2007.08.30 icis2007@jeju, korea highly charged ion beam applied to ... - kochi-tech… ·...

2007.08.30 ICIS2007@Jeju, Korea

Highly charged ion beam applied to

lithography technique

Sadao MomotaKochi University of Technology

ContentsObjectivePrinciple of IBLApplication of HCI beams to IBLHCI beam facilityExperimental resultsDiscussionConclusion

Objective

Integration of 2D patternDesign rule of LSI

ArF (193 nm)KrF (248 nm)

Laser 100 nm 70 nm130 nm



Laser 100 nm 70 nm

EUV 32 nm on TOKSelete-EUVA-Canon

F2 (157 nm)

130 nm



Laser 100 nm 70 nm

EUV 32 nm on TOKSelete-EUVA-Canon

F2 (157 nm)

130 nm

20 nm wide bridgeIBM

e-Beam

Ion beam

Applications of 3D micro-nano structures

MEMS Micro Electro Mechanical System

Optical deviceMoldBiochipMicro-machining tool

3-Axis Accelerometer

Analog Devices Co.

20 µm



Photonic crystal


National Inst. for Material Sciencehttp://www.nims.go.jp/jpn/news/nimsnow/Vol4/2004-03/05.html

Pile up of layers

http://www.nims.go.jp/jpn/news/nimsnow/Vol4/2004-03/05.html






Pattern transfer


10nm diam. & 60nm pitch

SiO2/Si PMMA

S.Y. Chou et al. J. Vac. Sci. Technol., B15(1997)2897

100 nm

100 nm



Micro inspection chip


Hitachi, Ltd.



Diamond array tool


Morita Gr. (Toyama Univ.)

Feasibility of IBL to fabricate 3D structures

Ion range controlled by beam energy• E ∝ V

Small lateral stragglingHigh reactivity• Large energy deposition in materials

Goal of this researchFabrication of 3D nano-scale structure

Application of HCI to IBL technique⇓

Efficient fabricationControllability/Enhancement of fabrication depth compared with conventional IBL

Principle of IBL

Exposure processIrradiation of ion beam• Mask or FIB

Irradiation effect• Implantation of impurities

• Change in chemical structure / component Crystal ⇔ Amorphous Polymer ⇔ Monomer

Exposure processIrradiation of ion beam• Mask or FIB

Irradiation effect• Implantation of impurities

•Change in chemical structure / component Crystal ⇔ Amorphous Polymer ⇔ Monomer

Development processEtching by chemicals• Wet / Dry

Difference in etching rate caused by• Impurity• Change in chemical

structure / component

Fabricated structure•Concave : positive•Hillock : negative

Development processEtching by chemicals• Wet / Dry

Difference in etching rate caused by• Impurity• Change in chemical

structure / component

Fabricated structure•Concave : positive•Hillock : negative

Positive

Negative

Application of HCI beams to IBL

Why HCI beam?

Why HCI beam?Availability of HCI sources• ECRIS, EBIS, Laser IS

Why HCI beam?Availability of HCI sources• ECRIS, EBIS, Laser IS

Expected advantages to use HCIcompared with singly charged ion

Expected advantage to apply HCI beams


Efficient fabrication• High reactivity of HCI beams in materials


Efficient fabrication• High reactivity of HCI beams in materials

Controllability/Enhancement of fabrication depth ⇐ E ∝ qVAcl.

compared with conventional lithography technique

Unique phenomena induced by HCI beams

Enhancement of dE

Pot. emission

Hollow atom

Local modification

Coulomb explosion etc.

Unique phenomena induced by HCI

Enhancement of dE

Pot. emission

Hollow atom

Local modification


Enhancement of dry etching process

Mat. Sci. Eng. B74 (2000) 40 T. Meguro et al.

Unique phenomena induced by HCI

Enhancement of dE

Pot. emission

Hollow atom

Local modification


Creation of nano-diamonds in HOPG

Appl. Phys. Lett. 79 (2001) pp. 3866, T. Meguro et al. sp2 -> sp3

Xe44+ from EBIT at NIST(11x106 ions/s)

L.P. Ratliff et al.Appl. Phys. Lett. 75 (1999) pp.590

Exposure : Xe44+ (350keV) Ar* (~0.1 eV)

Development : Remove Au in irradiated region

Measurement : Loss of reflectivity

IBL of self-assembled monolayers






Epot. (keV)

Dose(ions/cm2)

Xe44+ 51.3 1.3x1011

Ar* 0.012 6.6x1015







Epot. (keV)

Dose(ions/cm2)

Xe44+ 51.3 1.3x1011

Ar* 0.012 6.6x1015x 4400 x 1/50000

2D pattern


Exposure : Xe44+ (210keV) on PMMA

Development : Remove PMMA in irradiated region

Measurement : SEM, AFM

IBL of PMMAXe44+ from EBIT at NIST(11x106 ions/s)

J.D. Gillaspy et al., J. Vac. Sci. Technol. B16 (1998) pp.3294

"... the method demonstrated here can be extended deep into the submicrometer range."

Exposure : Xe44+ (210keV) on PMMA

Development : Remove PMMA in irradiated region

Measurement : SEM, AFM

IBL of PMMAXe44+ from EBIT at NIST(11x106 ions/s)

J.D. Gillaspy et al., J. Vac. Sci. Technol. B16 (1998) pp.3294

Epot. (kV)

Dose(ions/cm2)

Xe44+ 51.3 2x1010

Xe1+ 0.011 4x1011

Ga1+ 0.006 6x1011

x 50,000 x 1/20"... the method demonstrated here can be extended deep into the submicrometer range."

Goal of this research

Efficient fabrication• High reactivity of HCI beams with materials

Controllability/Enhancement of fabrication depth• Controlled by V and q• Application of larger q

Fabrication of 3D nano-scale structure

HCI beam facility

Production of HCI beams10GHz-NANOGAN• PRF = 0~80 W• VExt. = 0~30 kVVAcl. = 0~100 kVCompact installECRIS and acceleration system installed in L~1 m.

ICIS2003 : S. Momota et al., Rev. Sci. Instrum., 75(2004), pp.1497 - 1498

Separation of HCI beamsRigidity analysis• θ = π/4 rad

• Bρ = 0~0.33 T⋅mIons• Ar1+~Ar9+

Irradiation of HCI beamsStencil mask• Cu

On-line current monitor• Collimator• Secondary electron

suppressor• Current integration

Irradiation of HCI beamsStencil mask• Cu

On-line current monitor• Collimator• Secondary electron

suppressor• Current integration

A

Experimental results

0.012

46

0.12

46

12

46

E Pot

. (ke

V)

12840 q

IBL on SOGIrradiation of Arq+

• q = +1~+9• 80~240 keV•Cu-Mask (43×43 μm)

Wet etching BHF (HF, NH4F)

Surface profile• Optical microscopy • Profilometer

EPot. of Ar ions

http://www.dreebit.com/en/highly_charged_ions/data/

Ar1+

0.015keV

Ar9+

1 keV



IBL on SOGIrradiation of Arq+

• q = +1~+9• 80~240 keV•Cu-Mask (43×43 μm)



IBL of SOGOptical micrograph

Irradiation of Arq+

• q = +1~+9• 80~240 keV•Cu-Mask (43×43 μm)



IBL of SOGIrradiation of Arq+

• q = +1~+9• 80~240 keV•Cu-Mask (43×43 μm)



Profile observed by Alpha step

Depth

X (μm)

Dept

h (n

m)

IBL on SiIrradiation of Arq+

• q = +1~9• E = 40~540 keV• Cu-Mask (43×43 μm)Etching• 46mass% HF

Surface profile• AFM

IBL on SiIrradiation of Arq+

• q = +1~9• E = 40~540 keV• Cu-Mask (43×43 μm)Etching• 46mass% HF

Surface profile• AFM

Ar4+

240 keV, 1.3x1015 ions/cm2

Tetch. = 0 min. Tetch. = 120 min.Hillock structure

Etching process of SOGAr1+: 90 keV, 6.3x1013 ions/cm2

200

150

100

50

0

Dept

h (n

m)

200150100500Eching time (sec)


I II III

200

150

100

50

0

Dept

h (n

m)



200

150

100

50

0

Dept

h (n

m)


200

150

100

50

0

Dept

h (n

m)



200

150

100

50

0

Dept

h (n

m)


200

150

100

50

0

Dept

h (n

m)


Initial depth

T1

Etching rate

Etching depth

400

300

200

100

0

Dept

h (n

m)

12080400Eching time (min.)

Etching process of SiAr4+: 240 keV, 1.3x1015 ions/cm2

400

300

200

100

0

Dept

h (n

m)

12080400Eching time (min.)

Etching process of SiAr4+: 240 keV, 1.3x1015 ions/cm2

Hillock structure

Etching-resistant layer

40

30

20

10

0

Dept

h (n

m)

6 81013

2 4 6 81014

2 4 6 8

Dose (ions/cm2)

Ar1+ Ar9+

Fabrication of concave structureSputtering of SOG

200

150

100

50

0

Dept

h (n

m)


40

30

20

10

0

Dept

h (n

m)

6 81013

2 4 6 81014

2 4 6 8

Dose (ions/cm2)

Ar1+ Ar9+

Fabrication of concave structureSputtering of SOG

Removal of etching-resistant

layer

200

150

100

50

0

Dept

h (n

m)


50

40

30

20

10

0

Heig

ht (n

m)

4 6 81015

2 4 6 81016

2

Dose (ions/cm2)

4+

Protrusion of SiFabrication of hillock structure

Dose dep.Increase with dose.

E dep.Increase with E.

q dep.Not depend on q.

Ar4+, 240 keV

15

10

5

0

Heig

ht (n

m)

5004003002001000E (keV)

V = 20~100 kV, q = 4+

Protrusion of SiFabrication of hillock structure

Ar4+, 1.5×1015 ions/cm2

Dose dep.Increase with dose.

E dep.Increase with E.

q dep.Not depend on q.

120

80

40

0

T 1 (s

ec)

6 81013

2 4 6 81014

2 4 6 8

Dose (ions/cm2)

Ar1+ Ar9+

T1 of SOGArq+, E = 90 keV

200

150

100

50

0

Dept

h (n

m)


120

80

40

0

T 1 (s

ec)

6 81013

2 4 6 81014

2 4 6 8

Dose (ions/cm2)

Ar1+ Ar9+

T1 of SOGArq+, E = 90 keV

200

150

100

50

0

Dept

h (n

m)


40

30

20

10

0

Dept

h (n

m)

6 81013

2 4 6 81014

2 4 6 8

Dose (ions/cm2)

Ar1+ Ar9+

2.5

2.0

1.5

1.0

0.5

0.0Etch

ing

rate

(nm

/sec

)

1013 1014 1015

Dose (ions/cm2)

Ar1+ Ar9+

Etching rate of SOGArq+, E = 90 keV

200

150

100

50

0

Dept

h (n

m)


300

200

100

0

Dept

h (n

m)

6 81013

2 4 6 81014

2 4 6 8

Dose (ions/cm2)

Ar1+ Ar9+

Etching depth of SOGArq+, E = 90 keV

200

150

100

50

0

Dept

h (n

m)


300

200

100

0

Dept

h (n

m)

6 81013

2 4 6 81014

2 4 6 8

Dose (ions/cm2)

Ar1+ Ar9+

Etching depth of SOGArq+, E = 90 keV

200

150

100

50

0

Dept

h (n

m)


HCI effect

800

600

400

200

0

Etching depth [nm]

6004002000

E (keV)

Ar4+

Etching depth of SOGAr4+ on SOG

Ion range

800

600

400

200

0

Etching depth [nm]

6004002000

E (keV)

Ar4+ Ar9+

Etching depth of SOGAr4+ on SOG

800

600

400

200

0

Etching depth [nm]

6004002000

E (keV)

q = 4+

Etching depth of SiAr4+ on Si

800

600

400

200

0

Etching depth [nm]

6004002000

E (keV)

V=20̃100kV, q = +4 V=60 kV, q = +1̃+9

Arq+ on Si

Etching depth of Si

Ion rangeDefect

Ar1+

Ar8+Ar9+

Ar6+

Ar4+

Ar2+

800

600

400

200

0

Etching depth [nm]

6004002000

E (keV)

V=20̃100kV, q = +4 V=60 kV, q = +1̃+9

Arq+ on Si

Etching depth of Si

Ion rangeDefect

Ar1+

Ar8+Ar9+

Ar6+

Ar4+

Ar2+

No HCI effect on Si

100

80

60

40

20

0

T 1 (s

ec)

6004002000E (keV)

Ar4+, 20~80kV

T1 vs. E : SiEtching start time increases withE.

100

80

60

40

20

0

T 1 (s

ec)

6004002000E (keV)

Ar4+, 20~80kV Ar1+~9+, 60kV


Ar1+

Ar8+

Ar4+Ar2+

100

80

60

40

20

0

T 1 (s

ec)

6004002000E (keV)

Ar4+, 20~80kV Ar1+~9+, 60kV


Ar1+

Ar8+

Ar4+Ar2+

Deeper but longer time with high energy ions

Discussion

Modification of surface: SOGTop surface : resistant layer for etching

Energy deposition at surface

Promotion of sputtering/modification

Concave structure

Removal of resistant layer

Modification of surface: SOGTop surface : resistant layer for etching


Promotion of sputtering/modification

Concave structure

Removal of resistant layer

1+ ⇒ 9+

Modification of surface: SiTop surface : resistant layer for etching


Promotion of amorphousization

Hillock structure Rise of etching rate





Beam energy





Why?Depth

Beam energy

Reduction of energy deposition at surfaceBecause

calculated by SRIM

Defect density distribution in Si induced by Ar irradiation

Modification of inside: SOGEtching rate

not depend on q

Etching depthanomalously deeper than ion rangeincrease with q

q dep. does not observed for Si.

Indirect irradiation effectAnomalously deep structural change• Secondary e-

• Shock waves

• Stress etc.

Remarkable for glassesA. Deshkovskaya, Nucl. Instr. and Meth. in Phys. Res. B166-167 (2000) pp.511

HCI effect is material dependent.

Modification of mechanical properties

Nano-indentation meas.12

8

4

0

Nano

hard

ness

[GPa

]

3002001000Depth [nm]

SiO2 SiPreliminary

Modification of mechanical properties

Nano-indentation meas.12

8

4

0

Nano

hard

ness

[GPa

]

3002001000Depth [nm]

SiO2 SiPreliminary

After irradiationAr4+, 1.25×1015 ions/cm2

12

8

4

0

Nano

hard

ness

[GPa

]

3002001000Depth [nm]

Conclusion

HCI effect on IBLHCI beams reduces etching time.• Reduction of T1

HCI enhances fabrication depth.• Anomalously deep structural change

(Material dependent)• HCI beams

Fabrication depth can be controlled.• ±10nm• V and q

For deep fabricationEnergy deposition promotes fabrication.

More energy deposition at surface.

• Co-irradiation of low energy IB

• Irradiation of HCI beams

Defect density distribution

calculated by SRIM

ProspectsFurther development of IBL with HCI beams• Application of higher Epot.

• Fabrication of unique structure

Further development of ion source• More intense / more focused HCI

beams

Collaboration

Kochi Univ. of Tech.

Tokyo Univ. of Sci.

Univ. of Toyama

Y. Nojiri, S. Momota Irradiation of HCI beam

J. Taniguchi, I. Miyamoto IBL process, Measurements

N. Morita, N. Kawasegi Etching, Measurements

Appendix

80

60

40

20

0

-20

dW (n

m)

76543210Etching time (min.)

1 leyer, ~500 nm 2 leyer, ~1000 nm

Change in thickness of SOG by etching process

dW vs. etching time

Enhancement of E-lossdE of HCI beam in C-foil (~10 nm)

E = 35.5 ± 0.2 (16O), 92.3 ± 0.6 (40Ar),197.7 ± 1.0 (86Kr), 312.4 ± 2.0 (136Xe), and 454.4 ± 3 (197Au) keV

T. Schenkel et al., Phys. Rev. Lett. 79 (1997) pp.2030

2007.08.30 icis2007@jeju, korea highly charged ion beam applied to ... - kochi-tech… ·...

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