The source of carbon contamination for EUV mask production

Kim, Yong‐Dae; Lee, Jun‐Sik; Choi, Yongsoo; Kim, Changreol

doi:10.1117/12.799668

Cited by 4 publications

(2 citation statements)

References 1 publication

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“…Given that carbon readily absorbs EUV radiations at 13.5nm, it reduces the reflectivity of Mo/Si multilayer (ML) and degrades exposure uniformity, heavily effecting Critical Dimension (CD) control [17]. Various dry and wet cleaning methods have been evaluated for carbon contamination removal [15,[18][19][20][21] however, damage to the multilayer from use of these removal methods has not been documented in the respective literature. Carbon removal is essential, but preserving Ru layer integrity while doing so is imperative.…”

Section: Carbon Contaminationmentioning

confidence: 99%

Effective EUVL mask cleaning technology solutions for mask manufacturing and in-fab mask maintenance

Dietze¹,

Dress²,

Waehler³

et al. 2011

27th European Mask and Lithography Conference

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Extreme Ultraviolet Lithography (EUVL) is considered the leading lithography technology choice for semiconductor devices at 16nm HP node and beyond. However, before EUV Lithography can enter into High Volume Manufacturing (HVM) of advanced semiconductor devices, the ability to guarantee mask integrity at point-of-exposure must be established. Highly efficient, damage free mask cleaning plays a critical role during the mask manufacturing cycle and throughout the life of the mask, where the absence of a pellicle to protect the EUV mask increases the risk of contamination during storage, handling and use. In this paper, we will present effective EUVL mask cleaning technology solutions for mask manufacturing and in-fab mask maintenance, which employs an intelligent, holistic approach to maximize Mean Time Between Cleans (MBTC) and extend the useful life span of the reticle. The data presented will demonstrate the protection of the capping and absorber layers, preservation of pattern integrity as well as optical and mechanical properties to avoid unpredictable CD-linewidth and overlay shifts. Experiments were performed on EUV blanks and pattern masks using various process conditions. Conditions showing high particle removal efficiency (PRE) and minimum surface layer impact were then selected for durability studies. Surface layer impact was evaluated over multiple cleaning cycles by means of UV reflectivity metrology XPS analysis and wafer prints. Experimental results were compared to computational models. Mask life time predictions where made using the same computational models. The paper will provide a generic overview of the cleaning sequence which yielded best results, but will also provide recommendations for an efficient in-fab mask maintenance scheme, addressing handling, storage, cleaning and inspection.

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Section: Carbon Contaminationmentioning

confidence: 99%

Effective EUVL mask cleaning technology solutions for mask manufacturing and in-fab mask maintenance

Dietze¹,

Dress²,

Waehler³

et al. 2011

27th European Mask and Lithography Conference

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show abstract

“…Consequently, wet cleaning methods, which do not require intricate equipment and induce less damage to photomask patterns and thin films compared to physical and dry cleaning methods, are currently widely employed. According to Kim et al and Nii et al, wet cleaning with SPM and SC-1 is commonly conducted in a temperature range of 80 °C-100 °C [17,18]. Choi et al revealed that a cleaning loss of 2 nm in the ARC layer thickness of a Ta-based EUV photomask occurred after 30 cycles of high temperature SPM cleaning and 20 cycles of EUV exposure [19].…”

Section: Introductionmentioning

confidence: 99%

Wet cleaning of Ta-based extreme ultraviolet photomasks at room temperature

Park,

Choi,

Kim

2024

Nanotechnology

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Owing to the wavelength-dependent limits of the deep ultraviolet (DUV) exposure process, the semiconductor industry introduced extreme ultraviolet (EUV) lithography operating at a 13.5-nm wavelength. Traditional photomasks employ pellicles for protection; however, EUV-specific pellicles are not widely applicable to commercial processes, requiring the development of a EUV photomask cleaning method. In this study, a wet cleaning method for Ta-based EUV photomasks at room temperature was systematically examined in terms of key parameters, including the pattern step height, surface topography, and particulate count, via atomic force microscopy and X-ray reflectivity. Post sulfuric acid-hydrogen peroxide mixture (SPM) treatment, the photomask exhibited a stable step height, indicating minimal pattern degradation. Additionally, discernible alterations in the surface roughness and a decrease in particle count were observed, further indicating to the effectiveness of SPM-mediated cleaning. Conversely, following SC-1 treatment, while the pattern step height remained relatively unchanged, a notable increase in surface irregularities and macroscopic particulates was observed, suggesting a suboptimal cleaning efficiency of the SC-1 solution despite its potential for pattern structure preservation. Our room temperature wet cleaning method efficiently reduces wear-out and successfully eliminates contaminants, potentially prolonging the EUV photomask's productivity and durability.

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Effect on Critical Dimension Performance for Carbon Contamination of Extreme Ultraviolet Mask Using Coherent Scattering Microscopy and In-situ Contamination System

Doh

Lee

et al. 2012

Jpn. J. Appl. Phys.

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The impact of carbon contamination on imaging performance was analyzed using an in-situ accelerated contamination system (ICS) combined with coherent scattering microscopy (CSM) which was installed at 11B extreme ultraviolet lithography (EUVL) beamline of the Pohang Accelerator Laboratory (PAL). The CSM/ICS is composed of CSM for measuring imaging properties and ICS for implementing acceleration of carbon contamination. The mask critical dimension (CD) and reflectivity were compared before and after carbon contamination through accelerated exposure. The reflectivity degradation was measured as 1.3, 2.0, and 2.8% after 1, 2, and 3 h exposure, respectively, due to carbon contamination of 5, 10, and 20 nm as measured by Zygo interferometer. The mask CD change for 88 nm line and space pattern was analyzed using CSM and a CD scanning electron microscope (SEM), and the result shows CD-SEM and CSM give large difference of 3.8 times in mask ΔCD after carbon contamination. This difference confirms the importance of using actinic inspection technique that employs exactly the same imaging condition as exposure tool.

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The source of carbon contamination for EUV mask production

Cited by 4 publications

References 1 publication

Effective EUVL mask cleaning technology solutions for mask manufacturing and in-fab mask maintenance

Effective EUVL mask cleaning technology solutions for mask manufacturing and in-fab mask maintenance

Wet cleaning of Ta-based extreme ultraviolet photomasks at room temperature

Effect on Critical Dimension Performance for Carbon Contamination of Extreme Ultraviolet Mask Using Coherent Scattering Microscopy and In-situ Contamination System

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