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This Recommended Practice (RP) describes a test method appropriate for semiquantitative determination and qualitative characterization of organic compounds outgassed from materials or components exposed to air or gases in cleanrooms or other controlled environments. This RP specifies four outgassing temperatures-50 °C (122 °F), 75 °C (167 °F), 100 °C (212 °F), and 150 °C (302 °F)-to 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 materials where outgassing is a concern.

BACKGROUND AND PURPOSE

This document is relevant to industries that may experience adverse production yields as a result of gaseous organic contamination, also known as volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs). The deposition of outgassed 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 materials may reduce integrated circuit (IC) processing yields and degrade tool performance. Organic compounds deposited on silicon wafers may make the wafer surfaces hydrophobic, which may affect etching, wetting, cleaning, and other waferprocessing steps. Organic compounds may decompose to form silicon carbide on silicon wafers and affect gate oxide integrity (GOI) and polysilicon deposition. Organophosphorus 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, lithography processing and inspection tools) used in the semiconductor and optical industries may become fogged, resulting in reduced transmission and tool performance.

In aerospace, the presence of molecular contamination can significantly degrade spacecraft performance goals and hasten end-of-life (EOL) projections. The on-orbit outgassing of organic compounds deposited during cleanroom processing onto thermal control surfaces will alter absorptance/emittance ratios and change thermal balance. Contamination on solar arrays will decrease power output. Molecular contamination in optical instruments will decrease signal throughput and can scatter the signal beyond the diffraction design, thus further decreasing performance.

The method described in this RP is designed to focus on medium- and low-vapor-pressure organic compounds. These compounds tend to adsorb on critical surfaces, including hardware, wafers, and optics, and may potentially lead to processing problems. This RP provides both a semiquantitative determination and a qualitative identification of a large range of compounds that may outgas from cleanroom materials. The document recommends several key test method conditions, such as outgassing time and temperature of analysis and reporting parameters, in order to obtain similar results from different laboratories. The method described in this RP is not designed to recover air, water, hydrocarbons smaller than C6, lowmolecular- weight alcohols (for example, isopropanol [IPA]), or compounds with a higher molecular weight than C25. Chemically reactive compounds (for example, amines) may have variable and unreliable recoveries due to reaction with acids and low response factors in GC-MS. However, the method may detect many organic compounds that have been found to outgas under ambient and high temperature conditions and affect processing or products. These limitations acknowledged, the method presented in this RP is believed to be the most appropriate analysis 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 example, very volatile organics and certain amines), modifications of the method or alternative methods may be required.