Double Patterning Combined with Shrink Technique to Extend ArF Lithography for Contact Holes to 22nm Node and Beyond

Transcription

1 Double Patterning Combined with Shrink Technique to Extend ArF Lithography for Contact Holes to 22nm Node and Beyond Juliet Xiangqun Miao, Lior Huli b, Hao Chen, Xumou Xu, Hyungje Woo, Chris Bencher, Jen Shu, Chris Ngai, Christopher Borst b Applied Materials b College of Nanoscale Science and Engineering of the University at Albany Outline 1. Introduction 2. Double Patterning Dry ArF Lithography Combined with Shrink Process 3. Double Patterning Immersion ArF lithography Combined with Shrink Technique 4. Summary 1

2 1. Introduction Lithography becomes much more challenging when CD shrinks to 22nm node and beyond. Since EUV is not ready, double patterning combined with Resolution Enhancement Technology (RET) such as shrink technique seems to be the most possible solution. Last year, we published the best resolution of 50nm contact holes at 100nm pitch using double patterning dry ArF lithography with SAFIER shrink. To improve the contact hole resolution, we further extend our dry ArF lithography capability using ASML XT1400EX at Applied Materials. We developed immersion ArF double patterning process using ASML XT1700i- P at CNSE combined with SAFIER shrink and etch at Applied Materials. SAFIER (Shrink Assist Film for Enhanced Resolution) Process Coat/Expose/Develop SAFIER Coat SAFIER Bake SAFIER Rinse Outline 1. Introduction 2. Double Patterning Dry ArF Lithography Combined with Shrink Process 3. Double Patterning Immersion ArF lithography Combined with Shrink Technique 4. Summary 2

3 2. Double Patterning Dry ArF Lithography 2.1. DOF window for dry ArF lithography combined with Shrink DOF is > 0.15μm for targeting contact holes > 50nm. Images show good profile through focus window for 45nm contact holes. 2. Double Patterning Dry ArF Lithography 2.2. CD trends after 1 st HM litho & shrink, and after etch For both 40 and 50nm targeting contact holes: DICD and FICD show stable trends. Etch bias is about -10nm. 3

4 2. Double Patterning Dry ArF Lithography 2.3. Schematic Double Patterning Flow Schematic diagrams illustrate double patterning to form 40nm HP. 2. Double Patterning Dry ArF Lithography 2.3. Schematic Double Patterning Flow and actual wafer images Schematic diagrams illustrate double patterning to form 40nm HP. Wafer images demonstrate double patterning to form 45nm HP. 4

5 2. Double Patterning Dry ArF Lithography 2.4. Contact holes at different resolution using two HM schemes Wafers with different resolution can be achieved by applying different X and Y shift at 2 nd HM litho step. Both TiN and a-si worked well as HM in the double patterning schemes. Overlay is a challenge for DP process and it needs further improvements. 2. Double Patterning Dry ArF Lithography 2.5. Contact profile at 37 and 40nm half pitches using TiN HM 73nm pitch 80nm pitch 37nm Half Pitch 40nm Half Pitch 146nm pitch 73nm pitch after DP 160nm pitch 80nm pitch after DP The best resolution of 37nm half pitch (HP) contact holes is achievable by using more aggressive illumination. However, the illumination will not be in favor to print many pitches including isolated contact holes. 40nm HP seems to be the most reasonable resolution for contact holes from dry ArF double patterning process. 5

6 Outline 1. Introduction 2. Double Patterning Dry ArF Lithography Combined with Shrink Process 3. Double Patterning Immersion ArF lithography Combined with Shrink Technique 4. Summary 3. Double Patterning Immersion ArF Lithography 3.1. DOF window for immersion ArF lithography DOF Window before SAFIER Shrink DOF > 0.15μm If pre-safier contact hole CD 55nm. 6

7 3. Double Patterning Immersion ArF Lithography 3.1. DOF window for immersion ArF lithography and image after SAFIER DOF Window before SAFIER Shrink 25nm holes after SAFIER shrink DOF > 0.15μm If pre-safier contact hole CD 55nm. Established SAFIER condition for immersion litho processed wafers. 25nm contact holes at 130nm pitch after SAFIER show good profile. 3. Double Patterning Immersion ArF Lithography 3.2. DOF and contact hole profile before and after SAFIER shrink DOF window remains similar before and after SAFIER shrink. DOF > 0.15μm for 30nm holes after SAFIER shrink. 30nm contact holes show good profile through defocus positions. 7

8 3. Double Patterning Immersion ArF Lithography 3.3. Contact holes at different double patterning steps using a-si HM The images demonstrate Immersion DP process capability of printing 22nm Contact holes at 64nm pitch. Outline 1. Introduction 2. Double Patterning Dry ArF Lithography Combined with Shrink Process 3. Double Patterning Immersion ArF lithography Combined with Shrink Technique 4. Summary 8

9 4. Summary We have developed the double patterning (DP) processes using both dry and immersion ArF lithography combined with SAFIER shrink technique. We created double patterning schemes using two hard mask materials, i.e. TiN and a-si. We successfully achieved the contact hole resolution of 40nm at pitch of 80nm using dry ArF DP process. We demonstrated the printability of 22nm contact holes at pitch of 64nm using immersion ArF DP process. Etching small contact holes for 22nm node and beyond is very challenging. g It needs additional development effort. Improvements on overlay and work on CD uniformity will be continued. ACKNOLEDGEMENTS We would like to thank Liyan Miao and Ping Xu for thin film deposition, Han Cho for some help on TiN HM etch, Nicolas Gani for suggestion on a-si etch, and the support from operation, Maydan Technology Center Group, Applied Materials. We also like to thank Steve Hansen, D.H. Son and Nandasiri Samarakone from ASML for their assistance on some illumination simulation. 9

10 Thank you for your attention! 10