Interconnect processes

What is the main purpose of barrier metals such as Ta and TaN in copper wiring?

  1. ATo reduce wire resistance
  2. BTo prevent copper from diffusing into insulators and silicon
  3. CTo oxidize the copper surface
Show answer and explanation

Answer: B. To prevent copper from diffusing into insulators and silicon

Copper diffuses easily into insulators and silicon, degrading transistor characteristics and insulation between wires. Copper wiring is therefore surrounded by barrier metals such as Ta/TaN to prevent diffusion. Barrier metals also improve adhesion to the insulator.

Practice this topic Back to topic

More Interconnect processes questions

  1. Which correctly describes a via in multilevel interconnects?
  2. If a wire's length is doubled without changing its cross-section or spacing, approximately how many times larger does its RC delay become?
  3. What is the purpose of forming silicides such as NiSi on the surfaces of a transistor's source, drain and gate?
  4. Which metal has been widely used to fill contact holes connecting transistors to the lowest wiring layer?
  5. When copper wires become very narrow, what is the main reason their effective resistivity rises?