Evaluation of protection schemes for extreme ultraviolet lithography (EUVL) masks against top–down aerosol flow

Yook, Se-Jin; Fißan, H.; Asbach, Christof; Kim, Jung Hyeun; Wang, Jing; Yan, Pei Yang; Pui, David Y.H.

doi:10.1016/j.jaerosci.2006.11.010

Cited by 35 publications

(27 citation statements)

References 41 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Deposition velocity, defined as the ratio of particle flux toward a surface to aerosol concentration above that surface, is accepted as the criterion to assess the level of particulate contamination. Previous researches of deposition velocity have focused on the horizontal free-standing wafer to which air flow is perpendicular (Liu and Ahn 1987;Opiolka et al 1994;Otani et al 1989;Pui et al 1990;Ye et al 1991;Yook et al 2007b). Since horizontal wafers or photomasks are transported horizontally by robots in the cleanroom, aerosol particles may approach and contaminate the wafers or photomasks by the air flow parallel to the surfaces.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Deposition Velocity onto an Inverted Flat Surface in a Laminar Parallel Flow

Choi

Yook

2010

Aerosol Science and Technology

Self Cite

View full text Add to dashboard Cite

Wafers and photomasks in the cleanroom are exposed to airflows not only vertical but also parallel to the surfaces. In this study, Gaussian Diffusion Sphere Model (GDSM) was adjusted to predict deposition velocity onto an inverted flat surface in a laminar parallel flow by considering Brownian diffusion and gravitational settling of aerosol particles. The GDSM was validated by comparing with the simulation of solving flow and aerosol-concentration fields for an inverted flat surface and also with the mass transfer correlation for a finite flat surface of circular or rectangular areal shape. The GDSM was proven to correctly predict the deposition velocities onto the inverted flat surfaces, by taking one hour with a 2.66-GHz-CPU personal computer to obtain deposition velocities for 20 particle sizes, which is a very much shorter time compared with the time for simulating the flow and aerosolconcentration fields. Deposition velocities onto the inverted 45-cmwafer and 15.2-cm-photomask in parallel airflows were predicted using the GDSM, for the particle size ranging from 0.003 to 1.5 µm and the airflow velocity varying from 5 to 500 cm/s. The deposition velocity decreased with increasing particle size, with a steep declination especially for particles larger than approximately 0.1 µm. From the qualitative comparison of the deposition velocities onto the inverted square flat surfaces, representing the photomasks with different orientations in the parallel flow, it was suggested to transport the EUVL photomask with its side facing the airflow rather than with its corner confronting the airflow, in order to minimize particulate contamination.

show abstract

Section: Introductionmentioning

confidence: 99%

“…One of the schemes to minimize particulate contamination of EUVL photomasks is the use of the gravity by letting the critical surfaces facing down (Asbach et al 2006;Yook et al 2007bYook et al , 2007c. It is thus helpful to render the critical surfaces of wafers or photomasks facing-down even at the stages of transporting them by robots.…”

Section: Introductionmentioning

confidence: 99%

Deposition Velocity onto an Inverted Flat Surface in a Laminar Parallel Flow

Choi

Yook

2010

Aerosol Science and Technology

Self Cite

View full text Add to dashboard Cite

show abstract

“…Deposition velocity, which is the ratio of particle flux towards a surface to aerosol concentration above the surface, is used as a measure of particulate contamination level. Many investigations were performed to predict deposition velocity onto a free-standing wafer in an air flow perpendicular to the wafer surface, considering top-down air flow from ceiling in a clean room (Liu & Ahn, 1987;Opiolka, Schmidt, & Fissan, 1994;Otani, Emi, Kanaoka, and Kato, 1989;Pui, Ye, and Liu, 1990;Ye et al, 1991;Yook et al, 2007a).…”

Section: Introductionmentioning

confidence: 99%

Particle deposition velocity onto a face-up flat surface in a laminar parallel flow considering Brownian diffusion and gravitational settling

Yook

Asbach

Ahn

2010

Journal of Aerosol Science

Self Cite

View full text Add to dashboard Cite

“…Once the particle hit any walls including the impaction plate, the particle was assumed to be trapped. In order to calculate the collection efficiency of inertial impactors, the Statistical Lagrangian Particle Tracking (SLPT) model, developed by Yook et al (2007), was employed and adjusted. Fig.…”

Section: Calculation Of Impactor Collection Efficiencymentioning

confidence: 99%