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Safety and Health Topics > Semiconductors > Silicon > Metallization: Alloying and Annealing

Metallization: Alloying and Annealing
After the metallized interconnections have been deposited and etched, a final step of alloying and annealing may be performed. To perform alloying, the metallized substrate is placed in a low-temperature diffusion furnace. Usually aluminum is placed in the furnace to form a low-resistance contact between the aluminum metal and silicon substrate. Finally, either during the alloy step or following it, the wafers are often exposed to a gas mixture containing hydrogen in a diffusion furnace at 400-500ºC. This annealing step is designed to optimize and stabilize the characteristics of the device by combining hydrogen with uncommitted atoms at or near the silicon-silicon dioxide interface.

Potential Hazards
Metals
Potential Hazard
  • Possible employee exposure to various metals, aluminum being the most common.
Possible Solutions
  • Identify metal hazards and perform appropriate exposure evaluations.

    • Perform exposure measurements for the compounds used.

    • Keep exposures below acceptable exposure levels.
  • Address all dermal exposures.

  • Provide appropriate ventilation to reduce metals concentration levels in the air.

  • Provide PPE [1910 Subpart I] as appropriate to prevent contact.

  • Use respiratory protection [1910.134] when necessary to further reduce exposure and protect employees.

  • Maintain adequate housekeeping to remove unwanted metals and reduce concentration levels.
Additional Information

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