The broad-spectrum and high-throughput analysis provided by Syft Technologies’ SIFT-MS solution, coupled with high sensitivity and selectivity provides simple, economic analysis of volatile emissions from front-opening unified pods (FOUPs) and components.

Volatile emissions – or airborne molecular contaminants (AMCs) – from front-opening unified pods (FOUPs) used to transport semiconductor wafers, can contaminate wafers and therefore impact subsequent processing. For certain AMCs, product quality issues arise even at very low levels (part-per billion by volume (ppbv) concentrations and below). Since FOUPs are constructed from a wide range of materials, the volatile emissions are diverse.

Currently, multiple analytical tools are used to detect specific suites of AMCs due to the chemical diversity. Selected ion flow tube mass spectrometry (SIFT-MS) is a unique analytical technique that provides comprehensive, high-sensitivity detection of volatile organic and semivolatile organic compounds (VOCs and SVOCs), and inorganic gases (including HCl, HF, and SOx) within seconds (see Table 1). As a single, comprehensive tool with rapid analysis, SIFT-MS provides great economic benefit because it detects and identifies the widest range of emitted compounds faster, enabling more comprehensive quality assurance testing of FOUPs from component level to the full assembly. Furthermore, with SIFT-MS any combination of compounds can be included in any given analysis, and analyses are easily customized for monitoring different compound suites– from component through to points or discrete sample types.

Compounds ClassExample ClassesExample Compounds
HydrocarbonsAromatics, aliphatic, cyclic, unsaturatedBenzene, toluene, ethylbenzene, isooctane, tetradecane, limonene
OxygenatesAlcohols, aldehydes, carboxylic acids, esters, ketonesIsopropyl alcohol, formaldehyde, formic acid, dibutyl phthalate, acetone
Nitrogen-containing speciesAmides, amines, heterocyclics, nitrilesDimethyl formamide, ammonia, trimethylamine, 1-methyl-2-pyrrolidone, acetonitrile
Halogenated speciesChlorinated hydrocarbons, Freons perfluorinated compoundsPerchloroethylene, chlorobenzene, Freon 11, COF, CNF
Sulfur-containing speciesThioethers, mercaptans, heterocyclicsHydrogen sulfide, dimethyl sulfide, carbonyl sulfide
Silicon-containing speciesSilanes, siloxanes, silazanesTetramethylsilane, triethylsilanol, hexamethylcyclotrisiloxane, hexamethyldisilazane
Other inorganic gasesAcidic gases, dopantsHydrogen fluoride, hydrogen chloride, nitrogen dioxide, sulfur dioxide, sulfur trioxide, arsine, germane, phosphine, fluorine

 

Figure 1 provides an example of analysis of air contained within a fully assembled FOUP. It shows the wide range of species that can be detected, including aldehydes, organochlorine and organosulfur species, as well as the organometallic compound, iron pentacarbonyl. Each data cycle generates concentration data that are equivalent to a complete chromatographic analysis, but with SIFT- MS the timescale is tens of seconds for answers, rather than tens of minutes.

 

example of analysis of air contained within a fully assembled FOUP

Figure 1. Rapid screening of an assembled FOUP using SIFT-MS for diverse volatile emissions / AMCs.

 

Residual monomer emissions from the polymeric materials used to construct FOUPs are also readily detected using SIFT-MS. Figure 2 illustrates the rapid determination of monomer impurities in three different polymers. For illustrative purposes, all samples were analyzed for all compounds in one scan, with a throughput of 60 seconds per sample.

The rapid, direct, and comprehensive analysis provided by SIFT-MS means that it is ideal for enhancing FOUP quality assurance while keeping per-sample testing costs under strict control. By utilizing different inlet options for the Voice200ultra instrument, screening can be undertaken from component level right through to complete FOUP assemblies.

 

igure 2 illustrates the rapid determination of monomer impurities in three different polymers.

Figure 2. Rapid analysis of monomers present in the headspace of polystyrene (PS), polyoxymethylene (POM) and polyethylene (PET) polymers used for packaging. Ground samples of the polymers were incubated at 80 ̊C for 15 mins, followed by a 2.5 mL headspace injection into the SIFT-MS instrument at 100 μL s-1.

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