Plasma cleaning of nanoparticles from EUV mask materials by electrostatics

Lytle, W. M.; Raju, R.; Shin, H.; Das, Champak; Neumann, M.; Ruzic, D. N.

doi:10.1117/12.772363

Cited by 6 publications

(6 citation statements)

References 7 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, the use of these harsh chemicals leads to surface damage and introduces particles [3], all of which lead to a loss in reflectivity [4]. It has been well established in various studies that the current cleaning methods incur a severe EUV reflectivity loss which is not acceptable and that there's a need to come up with alternative cleaning methods which would be effective and not have a deteriorating impact on reflectivity [5,6,7]. To achieve this goal, we need to have a clear and comprehensive understanding of the various cleaning steps and develop an understanding regarding what impact each step has on the mask structure, and how that contributes to the loss in reflectivity.…”

Section: Introductionmentioning

confidence: 99%

A simulation study of cleaning induced EUV reflectivity loss mechanisms on mask blanks

Upadhyaya

Denbeaux

Kadaksham³

et al. 2012

SPIE Proceedings

View full text Add to dashboard Cite

It is widely recognized in the semiconductor industry that getting to defect-free extreme ultraviolet (EUV) mask blanks is critical in achieving high volume chip manufacturing yield beyond the 22 nm halfpitch node. Total defectivity of an EUV mask blank depends on the defectivity of substrate and finished mask blank. Finished mask blanks are normally subjected to a cleaning process to get rid of the loosely adhered particles on the top. This is normally done in a spin-spray mask cleaning tool using traditional mask cleaning processes. It is important that this cleaning process does not degrade the properties of the multilayer blank or introduce additional particles or pits during the process. However, standard cleaning processes used to clean multilayer blanks result in EUV reflectivity loss, loss of uniformity in reflectivity, increased roughness and adds pits and particles on mask blanks. The standard cleaning process used consists of multiple steps, each of which may cause the oxidation of Ru capping layer as well as other underlying bilayers, etching of the multilayer stack and increased roughness of the bilayers thus leading to a loss in EUV reflectivity. It is a challenging task to experimentally correlate the processing steps to the resulting damage and to quantify the reflectivity loss. Furthermore, due to the high cost of materials we have not been able to do extensive experiments to determine the root cause of problems. In this work, we have combined mask blank cleaning using standard processes, TEM cross section studies and simulations to quantify the impact of the multilayer oxidation, etching and roughness on the EUV reflectivity loss and mask blank degradation.

show abstract

Section: Introductionmentioning

confidence: 99%

A simulation study of cleaning induced EUV reflectivity loss mechanisms on mask blanks

Upadhyaya

Denbeaux

Kadaksham³

et al. 2012

SPIE Proceedings

View full text Add to dashboard Cite

show abstract

“…Plasma assisted cleaning by electrostatics (PACE) has shown stripping efficiencies greater than 90% for polystyrene latex (PSL) particles (Lytle et al 2008). Unfortunately, those approaches rely on expensive equipment.…”

Section: Introductionmentioning

confidence: 99%

Cleaning of structured templates from nanoparticle accumulation using silicone

et al. 2011

View full text Add to dashboard Cite

Polydimethylsiloxan (PDMS) turned out to be a simple and cost efficient material for the removal of nanoparticles from patterned surfaces. After molding the particle-laden surface using liquid silicone, surface cleaning is realized by curing the PDMS comprising the encapsulated particles and subsequent removal. The method is proven for silicon, SiO 2 and gold surfaces occupied by carbon and Polytetrafluorethylen (PTFE or Teflon) particles. Samples up to 2 inch wafers were successfully cleaned. The effect of PDMS on the surface energy is verified by contact angle measurements showing a clear change in wetting for H 2O. This effect is abolished by oxygen plasma and HF-Dip

show abstract

“…Another approach is Plasma Assisted Cleaning by Electrostatics (PACE) with efficiencies greater than 90% for polystyrene latex (PSL) particles [4]. Those methods were used to avoid particles in EUV-mask production and imprint processes.…”

Section: Introductionmentioning

confidence: 99%

Cleaning of nanopillar templates for nanoparticle collection using PDMS

et al. 2011

View full text Add to dashboard Cite

Nanoparticles are easily attracted by surfaces. This sticking behavior makes it difficult to clean contaminated samples. Some complex approaches have already shown efficiencies in the range of 90%. However, a simple and cost efficient method was still missing. A commonly used silicone for soft lithography, PDMS, is able to mold a given surface. This property was used to cover surface-bonded particles from all other sides. After hardening the PDMS, particles are still embedded. A separation of silicone and sample disjoins also the particles from the surface. After this procedure, samples are clean again. This method was first tested with carbon particles on Si surfaces and Si pillar samples with aspect ratios up to 10. Experiments were done using 2 inch wafers, which, however, is not a size limitation for this method.

show abstract

Plasma cleaning of nanoparticles from EUV mask materials by electrostatics

Cited by 6 publications

References 7 publications

A simulation study of cleaning induced EUV reflectivity loss mechanisms on mask blanks

A simulation study of cleaning induced EUV reflectivity loss mechanisms on mask blanks

Cleaning of structured templates from nanoparticle accumulation using silicone

Cleaning of nanopillar templates for nanoparticle collection using PDMS

Contact Info

Product

Resources

About