Optimizing Materials and Processes for Directed SelfAssembly Applications

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1 Optimizing Materials and Processes for Directed SelfAssembly Applications Phil Hustad, Jeff Weinhold, Rahul Sharma, Valeriy Ginzburg, Erin Vogel, Dan Murray, Vivian Chuang, Shih-Wei Chang, Peter Trefonas The Dow Chemical Company

Rahul Sharma, Valeriy Ginzburg, Erin Vogel, Dan Murray,

2 Chemoepitaxy with HCP Cylinders Pattern rectification Density multiplication Ruiz, Nealey et al. Science 2008, 321, 936 Prepattern with e-beam oxidized PS O2 plasma etch PS brush Spin coat PS-PMMA O O anneal 2

3 Registered Spheres from Sparse Posts Ross et al. Science 2008, 321, 939 3

4 Many Sparse Pattern Layouts Possible <1 0> 0 <1 1> ±30 j=1 <1 1> i=1 <2 0> 0 <2 1> ±19 <2 2> ±30 <3 0> 0 <3 1> ±14 <3 2> ±23 <3 3> ±30 4

5 Examples of Commensurate States Ross et al. Science 2008, 321, 939 5

6 Free Energy of Templated Systems Ross proposed the BCP will compress or stretch to be commensurate with nearest lattice 2 Mb Fchain / kt L AB 1 L2 4b M Mb L 30 Ross et al. Science 2008, 321,

nearest lattice 2 Mb Fchain / kt L AB 1 L2 4b M 3 2 6

7 Post Graphoepitaxy vs Chemoepitaxy Matrix: PS (or P(S-r-MMA) Spots: oxidized PS Favorable: Cylinder-Spot Matrix-Space Unfavorable: Cylinder-Space Matrix-Spot 7

8 What About Incommensurate Systems? Lpattern = 90 nm <2 2> L0 = 26 nm Twist 30 <3 0> L0 = 30 nm L0 = 28 nm 30 What happens when the BCP is not perfectly commensurate with the pattern? 8

9 Perfect Overlap Produces Large Grains 9

10 Perfect Overlap Produces Large Grains 10

11 A Small (2%) Reduction in BCP Pitch 11

12 Likely Produces Multiple Grains 12

13 Surface Area Overlap Model d R r For (R r) < d < (R + r) d 2 r 2 R d R r R cos A r cos ( d r R)(d r R )(d r R)(d r R) 2 dr 2 dr 2 For d < (R r) 2 1 A( d ) min( R, r ) 2 13

14 Examples of Commensurability Pattern: 20 nm spot size 80 nm pitch BCP: 20 nm cylinder 40 nm pitch 0 <2 0> 14

15 Examples of Commensurability Pattern: 20 nm spot size 80 nm pitch BCP: 15 nm cylinder 30 nm pitch <2 1> 0> 15

16 Estimating Grain Size from Overlap Pattern: 20 nm spot size 80 nm pitch BCP: 20 nm cylinder 40 nm pitch L0 = 40 nm 16

17 Estimating Grain Size from Overlap Pattern: 20 nm spot size 80 nm pitch BCP: 20 nm cylinder 39.6 nm pitch L0 = 39.6 nm L0 = 40 nm 17

18 Estimating Grain Size from Overlap Pattern: 20 nm spot size 80 nm pitch BCP: 20 nm cylinder 39 nm pitch L0 = 39.6 nm L0 = 39 nm 18 L0 = 40 nm

19 Experimental Validation <2 0> sparse pattern 2.0* L0 Lpattern = 74 nm L0 = 37 nm 1.95* L0 Lpattern = 72 nm Tada et al. Macromolecules 2008, 41,

20 Subtle Effects Are Even Identified 24o 0o 36o 36o 0o Pattern: 20 nm spot size 71 nm pitch BCP: 20 nm cylinder 37 nm pitch 24o o 24o 36o 0o Normalized Area 36o angle ( ) Tada et al. Macromolecules 2008, 41,

50 0o 24o 36o 0o Normalized Area 36o 0 1.25 24 36 1.00 0.75 0.

21 E-beam vs 193i for Patterning Prepattern with e-beam Pattern: 20 nm spot size, 80 nm pitch BCP: 20 nm cylinder, 40 nm pitch O2 plasma etch Spin coat PS-PMMA anneal Small spot sizes and pitch are possible with e-beam 21

22 E-beam vs 193i for Patterning Prepattern with e-beam Pattern: BCP: 20 nm spot size, 40 nm pitch (every other row) 20 nm cylinder, 40 nm pitch O2 plasma etch Spin coat PS-PMMA anneal Small spot sizes and pitch are possible with e-beam 22

23 E-beam vs 193i for Patterning Prepattern with 193i lithography Pattern: 20 nm spot size, 80 nm pitch BCP: 20 nm cylinder, 40 nm pitch O2 plasma etch Spin coat PS-PMMA anneal but with 193i lithography, it will be difficult to make spots smaller than ~40 nm (or closer together than 80 nm) 23

24 Effect of Spot Size Pattern: 20 nm spot size 80 nm pitch BCP: 20 nm cylinder 40 nm pitch Spot CD = 20 nm 24

25 Effect of Spot Size Pattern: 30 nm spot size 80 nm pitch BCP: 20 nm cylinder 40 nm pitch Spot CD = 30 nm Spot CD = 20 nm 25

26 Effect of Spot Size Pattern: 40 nm spot size 80 nm pitch BCP: 20 nm cylinder 40 nm pitch Spot CD = 40 nm Spot CD = 30 nm Spot CD = 20 nm 26

27 More Complete Model Being Developed d R r For (R r) < d < (R + r) d 2 r 2 R2 d 2 R2 r 2 1 R 2 cos 1 A r 2 cos 1 ( d r R)(d r R )(d r R )(d r R ) 2dr 2dR 2 For d < (R r) A( d ) min( R, r ) Mb Fchain / kt L AB 1 L2 4b M Mb L Model being adapted to account for BCP stretching/compression, and more details will be shared at SPIE. 27

28 Difficult to Integrate with 193i Patterning Prepattern with e-beam Prepattern with 193i lithography PS brush PS brush Spin coat PS-PMMA Spin coat PS-PMMA anneal anneal 28

29 Contact Shrink Demonstrated by IBM J. Cheng, SPIE 2010 Cheng et al. ACS Nano 4, 4815 (2010) We use modeling to also understand these systems and optimize conditions to give lowest CDU 29

30 Shrink Determined by Wall Interactions Cylinder phase is attracted to the wall Morphology from minimization of free energy X nm Final hole size is ~¼ the original hole size ~.25 X Matrix phase is attracted to the wall Morphology is determined by geometry (when no homopolymer is used) X nm D X f PMMA For cylindrical BCP, the D final hole is half the size 30

31 Modeling Guides BCP Selection Self Consistent Field Theory (SCFT) can guide when N < 30 Hole CD PMMA-like walls X nm ~.25 X PS-like walls D PS PMMA X nm Hole 31

32 Modeling Guides BCP Selection Strong Segregation Theory (SST) used for higher N Free Energy per chain /kt PMMA Cylinder CD (nm) 30 PS Walls PMMA Walls Hole CD (nm) Free energy as function of hole size Hole CD (nm) 85 Size of center cylinder and free energy can be evaluated 32 95

DSA Can Give Very Uniform Holes <20 nm 50-60 nm

33 DSA Can Give Very Uniform Holes <20 nm nm DSA Etch ARC ARC ARC Si Si Si Holes too small Holes just right Holes too big Some unopened holes Very uniform final size! Large CD variation 33

34 Summary and Conclusions At Dow, we are using our modeling capability to improve our understanding of DSA systems and guide selection of materials and process toward optimal results A surface area overlap model was developed to help us understand the factors controlling grain size and defects in chemoepitaxy systems Simulations indicates that both incommensurability will cause the system to break up into multiple grains, while increasing size of directing spots results in loss of orientation We are refining this model to account for stretching/compression and will report on this more complete model at SPIE We are also applying SCFT and SST modeling to graphoepitaxy contact shrink scenarios, and have used this understanding to produce contact shrink with very good CDU 34

35 Thank You! Jeff Weinhold (surface model), Valeriy Ginzburg (SCFT) Erin Vogel, Dan Murray Vivian Chuang, Shih-Wei Chang, Peter Trefonas 35

Directed Self- Assembly of Block Copolymers; an Alternative Tool for Sub- 20 nm Lithography Parvaneh Mokarian

Directed Self- Assembly of Block Copolymers; an Alternative Tool for Sub- 20 nm Lithography Parvaneh Mokarian Department of Chemistry, University College Cork (UCC) and Tyndall National Institute, Cork,