Oxidation and diffusion

Which is a typical use of thermally grown silicon oxide?

  1. AAs the conductor in wiring
  2. BAs gate insulators, isolation between devices, and masks that define where impurities are introduced
  3. CAs a light-emitting layer
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Answer: B. As gate insulators, isolation between devices, and masks that define where impurities are introduced

Thermally grown SiO2 is highly insulating and forms a high-quality interface with silicon, so it has been used as the gate insulator of MOSFETs, for electrically isolating devices from each other, and as a mask for ion implantation and diffusion.

  • A. SiO2 is an insulator and cannot be used as a wiring conductor.
  • B. Correct. It is used for insulators, isolation and masks.
  • C. SiO2 is an insulator and is not used as a light-emitting layer.
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More Oxidation and diffusion questions

  1. What is the correct unit of the diffusion coefficient D?
  2. Which correctly expresses Fick's first law? (J: diffusion flux, D: diffusion coefficient, C: concentration, x: position)
  3. When diffusing impurities at the same temperature, if the diffusion time is quadrupled, by roughly what factor does the spreading distance change?
  4. In thermal diffusion, which pair correctly gives the profile shapes for diffusion with a constant surface concentration and for diffusion of a fixed amount of impurity?
  5. Which compound has been used as a liquid diffusion source for introducing phosphorus into silicon by thermal diffusion?