Department of Labor Seal photos representing the workforce - digital imagery© copyright 2001 photodisc, inc.
Department of Labor Seal www.osha.gov   [skip navigational links] Search    Advanced Search | A-Z Index
Safety and Health Topics > Semiconductors > Silicon > Device Fabrication: Mask Alignment and Photoexposure

Device Fabrication: Mask Alignment and Photoexposure
Stepper deep ultraviolet (DUV) tool

A photomask is aligned and placed on the coated wafer with precision instruments. The wafer and mask are then exposed to ultraviolet (UV) radiation from an intense mercury arc lamp. This causes exposure to the photo resist in places not protected by opaque regions of the mask. With a typical positive photoresist, the areas struck by light undergo a chemical reaction that will make the photoresist more soluble in an alkaline solution. UV exposure is the most common; however, x-ray and electron beam sources also may be used. Technician examining a reticle
Potential Hazards

UV Radiation
Potential Hazard
  • Possible employee exposure to ultraviolet (UV) radiation during photoexposure.
Possible Solutions
  • Identify UV hazards; perform exposure evaluations when applicable.

  • Enclose operations with UV emissions; provide shielding and interlocks as necessary.

  • Provide PPE [1910 Subpart I] as appropriate during operations when exposure is necessary.

  • Implement UV radiation safety programs to further identify and control UV hazards. Ozone gas may also be generated from the UV radiation.

  • Provide adequate ventilation to control ozone concentrations.
Additional Information

OSHA Safety and Health Topic pages:


Mercury
Potential Hazard
  • Possible employee exposure to mercury from lamp rupture. Improper maintenance or infrequent bulb replacement can cause deteriorated or older lamps to rupture.
Possible Solutions
  • Implement preventive maintenance to inspect and replace lamps routinely.

  • Implement proper work practices to ensure that lamps are replaced carefully in order to avoid accidental breakage.

  • Store and dispose of lamps properly.

  • Respond to and clean up mercury spills properly.

  • Provide adequate PPE as necessary to minimize exposure.
Additional Information

OSHA Safety and Health Topic pages:

 
Back to Top Back to Top www.osha.gov www.dol.gov
Contact Us | Freedom of Information Act | Customer Survey
Privacy and Security Statement | Disclaimers
Occupational Safety & Health Administration
200 Constitution Avenue, NW
Washington, DC 20210