Sub 10-nm contact holes with aspect ratio over sixty formed by e-beam resist shrinkage techniques

Wei-Su Chen; Ming-Jer Kao; Ming-Jinn Tsai

doi:10.1117/12.708436

22 March 2007 Sub 10-nm contact holes with aspect ratio over sixty formed by e-beam resist shrinkage techniques

Wei-Su Chen, Ming-Jer Kao, Ming-Jinn Tsai

Proceedings Volume 6519, Advances in Resist Materials and Processing Technology XXIV; 651945 (2007) https://doi.org/10.1117/12.708436
Event: SPIE Advanced Lithography, 2007, San Jose, California, United States

Abstract

E-beam chain scission resist ZEP520A with 400 nm thickness was studied for sub-10 nm contact holes with high aspect ratio formed by CD shrinkage techniques of thermal reflow and SAFIER. CD shrinkage temperatures and repeating times were process parameters to be studied. Design parameters of initial CD of 40-100 nm and line/space ratio of contact hole with 1/3 and >1/20 before shrinkage were also studied. Process window of thermal reflow for the aforementioned initial CDs is 155-165 °C while that of SAFIER is 150-165 °C. There is no shrinkage for both methods for temperatures below 140 °C. CD shrinkage rates of both methods decrease for more than one time of heating. Thermal reflow has a larger CD shrinkage rate than SAFIER. The dependence of shrinkage rate on initial CD size and spatial frequency is not apparent. CD nearly ceases shrinking for further heatings as the CD reaches an ultimate CD size. The ultimate CD for a larger initial CD is also larger. The smallest shrunk CD is found to be 5.8 nm with aspect ratio over sixty for 50 nm initial designed CD. CD uniformity also studied for both processes with 3-sigma smaller than +/-10%. The contact holes shrunk by thermal reflow process generally show funnel-shape profiles while those shrunk by SAFIER process show similar profiles with wider undercut. In summary, the thermal reflow process results in better profile while the SAFIER with slower CD shrinkage rate has a better control on CD and uniformity.

Citation Download Citation

Wei-Su Chen, Ming-Jer Kao, and Ming-Jinn Tsai "Sub 10-nm contact holes with aspect ratio over sixty formed by e-beam resist shrinkage techniques", Proc. SPIE 6519, Advances in Resist Materials and Processing Technology XXIV, 651945 (22 March 2007); https://doi.org/10.1117/12.708436

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