Emission characteristics of gallium and bismuth liquid metal field ion sources

Swanson, L. W.; Schwind, G. A.; Bell, Andy; Brady, James E.

doi:10.1116/1.570314

Cited by 124 publications

(28 citation statements)

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“…In order to test the validity of the values of Ro, fl, and a, the removed thickness d is calculated by /~ dz [4] …”

Section: Dz I M--~ D~ {Gel Sel(z) + Gn Sn(z)} ] [3] Dt -R~ + Flmentioning

confidence: 99%

“…A liquid metal ion source (4)(5)(6)(7)(8) can be used for direct writing, as in electron beam lithograpy, but with reduced computing time owing to the absence of proximity effects and enhanced ion sensitivity. Another method of transferring patterns to resists is through direct contact masking of the resist; channeling (9) may also be used; typical mask to resist distances are 20 ~m.…”

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confidence: 99%

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Ion Beam Exposure of Polymer Resist PMMA

Tung¹

1984

J. Electrochem. Soc.

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Ion beam exposure characteristics of a positive polymer resist, polymethylmetacrylate (PMMA) have been investigated. The samples were irradiated with B § ions in the energy range of 20-160 keV, the ion dose varying between 8 x 10" and 5 • 10 '3 cm -2. In the energy range considered, beam sensitivity and resist contrast were found to be between 4-5 • 10 '2 cm --~ and 2.3-2.5, respectively. An empirical formula is proposed to approximate the characteristic dissolutiOn curves (thickness removed vs. dissolution time). The empirical values agree with the experimental results within an accuracy better than 12%. A procedure is described whereby the total number of scission chain fragments as a function of resist depth may be extracted from the experimental curves.Ion beam lithography is a novel technique which bypasses some of the drawbacl}s of electron beam lithography. In general, resists are more sensitive to ions than to electrons. This is due to a greater energy deposition per unit volume. Another advantage in ion beam lithography is its feeble lateral spread (100k) for heavy ions. Ion beams, as compared to electron beams, produce low energy electrons and negligible amount of high energy backscattered electrons. In the case of direct writing using an ion beam, pattern dimensions are limited only by the beam size. Indeed, pattern dimensions inferior to 1000~ (1, 2) have been obtained with a liquid-metal gallium ion source.Ion lithography can be carried out in two different ways: through direct writing and through the ion projection exposure technique as developed by Sacher Technik Wien (3). A liquid metal ion source (4-8) can be used for direct writing, as in electron beam lithograpy, but with reduced computing time owing to the absence of proximity effects and enhanced ion sensitivity. Another method of transferring patterns to resists is through direct contact masking of the resist; channeling (9) may also be used; typical mask to resist distances are 20 ~m.Komuro et al. (10) have investigated the ion beam sensitivity of positive PMMA and negative PDMS (polydimethylsiloxane) using He + ions (60-and 200 keV) and Ar ~ ions (150 and 250 keV). According to their measurements, the calculated Gel and Gn values are 1.7 and 0.9, respectively, for PMMA whose average molecular weight is 1.85 x 105. Gel and Gn are the radiation yields per 100 eV absorbed for main chain scission brought about by electronic and nuclear collisions, respectively. Hall et al. (11) have studied the behavior of positive and negative resists using high energy ions: hydrogen, helium, and oxygen at 1.5 MeV. They proposed a model to account for the variation of the energy distribution around the particle track in terms of the number of sites required for exposure. Ryssel et al. (12) presented the dissolution characteristics of both positive and negative resists exposed to argon, gallium, hydrogen, and helium ions.Karapiperis et al. (13) have used Monte Carlo computer simulations to calculate the electronic and nuclear energy losses of 60 keV H + ions i...

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“…In order to test the validity of the values of Ro, fl, and a, the removed thickness d is calculated by /~ dz [4] …”

Section: Dz I M--~ D~ {Gel Sel(z) + Gn Sn(z)} ] [3] Dt -R~ + Flmentioning

confidence: 99%

mentioning

confidence: 99%

Ion Beam Exposure of Polymer Resist PMMA

Tung¹

1984

J. Electrochem. Soc.

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“…Today LMIS are available for a large number of a) martin.wortmann@rub.de materials using either pure metals 16,17 or eutectic alloys 18,19 for metals with a high melting temperature.…”

Section: Introductionmentioning

confidence: 99%

High-resolution mass spectrometer for liquid metal ion sources

Wortmann

Ludwig

Meijer

et al. 2013

Review of Scientific Instruments

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Recently, a mass spectrometer for liquid metal ion sources (LMIS) has been built and set into operation. This device uses an E × B-filter as mass dispersive element and provides sufficient resolution to analyse the emission of clusters from LMIS to much higher mass ranges (>2000 amu) than commercially available mass filters for focused ion beam systems. It has also been shown that for small masses the composition of clusters from different isotopes can be resolved. Furthermore, a rather high fluence of monodisperse clusters in the range of 10(6)-10(7) clusters/s can be achieved with this setup. This makes it a promising tool for the preparation of mass selected clusters. In this contribution, theoretical considerations as well as technical details and the results of first measurements are presented.

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“…To date, the source has produced Li ion beam intensities up to 15 pA at an Analysis of beam using a 90° magnet revealed a variety of ion species, including 6 Li+, 7 Li+, …”

Section: Source Performancementioning

confidence: 99%

A lithium liquid metal ion source suitable for high voltage terminal applications

Read¹,

Maskrey²,

Alton

1990

Review of Scientific Instruments

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Liquid metal ion sources offer potential improvement in lateral resolution over conventionally used gaseous sources for MeV microprobe applications because of their intrinsic brightnesses. The use of a Li liquid metal ion source is particularly attractive because of the increased sensitivity of lithium for detecting hydrogen (hydrogen profiling) and for detecting near surface contaminants through highresolution Rutherford backscattering spectrometry. However, the technical difficulty of occasional sparking between the needle and extraction electrode requires that the needle of the Li liquid metal ion source be rewetted before reignition can be effected; this problem makes Li liquid metal ion sources of the usual design risky for operation in the insulated high-voltage terminals of accelerators used in such applications. We have designed a reliable, long-lived, Li liquid-metal ion source which has provisions for overcoming this limitation. The design features and performance characteristics of tne buu,rce

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Emission characteristics of gallium and bismuth liquid metal field ion sources

Cited by 124 publications

References 0 publications

Ion Beam Exposure of Polymer Resist PMMA

Ion Beam Exposure of Polymer Resist PMMA

High-resolution mass spectrometer for liquid metal ion sources

A lithium liquid metal ion source suitable for high voltage terminal applications

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