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Safety and Health Topics > Semiconductors > Silicon > Metallization: Passivation Metallization: Passivation Silicon nitride is often used as a final passivating or protective layer for silicon devices. Passivation is accomplished with a chemical vapor deposition process using silane and ammonia gases. Sometimes a layer known as "p-glass" is deposited with a layer of SiO2 doped with phosphorous. Phosphine gas is used as a source for phosphorous for this type of deposition. Potential Hazards Toxic Gases Toxic Gases Potential Hazard Possible employee exposure to toxic gases. Typical gases include silane, ammonia, and phosphine. Possible Solutions Identify gas hazards and perform appropriate exposure evaluations. Perform exposure measurements for the chemicals used. See 1910.1000, Table Z-1, which contains permissible exposure limits for various chemicals. Provide appropriate ventilation to reduce concentration levels in the air. Provide PPE [1910 Subpart I] as appropriate to prevent eye and skin contact. Use respiratory protection [1910.134] when necessary to further reduce exposure and protect employees. Use gas monitoring systems with automatic shut-offs and alarm systems, as appropriate. Design and use specialized processing, material handling, and storage equipment for gases. Consider both normal use and emergency scenarios. Reduce gas cylinder inventories and quantity of gas per cylinder, when possible. Additional Information OSHA Safety and Health Topic pages: Compressed Gas and Equipment Health Guidelines Personal Protective Equipment (PPE) Process Safety Management (PSM) Respiratory Protection Sampling and Analysis Ventilation

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