Epitaxial growth

When silicon is grown epitaxially on a substrate with patterns such as buried layers, what is the phenomenon called in which the steps appearing on the surface are offset from the underlying pattern or distorted in shape?

  1. APattern shift
  2. BLoading effect
  3. CMicroloading
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Answer: A. Pattern shift

In epitaxy, growth rates differ with crystal orientation, so steps shift sideways as growth proceeds (pattern shift) or lose their shape (pattern distortion). This causes errors when later lithography steps align to the underlying layer, so it is suppressed through growth conditions and choice of orientation.

  • A. Correct. It is the shifting of step positions.
  • B. The loading effect is a change in etch or deposition rate depending on the area being processed.
  • C. Microloading is a local change in etch rate depending on pattern density and similar.
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More Epitaxial growth questions

  1. What is the main purpose of epitaxially growing and embedding Si:C (silicon with a small amount of carbon) in the source and drain of nMOS transistors?
  2. Which research-stage technique grows a crystal on a substrate covered with a 2D material such as graphene so that the grown film can be peeled off and the substrate reused?
  3. In epitaxial structures for GaN HEMTs, what is the main purpose of adding carbon or iron to the GaN buffer layer beneath the channel?
  4. When a polar compound semiconductor such as GaAs is grown on a non-polar silicon substrate, what is the boundary called between regions in which the Ga and As positions are inverted?
  5. In SiC epitaxy, what is the phenomenon called in which many atomic surface steps gather into large steps, roughening the surface?