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Safety and Health Topics > Semiconductors > Silicon > Device Fabrication: Oxidation

Device Fabrication: Oxidation
The fabrication of an integrated circuit involves a sequence of processes that may be repeated many times before a circuit is complete. The device fabrication steps discussed in this and subsequent sections may be repeated anywhere from six to 15 times to achieve the desired product.

Robotic arm transfers a wafer Generally, the first step in semiconductor device fabrication involves the oxidation of the wafer surface in order to grow a thin layer of silicon dioxide (SiO2). This oxide is used to provide insulating and passivation layers.
  • The most common method of oxidation is thermal, and can be classified as either "dry" or "wet" oxidation. Wafers are loaded into quartz boats and slid into a furnace heated to approximately 1200ºC.
    • In dry oxidation, thin oxide layers are grown in an environment containing oxygen and hydrogen chloride near atmospheric pressure.
    • Thicker oxide layers require higher pressures and the use of steam (wet oxidation). Wet oxidation is performed by exposing the wafer to a mixture of oxygen and hydrogen in the furnace chamber. Water vapor is formed when the hydrogen and oxygen react.
Potential Hazards
Toxic Exhaust Gases
Potential Hazard
  • Possible employee exposure to corrosive exhaust gases, including hydrogen chloride. Gases such as hydrogen chloride can be irritating and corrosive to the eyes, skin, and mucous membranes. Exposure to high concentrations can cause laryngitis, bronchitis, and pulmonary edema.
Possible Solutions Additional Information

 
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