Ion beam lithography - Iindico.ictp.it/event/a11182/session/33/contribution/19/material/0/0.pdf · 2 Outline •Ion‐matter interaction •Ion‐beam lithography → MeV ions →

2359-13

Joint ICTP-IAEA Workshop on Physics of Radiation Effect and its Simulation for Non-Metallic Condensed Matter

Paolo Olivero

13 - 24 August 2012

University of Turin Italy

Ion beam lithography - I

1

Ion beam lithography ‐ I

Paolo Olivero

Physics DepartmentNIS Centre of ExcellenceUniversity of Torino

INFN Section of Torino

CNISM Consortium

ICTP‐IAEA Workshop, Trieste, 13‐24 August 2012

[email protected]

2

Outline

• Ion‐matter interaction

• Ion‐beam lithography

→ MeV ions

→ keV ions

→ MeV ions

→ keV ions

→ resists→ silicon

→ single ion tracks

•MeV ion beam lithography

→ other materials

• keV ion beam lithography

→ FIB milling→ FIB‐assisted deposition

→ Helium‐ion microscope

→ conven onal techniques

Introduction Case studies

3

Outline



→ MeV ions

→ keV ions

→ MeV ions

→ keV ions




→ other materials






4

Ion‐matter interaction: MeV ions

1 MeV H+ in Si

Longitudinal trajectory Lateral trajectory

@ : SRIM Monte Carlo code

5

Longitudinal range Lateral range


1 MeV H+ in Si


6

Electronic energy loss Nuclear energy loss


1 MeV H+ in Si


7

Sputtering yield: 0 atoms / ion


1 MeV H+ in Si


8

Outline



→ MeV ions

→ keV ions

→ MeV ions

→ keV ions




→ other materials






9

Ion‐matter interaction: keV ions

30 keV Ga+ in Si

Longitudinal trajectory Lateral trajectory


10

Longitudinal range Lateral range


30 keV Ga+ in Si


11

Electronic energy loss Nuclear energy loss


30 keV Ga+ in Si


12

Sputtering yield: 2.17 atoms / ion


30 keV Ga+ in Si


13

Outline



→ MeV ions

→ keV ions

→ MeV ions

→ keV ions




→ other materials






14

Conventional lithography techniques

Lithography in positive and negative resists

15


Photolithography

mask aligner (λ=365 nm)

photoresists: PPMA, PMGI, SU‐8, etc.schematics

depth of focus:

very‐large‐scale integration (VLSI)

minimum feature size:

16

Electron‐beam lithographydirect‐write mask‐less process

electron beam lithograph (SEM)

schematics

best resolution: 30‐60 nm

resists: ZEP‐520, PMMA

resolution: e‐beam size (nm)beam‐target interaction

other issues: scatteringproximity effectscharging


17

Outline



→ MeV ions

→ keV ions

→ MeV ions

→ keV ions




→ other materials






18

Ion‐beam lithography: MeV ions

as for EBL:

• scanning focused/collimatedbeam

• mask‐less direct writing• typical EBL resists

Processes

• ion implantation (doping, luminescent centers, …)

• change in chemical reactivity in a latent image

• local modification of physical (electrical, optical,magnetic, …) properties

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• nuclear interac on: damage → structural modifica on• electronic interac on: ioniza on → chemical modifica on

Tools


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• nuclear interac on: damage → structural modifica on• electronic interac on: ioniza on → chemical modifica on

Tools


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2 MeV H+ 50 keV e‐

PMMA

Key issue: beam‐target interaction

• nm beam focusing

• low lateral straggling

• low longitudinal straggling

• tunable penetration depth (ion energy& species)

• lower emission of high‐energy secondary electrons (δ rays):no proximity effects


22

Beam‐target interaction:particularly relevant in shallow regions

in PMMA


@ : DEEP Monte Carlo code

23

Unique capabilities offered by IBL


High penetration depth → High aspect‐ratios

Low lateral straggling → Smoothness in lateral features

Focusing, no proximity effects → High resolution

End‐of‐range peak → Depth resolution

Low longitudinal straggling → Multi‐level structures

Structural modification → Functionalization of physicalproperties

24

Proton beams: ideal in terms of: focusingpenetration profile

Proton Beam Writing (PBW)


In several specific applications, other ions species (He, C, N, O, Si, Ar, Br, Au, …) were employed

P‐LIGA (Proton – Lithographie, Galvanoformgung, Abformung: Proton – Lithography, Electroplating and Molding)

25

Scanning μ‐beam systemion accelerator

switching magnet

object aperturevacuum pipe

collimator aperture

scan coils focusing lenes

sample chamber

feedback system

scan controller


@ : CIBA – National University of Singapore

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Programmable aperture system

collimators

broad beam

collimated beam

sample


@ : University of Jyväskylä

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Ion projection system

collimated beam

focusing system

broad beam

collimatorprojected image


@ : RUBION – Ruhr‐Universität Bochum

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Proximity mask system

collimator

broad beam

collimated beam

sample


@ : Friedrich‐Schiller‐Universität

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Contact mask system

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Scanning beams vs masks

Scanning beam systems Mask‐based systems

:‐) Fast pattern definition :‐( Slow pattern definition

:‐( Serial & slow irradiation :‐) Fast & parallel irradiation

:‐) High resolution :‐( Mask scattering & heating

:‐( Limited scan field :‐) Broad scan field


31

(Some of the many) MeV‐IBL setups around the world

Shibara Institute of Technology

University of Melbourne

Legnaro National Laboratories

Ruđer Bošković InstituteUniversity of Surrey

National Universityof Singapore

Louisiana Accelerator Center


32

Outline



→ MeV ions

→ keV ions

→ MeV ions

→ keV ions




→ other materials






33

Ion‐beam lithography: keV ionsFocused ion beam (FIB) direct milling

typical FIB setup

FIB columnschematics

34

Focused ion beam (FIB) direct millingDual beam systems

52°e‐beam

i‐beam 52°

Ion‐beam lithography: keV ions

35

FIB: key issuesRange of ion sources

Wien filter setup

Sample chargingSample coating and/or electron flooding

Material redeposition

ideal case real case

Enhanced etching, limiting aspect ratio


36

Other FIB processes

Gas‐assisted FIB etching Gas‐assisted deposition


37

Outline



→ MeV ions

→ keV ions

→ MeV ions

→ keV ions




→ other materials






38

MeV Ion‐beam lithography: resists


39


Positive process: polytetrafluoroethylene (PTFE)

1.5–3 MeV H+

@ : Department of Physics – University of Surrey

40


Negative process: SU‐8, DiaPlate 133

0.8–3.5 MeV H+

SU‐8 DiaPlate 133

@ : Ion Beam Analysis Center – CAFI

41


Negative process: SU‐8, DiaPlate 133

0.8–3.5 MeV H+


SU‐8

42


2 MeV H+

High‐aspect‐ratio structures


43


2 MeV H+

Three‐dimensional structures

0.5 MeV H+


44


2.7 MeV H+ 1 MeV H+



45



2.25 MeV H+

@ : LIPSION – University of Leipzig

46



PMMA‐on‐PMMA microchannels

thermal bonding process

47



PMMA‐on‐PMMA microchannels

thermal bonding process

48


2 MeV H+

Low‐loss optical waveguides in polymer


key fabrication issue: lateral smoothness

49


Metallic nano‐electodes with lift‐off method


Ti/AuSiO2 PMMAimpressed PMMA

2 MeV H+

50


@ : Lund Institute of Technology, Sandia National Laboratory

Metallic micro‐grids

2.5 MeV H+

SU‐8 pillars

51


@ : Lund Institute of Technology, Sandia National Laboratory

Metallic micro‐grids

2.5 MeV H+

Au grid

52


3 MeV H+

High‐aspect‐ratio microfluidic channels

@ : Louisiana Accelerator Center – The University of Louisiana

fluence study

53


3 MeV H+

High‐aspect‐ratio microfluidic channels

@ : Louisiana Accelerator Center – The University of Louisiana

final structures

54



2.5 MeV H+

Buried microfluidic channels

55

Outline



→ MeV ions

→ keV ions

→ MeV ions

→ keV ions




→ other materials






56

MeV Ion‐beam lithography: Silicon

• Si sample

pristine Si heavily damaged Si

lightly damaged Si

• MeV ion implantation

• wet chemical etching in KOH

• electrochemical etching in HF

porous Si

57


• Si sample

pristine Si heavily damaged Si

lightly damaged Si

• MeV ion implantation


porous Si • wet chemical etching in KOH

@ : Physics Department – University of Torino, LIBI – Ruđer Bošković Institute

58



non‐channeling implantation channeling implantation

Micro‐rod arrays

59




60


Low‐loss waveguides


thermalannealing

oxidized p‐Si

KOH wetetching

61



Free‐standing waveguides

62


@ : Advanced Machinery Department – AIST

Cantilever MEMS structures

single layer (2.1 MeV Au) double layer (2.1 MeV Au, 1.5 MeV C)

63

MeV Ion‐beam lithography: SiliconBragg reflector


• electrochemical etching in HF at different currents → different porosity → different refractive index (1.2 – 3)

• electrochemical etching in HF at alterna ng currents →alternating layers of different refractive index

• Bragg law: n∙λ = 2∙d∙sin(θ)

64

MeV Ion‐beam lithography: SiliconBragg reflector


• electrochemical etching in HF at different currents → different porosity → different refractive index (1.2 – 3)

• electrochemical etching in HF at alterna ng currents →alternating layers of different refractive index

• Bragg law: n∙λ = 2∙d∙sin(θ)• different fluence → different refrac ve index modula on

65


• electrochemical etching in HF at variable current• modulation of the refractive index (1.2 – 3)

Bragg‐cladding bulk waveguide


66





67





68


Local modifica on of the refrac ve index → Distributed Bragg reflector

• variable‐thickness mask• 0.2 MeV H+, 0.35 MeV H+



69


Four implantation energies, 2‐D mask geometry → Pixel array

• variable‐thickness mask• 0.2 MeV H+, 0.35 MeV H+



70


Refractive index modulation with a scanning microprobe

@ : CIBA – National University of Singapore“The Red Armchair”, Picasso (1931)

71


Refractive index modulation with a scanning microprobe

@ : CIBA – National University of Singapore“The Dance”, Matisse (1910)

72

Charge Collection Efficiency modulation with a scanning microprobe


@ : LIBI – Ruđer Bošković InstituteP. Mondrian

73

Outline



→ MeV ions

→ keV ions

→ MeV ions

→ keV ions




→ other materials






74

MeV IBL: Other materialsGallium Arsenide

@ : Department of Physics – University of Surrey

Negative process based on the modulation of the material sensitivityto reactive ion etching

75@ : LIPSION – University of Leipzig

MeV IBL: Other materialsIndium Phosphide

Negative process based on the modulation of the material sensitivityto electrochemical etching (→ Si)

76@ : LIPSION – University of Leipzig

MeV IBL: Other materialsAgar gel

Positive process with 2.25 MeV H+ ionsAgar‐free regions: cell adhesion on underlying Petri dish

77

MeV IBL: Other materialsNd:YAG

Modulation of the refractive index by H+‐induced damage


78

MeV IBL: Other materials

Photo‐sensitive glass (FoturanTM)

Modulation of the refractive index by 2 MeV H+‐induced damage


79


LiNbO3 (non‐linear optics applications)

Modulation of the refractive index by 1.6‐2.2 MeV O3+ induced damage

@ : School of Physics and Microelectronics – Shandong University

80


Nd3+‐doped SiO2

Modulation of the refractive index by 6 MeV O3+ induced damage

@ : School of Physics and Microelectronics – Shandong University

FEM simulation

81


Sapphire

Lift‐off in sapphire based on He+ ion implantation

@ : Swiss Federal Institute of Technology

Positive process based on change in reactivity to wet chemical etching

82

Outline



→ MeV ions

→ keV ions

→ MeV ions

→ keV ions




→ other materials






83

MeV IBL: Single ion tracks

• Tool: single Swift Heavy Ions (SHI)

• Instantaneous & localized release of energy in the materialcoulomb explosionthermal spike

• Ideal samples: organic polymershigh electrical & thermal resistivity → semiconductors, insulatorscrystals: transition to an amorphous phase

• Spike: 10 nm, L 101 – 102 μm → high aspect ratio (up to 1:104) nano‐wires

• Tracks: overlapping lumps of modified material: dE/dx → continuous/discontinuous tracks

@ : Centre de Recherche sur les Ions, le Matériaux et la Photonique (CIMAP)

84

MeV IBL: Single ion tracksTrack etching

Electrolytic cell

Vsource Imeter

membrane

single track

sealing

solution

@ : Gesellschaft für Schwerionenforschung mbH, Darmstadt

• Current flowing through a 30‐μm‐thick polycarbonate membrane with 5 tracks

• Quadratic increase after breakthrough

• Solution: 2.5 M NaOH + 5% methanol

• Applied voltage: 0.5 V

85


Electrolytic cell

Vsource Imeter

membrane

single track

sealing

solution


• Equivalent pore diameter vs.time

• Linear increase after breakthrough

86


Electrolytic cell

Vsource Imeter

membrane

single track

sealing

solution


• Radial etch rate vs. time

• 5 peaks corresponding to the 5 tracks

87

MeV IBL: Single ion tracksTip enhanced electric field


High field region

• Increasing etching rate as the residual thickness decreases

• Tracks develop in sequence

88


Porous membranesfor counting and seizing cells, molecules and nanoparticles

At

i

89



At

i

90



At

i

91


Porous membranes for detection of DNA strands

@ : Kavli Institute of Technology – Delft University

Spike dura on → length of the DNA strand

92


Mica nano‐masks for high‐resolution single ion implantation


93


Mica nano‐masks for high‐resolution single ion implantation


Single 1 MeV N+ ion implantation

94


Ordered nanopores in TiO2 by SHI implantationthrough a porous anodic alumina mask

@ : Material Science Institute of Madrid

Porous Anodic Alumina (PAA)

anodic oxidation of Alin presence of acidic electrolytes

95





• Broad implantation of 25 MeV Br7+ ions

• Wet chemical etching in HF


96






• Broad implantation of 25 MeV Br7+ ions

• Wet chemical etching in HF

97


Templates for nanowires growth

• Single ion tracks

• Electrochemical etching

• Metal deposition

• Metal electro‐deposition1:100 Cu nanowire

@ : Gesellschaft für Schwerionenforschung, Darmstadt

98



Nanowire array• Single ion tracks



• Metal electro‐depositiontip‐enhanced electro‐deposition

@ : Gesellschaft für Schwerionenforschung, Darmstadt

99



@ : Acreo Research Institute & Seagate Technology

Compositionally modulated nanowire(→ magnetometry, spintronics, …)

• Single ion tracks



• Modulated electro‐deposition in a mixed electrolyte

100

Outline



→ MeV ions

→ keV ions

→ MeV ions

→ keV ions




→ other materials






101

keV IBL: FIB milling

Devices cross‐sectioningTEM sample preparation

Nano‐tips Photonic crystals

102

Outline



→ MeV ions

→ keV ions

→ MeV ions

→ keV ions




→ other materials






103

keV IBL: FIB‐assisted deposition

TEM sample preparation Cross‐section lift‐out

Nano‐contacting Advertising stuff

104

keV IBL: FIB‐assisted depositionNanoelectromechanical devices with DLC deposition

@ : School of Engineering – University of Tokio

105

Outline



→ MeV ions

→ keV ions

→ MeV ions

→ keV ions




→ other materials






106

keV IBL: Helium Ion Microscope

@ : Carl Zeiss SMT

• Smaller De Broglie wavelength

• Higher resolution• Higher secondary emission yield → lower current

107

Content sources• www.pbeam.com• www.srim.org• www.wikipedia.org

• Acreo Research Institute & Seagate Technology• Advanced Machinery Department – AIST• Centre de Recherche sur les Ions, le Matériaux et la Photonique• Carl Zeiss SMT• CIBA – National University of Singapore• Department of Physics – University of Surrey• Department of Nuclear Physics – Lund Institute of Technology• Gesellschaft für Schwerionenforschung, Darmstadt• Ion Beam Analysis Center – CAFI• IONLAB – Institut des Microtechnologies Appliquées• Kavli Institute of Technology – Delft University• LIBI – Ruđer Bošković Institute• LIPSION – University of Leipzig• Louisiana Accelerator Center – The University of Louisiana• Materials Science Institute of Madrid• RUBION – Ruhr‐Universität Bochum• Sandia National Laboratory• School of Physics and Microelectronics – Shandong University• School of Engineering – University of Tokio• Solid State Physics Group – University of Torino• Swiss Federal Institute of Technology• University of Jyväskylä

Documents

Ion beam lithography - Iindico.ictp.it/event/a11182/session/33/contribution/19/material/0/0.pdf · 2 Outline •Ion‐matter interaction •Ion‐beam lithography → MeV ions →