Arsenic-rich waste generated during gallium arsenide wafer manufacturing and packaging

Keith Torrance, Helen Keenan, Andrew S. Hursthouse, Jan Sefcik

Research output: Contribution to conferencePaper

Abstract

The toxicology of gallium arsenide is well established; it is classified by the state of California as a known carcinogen. Consequently, environmental aspects of GaAs wafer manufacture are coming under greater scrutiny, with the cost of waste disposal becoming an economic issue for fabs operating under this jurisdiction. It is estimated that 85% of a GaAs boule is lost during manufacturing and device
packaging, which usually ends up land filled as hazardous waste. This percentage is likely to increase as final wafer thickness is reduced to improve thermal
dissipation. GaAs wafer backthinning and polishing generates waste slurries that are contaminated by arsenic and must be disposed of as hazardous waste.
Although GaAs is largely insoluble in H2O, it is readily oxidized to soluble oxides and hydroxides, especially during chemo-mechanical polishing. Further, the
valency state of the arsenic species determines the toxicity of effluent. Waste slurries from three sources were studied by ICP-MS and ICP-OES analysis to
determine the amount of arsenic in the supernate and the form of the arsenic species. This data was related to mechanical lapping processes, such as the size
distribution of particles in the slurry, and to the oxidation chemistry of the polishing processes. The analytical results provide guidance as to the most
effective strategy to minimize the environmental impact of slurries produced during wafer thinning and polishing.
Original languageEnglish
Publication statusPublished - May 2009
EventCS ManTech 2009 - Tampa, United States
Duration: 11 May 200914 May 2009

Conference

ConferenceCS ManTech 2009
CountryUnited States
CityTampa
Period11/05/0914/05/09

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Keywords

  • gallium arsenide
  • pollutants
  • carcinogen

Cite this

Torrance, K., Keenan, H., Hursthouse, A. S., & Sefcik, J. (2009). Arsenic-rich waste generated during gallium arsenide wafer manufacturing and packaging. Paper presented at CS ManTech 2009, Tampa, United States.