Replica molding using polymeric materials: A practical step toward nanomanufacturing

Xia, Younan; McClelland, Jabez J.; Gupta, Rajeev; Qin, Dong; Zhao, Xiaomei; Sohn, Lydia L.; Celotta, Robert; Whitesides, George M.

doi:10.1002/adma.19970090211

Cited by 287 publications

(197 citation statements)

References 15 publications

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“…All the soft lithographic procedures that were applied here may be used at a much smaller size scale than the 100-m scale used in this work (15). We anticipate that reduction of feature sizes to micrometer or to submicrometer scales is feasible; the depths on the stamp will scale accordingly.…”

Section: Resultsmentioning

confidence: 99%

Fabrication of aligned microstructures with a single elastomeric stamp

Tien

Nelson²,

Chen³

2002

Proc. Natl. Acad. Sci. U.S.A.

145

103

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The fabrication of complex patterns of aligned microstructures has required the use of multiple applications of lithography. Here we describe an approach for microfabrication that encodes the twodimensional spatial information of several photomasks onto a single elastomeric stamp by mapping each photomask onto distinct heights on the surface of the stamp. Pressing the stamp against a surface collapses the topography of the stamp such that each recessed layer contacts the surface in stepwise sequence; the greater the applied pressure, the larger the area of the stamp that contacts the surface. After contact of each new layer with the surface, we use techniques of soft lithography (microcontact printing, microfluidics, and patterning through membranes) to pattern the surfaces that contact the stamp and those that do not with inorganic, organic, or living materials. Microfabrication through the use of multilevel stamps provides a promising alternative to conventional lithography for the construction of multicomponent, aligned surfaces; these structures may find use as components of microfluidic devices or biological patterns. Microlithography is a binary process. That is, lithography segregates a surface into regions that are exposed to a modification and regions that are masked from that modification. In photolithography, irradiation through a mask that consists of two regions (clear and opaque) defines a map of exposed and unexposed regions. Similarly, in soft lithography, placement of an elastomeric stamp that possesses two regions (recessed and nonrecessed) onto a surface defines regions that are stamped and those that are not (1, 2). Fabrication of complex, multilevel structures that contain more than two types of elements is required often for microelectronic, microfluidic, and microelectromechanical systems and necessitates multiple applications of lithography in which each step must be aligned spatially with previous ones. Alignment of patterning steps in the fabrication of organic, living, or soft structures has proven to be cumbersome for many reasons; the elastomeric stamps used in soft lithography are difficult to align over large areas, alignment of biological materials requires sterile working conditions throughout the fabrication process, and patterning onto devices that are not openly accessible (such as a sealed microfluidic device) is extremely challenging. Here, we describe an alternate approach toward the fabrication of complex structures that alleviates these difficulties by using lithographic patterning elements that are not binary. This approach relies on the use of a single multilevel, elastomeric stamp to generate a multicomponent, aligned structure. Fig. 1 outlines our experimental approach. We use photolithography to define features of photoresist that possess different heights on a silicon wafer. Curing a prepolymer of PDMS against the photoresist master generates a PDMS stamp (1) or membrane (2) that has a surface relief with various depths. Placing this stamp on a substrate brings an i...

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Section: Resultsmentioning

confidence: 99%

Fabrication of aligned microstructures with a single elastomeric stamp

Tien

Nelson²,

Chen³

2002

Proc. Natl. Acad. Sci. U.S.A.

145

103

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“…In this work, a series of lines with width 65 nm, height 34 nm, and spacing 212.8 nm was fabricated, covering an area of 0.4 mm!1 mm. In subsequent work, extension to a two-dimensional array of dots was demonstrated [7,8], and a number of further extensions and improvements were carried out, such as reducing the line spacing to 53 nm [9], performing reactive ion etching to transfer the pattern to a substrate [10], replicating the pattern with polymer molding [11], and using the pattern as a template for making magnetic nanowires [12].…”

Section: Laser-focused Atomic Depositionmentioning

confidence: 99%

Nanotechnology with atom optics

McClelland

Hill

Pichler

et al. 2004

Science and Technology of Advanced Materials

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A brief review of atom optics is presented, with emphasis on how it can be applied in the field of nanotechnology. Two specific examples are discussed: laser-focused atomic deposition and deterministic production of single atoms. Results are summarized for these two techniques, and discussion is presented on how they can impact progress in the development of nanotechnology. Published by Elsevier Ltd.

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“…3). [13,31,32] Replica molding (RM), [33] microtransfer molding (mTM), [34] micromolding in capillaries (MIM-IC), [35] and solvent-assisted micromolding (SAMIM) [36] are four soft-lithographic techniques that replicate features by the molding of polymers. For many of these techniques, the inherent low surface free energy of PDMS is enough to permit the stamp to be separated from the replica without the need of a release layer.…”

Section: Techniques For the Replication Of Nanostructures By The Moldmentioning

confidence: 99%