Double Patterning Chris Chase EE235 4/9/07

Introduction  ITRS Roadmap  Double Patterning will likely be introduced at the 45 nm node   Is projected to be present in all 32 nm node technologies Will likely be extended to the 22 nm node  Rayleigh criteria:

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 Data and figures from Lim et al., Proceedings of SPIE, 2006  Chris Chase, EE235 2

Basic Idea Chris Chase, EE235 3

Pros and Cons of Double Lithography   Advantages  Can use existing 65 nm equipment to go to 45 nm node  Easiest to implement and most cost effective technology to implement at the next node Disadvantages      Requires 2 steps of lithography where there could be one, so there is lower throughput/higher capital/material costs Some additional mask complexity is required in order to connect the two layers Yield is proportional to number of photolithograpy layers so it also drops as a result.

More potential misalignment risk Still requires a new photoresist to work at 32nm node 4 Chris Chase, EE235

Cross-section through the process Chris Chase, EE235 5

Positive and Negative Processes Chris Chase, EE235 6

Example Devices  Figure from Drapeau et al, Proc. Of SPIE, Vol. 6521 Chris Chase, EE235 7

Conclusion     Double Patterning Lithography is a promising technology that is projected to be a major part of the 45, 32, and 22 nm nodes by ITRS Double Patterning will very likely be incorporated into the processes at most of the industry leaders in the next few years.

It still requires more development in the form of a higher resolution photoresist.

Questions?

Chris Chase, EE235 8