Double Patterning Combined with Shrink Technique to Extend ArF Lithography for Contact Holes to 22nm Node and Beyond Huli b , Hao Che n, Xumou Julie t Xiangqun Miao, L ior Xu, Hyungje Woo, Chr is Be nc he r , Je n Shu, Chr is Ngai , Chr istophe r Bor st b Applie d Mate r ials b Colle ge of Nanosc ale Sc ie nc e and E ngine e r ing of the Unive r sity at Albany External Use 6924-9 SPIE Advanced Lithography 2008 Outline 1. Introduction 2. Double Patterning Dry ArF Lithography Combined with Shrink Process with Shrink Process 3. Double Patterning Immersion ArF lithography Combined with Shrink Technique 4. Summary External Use 6924-9 SPIE Advanced Lithography 2008 1
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 Bake SAFIER Rinse SAFIER Coat External Use 6924-9 SPIE Advanced Lithography 2008 Outline 1. Introduction 2. Double Patterning Dry ArF Lithography Combined with Shrink Process with Shrink Process 3. Double Patterning Immersion ArF lithography Combined with Shrink Technique 4. Summary External Use 6924-9 SPIE Advanced Lithography 2008 2
2. Double Patterning Dry ArF Lithography 2.1. DOF window for dry ArF lithography combined with Shrink � DOF is > 0.15 μ m for targeting contact holes > 50nm. � Images show good profile through focus window for 45nm contact holes. External Use 6924-9 SPIE Advanced Lithography 2008 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. External Use 6924-9 SPIE Advanced Lithography 2008 3
2. Double Patterning Dry ArF Lithography 2.3. Schematic Double Patterning Flow Schematic diagrams illustrate double patterning to form 40nm HP. External Use 6924-9 SPIE Advanced Lithography 2008 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. External Use 6924-9 SPIE Advanced Lithography 2008 4
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. External Use 6924-9 SPIE Advanced Lithography 2008 2. Double Patterning Dry ArF Lithography 2.5. Contact profile at 37 and 40nm half pitches using TiN HM 40nm @ 73nm pitch 40nm @ 80nm pitch 40nm Half Pitch 37nm Half Pitch 160nm pitch 160nm pitch 80nm pitch after DP 80nm pitch after DP 146nm pitch 146nm pitch 73nm pitch after DP 73nm 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. External Use 6924-9 SPIE Advanced Lithography 2008 5
Outline 1. Introduction 2. Double Patterning Dry ArF Lithography Combined with Shrink Process with Shrink Process 3. Double Patterning Immersion ArF lithography Combined with Shrink Technique 4. Summary External Use 6924-9 SPIE Advanced Lithography 2008 3. Double Patterning Immersion ArF Lithography 3.1. DOF window for immersion ArF lithography DOF Window before SAFIER Shrink DOF Wi d b f SAFIER Sh i k � DOF > 0.15 μ m If pre-SAFIER contact hole CD ≥ 55nm. External Use 6924-9 SPIE Advanced Lithography 2008 6
3. Double Patterning Immersion ArF Lithography 3.1. DOF window for immersion ArF lithography and image after SAFIER 25nm holes after SAFIER shrink 25nm holes after SAFIER shrink DOF Window before SAFIER Shrink DOF Wi d b f SAFIER Sh i k � DOF > 0.15 μ m 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. External Use 6924-9 SPIE Advanced Lithography 2008 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 > 0.15 μ m for 30nm holes after SAFIER shrink SAFIER shrink. � 30nm contact holes show good profile through defocus positions. External Use 6924-9 SPIE Advanced Lithography 2008 7
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. External Use 6924-9 SPIE Advanced Lithography 2008 Outline 1. Introduction 2. Double Patterning Dry ArF Lithography Combined with Shrink Process with Shrink Process 3. Double Patterning Immersion ArF lithography Combined with Shrink Technique 4. Summary External Use 6924-9 SPIE Advanced Lithography 2008 8
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. It needs additional development effort. g g p � Improvements on overlay and work on CD uniformity will be continued. External Use 6924-9 SPIE Advanced Lithography 2008 ACKNOLEDGEMENTS � We would like to thank L iyan Miao and Ping Xu for thin film de position, Han Cho for some he lp on T iN HM e tc h, Nic olas Gani for sugge stion on a-Si e tc h, and the suppor for sugge stion on a Si e tc h and the suppor t fr t fr om ope r om ope r ation ation, Maydan T e c hnology Ce nte r Gr oup, Applie d Mate r ials. � We also like to thank Steve Hanse n, D.H. Son and Nandasir i Samar akone fr om ASMLfor the ir assistanc e on some illumination simulation. External Use 6924-9 SPIE Advanced Lithography 2008 9
T hank you for your atte ntion! External Use 6924-9 SPIE Advanced Lithography 2008 10
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