Physical Verification Interview Questions : Question set – 3

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Code: INTL2Y052020PV

Floorplan

  1. What are the inputs for floorplan?
  2. In order to make sure integration is DRC clean, what rules or guidelines need to be followed at the floorplan stage?
  3. Can we abut macros on par boundary?
  4. How will judge the congestion between two IPs during floorplan stage without actual routing being done?
  5. Apart from IP alignment, what analysis have you done?
  6. What do you check at the placement stage? 

Physical Only Cell

  1. What are the types of physical only cells in the design?
  2. In what stage are physical only cells placed in the design?
  3. Why are different types of physical only cells needed in design?

Latch-up

  1. Are you aware of latch-up in CMOS, can you elaborate?
  2. Explain how the parasitics are formed?

Antenna Effect

  1. What is the antenna effect?
  2. How can antenna effect be solved?
  3. Why metal jogging is done in the higher layer during antenna fixing?
  4. Which diode is used as an antenna diode?
  5. What parameters are considered while choosing the cutoff voltage of an antenna diode?
  6. How do you decide the number of diodes that needs to inserted for the failing net?
  7. On what basis have you inserted diodes?
  8. If M12 is the highest metal in the design and it has antenna, how do you fix it?
  9. Have you heard of nwell antenna?
  10. Can power net have an antenna effect?
  11. Can the antenna diode be placed in a different power from that of the affected cell?
  12. What is the impact of placing the antenna diode on timing?
  13. Where are the antenna diode terminals being connected?
  14. Voltage or current that is causing the antenna effect?
  15. How the gate area can be increased in antenna affected cell?
  16. How are you adding the antenna in antenna affected cell?
  17. What is the drive strength?
  18. What is the W/L ratio?
  19. Which layers are most susceptible to antenna violations, higher or lower layers? 
  20. How do you handle antenna in clock net?

ECO Implementation

  1. What are types of ECOs?
  2. Where the ECOs generated and given to you or you prepared ECOs?


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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