Digital thin-film color optical memory

J., C.; Steckl, A. J.

doi:10.1063/1.1339250

Cited by 2 publications

(1 citation statement)

References 16 publications

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“…In spirit, our approach is similar to the recent demonstrations of patterning through laminar flow (11) or with gray-scale masks (12,13) and of increasing information storage with a multidepth disk (14). All these approaches rely on increasing the amount of information stored in the patterning element itself rather than on repeatedly using a half-tone mask.…”

Section: Resultsmentioning

confidence: 89%

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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