Mechanisms for nano particle removal in brush scrubber cleaning

Huang, Yating; Guo, Dan; Lu, Xinchun

doi:10.1016/j.apsusc.2010.10.115

Cited by 33 publications

(15 citation statements)

References 22 publications

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“…Among various methods used for post-CMP cleaning, the brush scrubbing method has been accepted as the most efficient way to remove contaminants. , In this method, a rotating poly(vinyl alcohol) (PVA) brush (Figure a) is pressed onto a laterally rotating wafer in an aqueous environment. To improve the efficiency of scrubbing, various process conditions and methods have been explored. − In addition, nanoparticle removal mechanisms have been studied from theoretical and experimental aspects. − However, these previous efforts mostly focused on nanoparticle–wafer interactions so that phenomena and mechanisms related to nanoparticle–PVA interactions have not been well understood, especially on the nanometer scale.…”

Section: Introductionmentioning

confidence: 99%

Inhibition of Silica Nanoparticle Adhesion to Poly(vinyl alcohol) Surfaces by Ammonia-Mediated Hydration: Implications for Effective Post-Chemical–Mechanical Planarization Cleaning

Ikarashi

Yoshino

Nakajima

et al. 2020

ACS Appl. Nano Mater.

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Adhesion of silica abrasive nanoparticles to a poly(vinyl alcohol) (PVA) brush surface in a post-CMP (chemical mechanical planarization) cleaning leads to serious 1 problems in yield enhancement of semiconductor fabrication. However, the nanoscale adhesion mechanism and its correlation with process conditions have hardly been understood. In this study, we investigated the influence of ammonia in the cleaning solution on silica nanoparticle adhesion to a PVA surface. By atomic force microscopy (AFM), we directly measured adhesion forces between a nanoscale silica probe and a PVA brush surface in various solutions and found that ammonia has a significant inhibitory effect against silica nanoparticle adhesion to a PVA surface. Importantly, we found that this effect cannot be explained by the electrostatic interactions alone, but also involves steric repulsion between silica and hydrated PVA. We also performed molecular-scale three-dimensional scanning force microscopy (3D-SFM) imaging and contact angle measurements, and found that ammonia promotes hydration and swelling of PVA. Furthermore, we performed molecular dynamics simulations and found that ammonia promotes dynamic rearrangements of hydrogen bonding networks (HBNs) at a PVA-water interface, giving extra flexibility to the PVA chains. Such flexibility promotes local swelling of PVA and inhibits silica nanoparticle adhesion to a PVA surface. This provides important guidelines for optimizing nanoscale structures and interactions of brush surfaces and abrasive nanoparticles in post-CMP cleaning.

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Section: Introductionmentioning

confidence: 99%

Inhibition of Silica Nanoparticle Adhesion to Poly(vinyl alcohol) Surfaces by Ammonia-Mediated Hydration: Implications for Effective Post-Chemical–Mechanical Planarization Cleaning

Ikarashi

Yoshino

Nakajima

et al. 2020

ACS Appl. Nano Mater.

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“…Removing them completely is the main task in post CMP cleaning. Polyvinyl acetate brush cleaning and megasonic cleaning are the commonly used methods . In cleaning process, when external force detaches the adhered particles from wafer, some particles are washed away by the flow, and meanwhile, some particles deposit to the wafer again .…”

Section: Introductionmentioning

confidence: 99%

The quantitative description between zeta potential and fluorescent particle adsorption on Cu surface

Mei

2013

Surface & Interface Analysis

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The influence factor for polystyrene based fluorescent particles' adsorption on Cu surface in liquid environment was investigated. The fluorescent particles with a size of 100 nm were used as the adsorbing particle for avoiding the disturbance to the adsorption result. The contrast between the fluorescent image and SEM image showed that there was a one‐to‐one correspondence between the fluorescent spot and the particle. This revealed the method of counting the fluorescent spot to obtain the adsorbing particle result is accurate. Zeta potential and ionic strength would affect the value of electrical double layer force. And the electrical double layer force and Van der Waals force between particles and surface determined the behavior of particles when particles got close to Cu surface. Results showed that particle adsorption on Cu surface was linear to the multiply of zeta potential for particles and Cu surface. Also, the influence of ionic strength on fluorescent particle adsorption was investigated. Finally, the quantitative description between zeta potential, ionic strength and particle adsorption was given. Copyright © 2013 John Wiley & Sons, Ltd.

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“…Among several types of post-CMP cleaning processes, polyvinyl acetal (PVA) brush cleaning has been the most effective method for contaminant removal due to the physical force imposed by direct contact between the brush and wafer surface that also provides low cost of ownership (COO). [6][7][8] The contact elastic force, hydrodynamic drag force, and friction between brush and particles are the dominant removal forces during brush scrubbing. In the boundary lubrication regime, particles can be removed by both rolling and lifting, mainly due to van der Waals forces.…”

mentioning

confidence: 99%

“…In the boundary lubrication regime, particles can be removed by both rolling and lifting, mainly due to van der Waals forces. [8][9][10][11] Shear forces applied by brush scrubbing are inversely proportional to the radius of the particle, making it difficult to detach smaller nano-sized particles compared to large particles. 8 Many researchers have focused on defectivity after brush scrubbing and particle removal from the wafer surface as a function of the wafer-brush gap, pressure contour, rotation speed, and flow rate during scrubbing.…”

mentioning

confidence: 99%

“…[8][9][10][11] Shear forces applied by brush scrubbing are inversely proportional to the radius of the particle, making it difficult to detach smaller nano-sized particles compared to large particles. 8 Many researchers have focused on defectivity after brush scrubbing and particle removal from the wafer surface as a function of the wafer-brush gap, pressure contour, rotation speed, and flow rate during scrubbing. [12][13][14] However, the brush itself can be a source of defects if it is contaminated or the conditioning process is not optimized.…”

mentioning

confidence: 99%

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Study on PVA Brush Loading and Conditioning during Shallow Trench Isolation Post-CMP Cleaning Process

Sahir

Cho

Kim

et al. 2022

ECS J. Solid State Sci. Technol.

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Polyvinyl acetal (PVA) brush cleaning is a widely accepted and efficient process for removing contaminants of the chemical mechanical planarization process during semiconductor processing. However, contaminants can adhere to the PVA brush, due to its highly hydrophilic and porous nature, and deteriorates its performance. This contamination is a serious problem, especially for processing devices smaller than 10 nm. Here, the effect of cleaning solution pH was investigated for ceria removal from oxide wafers and subsequent transfer to the PVA brush during scrubbing. A cleaning solution of pH 7 resulted in lower ceria removal efficiency compared to pH 2 and 12. The pH 2 and 7 cleaning conditions resulted in high brush loading compared to the pH 12 condition. High brush contamination at pH 7 resulted in higher cross contamination, whereas very low cross-contamination was observed at pH 2 and 12. The effect of ultrasonication and scrubbing on improvement of brush performance and lifetime was evaluated. Scrubbing in the presence of NH4OH efficiently removed all ceria particles from contaminated brushes. Because the bonding between brush and ceria particles is strong, only a robust physical force combined with a high chemical action can remove ceria particles loaded onto a PVA brush.

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Mechanisms for nano particle removal in brush scrubber cleaning

Cited by 33 publications

References 22 publications

Inhibition of Silica Nanoparticle Adhesion to Poly(vinyl alcohol) Surfaces by Ammonia-Mediated Hydration: Implications for Effective Post-Chemical–Mechanical Planarization Cleaning

Inhibition of Silica Nanoparticle Adhesion to Poly(vinyl alcohol) Surfaces by Ammonia-Mediated Hydration: Implications for Effective Post-Chemical–Mechanical Planarization Cleaning

The quantitative description between zeta potential and fluorescent particle adsorption on Cu surface

Study on PVA Brush Loading and Conditioning during Shallow Trench Isolation Post-CMP Cleaning Process

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