Epitaxial growth

In advanced CMOS processes, why is it necessary to lower the temperature of silicon and SiGe epitaxial growth?

  1. ATo speed up epitaxial growth
  2. BTo make equipment larger
  3. CTo limit diffusion of dopants and deformation of structures already formed (thermal budget constraints)
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Answer: C. To limit diffusion of dopants and deformation of structures already formed (thermal budget constraints)

The fine structures and abrupt dopant profiles of transistors are degraded when exposed to high temperatures. Epitaxial growth performed later in the process must therefore be done at as low a temperature as possible. The total amount of heat the process can tolerate is called the thermal budget.

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More Epitaxial growth questions

  1. Which polytype is mainly used for SiC power devices?
  2. 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?
  3. What is the origin of the word "epitaxy"?
  4. What is the typical thickness range of the epitaxial layer on silicon epi wafers for LSIs and power devices?
  5. In silicon epitaxial growth, what is the main role of the large flow of hydrogen (H2) supplied along with the source gas?