Question: What is diffusion?

Subject: Electronics Engineering

Topic: IC Technology

Difficulty: Medium / High

ic technology • 202 views
modified 7 months ago  • written 7 months ago by gravatar for Sayali Bagwe Sayali Bagwe2.1k

It is the process of introduction of dopant atoms into the semiconductor. It alters the type of conductivity of the semiconductor.

Diffusion is the movement of impurity atoms in a semiconductor material at high temperatures.

Diffusion is applied to anneal the crystal defects after ion implantation or to introduce dopant atoms into silicon from a chemical vapor source. In the last case the diffusion time and temperature determine the depth of dopant penetration.

Diffusion is used to form the source, drain, and channel regions in a MOS transistor. But diffusion can also be an unwanted parasitic effect, because it takes place during all high temperature process steps.

Methods – Diffusion from a

  1. Chemical source
  2. Doped oxide source
  3. Diffusion and annealing from an ion implanted layer


  1. No crystal damage like its alternatives.
  2. Batch processing (handling many wafers in single process) is possible.
  3. High quality junction with minimum leakage current is possible.


  1. High temperature method
  2. It cannot independently control the dopant concentration and junction depth.
written 7 months ago by gravatar for Sayali Bagwe Sayali Bagwe2.1k
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