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I saw the following layout in one of the standard cell library provided to us by the University. In the layout, the yellow color diffusion layer is connected to blue color horizontal M1 metal layer using contacts. What is the use of the vertical metals which again connect the same diffusion with these metals? I mean why two contacts are used?

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Dual via placement (or "wire pairing", or "double-cut vias") is a layout technique used in ASIC designs to improve reliability of chips and make them up to automotive or military requirements.

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  • \$\begingroup\$ One of my classmates told that it is for decreasing the contact resistance. I did not agree with him as the contacts are already less resistive and adding one more contact in parallel won't affect the contact resistance much. Am I correct in this argument? \$\endgroup\$ – user3219492 Mar 6 '18 at 3:10
  • \$\begingroup\$ @user3219492, yes, you are correct. Multi-cut via patterns increase manufacturing yield and reliability over extended temperature range, simply due to redundancy. \$\endgroup\$ – Ale..chenski Mar 6 '18 at 3:15

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