Recent performance of EUV mask blanks with low-thermal expansion glass substrates

Shoki, Tsutomu; Yamada, Takeyuki; Shimojima, Shouji; Shiota, Yuuki; Tsukahara, Mitsuharu; Koike, Kesahiro; Shishido, Hiroaki; Nozawa, Osamu; Sakamoto, Toshiyuki; Hosoya, Morio

doi:10.1117/12.748369

Cited by 9 publications

(4 citation statements)

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“…We have been challenging to meet the ideal requirement using local polishing process. In 2007, a substrate with around 120 nm P-V as routine performance was achieved 9 . Furthermore, the flatness was improved by around 90 nm PV in 2008.…”

Section: Substrate Flatness Improvementmentioning

confidence: 99%

Improvement of total quality on EUV mask blanks toward volume production

et al. 2010

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Total quality on EUV mask blanks have to be improved toward future volume production. In this paper, progress in EUV blank development and improvement in flatness, bow and ML blank defects as critical issues on EUV blanks were reported. Steadily progress in flatness improvement was made in the past five years by improving polishing processes. A LTE substrate with a high flatness of 78 nm PV in 142 mm square area was achieved in average. Annealing process was developed to make small bow of less than 600 nm after ML coating. It was confirmed that annealed ML blank has stable performance in bow and centroid wavelength values through mask making process. Small bow of less than 300 nm was successfully demonstrated using annealing process and a CrN back side film with high compressive stress. Low defects of 0.05 defects/cm 2 at 70 nm SiO 2 sensitivity inspected by a Lasertec M1350 was demonstrated on a multilayer (ML) blank with a LTE substrate as best. Small defects over 50 nm in a M7360 were effectively reduced by improvement of polishing process consisting of local polish, touch polish and cleaning.

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Section: Substrate Flatness Improvementmentioning

confidence: 99%

Improvement of total quality on EUV mask blanks toward volume production

et al. 2010

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“…However, the path to establish the EUVL is not without technical difficulties, e.g., lack of sufficient light-source power, particle-free mask handling, defect-free and flat mask blanks, [1][2][3][4] and resist material development, and need to be resolved. From the viewpoint of EUV mask fabrication, mask pattern defect inspection [5][6][7] and repair [8][9][10][11][12][13] are some of the most demanding tasks to be addressed.…”

Section: Introductionmentioning

confidence: 99%

Residual-type mask defect printability for extreme ultraviolet lithography

Amano¹,

Iida²,

Hirano³

et al. 2012

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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“…11) Therefore, the LTEM is used to emit the absorbed heat energy. 12,13) Even with an LTEM substrate, the mask may be thermo-mechanically deformed. Deformation of the whole mask due to heat absorption in each layer may occur during exposure, which means that the mask may no longer be flat.…”

Section: Introductionmentioning

confidence: 99%

Modeling of thermomechanical changes of extreme-ultraviolet mask and their dependence on absorber variation

Ban¹,

Park²,

Park³

et al. 2018

Jpn. J. Appl. Phys.

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Thermal and structural deformation of extreme-ultraviolet lithography (EUVL) masks during the exposure process may become important issues as these masks are subject to rigorous image placement and flatness requirements. The reflective masks used for EUVL absorb energy during exposure, and the temperature of the masks rises as a result. This can cause thermomechanical deformation that can reduce the pattern quality. The use of very thick low-thermal-expansion substrate materials (LTEMs) may reduce energy absorption, but they do not completely eliminate mask deformation. Therefore, it is necessary to predict and optimize the effects of energy transferred from the extreme-ultraviolet (EUV) light source and the resultant patterns of structured EUV masks with complex multilayers. Our study shows that heat accumulates in the masks as exposure progresses. It has been found that a higher absorber ratio (pattern density) applied to the patterning of EUV masks exacerbates the problem, especially in masks with more complex patterns.

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Recent performance of EUV mask blanks with low-thermal expansion glass substrates

Cited by 9 publications

References 0 publications

Improvement of total quality on EUV mask blanks toward volume production

Improvement of total quality on EUV mask blanks toward volume production

Residual-type mask defect printability for extreme ultraviolet lithography

Modeling of thermomechanical changes of extreme-ultraviolet mask and their dependence on absorber variation

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