Physical Verification Interview Questions : Question set – 4


Code: QLCM2Y062020PV

General Questions

  1. What are lambda based design rules?
  2. What is nm in 10nm technology node?
  3. Do you know about under bum density?
  4. Any prior experience of PnR?
  5. How do you import design in PnR?
  6. Why ID layers have been given in lower nodes (10nm)?
  7. Why nwell continuity is required?
  8. Have you done scripting?
  9. Can you write an algorithm?
  10. What is drive strength?
  11. Why the industry is moving towards lower technology nodes like 7nm or 5nm?
  12. What are challenges seen in lower technology node?

Physical Only Cell

  1. What is a tap cell?
  2. What are the uses of tap cells?
  3. What is Endcap or boundary cell?
  4. How does halo cell avoid DRCs t boundary? What is there inside the halo cell that prevents DRCs ? How it is different from standard cells?
  5. What difference it makes when you add halo cell in boundary instead of standard cell?
  6. Why is the standard cell nwell bigger in size and slightly coming out of the standard cell? It is not so in halo cell.
  7. Suppose a tap cell is covering 10um distance, then where should the next tap cell be placed in the same row?
  8. How do you calculate the distance between tap cells in a row?


  1. What kind of base DRCs have you encountered?
  2. Have you seen DRCs between the standard cell and filler cell of the same height?
  3. What is Endcap or boundary cell?
  4. How did you solve DPT (double patterning)?
  5. What metal DRC have you encountered?
  6. What kind of via DRCs have you come across?
  7. What will happen if GDSII has DRC unfixed and sent to Fab?
  8. Is there any problem if the ID layers are interchanged?
  9. Which ID layer is manufactured first?


  1. Have you analyzed the LVS result or someone else analyzed the result and you fixed?
  2. Apart from short and opens what errors have you seen in LVS and How did you resolve?
  3. What kind of issues are seen in LVS?
  4. What is priority errors in LVS? Could there be false violations?
  5. Where does the tool start to calculate LVS from?

Post Credit: 

These questions are shared by Karthik K Umesh, one of our group member. Thanks, Karthik for sharing and helping people.



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