Submicrometer lithographic patterning of thin gold films with a scanning tunneling microscope

Stockman, L.; Neuttiens, G.; Haesendonck, C. Van; Bruynseraede, Y.

doi:10.1063/1.109202

Cited by 56 publications

(32 citation statements)

References 13 publications

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“…For example, spincoated polymer films and Langmuir-Blodgett films have been patterned using scanning tunneling microscopes (STMs) operated in vacuum [6 -8] as well as by using STMs or atomic force microscopes (AFMs) operated in air [9,10].…”

Section: *Present Address: Departmentmentioning

confidence: 99%

Organosilane Monolayer Resists for Scanning Probe Lithography.

Sugimura

Nakagiri

1997

J. Photopol. Sci. Technol.

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We report the preparation of organosilane monolayers by means of chemical vapor deposition and scanning probe lithography (SPL) using these monolayers as resists. Two types of monolayers having different alkyl groups, that is, trimethylsilyl [(CH3)3Si-, TMS] and octadecylsilyl [CH3(CH2)17Si=, ODS] monolayers, were deposited on Si substrate from precursor molecules of hexamethyldisilazane [(CH3)3Si-NH-Si(CH3)3,] and octadecyltrimethoxysilane [CH3(CH2)17Si(OCH3)3], respectively. The thicknesses of these monolayers as estimated by ellipsometry were 0.4 and 2.0 nm, respectively, and, therefore, were concluded to be defined by their alkyl chain lengths. Using an atomic force microscope (AFM) with an electrically conductive probe, a Si sample deposited with a TMS or ODS monolayer was patterned by flowing current through the AFM-probelsample junction. The pattern thus fabricated on the monolayer was transferred to the substrate Si by chemical etching in an aqueous solution of NH4F and H2O2. The etching proceeded area-selectively in the regions where the probe had passed, since, in these regions, the monolayer had been electrochemically degraded. The patterning was entirely accomplished through probe scanning without any need for further developing steps. The resist can thus be regarded as being self-developing. Both TMS and ODS successfully served as such SPL resists.

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Section: *Present Address: Departmentmentioning

confidence: 99%

Organosilane Monolayer Resists for Scanning Probe Lithography.

Sugimura

Nakagiri

1997

J. Photopol. Sci. Technol.

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“…Alternatively, the STM can be used to expose organic resist layers. For example, McCord et al 3 have used poly͑methylmethacrylate͒ PMMA, Marrian et al 4 have used SAL 601 and recently Stockman et al 5 have used a Langmuir-Blodgett film. Since these layers do not always conduct sufficiently, the STM tip can penetrate the resist during lithography which can limit the tip lifetime due to mechanical interactions between tip and layer.…”

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confidence: 99%

“…[1][2][3][4][5][6][7] In scanning tunneling microscopy tip-substrate interactions are very local, making it possible to modify the surface of a substrate to a very high lateral resolution ͑Ͻ20 nm͒. Several methods to fabricate metallic nanowires using this technique, have been demonstrated.…”

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confidence: 99%

Fabrication of metallic nanowires with a scanning tunneling microscope

Kramer

Birk

Jorritsma

et al. 1995

Applied Physics Letters

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A procedure to pattern thin metal films on a nanometer scale with a scanning tunneling microscope ͑STM͒ operating in air is reported. A 30 nm film of hydrogenated amorphous silicon ͑a-Si:H͒ is deposited on a 10 nm film of TaIr. Applying a negative voltage between the STM tip and the a-Si:H film causes the local oxidation of a-Si:H. The oxide which is formed is used as a mask to wet etch the not-oxidized a-Si:H and subsequently, the remaining pattern is transferred into the metal film by Ar ion milling. Metal wires as narrow as 40 nm have been fabricated. Since a-Si:H can be deposited in very thin layers on almost any substrate, the presented procedure can be applied to structure all kind of thin films on a nanometer scale. © 1995 American Institute of Physics.During the previous 5 years, the scanning tunneling microscope ͑STM͒ has attracted interest as a tool for lithography on a nanometer scale. [1][2][3][4][5][6][7] In scanning tunneling microscopy tip-substrate interactions are very local, making it possible to modify the surface of a substrate to a very high lateral resolution ͑Ͻ20 nm͒. Several methods to fabricate metallic nanowires using this technique, have been demonstrated. Ehrichs et al. 2 and McCord et al. 3 have used an STM induced chemical vapor deposition ͑CVD͒ process in which a metalorganic gas is decomposed between the STM tip and the substrate, depositing metal on the substrate surface. A drawback of this technique is that there is only a limited choice of metals which can be deposited, due to the number of gas precursors which are available. Alternatively, the STM can be used to expose organic resist layers. For example, McCord et al. 3 have used poly͑methylmethacrylate͒ PMMA, Marrian et al. 4 have used SAL 601 and recently Stockman et al. 5 have used a Langmuir-Blodgett film. Since these layers do not always conduct sufficiently, the STM tip can penetrate the resist during lithography which can limit the tip lifetime due to mechanical interactions between tip and layer.In this letter, we present a method to pattern a thin film on a nanometer scale with an STM operating in air, using on a conducting resist layer. The method was inspired by the work of Dagata et al. 1 who demonstrated that a hydrogen terminated silicon ͑111͒ surface can be locally oxidized with the STM. The oxide layer which is formed can act as a mask for etching the silicon, as was demonstrated by Snow et al. 6A thin film could be patterned with this method if a silicon layer which is both stable against oxidation in air and sufficiently conducting could be deposited on the metal film. Hydrogenated amorphous silicon ͑a-Si:H͒ is a material which can fulfill both requirements. It is stable against oxidation in air because of its high hydrogen content ͑Ϸ10 at. %͒.8 Thin films of a-Si:H can be highly doped, to make them electrically conducting for STM operation. In addition, with plasma enhanced chemical vapor deposition ͑PECVD͒ a layer of a-Si:H can be deposited on almost any surface at low temperature, because of the high r...

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“…Successful examples of the use of SAMs as lithographic resists [1] and as dielectric materials [2][3][4] have demonstrated their potential in this context. Lithographic applications of SAMs have already been explored by our group and the results reported elsewhere [5].…”

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confidence: 98%