Interconnect processes

If a wire's length is doubled without changing its cross-section or spacing, approximately how many times larger does its RC delay become?

  1. A2 times
  2. B4 times
  3. C8 times
Show answer and explanation

Answer: B. 4 times

Both the wire's resistance R and capacitance C are proportional to its length, so RC delay is proportional to the square of the length. Doubling the length makes the delay about four times larger. This is why buffers (repeaters) are inserted along long wires to limit delay.

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More Interconnect processes questions

  1. What is the purpose of forming silicides such as NiSi on the surfaces of a transistor's source, drain and gate?
  2. Which metal has been widely used to fill contact holes connecting transistors to the lowest wiring layer?
  3. When copper wires become very narrow, what is the main reason their effective resistivity rises?
  4. In multilevel interconnects, what is the main reason upper-level wires are made wider and thicker?
  5. What is the main purpose of the technique that makes part of the insulator between wires a cavity (air gap)?