by Robert L. Mielke
A comprehensive look inside the work of one of the most active contamination control programs in the country.
When establishing a comprehensive contamination control program, one looks for tools (standards and practices) to assist in setting up the program. One such tool is the recommended practices that have been written by the Institute of Environmental Sciences and Technology (IEST). This series of practices, which has been ongoing since 1982, addresses contamination control topics such as clean air filters (HEPA, ULPA), cleanrooms and clean air device testing, cleanroom supplies (garments, wipers, gloves, etc.), and cleanroom design, cleanroom operation, etc.
The IEST Contamination Control Division has 34 Standards and Practices Working Groups. Through the efforts of these groups, more than 25 documents have been released for publication. Members of the various working groups devote their time and expertise to produce contamination control Recommended Practices (RP) and standards relating to cleanrooms and what it takes to make them operate.
The IEST Contamination Control Working Groups operate under a detailed policy in order to ensure fairness and balance. Thus, they provide the cleanroom industry with standardized procedures based on peer-reviewed applications of cleanroom technology. During the writing process, meetings are generally held twice a year. Currently, recommended practices must be reviewed within three years of their last published date. At this time, the IEST is reviewing their documents and could be pulling some of its practices if they do not meet all the requirements.
New working groups are formed when enough interest is generated on a specific contamination control topic, and the IEST Contamination Control Division deems there are enough resources to proceed with the topic. There have been times when a working group was formed but then had to be disbanded when the interest waned.
The working groups have so far generated the following documents:
· IEST-RP-CC001.3: HEPA and ULPA Filters covers basic provisions for HEPA and ULPA filter units as a basis of agreement between customer and supplier. Filters that meet the requirements of this RP are suitable for use in clean-air devices and cleanrooms that come within the scope of FED-STD-209, ISO 14644-1, 2, & 4, and for use in supply air and contaminated exhaust systems that require extremely high filter efficiency (99.97% or higher) for submicrometer particles.
· IEST-RP-CC002.2: Unidirectional Flow Clean-Air Devices includes definitions, procedures for evaluating performance, and major requirements of unidirectional flow clean-air devices.
· IEST-RP-CC003.2: Garments Required in Cleanrooms and Controlled Environments provides non-mandatory guidance to the specification, testing, selection and maintenance of apparel and accessories appropriate for use in cleanrooms and controlled environments.
· IEST-RP-CC004.2: Evaluating Wiping Materials Used in Cleanrooms and Other Controlled Environments describes methods for testing wipers used in cleanrooms and other controlled environments for characteristics related to both cleanliness and function.
· IEST-RP-CC005.2: Cleanroom Gloves and Finger Cots discusses parameters and tests that apply to gloves and finger cots using, whenever possible, standard tests approved by the American Society for Testing and Materials (ASTM) or government agencies. Where these bodies have developed no such tests, appropriate new tests have been devised. The specific intended use of the glove or finger cot being evaluated will determine which tests are appropriate for determining its acceptance or non-acceptance.
· IEST-RP-CC06.2: Testing Cleanrooms provides tests that evaluate and characterize the overall performance of the cleanroom and clean zone system. Included are recommended test equipment requirements and testing procedures for determining performance parameters. Where the type of cleanroom affects the test method, alternative procedures are defined.
· IEST-RP-CC007.1: Testing ULPA Filters covers production testing of filters for particle penetration and pressure drop of ultralow penetration air filters (ULPA). The penetration range of the procedure is 0.001% to 0.0001% using particle counters
· IEST-RP-CC008-84: Gas-Phase Adsorber Cells covers the design and testing of modular gas-phase adsorber cells for use where high-efficiency removal of gaseous contaminants is required. Two types of cells are discussed with respect to leak performance, materials, design, construction, packaging, installation, calculation of residence time and quality assurance requirements.
· IEST-RD-CC009.2: Compendium of Standards, Practices, Methods, and Similar Documents Relating to Contamination Control lists standards, practices, methods, technical orders, specifications and similar documents developed by government, industry and technical societies in the United States and other countries, which are related to the field of contamination control.
· IEST-RD-CC011.2: A Glossary of Terms and Definitions Relating to Contamination Control defines terms relating to contamination control and contains lists of frequently used abbreviations and acronyms. It also contains a list of IEST Recommended Practices and lists the RPs by subject area.
· IEST-RP-CC012.1: Considerations in Cleanroom Design makes recommendations regarding factors to consider in the design of cleanroom facilities. This discussion is limited to those environmental conditions that typically confront cleanroom designers and users. This RP is intended to provide users with a means to establish performance criteria for cleanrooms.
· IEST-RP-CC013-86-T: Equipment Calibration or Validation Procedures covers definitions and procedures for calibrating instruments used for testing cleanrooms and clean air devices, and for determining intervals of calibration.
· IEST-RP-CC015-87-T: Cleanroom Production and Support Equipment suggests many approaches for the design, installation and operation of production and support equipment used within a cleanroom or at a clean workstation so as to minimize the contribution of that equipment to the contamination of the product. It is intended to improve communication among the equipment designer, production layout personnel, production management, quality assurance and project management. It may also serve as an educational device to assist buyers in the preparation of bid specifications.
· IEST-RP-CC016.1: The Rate of Deposition of Nonvolatile Residue in Cleanrooms provides a uniform method and basis for determining the rate of deposition of nonvolatile residue (NVR) on surfaces in cleanrooms. In the design of the heating, ventilating and air conditioning system, the selection of suitable filters, and the selection of materials used in the construction of the cleanroom, the user should specify the requirements for the rate of deposition of NVR. Designers of cleanrooms should consider the maximum deposition rates suggested by this Recommended Practice when the deposition of NVR can affect the performance of products.
· IEST-RP-CC018.2: Cleanroom Housekeeping-Operating and Monitoring Procedures provides guidance for maintaining a cleanroom at the level for which it was designed. It is intended for use as a guide to establish appropriate housekeeping procedures. In addition, test procedures are provided for use in establishing the frequency and in monitoring the effectiveness of the housekeeping. The test methods also help to determine appropriate levels of surface cleanliness for specific cleanrooms.
· IEST-RP-CC020.2: Substrates and Forms Used for Documentation in Cleanrooms applies to substrates and forms used in cleanrooms for the purpose of documentation. Specifically included are copy paper, writing paper, labels, tags, self-adhesive notes, perforated and punched forms, envelopes, bound materials and all printed versions thereof.
· IEST-RP-CC021.1: Testing HEPA and ULPA Filter Media discusses test methods for physical and filtration properties of high-efficiency particulate air and ultralow penetration air filtration media.
· IEST-RP-CC022.1: Electrostatic Charge in Cleanrooms and Other Controlled Environments discusses methods for specifying and evaluating the effectiveness of techniques for controlling electrostatic charge. Controlling electrostatic charge reduces surface contamination and electrostatic discharge. This document describes methods of testing, provides guidelines for verifying charge neutralization and resistivity of surfaces and materials, and describes typical control systems and their applications.
· IEST-RP-CC023.1: Microorganisms in Cleanrooms provides guidelines for the control and quantitative measurement of viable air and surface contamination. Included is an introduction to the methods and devices currently available for the quantification of airborne and surface viable contamination.
· IEST-RP-CC024.1: Measuring and Reporting Vibration in Microelectronics Facilities establishes levels of vibration sensitivity to ensure that vibrations occurring in the facility or at the site are below those levels. This RP is intended to provide guidance in the microelectronics industry but may also apply to pharmaceutical and biological research, metrology laboratories and other contexts in which vibration control is important.
· IEST-RP-CC026.1: Cleanroom Operations offers guidance for maintaining the integrity of the cleanroom during ancillary operations. These operations include preparation of supplies and materials; modification of the facility; and installation and repair of equipment. Procedures are given for verifying the cleanliness of the equipment, the workstation and the area after these ancillary operations are completed.
· IEST-RP-CC027.1: Personnel Practices and Procedures in Cleanroom and Controlled Environments provides a basis for establishing personnel procedures and the development of training programs for cleanrooms and associated environments, not including specialized information needed for operations requiring control of living microbial contaminants.
· IEST-RP-CC029.1: Automotive Paint Spray Applications includes guidelines and recommended procedures for controlling dirt contamination (particles, fibrous material, etc.) in controlled environments used for paint spraying.
· IEST-RD-CC033.1: Building Code Reference Handbook: A Guide to Alternative Code Compliance Issues in the Semiconductor Industry is a reference guide for code issues that require alternative compliance approaches in order to design, construct or operate semiconductor facilities.
· IEST-RP-CC034.1: HEPA and ULPA Filter Leak Tests covers definitions, equipment and procedures for leak testing HEPA and ULPA filters in the factory as they are produced, at the job site before they are installed and after they are installed in cleanrooms and unidirectional-flow, clean-air devices.
Several Recommended Practices are scheduled for release in the next six months. These will include:
- IEST-RP-CC031.1: Method for Qualitative Analysis of Outgassed Compounds from Cleanroom Materials and Components.
- IEST-RP-CC016.2: The Rate of Deposition of Nonvolatile Residue in Cleanrooms
- IEST-STD-CC1246.1: Product Cleanliness Levels and Contamination Control Program
- IEST-RP-CC028.1: Minienvironments
- IEST-RP-CC001.4: HEPA and ULPA Filters
- IEST-RP-CC006.3: Testing Cleanrooms
IEST is also the Secretariat for Technical Committee 209 of the International Standards Organization (ISO/TC 209), charged with writing a series of international standards for cleanrooms and associated controlled environments. These documents are in various stages of development. Those currently available include: ISO 14644-1:1999, Cleanrooms and associated controlled environmentsPart 1: Classification of air cleanliness; and ISO 14644-2:2000, Cleanrooms and associated controlled environmentsPart 2: Testing and monitoring to prove continued compliance to ISO 14644-1. Soon to be released as a standard is ISO 14644-4, Cleanrooms and associated controlled environmentsPart 4: Design, construction and start up of facilities.
The IEST Contamination Control Division has recently released four Technical Guides that serve as complementary documents to ISO 14644-1 and ISO 14644-2. Included in the series are IEST-G-CC001: Counting Airborne Particles for Classification and Monitoring of Cleanroooms and Clean Zones; IEST-G-CC1002: Determination of the Concentration of Airborne Ultrafine Particles; IEST-G-CC1003: Measurement of Airborne Macroparticles; and IEST-G-CC1004: Sequential-Sampling Plan for Use in Classification of the Particulate Cleanliness of Air in Cleanrooms and Clean Zones. Three of these Guides (1002, 1003, and 1004) are referenced in ISO 14644-1 and thus will serve as sources of additional information on specific topics covered by the Standard.
In May of 2000, IEST received ANSI accreditation to write and publish American National Standards using the Canvass Method. This means that IEST will upgrade some of its RPs to American National Standards. IEST, through the Canvass Method, will submit the cleanroom standards that have been and will be published by ISO to become ANSI/ISO standards. These ANSI/ISO standards will be equivalent to the ISO standards but will have the American National Standard “stamp” on them.
I have found that there's no greater satisfaction than wrestling over a tough question with a multitude of viewpoints and finally coming up with one, agreeable answer, even if it wasn't the one you suggested. If you have not availed yourself of the opportunity to participate in the IEST Standards and Practices Program, I encourage you to do so.
Those who have many years of experience have a chance to share their knowledge. Those with less experience have a chance to challenge the experts.
For further information on these Guides, Recommended Practices, and Standards, contact IEST at 940 East Northwest Highway, Mount Prospect, Illinois 60056, website www.IEST.org, e-mail [email protected], or phone 847-255-1561.
Acknowledgments. The author wishes to thank Irma Komro and Corrie Roesslein of IEST for their help in the preparation of this paper.
Robert L. Mielke is a senior metrology engineer for Abbott Laboratories, North Chicago, IL. Prior to joining Abbott in 1992, he was employed for 24 years as an expert in metrology and contamination control by the U.S. Department of Energy's Mound Facility. He holds a B.S. from Miami University of Ohio. He has presented over 30 papers on contamination control related topics.
The IEST Contamination Control Standards and Practices Committee is divided into five sub-committees covering the general categories of filtration, operational products, procedural, facilities, and environmental control. The five sub-committees with their respective working groups (WG) are as follows:
Sub-Committee 1: Filtration
· WG-CC001: HEPA and ULPA Filters
· WG-CC002: Unidirectional Flow Clean-Air Devices
· WG-CC006: Testing Cleanrooms
· WG-CC007: Testing ULPA Filters
· WG-CC008: High-Efficiency Gas-Phase Adsorber Cells
· WG-CC021: Testing HEPA and ULPA Filter Media
· WG-CC034: HEPA and ULPA Filter Leak Tests
Sub-Committee 2: Operational Products
· WG-CC003: Garment System Considerations for Cleanrooms and Other Controlled Environments
· WG-CC004: Evaluating Wiping Materials Used in Cleanrooms and Other Controlled Environments
· WG-CC005: Gloves and Finger Cots Used in Cleanrooms and Other Controlled Environments
· WG-CC020: Substrates and Forms for Documentation in Cleanrooms
· WG-CC025: Evaluation of Swabs used in Cleanrooms
· WG-CC032: Packaging Materials for Cleanrooms
Sub-Committee 3: Procedural
· WG-CC013: Procedures for the Calibration or Validation of Cleanroom Test Equipment
· WG-CC014: Calibrating Particle Counters
· WG-CC018: Cleanroom Housekeeping-Operating and Monitoring Procedures
· WG-CC019: Qualifications for Agencies and Personnel Engaged in the Testing and Certification of Cleanrooms and Clean-Air Devices
· WG-CC026: Cleanroom Operations
· WG-CC027: Personnel in Cleanrooms
· WG-CC029: Contamination Control Considerations for Paint-Spray Applications
· WG-CC100: FED-STD-209: Airborne Particulate Cleanliness Classes in Cleanrooms and Clean Zones
Sub-Committee 4: Facilities
· WG-CC012: Sub-Group 1; Cleanroom Design Considerations
· Sub-Group 2; Installation of Cleanroom Production Equipment
· WG-CC024: Measuring and Reporting Vibration in Microelectronics Facilities
· WG-CC028: Minienvironments
· WG-CC030: Cleanroom Electrical Systems (joint WG with IEEE)
· WG-CC033: Environmental Code and Definitions
Sub-Committee 5: Environmental Control
· WG-CC016: The Rate of Deposition of Nonvolatile Residue in Cleanrooms
· WG-CC022: Electrostatic Charge in Cleanrooms and Other Controlled Environments
· WG-CC023: Microorganisms in Cleanrooms
· WG-CC031: Outgassing Performance Criteria for Cleanroom Materials
· WG-CC901: MIL-STD-1246: Product Cleanliness levels and contamination control program
· WG-CC902: MIL-HDBK-406: Contamination control technology: Cleaning materials for precision pre-cleaning and use in cleanrooms and clean work stations
· MIL-HDBK-407: Contamination control technology: Precision cleaning methods and procedures
There are two additional Working Groups that write reference documents reporting directly to the IEST Contamination Control Vice-President. They are:
· WG-CC009: Compendium of standards, practices, methods, and similar documents relating to contamination control
· WG-CC011: A glossary of terms and definitions relating to contamination control.
Be sure to attend Bob Mielke's presentation on IEST Recommended Practices at CleanRooms East 2001 in Boston. For more information, call 603-891-9267 or register on-site.