• our science our science Our Science
    • By Industry

      • Life Sciences

      • Microelectronics

        • Semiconductor

        • Data Storage

        • Flat Panel Display

        • LED

        • Solar

      • Industrial

        • Aerospace

        • Chemical Manufacturing

        • Chromatography and Analytical

        • Coatings, Inks, and Adhesives

        • General Industrial

        • Glass Forming

        • Polymer Manufacturing

        • Water Treatment

    • By Role

      • Logic Manufacturers

      • Memory Manufacturers

      • Semiconductor Equipment Manufacturers

      • Chemical Suppliers

    • By Solution Area

      • Contamination Control

      • Fluid Management

      • Life Sciences

      • Specialty Materials

      • Substrate Handling

    • By Service

      • Analytical Services

      • Field Support Services

      • FOUP Services

      • Refurbishment Services

      • Regeneration Services

      • Technology Centers

        • China Technology Center

        • Life Sciences Technology Center

  • product catalog product catalog Product Catalog
    • Bare Die/CSP Trays

      • Tray Wizard

      • H20 Series Accessories

      • H44 Series Accessories

    • Chemistries

      • Chemical Delivery Systems

        • Solid Chemical Delivery Systems

        • Liquid Chemical Delivery Systems

      • Specialty Chemicals

        • Catalysts

        • Coating, Ink, and Adhesive Ingredients

          • Resin Monomers and Components

          • Surface Modifiers

        • Post-CMP Cleaning Solutions

          • Semiconductor Cleaning Solutions

            • PlanarClean® Cleaning Solutions

            • ESC Cleaning Solutions

          • Wide Band Gap Semiconductor Cleaning Solutions

          • HDD Media Substrate Cleaning Solutions

        • Post Etch Cleaning Solutions

          • TitanKlean® Cleaning Solutions

          • ST Cleaning Solutions

          • NOE Etchant Cleaning Solutions

        • Precursors

          • Upstream ALD/CVD Precursors

          • Advanced Deposition Materials (ADM) ALD/CVD Precursors

        • Slurries

        • Ligands

        • Silanes

        • Organophosphorus Compounds

        • Specialty Acrylates and Methacrylates

        • Siloxanes

        • Specialty Additives

        • Wafer Reclaim

    • Fluid Management Systems

      • Liquid Packaging

        • Chemical and Bioprocessing Containers

          • FluoroPure® HDPE Blowmolded Drums

            • FluoroPure® Advantage Trilayer HDPE Blowmolded Drums

            • FluoroPure® Trilayer HDPE Blowmolded Drums

          • FluoroPure® Composite Drums

          • FluoroPure® Custom Products

        • Single-Use Assemblies

          • 2D and 3D Bags

          • Mixing Systems

          • Motion Bioreactor Bags

          • Microcarrier and Cell Separation Systems

        • NOWPak® Liner Based Systems

        • Sentry® Quick Connect Systems

        • FluoroPure® Intermediate Bulk Containers

        • FluoroPure® Port Options, Tools and Accessories

        • Tube Sets and Manifolds

        • Custom Dip Tubes, Tanks, and Containers

        • FluoroPure® Pressure Vessels

        • Process Tanks

      • Fluid Handling

        • Fittings

          • PrimeLock® Tube Fittings

          • PrimeLock® ESD Tube Fittings

          • PrimeLock® Accessories

          • Flaretek® Tube Fittings

          • Flaretek® Accessories

          • Cynergy® Fittings

          • Cynergy® Accessories

          • EP PFA Flare Fittings

          • EP PFA Flare Fitting Accessories

          • PureBond® Welded Tube Fittings

          • Quikgrip® Tube Fittings

          • Quikgrip® PFA Nuts

          • Integral Ferrule Tube Fittings

          • Integral Ferrule Accessories

          • Barb PFA Tube Fittings

          • Dual Containment Fittings

          • PureBond® Welded Pipe Fittings

          • PureBond® Accessories

          • NPT Pipe Fittings

          • NPT Accessories

        • Valves

          • CR and CH Series Valves

            • CR4 Series Valves

            • CR8 Series Valves

            • CH8 Series High-Temperature Valves

          • Integra® Valves

          • Cynergy® Valves

          • EP PFA Valves

          • Manifolds and Assemblies

          • SG Series Valves

          • Solenoid Valves

          • Stack Valves

          • Plug Valves

          • Needle/Metering Valves

          • Stopcock Valves

          • Check Valves

          • Valve Accessories

        • Fluid Handling Accessories

          • Gauge Protectors

          • Spray Products

          • Aspirators

          • Fasteners

        • Valves Selection Tool

        • Fittings Selection Tool

        • Tubing and Pipe

        • Custom Products

      • Process Monitoring

        • Process Control

          • Integrated Flow Controllers

          • NT™ Proportional Control Valves

          • Photochemical Dispense Pumps

        • Process Measurement

          • Concentration Monitors

          • Electronic Flowmeters

          • NT™ Pressure Transducers

        • Particle Characterization

    • Gas Filtration and Purification

      • Gas Diffusers

        • Chambergard™ Gas Diffusers

      • Gas Filters

        • In-line Alloy-22 Gas Filters

        • Vent Gas Filters

        • Other Gas Filters

        • In-Line PTFE Gas Filters

        • In-Line Stainless Steel Gas Filters

        • In-Line Nickel Gas Filters

        • Surface Mount Gas Filters

      • AMC Filters

        • Stepper and Scanner Filters

        • Process Tool Air Filters

        • Facility Filtration

        • Filter Housings and Stand-alone Filter Cabinets

      • Air and Gas Filter Membranes

      • Gas Purifiers

    • Hard Disk Component Handling

      • Storage Boxes and Individual Disk Packages

      • Read-Write Trays and Carriers

      • Disk Shippers

      • Disk Process Carriers

    • Liquid Filtration and Purification

      • Liquid Filters

      • Liquid Purifiers

      • Liquid Filter Housings

    • Mask and Reticle Handling

      • Reticle Pods and Purge Cabinets

      • Mask Carriers and Shipping Boxes

      • Mask Packages

    • Other Substrate Handling

      • Miscellaneous Device Processing

      • Solar Cell Solutions

    • Specialty Materials

      • Premium Graphite

        • Industrial Graphite Grades

        • Semiconductor Graphite Grades

        • Life Sciences Graphite Grades

        • Premium Graphite Components

        • Glass Forming Graphite Grades

        • GLASSMATE® Components

        • Graphite Processing Options

      • Coatings

        • Chucks

        • Plasma Enhanced Chemical Vapor Deposition (PECVD) Coatings

        • Caerus™ Coating Technology

        • Pegasus™ Coating Technology

      • Premium Silicon Carbide

        • SUPERSiC<sup>®</sup> Silicon Carbide Components

        • SUPERSiC<sup>®</sup> Silicon Carbide

    • Specialty Gases

      • Specialty Gas Mixtures

      • Gas Delivery Cylinder Systems

      • Gas Delivery Cabinet Systems

      • Gases

    • Wafer Handling

      • Wafer Processing

        • CMP Cleaning Brushes

        • CMP Pads and Pad Conditioners

        • 300 mm Front Opening Unified Pods (FOUPs)

        • 200 mm Wafer Processing

        • 200 mm Accessories

        • 150 mm Wafer Processing

        • 150 mm and Smaller Wafer Carrier Accessories

        • 125 mm Wafer Processing

        • 100 mm Wafer Processing

        • 76.2 mm 3" Wafer Processing

        • 2.5" and Smaller Wafer Processing

        • Labware

        • Chucks

      • Wafer Shipping

        • 300 mm Wafer Shippers

        • 200 mm Wafer Shippers

        • 150 mm Wafer Shippers

        • 125 mm Wafer Shippers

        • 100 mm Wafer Shippers

        • 76.2 mm (3") Wafer Shippers

        • 2.5" and Smaller Wafer Shippers

      • Finished Wafer Shipping

        • SmartStack® Contactless Horizontal Wafer Shipper

        • SmartStack® Horizontal Wafer Shippers

        • Film Frame Rings and Shippers

  • resources resources Resources
    • Reference Materials

    • Technical Information

      • Calculators and Tools

      • Chemical Compatibility

      • Chemlock® Filter Housing Technical Information

      • Component Technical Information

      • Entegris Test Standards and Protocols

      • FAQ

      • Formulas

      • Glossary

      • Material Properties and Safety

      • Particle Characterization Applications

    • Industry Insights

      • 3D NAND Solutions

      • Achieving SAE J2719 Quality Hydrogen for Fuel Cells

      • Advanced Coatings

      • Advanced Deposition Materials Innovation

      • Automotive Reliability

      • Cars and Chips: The Acceleration of Electronic Systems

      • Chasing the Perfect Pattern

      • Chemical Mechanical Planarization (CMP)

      • Clean Chemical Delivery

      • Clean Gas Delivery

      • CMP Process Monitoring

      • Dual Containment Tubing

      • Electrostatic Discharge (ESD) Prevention

      • Enabling Advanced Lithography

      • End-to-End Gas Filtration Solutions

      • Food and Beverage Contamination Control

      • Front-end to Back-end Solutions

      • Glass in Front; Glass in Back

      • High Purity Chemical Manufacturing

      • Holistic Approach to Enabling Device Performance, Yield, and Reliability

      • Internet of Things

      • More Than Just a Chip Tray

      • Operational Excellence

      • Particle Characterization

      • Pervasive Defectivity in Semiconductor Manufacturing

      • Protecting Your Data Center Environment from Gas-Phase Contamination

      • The Rare Air of the Semiconductor Fab

      • Silicon Carbide Slurries

      • The Silicon Precursor Toolbox for Low-Temperature Deposition

      • Solid Precursors and Delivery Systems

      • Solutions in Advanced Logic

      • Solving Advanced Technology Challenges with Innovative Materials

      • Storage Class Memory

    • Ensights (Blog)

  • about us about us About Us
    • Corporate Overview

    • Corporate Social Responsibility

    • Careers

    • Events

    • Investor Relations

    • Legal/Trademark Notices

    • Locations

    • News Releases

    • Media Coverage

    • Entegris Blog

Contamination Control in Ultrapure Chemicals and Water


How small are the particles that our filters are removing?

An average of 4 million cubic feet of water flow over Niagara Falls every minute. Filtration down to 1 ppq is the equivalent of finding and removing one drop of impurity from this flow over 1 day.

FAQ Series

Fundamentals of Contamination Control

Controlling contamination has a clear objective. Improving manufacturing yield by reducing wafer defect rates related to chemical contaminants. Particles, gels, and metals all cause varying types of surface abnormalities that lead to defective products. Liquid filters and purifiers provide a line of defense to prevent defect-causing contaminants from reaching the wafers and substrates. Not all contaminants can be removed, however. Take a look at the most frequently asked questions for the solutions that will help you gain a stronger understanding of the fundamental concepts, mechanisms and best practices to improve your chemical and water filtration and purification processes.

Frequently Asked Questions
  • Q.) What is the critical function of a filter membrane in semiconductor manufacturing?

    A.) A membrane is a selective barrier material that permits certain desirable elements in a fluid stream to pass through while retaining others than that can be damaging to the process.  Membranes used in chemical filtration are constructed of polymers and reduce the number of defects on the wafers or substrates by removing contaminants. 

  • Q.) What is the performance difference between filters?

    A.) Every chemical has a concentration of contaminants that should be removed to prevent the formation defects on the wafers. These particles are of various size and every process has a tolerance set for the maximum size allowable. 

    The chart shown demonstrates examples of how to remove particles of various sizes and concentrations with different filter combinations at the bulk (BCD) and point of tool (POT) filtration points.  As the performance of the filters improves (lower retention rating and strategic placement/combination), the particle counts drop to within the tolerance limit.

  • Q.) What are the differences between filter membrane structures?
    • Symmetric (Isotropic), pore size remains constant across membrane
    • Asymmetric (anisotropic), pore size varies across membrane
    • Composite (multi-layer), there are distinct layers of different pore sizes and materials

     

    Each structure is designed for particular performance characteristics found incontamination control programs.

  • Q.) What influences a filter’s retention rating and flow rate?

    A)  Membrane performance is dependent upon:  

    1. Materials to determine the surface energy of the membrane (wetting ability)
    2. Device structure to determine the flow path of the fluid (see video)
    3. Surface area of the membrane inside the filter (flow rate)
    4. Cleaning techniques to determine the presence of extractables (extractables)

     

    Each of these factors are interdependent and have an influence on the filter's performance.  

  • Q.) What are the most important aspects of replacing a cartridge filter in a housing?

    A.) Several aspects will influence the performance of the new filter (see video)

    1. Using the  correct PPE (personal protective equipment) - avoids interaction with chemistry
    2. Proper fit - choosing a compatible design for the housing style
    3. Material compatibility - choosing a filter that is compatible with the chemistry
    4. Clean tools and PPE - avoids introducing new contaminants
  • Q.) What's the difference between sieving versus non sieving contaminant removal mechanisms?  

    A.) Sieving retention is based upon size exclusion. 

    The physical size of the membrane pore structure will retain the larger sized particles.  A smaller pore size structure increases the retention of smaller particles.   

    Nonsieving retention is based on chemical attraction between the membrane and the contaminant.  The particles are typically much smaller than the dimensions of the membrane pores and are captured by adsorption to the filter's membrane surface.  

  • Q.) What is the difference between "dewetting" and a "non-dewetting" membranes?

    A.) The term "dewetting" refers to a membranes ability to adsorb a liquid in the open space in the pore structure as a method of preparing it to work effectively. 

    When a filter "dewets", the fluids in the pore structure release and dry out essentially.  This leaves the filter in a less than optimal state of performance.  

    The mechanism to keep the filter "wet" are surface energies of the chemistry and filter. These both must be in alignment to prevent nucleation sites from forming on the membrane.  When this happens, the open spaces in the filters pore structure close and prevent the chemistry from flowing through effectively.  For this reason, careful consideration of the chemistry and membrane combinations chosen is an important consideration for optimal performance.  

  • Q.) What is the value of a "prewet" membrane relative to the filter?

    A.) A prewet membrane is shipped in a fluid solution to enable it to be installed quickly, reducing the tool downtime. Membranes that are not prewet require additional "priming" time and chemical use.

    In both types, the goal of the preparation is to "wet" or "wet out" the membrane so that the chemistry will effectively flow through the membrane pore structure and capture contaminants more quickly. If this state is not reached, the chemistry will not flow through effectively and contaminants will not be removed efficiently.

  • Q.) What influences a filter’s retention rating and flow rate?

    A.)  Membrane performance is dependent upon:  

    1. Materials to determine the surface energy of the membrane 
    2. Device structure to determine the flow path of the fluid (see video)
    3. Surface area of the membrane inside the filter 
    4. Cleaning techniques to determine the presence of extractables

     

    Each of these factors are interdependent and have an influence on the filter's retention and flow rate performance.  

  • Q.) What effect does temperature have upon chemical and o-ring compatibility?

    A.) O-rings are a component in a polymer filter designed for use with specific chemical types and under certain conditions. 

    When an o-ring is installed into a chemical process that is outside its compatibility, it may break down and shed particles into the chemistry.  Temperature is also a consideration when choosing an o-ring for a particular process condition.  An elevated temperature can further strengthen the reaction between an o-ring and chemistry.

  • Q.) What are the benefits of serial filtration?  

    A.) Serial filtration utilizes several filters at distinct points in the chemical journey. 

    This approach provides faster tank cleanup in BCDS (bulk chemical delivery systems) with a progressive increase in the contaminant control performance as the fluids get closer to the water, and an extension of filter lifetime on tool.   

  • Q.) What is the difference between a filter and purifier?

    A) A filter is focused on removing particles and gels typically with a sieving removal mechanism (size exclusion) while purifiers are typically used to remove metal ions using nonsieving mechanism (adsorption).

    A purifier is a higher level of contamination control in chemical and water purification.  While the exterior filter/purifier shell may be the same, the internal membrane is the key difference between the two types.

  • Q.) Is removal efficiency of metals affected by an increase in flow rate with organic solvents?

    The removal of sodium and potassium metal ions from both PMGE and an aqueous solution using a solvent purifier. 

    Removal of sodium and potassium from an aqueous solution is possible even at different flow rates. In PGME solvent, potassium is effectively removed. However the removal of sodium in PGME solvent is reduced as the flow rate increases. This indicates that in PGME solvent, metals exist not only as dissociated metal ions but also as metal salts. This must be taken into consideration when purification of metals from organic solvents is implemented. 

    For more details, see the Application Note.