Correlation method for the measure of mask-induced line-edge roughness in extreme ultraviolet lithography

Naulleau, Patrick

doi:10.1364/ao.48.003302

Cited by 15 publications

(13 citation statements)

References 7 publications

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“…This roughness directly maps to phase roughness in the reflected field which in turn maps to image plane speckle and LER [4][5][6][7]. The concern over, this problem has recently increased since its experimental demonstration in printed wafers at EUV [8] in both an microfield exposure tool [9] and a full field EUV alpha tool [3]. The coupling from roughness to LER depends on many factors including roughness magnitude, roughness correlation length, illumination partial coherence, aberrations, defocus, and numerical aperture (NA) [10].…”

Section: Mask Multilayer Roughnessmentioning

confidence: 99%

“…The impact of the mask roughness on the wafer plane LER has also been directly experimentally verified using the SEMATECH Berkeley MET. To accentuate the effect, a small partial coherence (0.05) and large defocus (100 nm) was used [8]. Figure 3 shows printed line edge data for a single line edge exposed three separate times.…”

Section: Mask Multilayer Roughnessmentioning

confidence: 99%

“…The experimental results on the effect of mask roughness obtained on the SEMATECH Berkeley MET have been used to verify a model we have developed to predict this effect [8]. This model has subsequently been used to predict sensitivity of the mask roughness effect to a variety of mask and optical system parameters and to estimate future mask requirements [10].…”

Section: Mask Multilayer Roughnessmentioning

confidence: 99%

See 2 more Smart Citations

Accelerating EUV learning with synchrotron light: mask roughness challenges ahead

Naulleau

Goldberg²,

Gullikson

et al. 2011

SPIE Proceedings

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Despite significant progress in the commercialization of extreme ultraviolet (EUV) lithography, many important challenges remain, including in the area of masks. The issue of EUV phase roughness that can arise from either multilayer or capping layer roughness has recently garnered increasing concern. The problem with mask phase roughness is that it couples line-edge roughness (LER) through the formation of image plane speckle. The coupling from phase roughness to LER depends on many factors including roughness magnitude, roughness correlation length, illumination partial coherence, aberrations, defocus, and numerical aperture. Analysis shows that only on the order of 50 pm multilayer roughness may be tolerable at the 22-nm half-pitch node. Results also show that Atomic Force Microscopy (AFM) may not be a suitable method for measuring mask phase roughness due to its sensitivity to the surface only. Capping layer roughness is another significant concern especially given that it has been shown to increase with cleaning cycles. In this case, however, AFM does provide a reasonable metric.

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Section: Mask Multilayer Roughnessmentioning

confidence: 99%

Section: Mask Multilayer Roughnessmentioning

confidence: 99%

Section: Mask Multilayer Roughnessmentioning

confidence: 99%

See 1 more Smart Citation

Accelerating EUV learning with synchrotron light: mask roughness challenges ahead

Naulleau

Goldberg²,

Gullikson

et al. 2011

SPIE Proceedings

Self Cite

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“…More recently, these effects have been systematically characterized using an exposure to exposure con-elation method [13]. The results showed the masklimited LER under Ci = 0.05 illumination to be 3.4 nm.…”

Section: Mask Contributions To Lermentioning

confidence: 99%

The SEMATECH Berkeley MET pushing EUV development beyond 22nm half pitch

et al. 2010

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Microfield exposure tools (METs) playa crucial role in the development of extreme ultra\'iolet (EUV) resists and masks, One of these tools is the SEMATECH Berkeley 0.3 numerical aperture (NA) MET, Using conventional illumination this tool is limited to approximately 22-nm half pitch resolution. However, resolution enhancement techniques have been used to push the patterning capabilities of this tool to half pitches of 18 nm and below, This resolution was achieved in a new imageable hard mask which also supports contact printing down to 22 nm with conventional illumination. Along with resolution, line-edge roughness is another crucial hurdle facing EUV resists, Much of the resist LER, however, can be attributed to the mask. We have shown that intenssionally aggressive mask cleaning on an older generation mask causes correlated LER in photoresist to increase from 3.4 nm to 4,0 nm, We have also shown that new generation EUV masks (l00 pm of substrate roughness) can achieve correlated LER values of 1.1 nm, a 3x improvement over the correlated LER of older generation EUV masks (230 pm of substrate roughness), Finally, a 0.5-NA MET has been proposed that will address the needs of EUV development at the 16-nm node and beyond, The tool will support an ultimate resolution of 8 nm half-pitch and generalized printing using conventional illumination down to 12 nm half pitch.

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“…EUVL masks require high reflectivity from the mask and are fabricated by depositing reflective Mo/Si multilayer films onto superpolished substrates. Mask LER, which can easily be produced on the multilayer EUVL mask, can alter the reflected near-field image and the aerial image on the resist [2,3]. During the resist process, many materials of resists and process factors affect LER because LER is formed from a chemical inhomogeneity at the boundary between the soluble and insoluble regions [4,5].…”

Section: Introductionmentioning

confidence: 99%

Modeling and Simulation of Line Edge Roughness for EUV Resists

Kim¹

2014

JSTS:Journal of Semiconductor Technology and Science

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Abstract-With the extreme ultraviolet (EUV) lithography, the performance limit of chemically amplified resists has recently been extended to 16-and 11-nm nodes. However, the line edge roughness (LER) and the line width roughness (LWR) are not reduced automatically with this performance extension. In this paper, to investigate the impacts of the EUVL mask and the EUVL exposure process on LER, EUVL is modeled using multilayer-thin-film theory for the mask structure and the Monte Carlo (MC) method for the exposure process. Simulation results demonstrate how LERs of the mask transfer to the resist and the exposure process develops the resist LERs.

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Correlation method for the measure of mask-induced line-edge roughness in extreme ultraviolet lithography

Cited by 15 publications

References 7 publications

Accelerating EUV learning with synchrotron light: mask roughness challenges ahead

Accelerating EUV learning with synchrotron light: mask roughness challenges ahead

The SEMATECH Berkeley MET pushing EUV development beyond 22nm half pitch

Modeling and Simulation of Line Edge Roughness for EUV Resists

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