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BCP’s DSA for contact hole shrink: guiding patterns requiremets R.Tiron, A.Gharbi, M.Argoud, P.Pimenta-Baross, I.Servin, S.Barnola, J.Belledent, Leti

X.Chevalier, C.Navarro, Arkema

February 24th, 2013

© CEA. All rights reserved | 2 R.Tiron et al.

Outline

DSA: BCP specification

Commensurability

Process integration

Lithographic performances

Contact multiplication

Summary


fAfAfA

Different morphologies function of weight fractions fA & fB of each BCP sequence A & B

Block copolymers : definitions

6/1

0 ABaNL

L0 : characteristic domain length scale

a : statistical segment length

N : number of chain segment

AB : Flory Huggins parameters

= 2/3 in a strong segregation range

BA

AA

NN

Nf

L0

– Morphology concentration of each phase

– Pitch = period of the polymer = length of the chain

– 1 polymer 1 CD 1 pitch (L0)

– For constant morphology CD/pitch = ct


200 nm

200 nm

A

B

C

=> Influence of Litho1 design

rules & BCP material

a0

How to find optimum guiding litho process ?

Design rule compatibility “Optimization of block copolymer self-

assembly through graphoepitaxy: A defectivity

study” R.Tiron et al., JVST B29 06F206 (2011)

To generate zero defects configuration commensurability

between BCP and guid. patterns must be respected.


Zero Defect Configuration

– Defectivity measurement enables lithography and process optimization.

– This methodology may be easily scale up from laboratory environment to

a large scale industrial process.

500 nm

Defectivity Analyses: Number of Defects=101

50 100 150 200 250 300 350 400 450 500

50

100

150

200

250

300

350

400

450

500500 nm

Before litho1

optimization

After litho1

optimization


LETI’s DSA dedicated Process Implementation


No metallic contamination in polymers

POR using a cylindrical polymer PS-b-PMMA

from Arkema with L0=38nm

Spin casting solvent : PGMEA

Brush bake: 230C / 1min

Non grafted brush removal : using PGMEA

DSA bake: 245C / 1min

PMMA remove wet and/or dry processes

Pattern transfer by etching

DSA 300 mm process implementation

“Pattern density multiplication by direct self-assembly of BCP: towards

300mm CMOS requirements” R. Tiron et al,) - 8324-23, SPIE2012

BCP self-assembly by graphoepitaxy

Contact shrink


Two integration schema:

PMMA

PS

photoresist

Hard mask #2

Hard mask #1

Guiding

patterns

DSA

patterns

1.Double hard-mask 2. NTD Resist

NTD resist approach: less process steps but resist reflow and control of CD during DSA

bake still difficult


Contact shrink vs. BCP morphology A/ Cylindrical PS-b-PMMA

500nm 500nm

B/ Lamellar PS-b-PMMA

– Contact shrink is possible using both cylindrical and lamellar morphologies

𝐶𝐷𝐵𝐶𝑃

𝐶𝐷𝑔𝑢𝑖𝑑𝑒lamellar >

𝐶𝐷𝐵𝐶𝑃

𝐶𝐷𝑔𝑢𝑖𝑑𝑒cylindrical


Broad range of PS-b-PMMA

Customizable PS-b-PMMA platform with various pitch demonstrated

For more details see X.Chevalier et al. paper 8680-5 on February 26


Copolymer etching process fully compatible

with CMOS requirements

BCP Etching: capabilities demonstration on small samples

Transfer of BCP into Si by using

SiO2 hard mask

Transfer of BCP into 193 nm

hardmask


DSA LETI’s 300 mm pilot line

CD ~ 120nm CD ~ 15nm

193nm litho pattern

BCP self-assembly BCP pattern transfer

100nm

CD ~ 15nm

DSA Process of reference (lithographie and etch) available on

300 mm pilot line in Leti

For more details see R.Tiron et al. paper 8680-37 on February 28


Contact shrink process: lithographic performances


CD Metrology of Contact shrink

115

23.82

136

36.6

1.2

5.1

2.97

1.34

0

20

40

60

80

100

120

140

Pre-Pattern Pre-etch (Litho) Pre-etch (Copo) After-Etch

Process Step

CD

(n

m)

0

1

2

3

4

5

6

7

8

9

10

3σ

(n

m)

Average CD

Process Variation 3σ

J. Foucher, J.Hazar, R. Thérèse

For Manufacturing Solution

we have to manage several

metrology challenges: – High resolution patterns

– Complex morphologies

(contact in contact like

structures)

– Pattern placement control

– defectivity

15


Contact hole characterization

Need to combine different

metrology tools to fully

charactarize patterns (hybrid

metrology)

h1

CD1

h1

CD1

h2

CD2

h2

CD2

Guiding patterns

BCP patterns

CD SEM AFM-3D

CD-SEM AFM

CD-SEM AFM

- CD1 and CD2 by CD-SEM

- h1 and h2 by AFM3D

J. Foucher, J.Hazar, R. Thérèse


CH shrink: a quantification study

CD of BCP’s final contact hole depends on

both initial CD and initial pitch

CD of shrink contact vs. initial pitch CD of shrink contact vs. initial CD


56nm

60nm

67nm

75nm

Contact hole shrink by DSA

Contact shrink with DSA => large process latitude ( > 20nm)


Contact rectification using DSA

Contact rectification is possible with DSA

…but process latitude should be established

CD1 CD2 > CD1


Contact multiplication & simulation


Contact doubling by using BCP

Guiding template After PMMA removal After BCP transfer

– Contact doubling demonstrated by

using DSA

– Pitch sizing is possible using

contact doubling approach

100 nm


Exotic configurations accesible with BCP

Complex structures available for contact multiplication by DSA to

address design rules

15 nm

100 nm


How to predict polymer structures?

BF BD SZ0 BF BD+2% SZ+0.5 BF BD-2% SZ-0.5

Simulation contour

Contour variation w.r.t. dose, focus and mask CD error variations

+ Extracted Contour

+ Calculated CH

position

CH position on

wafer

Calculated CH

placement

Design

Experimental validation


Summary

DSA is a complementary lithography technique that could be inserted as early as the 14nm node – In a first step by using PS-b-PMMA like materials (lowest CD after etching

10nm)

– In a second step by using high materials (CD < 10nm)

A realistic application: contact hole shrink and multiplication

Thank you!

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