longer continuous exposure of masks, chances of photochemical reaction increases significantly on the masks. Most of the work published on this subject so far has been focused on defect growth on clear area (on the pattern surface) and on the back-glass of the mask. But there is a new generation of growing defects: crystals that grow on the half-tone (MoSi) film or on the chrome film, on the pattern side of the mask. It is believed that the formation mechanisms and rates are different for these new types of crystals. In light of this instability of masks in volume production, it becomes more important to understand the nature of such defects. The purpose of this investigation is to characterize the nature of these new defect growths and to understand the possible formation mechanisms involved in such problems.

7 citations

Proceedings ArticleDOI
23 Oct 2015
TL;DR: In this paper, an empirical error budget to compensate for various measurement errors, based on the latest HVM inspection and write tool capabilities, is first established and then verified post-patterning.
Abstract: Several challenges hinder EUV photomask fabrication and its readiness for high volume manufacturing (HVM). The lack in availability of pristine defect-free blanks as well as the absence of a robust mask repair technique mandates defect mitigation through pattern shift for the production of defect-free photomasks. By using known defect locations on a blank, the mask design can be intentionally shifted to avoid patterning directly over a defect. The work presented here provides a comprehensive look at pattern shift implementation to intersect EUV HVM for the 7 nm technology node. An empirical error budget to compensate for various measurement errors, based on the latest HVM inspection and write tool capabilities, is first established and then verified post-patterning. The validated error budget is applied to 20 representative EUV blanks and pattern shift is performed using OPC’d 7 nm node fully functional chip designs that were also recently used to fabricate working 7 nm node devices. Probability of defect-free masks are explored for various 7 nm mask levels, including metal, contact, and gate cut layers. From these results, an assessment is made on the current viability of defect-free EUV masks for the 7 nm node.

7 citations

Journal ArticleDOI
TL;DR: In this paper, the authors present an overview of currently on-going research endeavors that use a number of methods based on lensless imaging with coherent light, which constitute one of the core sources of cost of ownership for many of the metrology tools needed in the lithography process.
Abstract: Abstract The paradigm shift of the semiconductor industry moving from deep ultraviolet to extreme ultraviolet lithography (EUVL) brought about new challenges in the fabrication of illumination and projection optics, which constitute one of the core sources of cost of ownership for many of the metrology tools needed in the lithography process. For this reason, lensless imaging techniques based on coherent diffractive imaging started to raise interest in the EUVL community. This paper presents an overview of currently on-going research endeavors that use a number of methods based on lensless imaging with coherent light.

7 citations

Patent
30 Jan 1967

7 citations

Dissertation
01 Jan 2010
TL;DR: In this paper, the use of on-mask probable electrical test structures and measurement techniques to accurately characterise the imaging capabilities of advanced binary and phase-shifting chrome-on-quartz photomasks was examined.
Abstract: Existing photomask metrology is struggling to keep pace with the rapid reduction of IC dimensions as traditional measurement techniques are being stretched to their limits. This thesis examines the use of on-mask probable electrical test structures and measurement techniques to meet this challenge and to accurately characterise the imaging capabilities of advanced binary and phase-shifting chrome-on-quartz photomasks. On-mask, electrical and optical linewidth measurement techniques have highlighted that the use of more than one measurement method, complementing each other, can prove valuable when characterising an advanced photomask process. Industry standard optical metrology test patterns have been adapted for the direct electrical equivalent measurement and the structures used to characterise different feature arrangements fabricated on standard and advanced photomasks with proximity correction techniques. The electrical measurements were compared to measurements from an optical mask metrology and verification tool and a state-of-the-art CD-AFM system and the results have demonstrated the capability and strengths of the on-mask electrical measurement. For example, electrical and AFM measurements on submicron features agreed within 10nm of each other while optical measurements were offset by up to 90nm. Hence, electrical techniques can prove valuable in providing feedback to the large number of metrology tools already supporting photomask manufacture, which in turn will help to develop CD standards for maskmaking. Electrical test structures have also been designed to enable the characterisation of optical proximity correction to characterise right angled corners in conducting tracks using a prototype design for both on-mask and wafer characterisation. Measurement results from the on-mask structures have shown that the electrical technique is sensitive enough to detect the effect of OPC on inner corners and to identify any defects in the fabricated features. For example less than 10Ω (5%) change in the expected resistance data trends indicated a deformed OPC feature. Results from on-wafer structures have shown that the correction technique has an impact on the final printed features and the measured resistance can be used to characterise the effects of different levels of correction. Overall the structures have shown their capability to characterise this type of optical proximity correction on both mask and wafer level. Test structures have also been designed for the characterisation of the dimensional mismatch between closely spaced photomask features. A number of photomasks were fabricated with these structures and the results from electrical measurements have been analysed to obtain information about the capability of the mask making process. The electrical test structures have demonstrated the capability of measuring tool and process induced dimensional mismatches in the nanometer range on masks which would otherwise prove difficult with standard optical metrology techniques. For example, electrical measurements detected mismatches of less than 15nm on 500nm wide features. Declaration of Originality I hereby declare that the research recorded in this thesis and the thesis itself was composed and originated entirely by myself in the School of Engineering at The University of Edinburgh. List your exceptions here and sign before your printed name. Optical CD measurements with the MueTec were made by Andrew Hourd at Compugraphics. CD-AFM measurements with the Veeco SXM320 were performed by Ronald Dixson at NIST.

7 citations

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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202110
202016
201924
201819
201727
201632