Epitaxial growth

Which method measures the thickness of a lightly doped epitaxial layer on a heavily doped substrate using infrared interference?

  1. ASIMS
  2. BCross-sectional SEM observation
  3. CFourier transform infrared spectroscopy (FTIR)
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Answer: C. Fourier transform infrared spectroscopy (FTIR)

A heavily doped substrate and the epitaxial layer have slightly different refractive indices for infrared light, so reflection occurs at the interface. Measuring the interference between reflections from the surface and the interface with FTIR gives the epitaxial layer thickness non-destructively. It is widely used to control epitaxial wafer thickness.

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More Epitaxial growth questions

  1. What is the main challenge in growing GaN on Si substrates?
  2. What is it called when doping gas is flowed during epitaxial growth to add dopants at the same time as growth?
  3. What is the periodic structure called in which layers of different materials, each only a few nm thick, are stacked alternately?
  4. Which technology is used to form the base layer of a SiGe HBT?
  5. Compared with thermal diffusion, what is an advantage of adding dopants during epitaxial growth?