1. Double Patterning Chris Chase EE235 4/9/07

2. 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: • Data and figures from Lim et al., Proceedings of SPIE, 2006

3. Basic Idea

4. 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

5. Cross-section through the process

6. Positive and Negative Processes

7. Example Devices • Figure from Drapeau et al, Proc. Of SPIE, Vol. 6521

8. 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?