The Deposition of Contaminants from Deionized Water onto Hydrophobic Silicon Wafers

1991 ◽  
Vol 34 (6) ◽  
pp. 28-34
Author(s):  
Deborah Riley ◽  
Ruben Carbonell
Keyword(s):  
Zeta Potential ◽  
Particle Deposition ◽  
Hydrophobic Surface ◽  
Contact Angles ◽  
Silicon Wafers ◽  
Deionized Water ◽  
Silicon Surfaces ◽  
Bulk Solution ◽  
Wafer Surface ◽  
Auger Analysis

The liquid-based deposition of particles onto hydrophobic silicon surfaces was investigated by exposing hydrophobic silicon wafers to sample contaminants in a stirred deionized water bath. Wafers were rendered hydrophobic by exposure to dilute hydrofluoric acid, and a goniometer was employed to monitor wafer contact angles. As has been observed in the past for hydrophilic wafers, the zeta potential recorded for the test particle had a significant impact on the deposition resulting on the hydrophobic silicon surfaces. This suggests that, despite treatment with HF and an overall hydrophobic surface behavior, regions remain on the wafer surface which are ionizable in aqueous solutions. The behavior of the silicon test wafers used in these studies is consistent with the presence of a negative zeta potential at the hydrophobic silicon surface. In contrast to the deposition seen on hydrophilic wafers, however, deposition onto hydrophobic silicon is frequently nonuniform. Additionally, Auger analysis indicates that hydrophobic surfaces show a marked tendency to attract hydrocarbon contaminants from the deionized (DI) water. The rinsing technique employed when rendering wafers hydrophobic was found to have a significant effect on baseline particulate levels, and test results indicate that contamination differences between hydrophobic and hydrophilic wafers may be more strongly related to exposure to gas/liquid interfaces than to differences in the rates of particle deposition in bulk solution.

Hydrophobisation of mechanical pulp fibres with sodium dodecyl sulphate functionalised layered double hydroxide particles

Holzforschung ◽  
2012 ◽  
Vol 66 (4) ◽  
Author(s):  
Carl Lange ◽  
Tom Lundin ◽  
Pedro Fardim
Keyword(s):  
Sodium Dodecyl Sulphate ◽  
Sodium Dodecyl ◽  
Weight Ratio ◽  
Hydrophobic Surface ◽  
Fibre Surface ◽  
Contact Angle Measurement ◽  
Contact Angles ◽  
Angle Measurement ◽  
Mechanical Pulp ◽  
Pulp Fibres

Abstract Hydrogen peroxide bleached spruce (Picea abies L.) made of thermo mechanical pulp (BTMP) fibres were modified with layered double hydroxides (LDH). The LDH particles were precipitated onto the BTMP fibre surfaces from aqueous solutions of urea and NaOH. The modified BTMP was further functionalised with sodium dodecyl sulphate (SDS) surfactant to produce pulp with hydrophobic character. The contact angle measurement with water on paper showed that the functionalisation with SDS was successful. The apparent contact angles varied in between the initial θ= 75° of the reference pulp up to θ= 135° of the SDS functionalised pulp. A hydrophobic surface was obtained already with 2.0% weight to weight ratio of SDS in pulp suspension. A high affinity between the LDH particles and the BTMP fibres was found as well. The investigated fibre modification route offers a new feasible tool in fibre surface treatment.

scholarly journals Antimicrobial Coatings from Hybrid Nanoparticles of Biocompatible and Antimicrobial Polymers

2018 ◽  
Vol 19 (10) ◽  
pp. 2965 ◽  
Author(s):  
Carolina Galvão ◽  
Luccas Sanches ◽  
Beatriz Mathiazzi ◽  
Rodrigo Ribeiro ◽  
Denise Petri ◽  
...  
Keyword(s):  
Colloidal Stability ◽  
Contact Angles ◽  
Silicon Wafers ◽  
Hybrid Nanoparticles ◽  
Ammonium Bromide ◽  
Antimicrobial Coatings ◽  
Cell Counts ◽  
Conversion Rates ◽  
Nanoparticles Dispersions

Hybrid nanoparticles of poly(methylmethacrylate) synthesized in the presence of poly (diallyldimethyl ammonium) chloride by emulsion polymerization exhibited good colloidal stability, physical properties, and antimicrobial activity but their synthesis yielded poor conversion. Here we create antimicrobial coatings from casting and drying of the nanoparticles dispersions onto model surfaces such as those of silicon wafers, glass coverslips, or polystyrene sheets and optimize conversion using additional stabilizers such as cetyltrimethyl ammonium bromide, dioctadecyldimethyl ammonium bromide, or soybean lecithin during nanoparticles synthesis. Methodology included dynamic light scattering, determination of wettability, ellipsometry of spin-coated films, scanning electron microscopy, and determination of colony forming unities (log CFU/mL) of bacteria after 1 h interaction with the coatings. The additional lipids and surfactants indeed improved nanoparticle synthesis, substantially increasing the conversion rates by stabilizing the monomer droplets in dispersion during the polymerization. The coatings obtained by spin-coating or casting of the nanoparticles dispersions onto silicon wafers were hydrophilic with contact angles increasing with the amount of the cationic polymer in the nanoparticles. Against Escherichia coli and Staphylococcus aureus, bacteria cell counts were reduced by approximately 7 logs upon interaction with the coatings, revealing their potential for several biotechnological and biomedical applications.

scholarly journals Studies of Some Properties and the Structure of Polyethylene Glycol (PEG) Macromolecules Adsorbed on a TiO2 Surface

2001 ◽  
Vol 19 (5) ◽  
pp. 397-407 ◽  
Author(s):  
S. Chibowski ◽  
M. Paszkiewicz
Keyword(s):  
Molecular Weight ◽  
Polyethylene Glycol ◽  
Zeta Potential ◽  
Surface Charge ◽  
Adsorption Layer ◽  
Bulk Solution ◽  
Ionic Structure ◽  
Solution Interface ◽  
Main Factors ◽  
Presence And Absence

In the studies presented, the influence of the molecular weight of polyethylene glycol (PEG) on the adsorption and electrical properties at the metal oxide/polymer solution interface has been determined. The main factors responsible for the observed changes in the zeta potential and surface charge of titania were determined on the basis of the data obtained. It was demonstrated that changes in the ionic structure of the Stern layer depend on the molecular weight of PEG and its conformation. A possible mechanism for the changes in zeta potential both with pH and molecular weight was proposed on the basis of values of the surface charge difference (Δσ0) and the diffuse layer charge difference (Δσd) as determined in the presence and absence of the polymer. The thickness of the adsorption layer (δ) on the surface of titania was calculated from the zeta potential changes, both in the presence and absence of the polymer. A distinct influence of the PEG molecular weight was noted on the values of the adsorption layer thickness (δ) determined. The structures of the macromolecules in solution and at the solid/solution interface were compared and from the dependencies obtained some changes in the shape and dimensions of the polymer coils on passing from the bulk solution to the interface were proposed.

The Role of HO2− in SC-1 Cleaning Solutions

1997 ◽  
Vol 477 ◽  
Author(s):  
Steven Verhaverbeke ◽  
Jennifer W. Parker ◽  
Chris F. McConnell
Keyword(s):  
Hydrogen Peroxide ◽  
Silicon Oxide ◽  
Bubble Formation ◽  
Ammonium Hydroxide ◽  
Silicon Surfaces ◽  
Wafer Surface ◽  
Particle Removal ◽  
Oxide Interface ◽  
Protective Oxide ◽  
Industry Standard

The RCA Standard Clean, developed by W. Kern and D. Puotinen in 1965 and disclosed in 1970 [1] is extremely effective at removing contamination from silicon surfaces and is the defacto industry standard.[2]. The RCA clean consists of two sequential steps: the Standard Clean 1 (SC-1) followed by the Standard Clean 2 (SC-2). The SC-1 solution, consisting of a mixture of ammonium-hydroxide, hydrogen-peroxide, and water, is the most efficient particle removing agent found to date. This mixture is also referred to as the Ammonium- Hydroxide/Hydrogen-Peroxide Mixture (APM). In the past, SC-1 solutions had the tendency to deposit metals on the surface of the wafers, and consequently treatment with the SC-2 mixture was necessary to remove metals. Ultra-clean chemicals minimize the need for SC-2 processing. SC-I solutions facilitate particle removal by etching the wafer underneath the particles; thereby loosening the particles, so that mechanical forces can readily remove the particles from the wafer surface. The ammonium hydroxide in the solution steadily etches silicon dioxide at the boundary between the oxide and the aqueous solution (i.e., the wafer surface). The hydrogen peroxide in SC-I serves to protect the surface from attack by OH" by re-growing a protective oxide directly on the silicon surface (i.e., at the silicon/oxide interface). If sufficient hydrogen peroxide is not present in the solution, the silicon will be aniostropically etched and surface roughening will quickly occur. On the other hand, hydrogen peroxide readily dissociates and forms water and oxygen. If the concentration of the resulting oxygen is too high, bubbles will appear in the solution. The gas liquid interfaces that result from the bubble formation act as a “getter” for particles that can re-deposit on the wafer surface if a bubble comes in contact with the wafer.

The Capillary Force Between an AFM Tip and a Surface at Different Humidity

2008 ◽  
Author(s):  
Sheng Chau Chen ◽  
Jen Fin Lin
Keyword(s):  
Relative Humidity ◽  
Capillary Force ◽  
Present Model ◽  
Hydrophobic Surface ◽  
Contact Angles ◽  
Solid Surfaces ◽  
Hydrophilic Surface ◽  
Solid Bodies ◽  
Force Equilibrium ◽  
Good Agreement

In the present study, the meniscus profiles of water bridges formed at different relative humidity are determined using the geometric relationships including the Kelvin equation and the force equilibrium formula established for the meniscus. The pull-off forces predicted by the present model show good agreement with the experimental results reported in the literatures. When the contact angles at two solid bodies are equal, the pull-off force is slightly elevated by an increase of the relative humidity of air, and is significantly elevated by an increase of the asperity radius. Furthermore, two hydrophobic surfaces with equally large contact angles lower the pull-off force. If a difference exists between the contact angles of two solid surfaces, the asperity with a hydrophilic surface incorporating with a smooth flat plate with a hydrophobic surface reduces the pull-off force.

Analysis of Handling Stresses in Thin Solar Silicon Wafers Generated by a Rigid Vacuum Gripper

2015 ◽  
Vol 138 (3) ◽  
Author(s):  
Hao Wu ◽  
Shreyes N. Melkote
Keyword(s):  
Stress Distribution ◽  
Dominant Role ◽  
High Stress ◽  
Surface Profile ◽  
Silicon Wafers ◽  
Wafer Surface ◽  
Initial Surface ◽  
Fe Modeling ◽  
Solar Silicon ◽  
Surface Profiles

Breakage of thin solar silicon wafers during handling and transport depends on the stresses imposed on the wafer by the handling/transport device. In this paper, the stresses generated in solar silicon wafers by a rigid vacuum gripper are analyzed via a combination of experiments and numerical modeling. Specifically, stresses produced in monocrystalline (Cz) and multicrystalline (Cast) silicon wafers of different thicknesses when handled by a vacuum gripper are analyzed using the finite element (FE) method. With the measured surface profiles of the wafer and the gripper as input, the handling process is simulated using FE modeling and the stress distribution obtained. The FE modeling results are validated by experimental data of wafer surface profile during handling. The results show that while the vacuum level does not have significant impact on the stress distribution, the initial surface profiles of the thin wafer and gripper play a dominant role in producing regions of high stress in the wafer.

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