Epitaxial growth

Which technology is used to form the base layer of a SiGe HBT?

  1. AEpitaxial growth (sometimes grading the Ge concentration with depth)
  2. BCMP
  3. CSputtering
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Answer: A. Epitaxial growth (sometimes grading the Ge concentration with depth)

The base of a SiGe HBT is made by epitaxially growing a SiGe layer on silicon. Increasing the Ge concentration from the emitter side toward the collector side creates a built-in field in the base from the band-gap gradient, accelerating electrons, which favors high-speed operation.

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More Epitaxial growth questions

  1. Compared with thermal diffusion, what is an advantage of adding dopants during epitaxial growth?
  2. In advanced CMOS processes, why is it necessary to lower the temperature of silicon and SiGe epitaxial growth?
  3. Which polytype is mainly used for SiC power devices?
  4. In MBE, which technique observes growth in situ by directing an electron beam at the surface at a grazing angle and examining the diffraction pattern?
  5. What is the origin of the word "epitaxy"?