Laser-assisted removal of particles on silicon wafers

Vereecke, Guy; Röhr, E.; Heyns, Marc

doi:10.1063/1.369754

Cited by 115 publications

(64 citation statements)

References 10 publications

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“…As in the case of silicon, the repetition rate did not show any significant effect [17]. This should be expected as maximum thermal expansion is reached at the end of the nanosecond-laser pulse.…”

Section: Pmma Substratesmentioning

confidence: 83%

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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: 83%

“…at φ ≈ 17.5 mJ/cm 2 . Figure 2a shows that the thresholds for cleaning decrease with increasing particle size [1,17]. For the case of 110-nm particles, the cleaning efficiency only reaches values below (10 ± 10)% in the region below the modification threshold.…”

Section: Pi Substratesmentioning

confidence: 99%

Laser cleaning of polymer surfaces

et al. 2001

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“…Au cours de ces dernières années, ce procédé a fait l'objet de nombreuses études expérimentales [6,7] et plusieurs descriptions théoriques ont été proposées [8,9]. Ces dernières suggèrent différents mécanismes d'éjection tels que l'expansion rapide du substrat due à son échauffement par le faisceau [10], l'ablation locale du substrat sous la particule induite par une exaltation du champ par celle-ci [11], ou encore l'évaporation explosive de l'humidité résiduelle se trouvant à l'interface particule-substrat [12]. La plupart des modèles numériques développés pour 192 JOURNAL DE PHYSIQUE IV simuler ce processus d'enlèvement sont basés sur l'effet mécanique induit par l'expansion d'origine thermique de la surface.…”

Section: Introductionunclassified

Mécanismes d'éjection de particules par laser impulsionnel

et al. 2006

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Résumé. L'enlèvement de particules de dimensions nanométriques est l'un des principaux challenges à relever pour atteindre les futurs objectifs de l'industrie microélectronique. Les procédés laser présentent, dans certains cas, des performances très intéressantes, mais les mécanismes d'éjection des particules polluant la surface restent cependant fort mal connus. L'étude de la dynamique d'éjection des particules, par une technique optique, a mis en évidence l'existence de deux mécanismes dont l'importance relative dépend de la fluence d'irradiation. A forte fluence l'ablation locale du substrat sous la particule prédomine, alors que pour les fluences plus faibles le mécanisme semble être lié à l'enlèvement de l'humidité résiduelle à l'interface particule -substrat. Contrairement aux modèles précédemment proposés, la contribution de la force d'inertie s'exerçant sur la particule lors de l'expansion thermique rapide des matériaux est négligeable.

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“…The strong adhesion of these contaminants to the surface makes conventional processes inefficient, this problem being of major importance, among others, in the field of microelectronics. Two different procedures for laser cleaning have been described in the literature: dry laser cleaning (DLC) [1][2][3][4][5] and steam laser cleaning (SLC) [1,[6][7][8][9][10]. DLC is based on the interaction between the incident laser light and the substrate to be cleaned.…”

Section: Introductionmentioning

confidence: 99%

“…Laser cleaning [1][2][3][4][5][6][7][8][9][10] appears as one of the most promising techniques for the removal of sub-micron-sized particles from surfaces. The strong adhesion of these contaminants to the surface makes conventional processes inefficient, this problem being of major importance, among others, in the field of microelectronics.…”

Section: Introductionmentioning

confidence: 99%