Laser Shock Removal of Nanoparticles from Si Capping Layer of Extreme Ultraviolet Lithography Masks

Lee, Sang-Ho; Kang, Young‐Sun; Park, Jin-Goo; Busnaina, Ahmed; Lee, Jong Myung; Kim, Tae-Hoon; Zhang, Guojing; Eschbach, Florence O.; Ramamoorthy, Arun

doi:10.1143/jjap.44.5560

Cited by 23 publications

(11 citation statements)

References 16 publications

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“…2,4 However, previous studies also reported that LSC is far less effective in removing organic particles, such as polystyrene latex (PSL), than in removing inorganic particles. 5,6 For example, when 300 nm PSL particles and 280 nm silica particles were tested using the LSC setup employed in the present work, the particle removal efficiency was substantially lower ($30%) than that of the silica particles ($90%). Also, the fact that the removal of PSL particles is ineffective even when the cleaning experiment is conducted right after the particle deposition indicates that the adhesion-induced deformation 7 cannot explain the low removal efficiency.…”

mentioning

confidence: 79%

Shockwave-induced deformation of organic particles during laser shockwave cleaning

Kim

Cho

Busnaina

et al. 2013

Journal of Applied Physics

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Although the laser shockwave cleaning process offers a promising alternative to conventional dry-cleaning processes for nanoscale particle removal, its difficulty in removing organic particles has been an unexplained problem. This work elucidates the physics underlying the ineffectiveness of removing organic particles using laser shock cleaning utilizing polystyrene latex particles on silicon substrates. It is found that the shockwave pressure is high enough to deform the particles, increasing the contact radius and consequently the particle adhesion force. The particle deformation has been verified by high-angle scanning electron microscopy. The Maugis-Pollock theory has been applied to predict the contact radius, showing good agreement with the experiment.

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confidence: 79%

Shockwave-induced deformation of organic particles during laser shockwave cleaning

Kim

Cho

Busnaina

et al. 2013

Journal of Applied Physics

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“…Consequently, the laser-induced damage of the confining structure resulting in secondary particle generation is an important barrier to the practical implementation of the proposed LSC process to increase the cleaning performance. Previous studies indicate that the LIP produces thermal damage to a nearby silicon substrate [18]. In this work, laser-induced damages of three different materials (glass, silicon and quartz) were examined.…”

Section: Laser-induced Damage In the Confining Platementioning

confidence: 99%

Enhancement of cleaning efficiency by geometrical confinement of plasma expansion in the laser-shock cleaning process for nanoscale contaminant removal

Jang

Lee³

et al. 2009

SPIE Proceedings

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It has been shown that the laser shock cleaning (LSC) process is effective for removing nanoscale particles from solid surfaces and thus has various potential applications in microelectronic manufacturing. In this work, we propose a simple method to amplify the shock wave intensity generated by laser-induced breakdown (LIB) of air. The suggested scheme employs a plane shock wave reflector which confines the plasma expansion in one direction. As the half of the LIBinduced shock wave is reflected by the reflector, the intensity of the shock wave propagating in the opposite direction is increased significantly. Accordingly, the enhanced shock wave can remove smaller particles from the surface than the existing LSC process. The LSC process under geometrical confinement is analyzed both theoretically and experimentally. Numerical computation of the plasma/shock behavior shows about two times pressure amplification for the plane geometry. Experiments confirm that the shock wave intensity is enlarged by the effect of geometrical confinement of the plasma and shock wave. The result of cleaning tests using polystyrene particles demonstrates that the particle removal efficiency increases by the effect of geometrical confinement.

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“…8. Various pinpoint cleaning methods that address particle removal have been proposed (28)(29)(30)(31)(32)(33). These pinpoint cleaning techniques are used by combining with wafer-surface inspection equipment that accurately maps the location and size of the nano-particles on the wafer (34).…”

Section: Pinpoint Cleaningmentioning

confidence: 99%

“…The use of laser-induced plasma shock waves instead of direct laser irradiation onto the substrate surface has been recently tried to clean EUVL masks (33). This method has been used, in combination with a x-y-z translation stage, for whole-wafer (or whole-mask) cleaning rather than local-area, pinpoint cleaning.…”

Section: Laser Irradiationmentioning

confidence: 99%

Non-Aqueous/Dry Cleaning Technology without Causing Damage to Fragile Nano-Structures

Hattori¹

2009

ECS Trans.

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With semiconductor-device geometry shrinking and becoming more complex, conventional aqueous cleaning/drying tends to collapse free-standing MEMS and high-aspect-ratio fragile LSI structures due to the high surface tension of aqueous chemicals and water. The use of physical cleaning aids such as megasonics with dilute chemistry or high-pressure atomizing jet sprays can also cause damage to nano-structures. The process window for damage-free cleaning is also becoming narrower as device geometry shrinks. This makes the development of new damagefree cleaning methods a high priority. In this paper, various alternative damage-free non-aqueous/dry cleaning techniques are described and discussed including low pressure, elevated temperature HF vapor cleaning, cryogenic aerosol cleaning, supercritical CO 2 cleaning, and pinpoint dry cleaning that employs lasers, nano-probes, or nano-tweezers. There will be more research challenges and opportunities in these environmentally-benign damage-free cleaning technologies in the future. IntroductionAs semiconductor devices become ever more highly integrated and their geometry continues to shrink, even slight silicon and oxide etching loss during wafer cleaning can have a negative impact on the characteristics of metal-oxide-semiconductor (MOS) transistors (1). Therefore, highly diluted chemicals are used during aqueous silicon-wafer cleaning (2, 3), such as conventional RCA cleaning, to minimize the material loss. Dilute chemistry is also preferable from the viewpoints of both micro-roughness control of the silicon surface and environmental control of the chemical consumption.However, it is difficult to remove particles to the extent desirable with highly diluted chemicals. In order to enhance the particle-removal efficiency, physical aids such as megasonic agitation are generally employed (4), but it tends to cause structural damage to fragile LSI circuit patterns. Reducing the megasonic power can reduce the megasonic damage to the fragile structures, but it also reduces the particle-removal efficiency. In order to reduce the device damage by the megasonic energy, some modifications such as an addition of lower-ionization-potential gas and/or liquids to DI water have been proposed (5). In general, conventional aqueous cleaning methods using any kind of sonification become less effective as the particle diameters get smaller.An alternative physical technique, a DI-water/gas-mixture jet spray cleaning technique, has been reported (6). This technique has an advantage over megasonics because it can remove smaller particles due to the greater impact of droplets at near-sonic speed. Thus, the water/gas jet spray at a high flow rate or at high speed of the carrier gas without any addition of chemicals can remove particles on unpatterned wafer surfaces without material loss caused by chemical etching. But we must be mindful of the possibility of structural damage on patterned wafers that can be caused by this type of physically assisted treatment as well as megasonic agitation. In fact,...

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Laser Shock Removal of Nanoparticles from Si Capping Layer of Extreme Ultraviolet Lithography Masks

Cited by 23 publications

References 16 publications

Shockwave-induced deformation of organic particles during laser shockwave cleaning

Shockwave-induced deformation of organic particles during laser shockwave cleaning

Enhancement of cleaning efficiency by geometrical confinement of plasma expansion in the laser-shock cleaning process for nanoscale contaminant removal

Non-Aqueous/Dry Cleaning Technology without Causing Damage to Fragile Nano-Structures

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