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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
© CEA. All rights reserved | 3 R.Tiron et al.
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
© CEA. All rights reserved | 4 R.Tiron et al.
© CEA. All rights reserved | 5 R.Tiron et al.
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.
© CEA. All rights reserved | 6 R.Tiron et al.
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
© CEA. All rights reserved | 7 R.Tiron et al.
LETI’s DSA dedicated Process Implementation
© CEA. All rights reserved | 8 R.Tiron et al.
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
© CEA. All rights reserved | 9 R.Tiron et al.
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
© CEA. All rights reserved | 10 R.Tiron et al.
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
© CEA. All rights reserved | 11 R.Tiron et al.
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
© CEA. All rights reserved | 12 R.Tiron et al.
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
© CEA. All rights reserved | 13 R.Tiron et al.
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
© CEA. All rights reserved | 14 R.Tiron et al.
Contact shrink process: lithographic performances
© CEA. All rights reserved | 15 R.Tiron et al.
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
© CEA. All rights reserved | 16 R.Tiron et al.
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
© CEA. All rights reserved | 17 R.Tiron et al.
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
© CEA. All rights reserved | 18 R.Tiron et al.
56nm
60nm
67nm
75nm
Contact hole shrink by DSA
Contact shrink with DSA => large process latitude ( > 20nm)
© CEA. All rights reserved | 19 R.Tiron et al.
Contact rectification using DSA
Contact rectification is possible with DSA
…but process latitude should be established
CD1 CD2 > CD1
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Contact multiplication & simulation
© CEA. All rights reserved | 21 R.Tiron et al.
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
© CEA. All rights reserved | 22 R.Tiron et al.
Exotic configurations accesible with BCP
Complex structures available for contact multiplication by DSA to
address design rules
15 nm
100 nm
© CEA. All rights reserved | 23 R.Tiron et al.
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
© CEA. All rights reserved | 24 R.Tiron et al.
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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