Prevention of chemical residue from growing into Haze defect on PSM pattern edge after normal cleaning process

Choi, Jinsung; Jung, Jin-Sik; Lee, Han-Shin; Oh, Jong-Keun; Kang, Soo‐Jung; Jeong, Hae-Yong; Kim, Yong‐Hoon; Cho, Han-Ku

doi:10.1117/12.793049

Cited by 6 publications

(4 citation statements)

References 7 publications

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“…The illumination drives also diffusion of ion contaminants through the bulk towards mask surface. 5 The contamination level of the absorber is influencing the timeframe until haze can be detected. This contamination originates from mask blank, processes used during mask manufacturing or environment during exposure and storage of the mask.…”

Section: Influence Of Exposurementioning

confidence: 99%

“…One in literature mentioned approach is blocking of the sulphate molecules adsorbed on the mask surface by additional treatment of mask surface for HT-PSM mask. 5 The main task for clean processes with respect to haze remains the reduction of sulphate contamination of the mask, usually measured as concentration of sulphate in water sample, extracted at defined conditions and analyzed via ion chromatography (IC). Main focus of our work is to estimate the effectiveness of sulphate removal by previously mentioned processes and provide rough estimate of the critical contamination level at the freshly manufactured mask.…”

Section: Introductionmentioning

confidence: 99%

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Haze risk reduced mask manufacturing process

et al. 2010

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Since introduction of 193nm exposure wavelength, the haze formation becomes a serious challenge especially at mask used for big number of exposures. Several compounds present in air as low concentration contaminants are leading to haze building. Well understood is the sulphate based haze formation, however, still causing significant losses and demanding for re-cleaning of the mask during mask life time. There are plenty of publications taking different approaches to reduction of the final sulphate concentration on the mask and reduction of the use of sulphuric acid during the mask manufacturing. Beside traditional process as hot water extraction, UV exposure, baking, IR exposure at vacuum, Ammonia solution treatment more exotic method were published as surface treatment preventing migration of the sulphate ions on mask surface. The number of exposures till haze crystals growth prevents further use of the mask is not solely dependent on the sulphate concentration on the freshly manufactured mask. Additional factors as storage and use conditions are significantly influencing the period till re-clean of the mask is needed. In this work we try to assess above mentioned approaches and provide rough estimate of their limits.

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Section: Influence Of Exposurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Haze risk reduced mask manufacturing process

et al. 2010

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“…The decrease of sulfate residue was successfully accomplished through combination of various cleaning methods including functional water cleaning or dry cleaning process (e.g. UV, Bake, or plasma applications) [2][3][4] . Nevertheless, we have experienced that the amount of those Haze ionic residue is severely increased on mask surface during laser exposure or during simple storage in wafer production line even without exposure (Fig.…”

Section: Intrinsic Drop Of Haze Resistancementioning

confidence: 99%

“…Worldwide development endeavors dealing with Haze issues have been focusing on decreasing of Sulfate and Ammonium ionic residues from mask surface so far [1][2][3][4] . Based on Toppan's Report on 2007, the amount of sulfate residue on mask surface has been dramatically reduced from 2002 up to 2007 [1] (Fig.…”

Section: Intrinsic Drop Of Haze Resistancementioning

confidence: 99%

A new paradigm for haze improvement: retardation of haze occurrence by creating mask substrate insensitive to chemical contamination level

Lee

Choi

Jung

et al. 2008

Photomask Technology 2008

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Haze issues are getting more serious since size of Haze defect printable on the water surface that could matter is decreasing further with reduced pattern size. Many efforts have been made to reduce the contamination level on the photomask surface by applying wet or dry processes. We have successfully reduced surface contamination down to subppb level for organic and inorganic chemicals. No matter how well the mask surface is cleaned, chemical contaminant cannot be perfectly eliminated from the surface. As long as contaminants exist on the surface, they are getting aggregated around certain points with higher energy to create defects on it during laser exposure. Also, the cleaned mask surface could be contaminated again during following processes such as shipping and storage.Here, we propose a new paradigm for Haze retardation where we severely decelerate defect generation and growth rather than eliminate chemical contaminants on the mask surface. We have made mask surface on which chemical contaminants are hardly accumulated to generate Haze defects even during laser exposure. By creating mask surface insensitive to chemical impurity level up to a certain degree, we are able to retard Haze occurrence much better than by reducing surface impurities down to sub-ppb level. This approach has another advantage of allowing a freedom for mask environment during the process of shipping, storage, and exposure.We further investigate how the treated mask surface should have strong resistance against chemical contaminant aggregation towards Haze defect generation around specific points with high energy.

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