A Theoretical Model for Laser Cleaning of Microparticles in a Thin Liquid Layer

Lu, Yongfeng; Zhang, Yong; Wei, Song; Chan, D.S.H.

doi:10.1143/jjap.37.l1330

Cited by 13 publications

(9 citation statements)

References 16 publications

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“…Improved cleaning is most possibly initiated by the strong absorption of the substrate, which induces explosive evaporation and/or boiling of water, which takes the particles off the surface. Thus, cleaning with an increased RH becomes similar to the SLC method extensively studied [5,6,13,19,31,32] for the case of silicon. The main advantage offered here is that this technique requires no direct liquid deposition on the surface, which may represent a technical difficulty or critical chemical invasion, especially in the case of polymers.…”

Section: Pmma Substratesmentioning

confidence: 92%

Laser cleaning of polymer surfaces

et al. 2001

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Abstract.We have investigated the removal of small spherical particles from polymer surfaces by means of 193-nm ArF and 248-nm KrF laser light. Polystyrene (PS) particles with diameters in the range of 110 nm to 1700 nm and silica particles (SiO 2 ) with sizes of 400 nm and 800 nm are successfully removed from two different substrates, polyimide (PI) and polymethylmethacrylate (PMMA). Experiments were performed in air (23• C, relative humidity 24%-28%) and in an environment with a relative humidity (RH) of about 90%. PACS: 42.62.CfLaser cleaning of surfaces from particles with diameters in the range from 100 nm to several microns has become increasingly important in lithography [1], semiconductor device fabrication [2-6], micromechanics, optics, telecommunications, etc.Conventional techniques such as ultrasonic and megasonic cleaning, wiping and scrubbing, high-pressure jet spraying, etching, plasma cleaning, etc., are often inadequate for the removal of particulate contaminants of micron and submicron size. The problems with these techniques include ineffectiveness, addition of contaminants, damage of prefabricated parts, etc. It has been demonstrated that laser cleaning can be used to efficiently remove micron and submicron particles from solid surfaces. Such particulates adhere with relatively strong forces [7] that are difficult to overcome with the traditional cleaning techniques. Laser cleaning based on the absorption of pulsed-laser radiation by the substrate and/or the particulates is denoted as dry laser cleaning (DLC) [6,8]. If the removal of particulates is related to the superheating and explosive evaporation of an auxiliary thin liquid film, the technique is denoted as steam laser cleaning (SLC) [4,5].Since 1991 of the particles from the surface and their spatial distribution after leaving the substrate in relation to the surface roughness [9]. In recent publications there has been a significant increase in the use of polymer science in the fields of microelectronics and sensor technology [10]. From polymers used in packaging to polymers used as electrets, polymers will soon be facing the same cleaning difficulties as conventional semiconductor materials. Only a few existing papers [11,12] describe the removal of residues of polymers from polymers. Nonetheless, to the authors' knowledge, no papers have dealt with laser-induced removal of particles from polymer substrates.In this paper we investigate laser cleaning of PI (polyimide) and PMMA (polymethylmethacrylate) from PS (polystyrol) and SiO 2 (silica) microspheres of different sizes. Experimental procedureThe experimental setup consists of a KrF excimer laser (Lambda Physik LPX 205), which provides at λ = 248 nm a maximum pulse energy of E ≈ 470 mJ (at a ν r = 1 Hz repetition rate). Its pulse length is τ (FWHM) ≈ 31 ns and its repetition rate is between 1 Hz and 30 Hz. The pulse energy is computer-controlled by an external adjustable tunable dielectric attenuator.The output from a circular aperture was imaged using a lens onto the polymer target...

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Section: Pmma Substratesmentioning

confidence: 92%

Laser cleaning of polymer surfaces

et al. 2001

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“…In contrast, early simplistic models of the SLC process [12,13] predicted an increase of the cleaning threshold for smaller particle diameters.…”

Section: Methodsmentioning

confidence: 80%

Near field induced defects and influence of the liquid layer thickness in Steam Laser Cleaning of silicon wafers

Lang

Mosbacher

Leiderer

2003

Applied Physics A: Materials Science & Processing

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The removal of particles from commercial silicon wafers by Steam Laser Cleaning was examined. Polystyrene colloids were used as model contaminants due to their well defined size and shape. In contrast to previous studies, where the experimental conditions on the surface were only roughly determined, special care was taken to control the amount of liquid applied to the surface. We report measurements of the cleaning threshold for different particle sizes. The comparability of the results was ensured by the reproducible conditions on the surface. Moreover, we studied the influence of different liquid film thicknesses on the cleaning process. Investigations of laser induced liquid evaporation showed that the cleaning threshold coincides with the fluence necessary for the onset of explosive vaporization. After particle removal, the surface was examined with an atomic force microscope. These investigations demonstrated that near field enhancement may cause defects on the nm-scale, but also showed that Steam Laser Cleaning possesses the capability of achieving damage-free removal for a large range of different particle sizes.PACS 81.65.Cf; 79.60.Bm

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“…This technology has been studies thoroughly and systematically [1,2]. A complete set of theoretical model including laser steam cleaning [3,4] has been developed based on experimental results, The model fits the experimental results well and has been successfully used to predict some new cleaning results in complex chemical and physical environments. Laser surface cleaning has been demonstrated as a new technology to remove small particles and organic contamination from solid surface.…”

Section: Laser Cleaning Of Ic Molding Toolsmentioning

confidence: 99%

Laser applications in integrated circuits and photonics packaging

Mendu

et al. 2004

SPIE Proceedings

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Laser processing has large potential in the packaging of integrated circuits (IC). It can be used in many applications such as laser cleaning of IC mold tools, laser deflash to remove mold flash from heat sinks and lead wires of IC packages, laser singulation of BGA (ball grid array) and CSP (chip scale packages), laser reflow of solder ball on GBA, laser peeling for CSP, laser marking on packages and on Si wafers. Laser nanoimprinting of self-assembled nanoparticles has been recently developed to fabricate hemispherical cavity arrays on semiconductor surfaces. This process has the potential applications in fabrication and packaging of photonic devices such as waveguides and optical interconnections. During the implementation of all these applications, laser parameters, material issues, throughput, yield, reliability and monitoring techniques have to be taken into account. Monitoring of laser-induced plasma has been used to understand and to control the processes involved in these applications. Numerical simulations can provide useful information on process analysis and optimization.

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A Theoretical Model for Laser Cleaning of Microparticles in a Thin Liquid Layer

Abstract: The devitrijication characteristics of Jive Na,O-SiO, glasses have been examined by a new method, and some empirical relationships, applicable over the range of compositions studied, have been established. Comparisons are made with results given in other published work.

Cited by 13 publications

References 16 publications

Laser cleaning of polymer surfaces

Laser cleaning of polymer surfaces

Near field induced defects and influence of the liquid layer thickness in Steam Laser Cleaning of silicon wafers

Laser applications in integrated circuits and photonics packaging

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