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© 2015 IBM Corporation

Directed Self-assembly of Topcoat-free Polycarbonate-containing High-χ Block Copolymers

Ankit Vora, Kristin Schmidt, Gabriela Alva, Noel Arellano, Teddie Magbitang, Anindarupa Chunder, Melia Tjio, Elizabeth Lofano, Joy Cheng and Daniel P. Sanders

2015 DSA Symposium

Leuven, Belgium

Oct. 27th 2015


Ankit Vora

DSA Symposium 2015. 10/27/15

Background: Motivation for High-χ BCPs

14k-14k PS-b-PMMA15k-15k PS-b-PMMA

500 nmPitch (Lo) ~ 20 nm

� PS-b-PMMA is the most promising candidate as Generation 1 material for DSA

Potential benefits of High-χ BCPs• Smaller pitch

• Lower LER

• Higher etch-selectivity

Higher-χ BCPs needed for sub-20 nm pitch resolution

��~��/�/� = 10.5

Reduce pitch by increasing χ

2


Ankit Vora


Materials Development for Sub-20 nm Pitch Patterning

Desired Characteristics

� Perpendicular orientation by short thermal

annealing

� Top-coat free

� Fab compatible processing / solvents

� Compatible with existing DSA schemes

Orientation Control Strategy

Si substrate

underlayer

Si substrate

underlayer

Spin coat

BCP solution

Thermal anneal

Organocatalytic ROP at IBM- Jim Hedrick and team

RO

ON

R1 OO

R2

HH

PMDO

RO

OO

H

OO

O

O

RO

O

OH

OO

O

O

RO

HO O

O

SiOSi O

SiO

SiO

Si

O

O

RO

O

OH

RO

SiO

SiO

SiO

HR

OSi

SiO

H

O RO

OH

NO

O

OH R2

R1PTMC

PDMSPTMOCS

RO O

O

OH

RO

OO

OO

H

PLA

PVL

PCL

PEO

PBL

Chem. Rev., 2007, 107 (12), pp 5813–5840

New Block Copolymer Synthesis

3


Ankit Vora


Outline

� Phase-selective, surface active polymer (SAP) as additives for top orientation

control of polycarbonate-containing BCPs

� Design rules for making highly efficient SAP additives

– SAP molecular weight & PDI

– DSA compatible SAP additives

� Generation II high- χ materials – towards integration friendly materials

Polystyrene-b-Polytrimethylene Carbonate – Gen I BCP

1. Organocatalyst

2. TEA, AcCl

+PS-b-PTMC

4


Ankit Vora


Previous Results from Photopolymer 2015 Conference

Development of High Purity PS-b-PTMC

PS-OH Macroinitiator

Mn = 6.6k, PDI ~ 1.04

BCP MnGPC = 21.5k

PDI = 1.02

BCP MnNMR = 6.6k-7.5k

Carbonate-based Underlayer Materials

Sty = 62 mol%, 0.5 Lo islands

Neutral Underlayer

Surface active

Hydrogen bonding

w/ Polycarbonates

HFA-materials as Phase-selective, Surface-active

Polymer (SAP) Additives

Surface-active Additives for Top Orientation Control?

Neutral UL

Carbonate-basedNeutral UL

Neutral UL

Coat BCP +

Additive

Anneal

5


Ankit Vora


HFA Materials as Surface Active Polymer (SAP) Additives

� ┴ orientation of lamellae high-χ BCP by simple coat and bake

� Low annealing temperatures & fab-compatible processing

Formulation= BCP + 10% PHFA-Sty

Neutral UL

NeutralUnderlayer

BCP+ P(HFA-Sty)

Baking

Neutral UL

100 nm

P(HFA-Sty)PolycarbonateContaining BCP +

Formulation:

CF3F3C

OH

Pitch ~ 19 nm

PS-PTMC 6.2k -7.7k(Vf ~0.5) + 10% P(HFA-Sty),

Bake @ 140 C/5 min UL = Neutral

+ solvent

What are the design rules for developing highly-efficient SAP additives? 6


Ankit Vora


Effect of Additive Molecular Weight on Self Assembly

F3C CF3

OH

SAP Additive: Poly(HFA-Styrene) BCP: PS-b-PTMC

Mn ~ 7.0k, PDI 1.08 Mn ~ 12.0k, PDI 1.08 Mn ~ 18.0k, PDI 1.08

SAP amount = 5 wt%

w.r.t BCP

Molecular weight control of additives is important for good self assembly

BCP Mn = 6.6k-b-7.7k, VfPTMC ~ 0.49

BCP Pitch ~ 19 nm

400 nm

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Ankit Vora


Effect of Additive PDI on Self Assembly

Mw ~ 12.3k, PDI = 2.10 Mw ~ 12.9k, PDI = 1.08

Additive: P(HFA-Sty) 5wt%

BCP: PS-b-PTMC, Pitch ~ 19nm

Underlayer: Neutral, Sty ~ 62%

400 nm

No significant impact of SAP additive PDI on Self assembly of PS-b-PTMC

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Ankit Vora


HFA Methacrylate-based SAP Additives

9

OO

F3C

CF3

OH

F3C

F3C

HO

OO

F3C CF3OH

Bis-HFAcyclohexyl MA iPr-HFAMA

F3C CF3OH

HFA-Sty

400 nm

5 wt% additive

BCP: PS-b-PTMC

HFA Methacrylate-based additives did not perform as well


Ankit Vora


DSA Attempt of BCP + P(HFA-Sty) Additive

Graphoepitaxy DSA

PS

PTMCR R P(HFA-Sty)

Neutral

Better additive design needed

PS-b-PTMC + 10% P(HFA-Sty)

Where is SAP Additive? Resist sidewalls?

Resist BCP + SAP

SIMS of BCP + SAP Film

1E+0

1E+1

1E+2

1E+3

1E+4

1E+5

1E+6

1E+7

0 10 20 30 40

Sputtering Time (m)

Secondary

Ion Inte

nsity (c/s

)C O Si F

BCP + 10% SAP on Neutral UL

SAP present at substrate and air

interfaces

10


Ankit Vora


Increasing Surface-activity of the Additives

random

F3C CF3OH

F F

F

F

F

0.4 0.6

Pentafluorostyrene-r-HFA-Sty copolymer

PS-b-PTMC + 3% Additive

400 nmP ~ 19 nm

Lower SAP loading needed with more surface active materials

F3C CF3OH

P(HFA-Styrene) SAP

PS-b-PTMC + 3% Additive

Self-assembly defects

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Ankit Vora


DSA of PS-b-PTMC with P(PFS-r-HFASty) Additive

100 nm

9.5 nm HP Pitch Lamellae, 170 °C / 5 min

100nm1E+0

1E+1

1E+2

1E+3

1E+4

1E+5

1E+6

1E+7

0 10 20 30 40

Sec

onda

ry Io

n In

tens

ity (c

/s)

Sputtering Time (m)

FSiOC

PS-b-PTMC + 5% P(PFS-r-HFASty)

Good DSA with improved SAP additiveSAP mostly at BCP-air interface

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Ankit Vora


Mechanism of Orientation Control with SAP AdditivesTBC: PTMC-PS-PTMC Triblock Copolymer, Lo: 19 nm, UL: Neutral, SAP: 2 wt% w.r.t. TBC, Annealing: 170 °C / 5 min

Both hydrogen bond donors and surface active groups are needed for perpendicular orientation

PHOST: H-bonding only

400 nm

Parallel lamellae

P(PFS-r-AcSty): Surface active only

80 mol% PFS

Mostly Parallel lamellae

P(PFS-r-HOST): Surface active & H-bonding

80 mol% PFS

Perpendicular lamellae

13

random

F F

F

F

F

O

O


Ankit Vora


Etch Attempt for P(TMC-S-TMC) – 9.5 nm HP

� Dry etching of PS-b-PTMC resulted in complete

pattern collapse

� Moderate success with SIS + O2 etch

� We decided to investigate BCPs with

tunable χ parameter

14

20nm

X-section SEM Before Etching

Pitch ~ 19 nm

BCP After O2 Etch

BCP After O2 Etch

O2 Etch

SIS +

O2 etch

Trimethyl Aluminum

+ H2O cycles


Ankit Vora

DSA Symposium 2015. 10/27/15Generation II Polycarbonate High-χ BCPs

Decreasing BCP χ by Tuning Carbonate Group

Generation I BCP: PS-b-PTMC

BCP + 2% SAP

200 nm

Generation II BCP: PS-b-PMeCAR

Mn = 12.5k-14.6k, PDI 1.02

Pitch ~ 19.5 nm 200 nm

BCP + 2% P(HFA-Sty) SAP

� Perpendicular orientation on PS-r-PMMA ULs!

� Lower χ parameter

� Lower SAP loading needed!

� Needs special underlayer synthesis

� Higher χ parameter

Mn = 12.5k-16k, PDI = 1.03

BCP + 5% P(HFA-Sty) SAP

Pitch ~ 27 nm

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Ankit Vora


PS-r-PMMA Underlayers are Neutral for Gen II BCPs!

Integration-friendly: Fab compatible underlayers work for Gen II BCPs

SMMA, S = 20 % SMMA, S = 22% SMMA, S = 25% SMMA, S = 18%

Lo ~ 19.5 nm

SMMA, S= 30%

BCP: PS-b-PMeCAR, 12.5k-b-14.6k, VfPMeCAR ~ 0.48

SAP: P(HFA-Sty) 2 wt% w.r.t. BCP

Underlayers: PS-r-PMMA of varying composition

BCP Annealing: 170 c / 5 min

200 nmLo ~ 19.5 nm 19.5 nm

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Ankit Vora


Gen II BCP: PS-b-PMeCAR + P(HFA-Sty) SAP Additive

� Graphoepitaxy of PS-b-PMeCAR + 2 wt.% SAP

on neutral underlayer

1

10

100

Inte

nsity

0.150.100.05

q [Å-1

]

BCP only, no SAP

Parallel lamellae

BCP + 2 wt.% SAP

Perpendicular lamellae

GISAXS for PS-b-PMeCAR + SAP DSA of PS-b-PMeCAR + SAP

� GISAXS confirms perpendicular lamellae for 2nd

Gen BCPs + SAP

� Same SAP additive works for multiple

polycarbonate platforms

What about pattern transfer of 2nd Generation polycarbonate BCPs?17


Ankit Vora


Dry-etching of 19.5 nm Pitch PS-b-PMeCAR

Pattern transfer of all-organic high-χ BCP demonstrated

1. Spin Coat BCP + SAP, Δ

100 nm

SiNx (5 nm)

α-carbon (20 nm)

UL (~4 nm)

Silicon Substrate

2. O2 Etch 3. CF4 / CHF3 Etch 4. O2/N2 Etch

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Ankit Vora


Summary

PS-b-PMeCAR

Polycarbonate BCPs for DSA

random

F3C CF3OH

F F

F

F

F

0.4 0.6

STG2, S = 62Pattern Transfer in Hardmask

SAP Additive

Sub-10 nm Half-pitch

Top Orientation Control & DSA

Acknowledgements� Guanyang Lin, Margareta Paunescu, Durairaj Baskaran, Yi Cao – Merck. (PS-r-PMMA ULs and PS-OH macroinitiators)

� Vaughn Deline – IBM Almaden (SIMS)

� Krystelle Lionti – IBM Almaden (XRR)

� Kevin Yager – BNL (GISAXS of PS-b-PTMC)

2 wt% SAP

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