Process Name

Semiconductor Manufacturing

Description

Chemical exposures in the fabrication of integrated circuits or "chips" occur in: 1.) wafer manufacturing with potential release of toxic gases such as arsine, diborane, and phosphine; 2.) fabrication of semiconductors including oxidation, photolithography, etching, and doping; and 3.) electronic component assembly including soldering and encapsulation in epoxy and formaldehyde resins. Asthma caused by soldering fluxes, isocyanates, epoxy resins, and trimellitic anhydride have been reported in this industry. [Harber, p. 718-27] Other potential adverse health effects are reproductive toxicity from glycol ethers, hydrofluoric acid burns, arsenic poisoning, and contact dermatitis. "Because of the very low levels of airborne arsenic in modern silicon wafer fabs, it is unlikely that urinary biomonitoring is able to detect increments in exposure." Silicon is the substrate for about 95% of wafers made, and gallium arsenide is used in the remaining 5%. Gallium arsenide is used for military devices and other products requiring faster processing speeds. [Sullivan, p. 431-66] Hazards are found in 5 main types of chemical processing: 1.) PHOTORESISTS (solvents including glycol ethers); 2.) DEVELOPERS (xylene, Stoddard solvent, NaOH, & tetramethyl ammonium hydroxide); 3.) ETCHANTS (mainly strong inorganic acids but dry etchants used in newer technology); 4.) PHOTORESIST STRIPPERS (dry, plasma O2 used in newer technology); and 5.) DOPANTS (inorganic compounds containing antimony, arsenic, phosphorus, or boron). "For silicon and silicon dioxide materials, fluorine-based etchants, such as CF4, are often used. For aluminum etching, chlorine-based gases, such as BCl3, are typically used." Solvent-amine strippers are solutions of solvents (N-methyl-2-pyrrolidone, dimethyl sulfoxide, sulfolane, dimethylformamide, or dimethyl acetamide) and organic amines (ethanolamine and diethanolamine). Metals etched in semiconductor manufacturing include aluminum, chromium-nickel, gold, silver, tungsten, titanium tungsten, aluminum copper, gallium arsenide, and indium phosphide. The main areas of concern for maintenance procedures are: confined space entry, opening equipment, cleaning arsenic residues, soldering systems, plasma etchers, and ion implanters. [CSH, p. 18-23 & 43-50] The most common skin allergens found in the electronics industry are epoxy resins, nickel, acrylic resins, colophony/solder resins, rubber, formaldehyde resins, isothiazolinones (Kathon), and chromates. [Kanerva, p. 657] See "Exposure Assessment Among US Workers Employed in Semiconductor Wafer Fabrication." [PMID 21063185]

Category

Industry

Related Information in Haz-Map
Agents

Hazardous agents associated with this process: