1、 Institute of Environmental Sciences and Technology IEST-RP-CC031.3 Contamination Control Division Recommended Practice 031.3 Method for Characterizing Outgassed Organic Compounds from Cleanroom Materials and Components Arlington Place One 2340 S. Arlington Heights Road, Suite 100 Arlington Heights,
2、 IL 60005-4516 Phone: (847) 981-0100 Fax: (847) 981-4130 E-mail: informationiest.org Web: www.iest.org 2 IEST 2011 All rights reserved Institute of Environmental Sciences and Technology IEST-RP-CC031.3 This Recommended Practice is published by the INSTITUTE OF ENVIRONMENTAL SCIENCES AND TECHNOLOGY t
3、o advance the technical and engineering sciences. Its use is entirely voluntary, and determination of its applicability and suitability for any particular use is solely the responsibility of the user. This Recommended Practice was prepared by and is under the jurisdiction of Working Group 031 of the
4、 IEST Con-tamination Control Division. Copyright 2011 by the INSTITUTE OF ENVIRONMENTAL SCIENCES AND TECHNOLOGY First printing, September 2011 ISBN 978-09841330-8-6 PROPOSAL FOR IMPROVEMENT: The Working Groups of the INSTITUTE OF ENVIRONMENTAL SCIENCES AND TECHNOLOGY are continually working on impro
5、vements to their Recommended Practices and Reference Documents. Suggestions from those who use these documents are welcome. If you have a suggestion regarding this document, please use the online Proposal for Improvement form found on the IEST website at www.iest.org/proposal/form.html. INSTITUTE OF
6、 ENVIRONMENTAL SCIENCES AND TECHNOLOGY Arlington Place One 2340 S. Arlington Heights Road, Suite 100 Arlington Heights, IL 60005-4516 Phone: (847) 981-0100 Fax: (847) 981-4130 E-mail: iestiest.org Web: www.iest.org IEST-RP-CC031.3 Institute of Environmental Sciences and Technology IEST 2011 All righ
7、ts reserved 3 Method for Characterizing Outgassed Organic Compounds from Cleanroom Materials and Components IEST-RP-CC031.3 CONTENTS SECTION 1 SCOPE AND LIMITATIONS 5 2 REFERENCES 5 3 TERMS AND DEFINITIONS 5 4 BACKGROUND AND PURPOSE . 6 5 TEST METHOD . 8 6 REPORTING 10 APPENDIX AORGANIC COMPOUNDS OF
8、 CONCERN OUTGASSING FROM COMMON CLEANROOM MATERIALS 11 BBIBLIOGRAPHY 15 4 IEST 2011 All rights reserved Institute of Environmental Sciences and Technology IEST-RP-CC031.3 IEST-RP-CC031.3 Institute of Environmental Sciences and Technology IEST 2011 All rights reserved 5 Institute of Environmental Sci
9、ences and Technology Contamination Control Division Recommended Practice 031.3 Method for Characterizing Outgassed Organic Compounds from Cleanroom Materials and Components IEST-RP-CC031.3 1 SCOPE AND LIMITATIONS 1.1 Scope This Recommended Practice (RP) describes a test me-thod appropriate for semiq
10、uantitative determination and qualitative characterization of organic compounds outgassed from materials or components exposed to air or gases in cleanrooms or other controlled environ-ments. This RP specifies four outgassing temperatures50 C (122 F), 75 C (167 F), 100 C (212 F), and 150 C (302 F)to
11、 baseline cleanroom materials and components. The RP may become the basis of an agreement between customer and supplier in the specification, procurement, and certification of materials. This RP can also be applied for other mate-rials where outgassing is a concern. 1.2 Limitations The method descri
12、bed in this RP is designed to screen primarily cleanroom materials but can also be applied to materials used in other controlled envi-ronments for identification of outgassed compounds detectable by dynamic headspace gas chromatogra-phy-mass spectrometry (GC-MS). The method described is not designed
13、 to provide absolute quantit-ative results. Information on the composition of the materials under test may be useful in selecting the appropriate outgassing temperature to use. 2 REFERENCES Due to the pioneering nature of this document, nor-mative references are not available. Users are encouraged t
14、o investigate the possibility of applying other RP documents. 3 TERMS AND DEFINITIONS analytical sample A portion of material, or component, analyzed. cleanroom components The individual fabricated parts that may consist of one or more material types and are used in areas sub-ject to contamination c
15、ontrol specifications. Example: filter assemblies contamination-free aluminum foil An aluminum foil free of organic contamination within the detection limit of a chosen test method. dynamic headspace analysis The process of thermal desorption of a sample in a flowing gas stream and collecting the ou
16、tgassing compounds for subsequent analysis. gas chromatography-mass spectrometry (GC-MS) A single tool for the identification and quantitation of volatile and semivolatile organic compounds in com-plex mixtures. gate oxide integrity (GOI) A measure of the reliability of a thin gate oxide that contro
17、ls the switching of a transistor. integrated circuit An interconnected array of discrete devices (transis-tors, diodes, and capacitors) contained on a single semiconducting substrate to form a complete circuit or multiple circuits. n-dope To introduce an impurity (dopant) into the crystal lattice of
18、 a semiconductor to modify its electronic properties; for example, adding phosphorous to sili-con to make the material n-type. 6 IEST 2011 All rights reserved Institute of Environmental Sciences and Technology IEST-RP-CC031.3 outgassing (offgassing) The release of molecular species in the gaseous or
19、 vapor state from a material under ambient or greater pressure conditions. semiquantitation An analysis technique in which the response factors for all unknown compounds are assumed to be the same as the standard reference compound. target compound A contaminant detrimental to the manufacturing proc
20、ess, either by itself or in combination with other compounds. thermal desorption (TD) or thermal extraction The removal of volatile material using thermal ener-gy (that is, heat). volatile organic compound (VOC) A gaseous product released from polymeric or other materials under certain conditions of
21、 temperature and pressure. 4 BACKGROUND AND PURPOSE This document is relevant to industries that may expe-rience adverse production yields as a result of gaseous organic contamination, also known as volatile organic compounds (VOCs) and semi-volatile organic com-pounds (SVOCs). The deposition of out
22、gassed compounds on hardware, products, and wafer surfaces is recognized as a source of processing problems and hardware failures. Outgassing of organic compounds from various construction, fabrication, and other ma-terials may reduce integrated circuit (IC) processing yields and degrade tool perfor
23、mance. Organic com-pounds deposited on silicon wafers may make the wafer surfaces hydrophobic, which may affect etch-ing, wetting, cleaning, and other wafer-processing steps. Organic compounds may decompose to form silicon carbide on silicon wafers and affect gate oxide integrity (GOI) and polysilic
24、on deposition. Organo-phosphorus compounds may decompose and n-dope silicon wafers. In the disk drive industry, organic compounds may build up on disks or heads to cause stiction or read-write errors. Optics (for example, li-thography processing and inspection tools) used in the semiconductor and op
25、tical industries may become fogged, resulting in reduced transmission and tool performance. In aerospace, the presence of molecular contamina-tion can significantly degrade spacecraft performance goals and hasten end-of-life (EOL) projections. The on-orbit outgassing of organic compounds deposited d
26、uring cleanroom processing onto thermal control surfaces will alter absorptance/emittance ratios and change thermal balance. Contamination on solar ar-rays will decrease power output. Molecular contam-ination in optical instruments will decrease signal throughput and can scatter the signal beyond th
27、e dif-fraction design, thus further decreasing performance. The method described in this RP is designed to focus on medium- and low-vapor-pressure organic com-pounds. These compounds tend to adsorb on critical surfaces, including hardware, wafers, and optics, and may potentially lead to processing p
28、roblems. This RP provides both a semiquantitative determination and a qualitative identification of a large range of com-pounds that may outgas from cleanroom materials. The document recommends several key test method conditions, such as outgassing time and temperature of analysis and reporting para
29、meters, in order to ob-tain similar results from different laboratories. The method described in this RP is not designed to recov-er air, water, hydrocarbons smaller than C6, low-molecular-weight alcohols (for example, isopropanol IPA), or compounds with a higher molecular weight than C25. Chemicall
30、y reactive compounds (for ex-ample, amines) may have variable and unreliable recoveries due to reaction with acids and low re-sponse factors in GC-MS. However, the method may detect many organic compounds that have been found to outgas under ambient and high temperature condi-tions and affect proces
31、sing or products. These limitations acknowledged, the method presented in this RP is believed to be the most appropriate analy-sis to provide chemical information for a large range of organic compounds that may outgas under ambient or higher temperature conditions. For certain organic compounds (for
32、 example, very volatile organics and certain amines), modifications of the method or alter-native methods may be required. See Appendix A for a table illustrating generic classes of organic compounds of concern, associated potential problems, and materials of construction found to include the compou
33、nds. 4.1 Materials of interest Any material has the potential to outgas organic compounds under certain conditions. Examples of materials and components of construction that may outgas in cleanrooms or other controlled environ-ments include: adhesives antistatic coverings cables cable protectors cau
34、lks coatings (e.g., mold release and slip agents) IEST-RP-CC031.3 Institute of Environmental Sciences and Technology IEST 2011 All rights reserved 7 filters and the materials used in the filters (e.g., potting compounds) floor coverings foams (e.g., open cell and closed cell) furniture (e.g., chairs
35、) gaskets gel seals insulation: acoustical, electrical, thermal, and vibrational labels light fixtures lubricants (e.g., oils and greases) mats o-rings packaging (e.g., bags and films) paints personnel personal care products: cosmetics, deo-dorants, hair products, and perfumes) pipes: metal and plas
36、tic plastic curtains plastics used in wet benches or other equip-ment sealants tapes tubing wall coverings Consumable items that may be tested include: components from disk drives, lasers, reac-tors, or other equipment shippers or carriers for: wafers, disks, flat panels, heads, masks, and reticles
37、garments inks gloves paper photoresists wipes and swabs NOTE: Both new and used materials may need test-ing since some materials adsorb chemicals that desorb later to cause processing problems (for exam-ple, wafer or disk carriers). Examples of types of polymers that are commonly tested for outgassi
38、ng include: acrylonitrile butadiene styrene elastomers epoxies latex nitrile polyacetal polyacrylates polyamides polycarbonate polyesters polyetheretherketone (PEEK) polyfluorinated polymers polyimides polyolefins polyphenylenesulfide polystyrene polysulfones polyurethanes poly(vinyl chloride) (PVC)
39、 silicones Composites that contain any of the above polymers integrated with other fibers, fillers, or adhesives may also require testing. 4.2 Organic compounds of concern The types of organic compounds of concern will de-pend on the final use of a material or component. Target compounds vary for di
40、fferent industries and may change with improving technologies. Some tar-get compounds that often affect processes include: alcohols amides (for example, N-methyl-2-pyrrolidone NMP) amines (may require other methods not cov-ered here) antioxidants (for example, butylated hy-droxyanisole BHA and butyl
41、ated hydroxy-toluene BHT) aromatics esters (for example, dioctyl adipate and di-octyl sebacate) halocarbons hydrocarbons (for example C9 or 150C b.p.) organophosphate esters (for example, tri-butyl phosphate TBP, triethyl phosphate TEP, and triphenyl phosphate TPP) phenols phthalate esters, especial
42、ly dibutyl phthalate, butyl benzyl phthalate, bis(2-ethylhexyl) phthalate DEHP or dioctyl phthalate DOP siloxanes (for example, linear and cyclic polydimethylsilicones, phenylmethylsili-cones), hexamethylcyclotrisiloxane, and octamethylcyclotetrasiloxane See ISO 14644-8:2006(E), Annex B for an exten
43、sive list of contaminating chemicals that may be of con-cern to products manufactured or processes carried out in any cleanroom environment. 8 IEST 2011 All rights reserved Institute of Environmental Sciences and Technology IEST-RP-CC031.3 4.3 Using the test results This RP provides a method for pre
44、liminary screening of detectable outgassed compounds from materials. The vendor data for the materials under test should be reviewed before an outgassing test is considered. Additional information should be considered along with the test results for the specification and pro-curement of materials. C
45、onsiderations include: amount of material used in the application rate of outgassing air exchanges air temperature and relative humidity other chemicals and contaminants in the air exposed surface area Additional testing (beyond the scope of this RP) may be designed to model the specific application
46、 for which a material is considered. The end-users of the product should determine how much testing is neces-sary for acceptance of a material in a specific cleanroom. 5 TEST METHOD Cleanrooms and controlled environments may have dynamic air streams. Compounds with low vapor pressures may outgas at
47、low rates, yet still transfer to surfaces where they may accumulate. For less vola-tile organic compounds with low vapor pressures, little equilibrates into the gas phase during static headspace studies thus little is detected. For this rea-son, the dynamic headspace GC-MS method is preferred over a
48、 static headspace procedure. In the dynamic headspace GC-MS method, samples of known mass are placed in enclosed sample holders and heated to a specified temperature for a predetermined time, while being purged with helium. The organic compounds that are thermally desorbed from the sam-ple are trans
49、ported by the helium carrier gas to a cold trap (in other words, the compounds are cryotrapped) and preconcentrated. After the specified thermal de-sorption time, the collected outgassed compounds are thermally desorbed from the cold trap and subsequent-ly analyzed by GC-MS. Many parameters affect the concentration level and types of compounds outgassed from a material. Ma-terial variables
