Extrinsic Gettering To Remove Device-Degrading Impurities

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Extrinsic Gettering of Silicon Wafers

Below is a list of gettering techniques used to remove defects.

  • Intrinsic Gettering - Czochralski grown silicon wafers have large amounts of contaminating dissolved oxygen.
  • Halogenic Dopant Sources - Used during diffusion it converts metallic impurities into volatile halides. Halides must be carefully used so as to not pit the semiconductor surface.
  • Halogenic Oxydation - is an effective process preventing oxygen-induced staking faults on the silicon. This process works so well that is' often used in MOS circuit fabrication.
  • Mechanical Damage - using abrasives including sand blasting and ion implantation creates a damaged layer on the silicon wafer's backside. This damaged region works as a sink to remove metallac impurties and stacking faults.
  • Glassy Layers - borosilicate (BSG) and phosphosilicate (PSG) glass when contacting heated silicon are very good at removing a silicon wafer's deep impurities.
  • Chemical Cleaning - is considered one of the more powerful ways to reduce process contamination. The RCA Clean Process are used for this purpose.