© imec 2005 line edge roughness: status of resist excite/more moore meeting 12 may 2005 l.a....
DESCRIPTION
© imec 2005 Excite/More Moore, May Description of LER 3-parameter model (Demokritos): Classical LER 3 Correlation length : the distance after which the edge points can be considered uncorrelated and the edge looks flat” correlation length is a measure for the acid diffusion Roughness exponent : the relative contribution of high frequency fluctuations to LER Offline analysis of top-down SEM picturesTRANSCRIPT
© imec 2005
Line Edge Roughness: status of resist
Excite/More Moore meeting12 May 2005
L.A. Leunissen, A.M. Goethals, R. Gronheid, F. Van Roey
© imec 2005 Excite/More Moore, May 2005
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Introduction
A brick wall for current CAR’sresolution limited to 30-35nm half pitchMain cause is acid diffusion lengthExperimental EUV data Sensitivity
Resolution Line
Edg
eRo
ughn
ess
Shot Noise
Acid
Diff
usio
n
Acid Diffusion
© imec 2005 Excite/More Moore, May 2005
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Description of LER
3-parameter model (Demokritos): Classical LER 3 Correlation length : the distance after which the edge points can
be considered uncorrelated and the edge looks flat”correlation length is a measure for the acid diffusion
Roughness exponent : the relative contribution of high frequency fluctuations to LER
Offline analysis of top-down SEM pictures
© imec 2005 Excite/More Moore, May 2005
4
0
5
10
15
20
85 100 115 130 145
PEB temp [oC]
LER
3
[nm
]
0
5
10
15
20
Cor
rela
tion
leng
th [n
m]
LER (EBL)
corr. Length (EBL)
Film Thickness: 80nm
Line Edge Roughness AnalysisEUVL (@PSI) +EBL
Film Thickness: 100nm
Corr. Length ~ Acid Diffusion
0
5
10
15
20
85 100 115 130 145
PEB temp [oC]
LER
3
[nm
]
0
5
10
15
20
Cor
rela
tion
leng
th [n
m]
LER (EBL)LER (EUV)corr. Length (EBL)corr. Length (EUV)
10
15
20
25
90 100 110 120 130 140
PEB temp [oC]
Cor
rela
tion
leng
th [n
m]
© imec 2005 Excite/More Moore, May 2005
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LER analysis EUV (PSI exposures)
7 different resists Different sensitivity
Shot noise contribution to LER: (dashed line)Resist contribution larger
y = 11.756x-0.1128
0
5
10
15
20
0 10 20
dose [mJ/cm2]
3 L
ER
[nm
]
dose1
© imec 2005 Excite/More Moore, May 2005
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LER analysis through focusExposures at Berkeley (@MET)
Six resistsAnalysis through focus
linewidth (Bossung curve) 3 LER (Demokritos, Summit)
65
66
67
68
69
70
-150 -50 50 150 250
Defocus [nm]
CD
[nm
]
0
5
10
15
20
25
3 L
ER
[nm
]
© imec 2005 Excite/More Moore, May 2005
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Correlation length vs. focus
Correlation length (Lcor) through focusParabolic fit
0
10
20
30
-250 -150 -50 50 150 250
Defocus [nm]
corr
. len
gth
[nm
]
RE1RE2RE3
Focus offsetDiffusion length (Ld)
© imec 2005 Excite/More Moore, May 2005
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Focus effects
AIC contrast reduction Result in increased LER
Chemical contrast reduction Results in increased correlation length Lcor E.g. (Solid-C simulation):
diffusion length=10nm
0.00.10.20.30.40.50.60.70.80.9
-0.1 -0.05 0 0.05 0.1
position [mm]
Aci
d co
ncen
trat
ion
-200-1000100200
focus [nm]
diffusion length=30nm
0.00.10.20.30.40.50.60.70.80.9
-0.1 -0.05 0 0.05 0.1
position [m]
Aci
d co
ncen
trat
ion
[%]
-200-1000100200
focus [nm]Decreasein contrast
© imec 2005 Excite/More Moore, May 2005
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Conclusions
Several resists tested PSI MET
LER characterization to measure trade-off: Shot noise LER Acid diffusion LER
Through focus experiments (MET)
SensitivityResolution Li
ne E
dge
Roug
hnes
s
Shot NoiseAcid
Diff
usio
n
Acid Diffusion
© imec 2005 Excite/More Moore, May 2005
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