Highly charged ion beams applied to fabrication of Nano-scale 3D structures Sadao MOMOTA Kochi University of Technology
Introduction 1 Prospect of microscopic structures 2D Semiconductor 3D Ex. MEMS http://www.rise.waseda.ac.jp/proj/sci/s98s08/j-s98s08.html
Introduction 2 Application of 3D structures MEMS Micro Electro Mechanical System ex. 3-Axis Accelerometer Biochip Mold 20 µm Analog Devices Co.
Introduction 2 Application of 3D structures MEMS Micro Electro Mechanical System ex. Micro inspection chip Biochip Mold Hitachi, Ltd.
Introduction 2 Application of 3D structures MEMS Micro Electro Mechanical System ex. Pattern transfer 10nm diam. & 60nm pitch SiO 2 /Si PMMA Biochip Mold 100 nm S.Y. Chou et al. J. Vac. Sci. Technol., B15(1997)2897
Introduction 3 To be developed Fabrication process with 1. High precision/controllability in vertical direction 2. Efficient and simple process 3. Small-size facility
Introduction 4 Hopeful candidate Ion beams because 1. Small angular struggling 2. High reactivity 3. Controllable range
Introduction 4 Hopeful candidate Highly Charged Ion (HCI) beams
Introduction 4 Hopeful candidate beams Highly Charged Ion (HCI) because of remarkably high reactivity extension of Rp
Introduction 4 Hopeful candidate beams Highly Charged Ion (HCI) because of remarkably high reactivity extension of Rp IB litho. & swelling process
HCI beams 1 Energy of HCI beams E Pot. of Ar ions E = Ekin. + EPot. 6 4 Kinetic energy Ekin. ~ q E Pot. (kev) 2 1 6 4 2 0.1 6 4 Ar 9+ 1 kev 0.01 2 0 4 Ar 1+ 0.015keV q 8 12 http://www.dreebit.com/en/highly_charged_ions/data/
HCI beams 1 Energy of HCI beams E Pot. of Ar ions E = Ekin. + EPot. 6 4 Kinetic energy Ekin. ~ q Potential energy EPot. ~ q 2.8 E Pot. (kev) 1 6 4 0.1 6 4 0.01 2 2 2 0 Ar 9+ 1 kev 4 Ar 1+ 0.015keV q 8 12 http://www.dreebit.com/en/highly_charged_ions/data/
HCI beams 2 Enhanced irradiation effect - Additional energy deposition ex. Nano-diamonds created in HOPG sp 2 -> sp 3 Appl. Phys. Lett. 79 (2001) pp. 3866, T. Meguro et al.
HCI beams 3 Extension of R p - Higher accelerability ex. 40 Ar q+ on Si, V=100 kv 1+ 10+ 100 kev ~100 nm Si
HCI beams 3 Extension of R p - Higher accelerability ex. 40 Ar q+ on Si, V=100 kv 1+ 10+ 100 kev 1,000 kev ~100 nm Si
HCI beams 3 Extension of R p - Higher accelerability ex. 40 Ar q+ on Si, V=100 kv 1+ 10+ 100 kev 1,000 kev ~100 nm Si ~1000 nm
IB lithography 1 IB lithography Irr. of Ar-beam Modification of material Stencil mask Etching by BHF/HF Difference in etching rate Sample
IB lithography 1 IB lithography Irr. of Ar-beam Modification of material Etching by BHF/HF Difference in etching rate
IB lithography 1 IB lithography Irr. of Ar-beam Modification of material Etching by BHF/HF Difference in etching rate
IB lithography 1 IB lithography Irr. of Ar-beam Modification of material Etching by BHF/HF Difference in etching rate
IB lithography 2 Etching process of SOG Ar 1+ : 90 kev, 6.3x10 13 ions/cm 2 200 Depth (nm) 150 100 50 I II III 0 0 50 100 150 Eching time (sec) 200 Rev. Sci. Instrum. 79 (2008) 02C302, S. Momota et al.
IB lithography 2 Etching process of SOG Ar 1+ : 90 kev, 6.3x10 13 ions/cm 2 200 Depth (nm) 150 100 50 I II III 0 0 50 100 150 Eching time (sec) 200 Rev. Sci. Instrum. 79 (2008) 02C302, S. Momota et al.
IB lithography 2 Etching process of SOG Ar 1+ : 90 kev, 6.3x10 13 ions/cm 2 Depth (nm) 200 150 100 50 T 1 Etching rate I II III Max. Etching depth Initial depth 0 0 50 100 150 Eching time (sec) 200 Rev. Sci. Instrum. 79 (2008) 02C302, S. Momota et al.
IB lithography 3 Reduction of etching time Ar 1+,9+, E = 90 kev T 1 (sec) 120 80 40 d 1+ 9+ Depth (nm) 200 150 100 50 0 0 T 1 50 100 150 Eching time (sec) 200 0 6 8 10 13 2 4 6 8 10 14 2 4 6 8 Fluence (ions/cm 2 ) Rev. Sci. Instrum. 79 (2008) 02C302, S. Momota et al.
IB lithography 4 Enhanced fabrication depth Ar 1+,9+, E = 90 kev Depth (nm) 200 150 100 50 Max. Etching depth 0 0 50 100 150 Eching time (sec) 200 Rev. Sci. Instrum. 79 (2008) 02C302, S. Momota et al.
IB lithography 4 Enhanced fabrication depth Ar 1+,9+, E = 90 kev Depth (nm) 300 200 100 1+ 9+ d HCI effect Depth (nm) 200 150 100 50 0 0 Max. Etching depth 50 100 150 Eching time (sec) 200 0 6 8 10 13 2 4 6 8 10 14 2 4 6 8 Fluence (ions/cm 2 ) Rev. Sci. Instrum. 79 (2008) 02C302, S. Momota et al.
IB lithography 5 In case of Si Irradiation of Ar q+ Ar 4+ 240 kev, 1.3x10 15 ions/cm 2 V = 60 kv E = 60 ~ 540 kev 1+ 9+ Cu-Mask (43 43 μm) 120 min. in 46 mass% HF Appl. Surf. Sci. 253 (2007) pp. 3284, N. Kawasegi et al.
IB lithography 6 Enhanced etching depth Ar 1~9+ on Si Rev. Sci. Instrum. 79 (2008) 02C302, S. Momota et al.
IB lithography 6 Enhanced etching depth Ar 1~9+ on Si Rev. Sci. Instrum. 79 (2008) 02C302, S. Momota et al.
IB lithography 6 Enhanced etching depth Ar 1~9+ on Si Defect Ion range E = 480 kev Rev. Sci. Instrum. 79 (2008) 02C302, S. Momota et al.
IB lithography 7 Just first step 1st step 2nd step Appl. Surf. Sci. 253 (2007) pp. 3284, N. Kawasegi et al.
IB lithography 7 Just first step 1st step 2nd step Appl. Surf. Sci. 253 (2007) pp. 3284, N. Kawasegi et al.
Swelling effect 1 Growing swelling structure - MD simulation J. Appl. Phys. 106 (2009) 044910, S. Satake et al. 2.99 x 10 14 ion/cm 2 4.02 x 10 14 ion/cm 2 6.52 x 10 14 ion/cm 2
Swelling effect 2 Growing swelling structure - Experimental results Ar 1+ (50 kev) on Si
Swelling effect 2 Growing swelling structure - Experimental results Ar 1+ (50 kev) on Si Expansion Sputtering
Swelling effect 3 Energy dependence Ar q+ on Si 50 kev to be published in J. Nanosci. and Nanotech., S. Momota et al.
Swelling effect 3 Energy dependence Ar q+ on Si 240 kev 50 kev to be published in J. Nanosci. and Nanotech., S. Momota et al.
Swelling effect 4 Control of swelling height Expansion rate x Depth of expanded layer Fluence Element Energy = q x V
Conclusions Possibility of HCI beams examined IB litho. Swelling process sputtering, NH and further higher precision crucial application theoretical research
Conclusions Possibility of HCI beams examined IB litho. Swelling process sputtering, NH HC ion source ECRIS, EBIS higher intensity/q lower cost and further higher precision crucial application theoretical research Microscopic simulation Molecular dynamics
Collaboration with Tokyo Univ. of Sci. Toyoma Univ. Thank you for your attention.
Appendices
HCI beam facility Prod. of HCIs Separation of q Rev.Sci.Instr. 75(2004) pp. 1497, S. Momota et al.
Ion beam lithography In case of SOG Irradiation of Ar q+ q = +1 9 90 kev Cu-Mask (43 43 μm) Wet etching BHF (HF, NH 4 F) Surface profile Optical microscopy Profilometer Depth (nm) Surface profile Depth X (μm) observed by Alpha step
IB lithography 5 In case of Si Irradiation of Ar q+ q = +1 9 V = 60 kv E = 60 540 kev Cu-Mask (43 43 μm) Etching 46mass% HF Surface profile AFM Ar 4+ 240 kev, 1.3x10 15 ions/cm 2 T etch. = 120 min. Appl. Surf. Sci. 253 (2007) pp. 3284, N. Kawasegi et al.
Sputtering Sputtering rate nin nout Emitted atoms!! S =!!!!!!!! = Irradiated ions!! nin nout
Sputtering Measurement of S 1.Irradiation of Ar q+ q = +1 9 100 ~ 900 kev Number of irradiated ions (A) 2.Meas. of mass before/after irradiation Number of sputtered Ag atoms (B) S = (B) (A)
Sputtering Sputtering rate vs. q
Nano hardness Nano hardness
Nano hardness Mod. of mechanical properties Ar-irradiated sapphire crystal 1.2 IB-induced modification of crystal structure!n a n o - h a r d n e s s! Young modulus etc. f D, max 1.0 0.8 0.6 0.4 0.2 0.0 Maximum of the accumulated damage HCI beams enhances modification? Nanohardness (GPa) 30 20 10 Virgin crystal Nanohardness Young modulus 400 300 200 100 Young modulus (GPa) 0 0 1 10 100 Irradiation fluence (x10 15 cm -2 ) Nucl. Instr. and Meth. B 240 (2005) pp. 111, J. Jagielski et al.
Nano hardness Softening of Si crystal Nano-indentation meas. Nanohardness [GPa] 12 8 4 0 0 SiO2 Diff. of NH After irradiation Ar 4+, 1.25 10 15 ions/cm 2 Si 100 200 300 Depth [nm] Ref. S.A. Pahlovy, Ph.D Thesis, Kochi Univ. of Tech., 2008
Nano hardness Charge state dep. of modification of NH Ref. S.A. Pahlovy, Ph.D Thesis, Kochi Univ. of Tech., 2008
Ion source for HCIs : 1 ECRIS (ECR ion source) NANOGAN by PANTECHNIK http://www.pantechnik.fr e - with high E acceleration by ECR process Microwave confinement of ions Mirror mag. field Mag. field Gas
Ion source for HCIs : 2 EBIS (Electron beam ion source) dresdenebis by DREEBIT http://www.dreebit.com/ e - with high E e - -beam (~10µmφ, >10keV) produced by electron gun confinement of ions Trapped by ele. field induced by electrodes and e - -beam
Ion source for HCIs : 3 ILIS (Intense laser ion source) At present no industrial products, but in future... e - with high E Heated by intense laser confinement of ions No fields for confinement because of high density of e - http://www2.gpi.ac.jp/jspf/jaea%20ion/jaeaion.html