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Yield and Reliability Improvement of Very Large Scale Integration Circuits by VIA Swapping

IP.com Disclosure Number: IPCOM000114129D
Original Publication Date: 1994-Nov-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Aipperspach, AG: AUTHOR [+5]

Abstract

Improving yield and reliability of integrated circuits by swapping vias in an intelligent manner using existing Computer Aided Design (CAD) tools is described.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 56% of the total text.

Yield and Reliability Improvement of Very Large Scale Integration
Circuits by VIA Swapping

      Improving yield and reliability of integrated circuits by
swapping vias in an intelligent manner using existing Computer Aided
Design (CAD) tools is described.

      Improving yield and reliability of integrated circuits as chips
increase in both density and area is a continuous task.  In addition,
time to market requires that the entire design process be very quick,
which provides a strong argument to using existing physical design
tools.

      New via types are being defined in order to meet various
current needs as via sizes shrink below 1 square micron in area.  As
opposed to 1 standard via size of past technologies, there are now
bar vias and fat vias as shown below:
  v   - standard via (takes 1 channel intersection)
  bb  or b   - bar via - takes 1 by 2 or 2 by 1 channels
         b
  fff
  fff        - fat via - takes a 3 by 3 channel area for wide wire
  fff

      The very simple means  of improving chip reliability is to
insert a step in the physical design process which takes an existing
design and locates opportunities to "upgrade" a standard via to a bar
via where no conflict or short with another net is produced.  An
example follows:

      Of course, the preferred wiring direction is taken into account
(e.g., a horizontal bar via is used in the above example as opposed
to vertical bar via which would block wiring...