Oxidation and diffusion

Which method is mainly used for device isolation in scaled LSIs?

  1. AWire bonding
  2. BLOCOS (local oxidation)
  3. CSTI (shallow trench isolation)
Show answer and explanation

Answer: C. STI (shallow trench isolation)

Today's scaled LSIs mainly use STI, which etches shallow trenches in silicon, fills them with insulator, and planarizes them by CMP. LOCOS, once mainstream, produces a 'bird's beak' where oxide encroaches sideways, making it hard to shrink isolation width, so it was replaced by STI as scaling progressed.

Practice this topic Back to topic

More Oxidation and diffusion questions

  1. Once the oxide has become sufficiently thick in thermal oxidation, how does its thickness relate to oxidation time?
  2. Why does oxide on silicon appear in different colors depending on its thickness?
  3. Which equipment is commonly used to thermally oxidize many wafers at once?
  4. In thermal diffusion, what is the step called that drives dopants deeper after a fixed amount has been introduced at the surface?
  5. How does the thermal oxidation rate of silicon depend on crystal orientation?