Fabrication of large area nanogap electrodes for sensing applications

ABSTRACTA large area nanogap electrode fabrication method combinig conventional lithography patterning with the of focused ion beam (FIB) is presented. Lithography and a lift-off process were used to pattern 50 nm thick platinum pads having an area of 300 μm × 300 μm. A range of 30-300 nm wide nanogaps (length from 300 μm to 10 mm ) were then etched using an FIB of Ga+ at an acceleration voltage of 30 kV at various beam currents. An investigation of Ga+ beam current ranging between 1-50 pA was undertaken to optimise the process for the current fabrication method. In this study, we used Monte Carlo simulation to calculate the damage depth in various materials by the Ga+. Calculation of the recoil cascades of the substrate atoms are also presented. The nanogap electrodes fabricated in this study were found to have empty gap resistances exceeding several hundred MΩ. A comparison of the gap length versus electrical resistance on glass substrates is presented. The results thus outline some important issues in low-conductance measurements. The proposed nanogap fabrication method can be extended to various sensor applications, such as chemical sensing, that employ the nanogap platform. This method may be used as a prototype technique for large-scale fabrication due to its simple, fast and reliable features.

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ION BEAM LITHOGRAPHY AND NANOFABRICATION: A REVIEW

International Journal of Nanoscience ◽

10.1142/s0219581x05003139 ◽

2005 ◽

Vol 04 (03) ◽

pp. 269-286 ◽

Cited By ~ 181

Author(s):

F. WATT ◽

A. A. BETTIOL ◽

J. A. VAN KAN ◽

E. J. TEO ◽

M. B. H. BREESE

Keyword(s):

Mass Production ◽

Large Scale ◽

Focused Ion Beam ◽

Extreme Ultraviolet ◽

Ion Beam ◽

Large Area ◽

Near Surface ◽

X Ray ◽

Projection Lithography ◽

New Generation

To overcome the diffraction constraints of traditional optical lithography, the next generation lithographies (NGLs) will utilize any one or more of EUV (extreme ultraviolet), X-ray, electron or ion beam technologies to produce sub-100 nm features. Perhaps the most under-developed and under-rated is the utilization of ions for lithographic purposes. All three ion beam techniques, FIB (Focused Ion Beam), Proton Beam Writing (p-beam writing) and Ion Projection Lithography (IPL) have now breached the technologically difficult 100 nm barrier, and are now capable of fabricating structures at the nanoscale. FIB, p-beam writing and IPL have the flexibility and potential to become leading contenders as NGLs. The three ion beam techniques have widely different attributes, and as such have their own strengths, niche areas and application areas. The physical principles underlying ion beam interactions with materials are described, together with a comparison with other lithographic techniques (electron beam writing and EUV/X-ray lithography). IPL follows the traditional lines of lithography, utilizing large area masks through which a pattern is replicated in resist material which can be used to modify the near-surface properties. In IPL, the complete absence of diffraction effects coupled with ability to tailor the depth of ion penetration to suit the resist thickness or the depth of modification are prime characteristics of this technique, as is the ability to pattern a large area in a single brief irradiation exposure without any wet processing steps. p-beam writing and FIB are direct write (maskless) processes, which for a long time have been considered too slow for mass production. However, these two techniques may have some distinct advantages when used in combination with nanoimprinting and pattern transfer. FIB can produce master stamps in any material, and p-beam writing is ideal for producing three-dimensional high-aspect ratio metallic stamps of precise geometry. The transfer of large scale patterns using nanoimprinting represents a technique of high potential for the mass production of a new generation of high area, high density, low dimensional structures. Finally a cross section of applications are chosen to demonstrate the potential of these new generation ion beam nanolithographies.

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Optimized Ordered Nanoprinting Using Focused Ion Beam

Advances in Materials Science and Engineering ◽

10.33140/amse/01/01/00001 ◽

2017 ◽

Vol 1 (1) ◽

Keyword(s):

Silicon Substrate ◽

Large Scale ◽

Focused Ion Beam ◽

Unit Area ◽

Ion Beam ◽

Beam Current ◽

Pixel Size ◽

Nanohole Arrays ◽

Determining Factor

Focused ion beam (FIB) is receiving great attention in nanopatterning due to its advantages such as direct milling and deposition. Like conventional lithography methods, dose is still the determining factor of pattern conformity in FIB. However, dose is also determined by many parameters such as ion beam current, pixel size and number of pixels of the bitmap file. In this work, we studied the effect of above parameters on dose per unit area, and thus on the pattern conformity. It was found that a dose approximately of 7.5-8.6 pC/μm2 or a bitmap file corresponding to 4000-5000 pixels/μm2 at a beam current of 30 pA is reasonable in order to obtain well-separated nanohole arrays. Although direct pattern designing on FIB working field yields better conformity, it is not practical for large scale patterning. Finally, a relatively larger scale nanoholes arrays with diameter and spacing of 100 nm was achieved by using a dose of 8.6 pC/μm2 . This work offers a few guidelines for nanopatterning on silicon substrate for photonic applications.

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Maskless fabrication of nanogap electrodes by using Ga-focused ion beam etching

Journal of Micro/Nanolithography MEMS and MOEMS ◽

10.1117/1.2172614 ◽

2006 ◽

Vol 5 (1) ◽

pp. 011006 ◽

Cited By ~ 6

Author(s):

Takashi Nagase

Keyword(s):

Focused Ion Beam ◽

Ion Beam ◽

Ion Beam Etching ◽

Nanogap Electrodes

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Large Area Photonic Crystal Slabs for Visible Light with Waveguiding Defect Structures: Fabrication with Focused Ion Beam Assisted Laser Interference Lithography

Advanced Materials ◽

10.1002/1521-4095(200110)13:20<1551::aid-adma1551>3.0.co;2-v ◽

2001 ◽

Vol 13 (20) ◽

pp. 1551 ◽

Cited By ~ 52

Author(s):

L. Vogelaar ◽

W. Nijdam ◽

H. A. G. M. van Wolferen ◽

R. M. de Ridder ◽

F. B. Segerink ◽

...

Keyword(s):

Photonic Crystal ◽

Visible Light ◽

Focused Ion Beam ◽

Ion Beam ◽

Interference Lithography ◽

Laser Interference Lithography ◽

Defect Structures ◽

Laser Interference ◽

Large Area ◽

Photonic Crystal Slabs

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Beyond grayscale lithography: inherently three-dimensional patterning by Talbot effect

Advanced Optical Technologies ◽

10.1515/aot-2019-0005 ◽

2019 ◽

Vol 8 (3-4) ◽

pp. 233-240

Author(s):

Roberto Fallica

Keyword(s):

Focused Ion Beam ◽

Ion Beam ◽

Three Dimensional ◽

Talbot Effect ◽

Large Area ◽

Projection Lithography ◽

Main Technique ◽

Direct Laser ◽

The Cost ◽

Diffraction Effects

Abstract There are a growing number of applications where three-dimensional patterning is needed for the fabrication of micro- and nanostructures. Thus far, grayscale lithography is the main technique for obtaining a thickness gradient in a resist material that is exploited for pattern transfer by anisotropic etch. However, truly three-dimensional structures can only be produced by unconventional lithography methods such as direct laser writing, focused ion beam electrodeposition, colloidal sphere lithography, and tilted multiple-pass projection lithography, but at the cost of remarkable complexity and lengthiness. In this work, the three-dimensional shape of light, which is formed by Talbot effect diffraction, was exploited to produce inherently three-dimensional patterns in a photosensitive polymer. Using light in the soft X-ray wavelength, periodic three-dimensional structures of lateral period 600 nm were obtained. The position at which the sample has to be located to be in the Fresnel regime was simulated using an analytical implementation of the Fresnel integrals approach. Exploiting the light shape forming in diffraction effects thus enables the patterning of high-resolution three-dimensional nanostructures over a large area and with a single exposure pass – which would be otherwise impossible with conventional lithographic methods.

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Large-Area Thermal Distribution Sensor Based on Multilayer Graphene Ink

Sensors ◽

10.3390/s20185188 ◽

2020 ◽

Vol 20 (18) ◽

pp. 5188

Author(s):

Tomi Koskinen ◽

Taneli Juntunen ◽

Ilkka Tittonen

Keyword(s):

Signal To Noise Ratio ◽

Graphene Film ◽

Multilayer Graphene ◽

Wearable Electronics ◽

Large Area ◽

Sensor Applications ◽

Thermal Distribution ◽

Sensing Applications ◽

Detection Of Objects ◽

Distribution Mapping

Emergent applications in wearable electronics require inexpensive sensors suited to scalable manufacturing. This work demonstrates a large-area thermal sensor based on distributed thermocouple architecture and ink-based multilayer graphene film. The proposed device combines the exceptional mechanical properties of multilayer graphene nanocomposite with the reliability and passive sensing performance enabled by thermoelectrics. The Seebeck coefficient of the spray-deposited films revealed an inverse thickness dependence with the largest value of 44.7 μV K−1 at 78 nm, which makes thinner films preferable for sensor applications. Device performance was demonstrated by touch sensing and thermal distribution mapping-based shape detection. Sensor output voltage in the latter application was on the order of 300 μV with a signal-to-noise ratio (SNR) of 35, thus enabling accurate detection of objects of different shapes and sizes. The results imply that films based on multilayer graphene ink are highly suitable to thermoelectric sensing applications, while the ink phase enables facile integration into existing fabrication processes.

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Characterization of FIB Damage in Silicon

Microscopy and Microanalysis ◽

10.1017/s1431927600017025 ◽

1999 ◽

Vol 5 (S2) ◽

pp. 740-741 ◽

Cited By ~ 3

Author(s):

C.A. Urbanik ◽

B.I. Prenitzer ◽

L.A. Gianhuzzi ◽

S.R. Brown ◽

T.L. Shofner ◽

...

Keyword(s):

Focused Ion Beam ◽

Ion Beam ◽

Target Material ◽

Beam Current ◽

Specimen Preparation ◽

Transfer Energy ◽

Transmission Electron ◽

Preparation Techniques ◽

Reactive Gas

Focused ion beam (FIB) instruments are useful for high spatial resolution milling, deposition, and imaging capabilities. As a result, FIB specimen preparation techniques have been widely accepted within the semiconductor community as a means to rapidly prepare high quality, site-specific specimens for transmission electron microscopy (TEM) [1]. In spite of the excellent results that have been observed for both high resolution (HREM) and standard TEM specimen preparation applications, a degree of structural modification is inherent to FIB milled surfaces [2,3]. The magnitude of the damage region that results from Ga+ ion bombardment is dependent on the operating parameters of the FIB (e.g., beam current, beam voltage, milling time, and the use of reactive gas assisted etching).Lattice defects occur as a consequence of FIB milling because the incident ions transfer energy to the atoms of the target material. Momentum transferred from the incident ions to the target atoms can result in the creation of point defects (e.g., vacancies, self interstitials, and interstitial and substitutional ion implantation), the generation of phonons, and plasmon excitation in the case of metal targets.

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Ion beam profiling from the interaction with a freestanding 2D layer

Beilstein Journal of Nanotechnology ◽

10.3762/bjnano.8.73 ◽

2017 ◽

Vol 8 ◽

pp. 682-687 ◽

Cited By ~ 4

Author(s):

Ivan Shorubalko ◽

Kyoungjun Choi ◽

Michael Stiefel ◽

Hyung Gyu Park

Keyword(s):

Focused Ion Beam ◽

Ion Beam ◽

Beam Current ◽

Exposure Dose ◽

Ion Beams ◽

Gaussian Profile ◽

Helium Ion ◽

Spread Function ◽

Sputtering Yields ◽

Pattern Resolution

Recent years have seen a great potential of the focused ion beam (FIB) technology for the nanometer-scale patterning of a freestanding two-dimensional (2D) layer. Experimentally determined sputtering yields of the perforation process can be quantitatively explained using the binary collision theory. The main peculiarity of the interaction between the ion beams and the suspended 2D material lies in the absence of collision cascades, featured by no interaction volume. Thus, the patterning resolution is directly set by the beam diameters. Here, we demonstrate pattern resolution beyond the beam size and precise profiling of the focused ion beams. We find out that FIB exposure time of individual pixels can influence the resultant pore diameter. In return, the pore dimension as a function of the exposure dose brings out the ion beam profiles. Using this method of determining an ion-beam point spread function, we verify a Gaussian profile of focused gallium ion beams. Graphene sputtering yield is extracted from the normalization of the measured Gaussian profiles, given a total beam current. Interestingly, profiling of unbeknown helium ion beams in this way results in asymmetry of the profile. Even triangular beam shapes are observed at certain helium FIB conditions, possibly attributable to the trimer nature of the beam source. Our method of profiling ion beams with 2D-layer perforation provides more information on ion beam profiles than the conventional sharp-edge scan method does.

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Focused Ion Beam Study of Ni5Al Single Splat Microstructure

MRS Proceedings ◽

10.1557/proc-983-0983-ll04-04-kk04-04 ◽

2006 ◽

Vol 983 ◽

Cited By ~ 1

Author(s):

Yuhong Wu ◽

Meng Qu ◽

Lucille A Giannuzzi ◽

Sanjay Sampath ◽

Andrew Gouldstone

Keyword(s):

Cross Sections ◽

Focused Ion Beam ◽

Surface Engineering ◽

Ion Beam ◽

Deposition Process ◽

Rapid Quenching ◽

Specimen Preparation ◽

Ion Milling ◽

Columnar Grains ◽

Lift Off

AbstractThermally sprayed (TS) coatings are widely used for surface engineering across a range of industries, including aerospace, infrastructure and biomedical. TS materials are formed via the successive impingement, rapid quenching and build-up of molten powder particles on a substrate. The impacted ‘splats’ are thus the fundamental microstructural constituents of the coatings, and their intrinsic properties, as well as intersplat bonding and morphology, dictate coating behavior. Beyond the obvious practical considerations, from a scientific standpoint, splats represent a fascinating template for study, due to the highly non-equilibrium processing conditions (rapid deceleration from sub-sonic velocities, million-degree/sec cooling rates). In the literature, many studies of isolated splats on substrates have been carried out, but these have focused on overall morphology (disc-shape vs fragmented). Direct observations of microstructure, in particular cross-section, are limited in the specimen preparation stage due to splat size (tens of microns in diameter, 1-2 microns in thickness). However, Focused Ion Beam (FIB) techniques have allowed this problem to be addressed in a robust manner; in this paper we will discuss such approaches to observe Ni5Al splats on stainless steel substrates. Cross-sections through the splat and the substrate were created by recourse to ion milling and the ion beam itself provided good channeling contrast for grain imaging. The typical splat microstructure with sub-micron Ni(Al) columnar grains, a chill zone at the bottom and a lift off area is observed in high detail. In addition, an amorphous aluminum oxide top layer of 100-200 nm is partially present on top of the Ni(Al) columnar grains. At the splat/substrate interface, defects such as micro- and nano-scale pores were characterized for the first time and will be discussed. These observations provide insights into splat and interface formation during the deposition process and may drastically improve our current understanding of Ni5Al splat properties.

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