Investigation of CA resist decomposition by EUV and EB

Investigation of CA resist decomposition by EUV
and EB exposure
Daiju Shiono 1, 2), Taku Hirayama 1), Hideo Hada 2), Junichi Onodera,
Takeo Watanabe 2), Hiroo Kinoshita 2)　1
C/N : 2120809057
Tokyo Ohka Kogyo Co., Ltd.,
2 LASTI, University of Hyogo
29 September 2008, EUVL symposium
Contents

Motivation of this work

Advantages of Prot-Mad-2 as a resist material
for decomposition analysis

Analysis method and experimental conditions

Analysis result of EB exposure and PEB

Contrast curve
Analysis of decomposition material by EB exposure
Comparison of decomposition behavior and surface roughness
Summary and next work
2
Motivation of this work 1
¾ The goal of this work is to achieve CD
control demand by controlling the
decomposition reaction of resist material.
¾ By optimizing the under-layer and baking
conditions, LER/ LWR can be improved.
(A. Ma et. al., Proc. SPIE, 6921 (2008) 69213O-1)
¾ However further LER/ LWR improvement
looks needed
for 22 and 16 nmhp.
A. Ma et. al., Proc. SPIE, 6921 (2008) 69213O-1.
3
Motivation of this work 2
¾ We try to analyze decomposition behavior of the resist material to know
what is happened in the resist film during exposure and PEB process.
OH
HO
OH
O
O
O
¾ In this presentation, we will report decomposition analysis of the resist film after exposure and PEB process using our molecular glass material
shown in the right because this has very simple structure attached with just
two protecting groups so that it would become much more easier to analyze
and assay the products generated during the process.
O
O
O
O
O
Prot-Mad-2
- TOK molecular glass resist material -
OR
OR
H3C
CH3
CH3
CH3
RO
O
OH
O
H3C
RO
<Positive tone type>
CH3
OR
CH3
OR
CH3
O-tBoc
R=
T. Hirayama et. al., Proc. SPIE 6153-18 (2006) .
HO
Jpn. Kokai Tokkyo Koho JP 08 33102
OH
OR
O
OH
O
OR
R = H or
O
O
O
OH
CH 3
CH 3
O
CH 3
H 3C
O
HO
D. Shiono et. al., Jpn. J. Appl. Phys. 45 (2006) 5435.
OH
OR
RO
RO
OR
OR
<Negative tone type> T. Hirayama et. al., J. Photopolym. Sci. Technol. 17 (2004) 435.
OR
O
CH3
RO
RO
CH3
H3C
CH3
OR
R = H or
OR
OH
OH
K. Kojima et. al., J. Photopolym. Sci. Technol. 19 (2006) 373.
4
Advantages of Prot-Mad-2 as a resist material
for decomposition analysis
< an example of HPLC data >
OH
OH
1000
HO
O
O
O
O
O
O
O
Mw; 6500
Mw/Mn; 1.70
PAG
OH
O
O
GPC chart of conventional polymer
Prot-Mad-2
Before exposure
500
O
??
0
Prot-Mad-2
Complicated !!
After exposure and PEB
Prot-Mad-2
Deprot-1-prot-Mad-1
Deprot-2
600
400
Conventional polymer consists of many
component mixture. It is difficult to analyze
what happens to each base polymer molecule
after and before exposure.
PAG
200
0
0
5
10
15
20
25
30
35
40
45
50
min
< Advantages of Prot-Mad-2
for decomposition analysis >
¾ High purity ( > 99%)
¾ Just only 2-part protection
From HPLC analyses, we can obtain the information
of qualitative and quantitative analysis at exposure
decomposition process.
5
Resist sample formulation and conditions at EB exposure
No.
Base material
Resist sample
OH
1
Resist-A
HO
O
O
O
O
O
O
Resist-B
HO
Exposure conditions
PAB;
Exposure;
PEB;
C4F9SO3
none
O
S
C4F9SO3
trioctylamine
Prot-Mad-2
OH
O
O
O
O
S
OH
O
OH
2
quencher
OH
O
O
PAG
OH
O
O
O
O
O
O
Prot-Mad-2
100°C for 90s
HL-800D (70kV), Hitachi Ltd.
100°C for 90s
HPLC analysis
Measurement tool; SCL-10AVP (SHIMADZU corporation)
Column; SUPERIOREX ODS (SHISEIDO fine chemical)
6
Sample preparation for HPLC analysis
1. Spin coating onto wafer
2.Baking
3. Exposure and PEB
wafer
4. Scratching resist film for HPLC
5. HPLC analysis
600
400
200
0
0
5
10
15
20
25
30
35
40
45
50
min
Condition of HPLC analysis
Measurement tool; SCL-10AVP (SHIMADZU corporation)
Column; SUPERIOREX ODS (SHISEIDO fine chemical)
HPLC; High performance liquid chromatography
7
Normalized film thickness
EB exposure result of Resist-A (without quencher)
1.2
OH
1
Contrast curve of resist-A
0.8
O
O
O
0.6
O
OH
O
O
O
O
O
O
Prot-Mad-2
0.4
0.2
0
0.1
1
10
100
OH
Decomposition rates of Prot-Mad-2
100
HPLC area (%)
HO
OH
HO
OH
O
O
O
Prot-Mad-2
80
60
O
OH
O
O
O
O
O
OH
Deprot-1-prot-Mad-1
Deprot-1-prot-Mad-1
40
OH
OH
Deprot-2
20
HO
O
O
O
0
0.1
1
10
EB exposure (µC/cm2)
100
O
OH
O
O
O
OH
O
OH
Deprot-2
¾ Resist film thickness decreases gradually following EB exposure increase.
¾ Decomposition of Prot-Mad-2 occurs gradually following EB exposure increase.
8
Conditions
Film thickness; 240nm
PAB;
100°C for 90s
Exposure;
HL800D (70kV)
PEB;
100°C for 90s
Development; NMD-3 2.38%
Normalized film thickness
EB exposure result of Resist-B (with quencher)
1.2
1
0.8
0.6
0.4
0.2
Contrast curve of resist-B
0
1
10
100
Conditions
Film thickness;
PAB;
Exposure;
PEB;
240nm
100°C for 90s
HL800D (70kV)
100°C for 90s
HPLC
SHIMADZU, SCL-10AVP
HPLC area (%)
100
80
Prot-Mad-2
Decomposition rates
of Prot-Mad-2
60
Deprot-1-prot-Mad-1
40
20
Deprot-2
0
1
10
100
EB exposure (µC/cm2)
¾ Resist film thickness decreases rapidly around 10µC/cm2 as decomposition products
of Deprot-1-prot-Mad-1 and Deprot-2 increase.
¾ Decomposition reaction of Prot-Mad-2 scarcely occurs at the area of below 10µC/cm29.
Surface roughness of resist-B at each decomposition rates
240nm
100℃ for 90s
HL800D (70kV)
100°C for 90s
HPLC
SHIMADZU, SCL-10AVP
HPLC area (%)
100
Conditions
Film thickness;
PAB;
Exposure;
PEB;
80
60
Deprot-1-prot-Mad-1
40
20
Deprot-2
0
Surface roughness
measurement tool; Atomic force
micro scope (AFM)
measurement area; 1µm* 1µm
Measurement mode; tapping mode
Probe; Si probe
¾
Surface roughness
RMS (nm)
1
Conditions
Film thickness; 150nm
PAB;
100℃ for 90s
Exposure;
HL800D (70kV)
PEB;
100°C for 90s
Development; NMD-3 2.38%
Prot-Mad-2
Decomposition rates
of Prot-Mad-2
16
14
12
10
8
6
4
2
0
10
100
10
100
Surface roughness
of resist-B
1
EB exposure (µC/cm2)
Surface roughness increases as the dose increases and achieves maximum
surface roughness at a dose of around 26µC/cm2 where area percentage of
Deprot-1-prot-Mad-1 is maximum in the HPLC spectrum.
10
Hypothesis of acid decomposition on Prot-Mad-2
OH
OH
OH
OH
OH
HO
O
O
O
O
OH
HO
O
O
O
O
O
O
O
O
O
Prot-Mad-2
Acid and PEB
(major path)
O
OH
O
HO
O
O
O
O
OH
O
O
O
OH
Deprot-1-prot-Mad-1
Acid and PEB
(major path)
O
OH
O
O
O
OH
O
OH
Deprot-2
Acid and PEB
(minor path)
11
Summary and next work

We analyzed decomposition behavior of Prot-Mad-2 at EB exposure and PEB by
HPLC.

We measured surface roughness of EB exposure and PEB by AFM.

Major decomposition products are Deprot-1-prot-Mad-1 and Deprot-2.
Without quencher, decomposition reaction of Prot-Mad-2 occurs gradually following EB
exposure increase.
With quencher, Resist film thickness decreases rapidly around 10µC/cm2 as decomposition
products of Deprot-1-prot-Mad-1 and Deprot-2 increase.
From the exposure tests, dissolution contrasts of resist-A and-B are attributed to
decomposition to Deprot-1-prot-Mad-1 and Deprot-2.
Decomposition reaction of Prot-Mad-2 seems to be stepwise.
Decomposition reaction of Resist-B occurs drastically at around the dose of 26µC/cm2 which
is a dose of maximum surface roughness.
Next work

Measuring dissolution rates of Prot-Mad-2, Deprot-1-prot-Mad-1 and Deprot-2, respectively.
Checking the relation between dissolution rates of each material and roughness property.
Measuring thermal property of each material.
EUV exposure and its analysis
12

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