Extensions of molecular ruler technology for nanoscale patterning

Abstract

Articles you may be interested inDeep UV patterning of 3-amino-propyl-triethoxy-silane self-assembled molecular layers on alumina By combining optical lithography and chemical self-assembly, the authors circumvent the limitations of photolithography and provide a parallel, low-cost alternative to fabricate sub-50 nm features. Self-assembled multilayers, composed of alternating layers of ␣ , -mercaptoalkanoic acids and copper ͑II͒ ions ͑"molecular rulers"͒, are used as an organic sidewall spacer resist on initial lithographic structures enabling the precise, proximal placement of a secondary structure via lift-off. Here, the authors implemented a positive-tone bilayer resist for improved line-edge characteristics of the secondary structure and evaluated the lithographic and electrical performance of nanostructures fabricated using this approach. Additionally, they describe extensions of this technique by which planar nanojunctions were created, and the generated nanometer-scale pattern was transferred to the underlying substrate.

Fabrication of quantum dots using multicoated self-assembled monolayer

“…13 In 1991, Evans et al 14 showed the forming of multilayer films using ionic interaction between ␣ , -mercaptoalkanoic acids ͑HS͑CH 2 ͒ x COOH͒ and copper ions͑Cu 2+ ͒. [16][17][18] Es-pecially, Anderson and co-workers [19][20][21][22] at Pennsylvania State University reported several attempts to fabricate various nanogaps. The acid surface is then converted to a copper salt and a second layer can be adsorbed onto the copper surface; it has been seen that thiols will readily adsorb onto copper.…”

Sub-30-nm patterning on quartz for imprint lithography templates

“…Following our previous work, 15 the LER for imprint molds is improved for the following reasons. The Au thin films are removed after molecular-ruler processing, and the Cr adhesion layer is retained on the quartz substrates.…”

“…1, Photolithography, EBL, or other methods are used to create the first generation ͑parent͒ Cr/ Au features. [12][13][14][15]22,23 A self-assembled multilayer film comprising alternating layers of ␣, -mercaptoalkanoic acids and Cu 2+ ions ͑molecular rulers͒ binds selectively to the parent structures and not to the underlying quartz substrate. The overall thickness of this organic thin film is selected by both the numbers and thicknesses of the molecular layers.…”

“…10,11 We describe a hybrid lithographic approach using conventional lithography and self-assembled multilayer films ͑molecular rulers͒ to create resolutionmultiplying sub-30-nm features over large areas on a quartz template in a low-cost parallel process. [12][13][14][15] The three major challenges for NIL template manufacturing are pattern resolution on quartz, uniformity of quartz etching, and inspection of defective patterns. The latter two are related to processing details.…”

Chemical Lift-Off Lithography of Metal and Semiconductor Surfaces

“…Molecular monolayers can be patterned via conventional lithographic techniques (e.g., photolithography) , but are more commonly patterned using low-cost and high-throughput soft-lithographic methods. ,,, Conventional soft lithography (e.g., microcontact printing, μCP), involves the additive patterning of SAM molecules onto surfaces by transfer of molecular inks via contact of patterned polydimethylsiloxane (PDMS) stamps with the corresponding surfaces. − While μCP has significantly advanced the field of SAM patterning, it is inherently limited in the resolution of features produced due to lateral diffusion of ink molecules during and after the patterning is performed. ,− Advances in soft lithography have improved feature resolution − ,, (e.g., polymer pen lithography and microdisplacement printing) …”