Nanoimprint mold

Fig. 8.7 Fabrication sequence of a polymer microring resonator (a) prepare a nanoimprint mold (b) spin coat a polymer thin film (c) perform nanoimprinting process (d) separate the sample from the mold (e) dry etch the residual layer (f) create pedestals by wet etch...

Ishii, Y. and J. Taniguchi. 2007. Fabrication of three-dimensional nanoimprint mold using inoiganic resist in low accelerating voltage electron beam lithography. Microelectronic Engineering 84 912-915. 

The ability to fabricate nanostructures is essential to modem science and technology [1], Nanoimprint lithography (NIL) in its various forms has demonstrated potential applications in the fabrication of semiconductor devices, microfluidic devices, optical components, photonic devices, replica mold components and biological objects [2],... 

The principle of nanoimprint is quite simple. As shown in Fig. lA, NIL uses a hard mold that contains nanoscale features defined on its surface to emboss into polymer material cast on the wafer substrate under controlled temperature and pressure, thereby creating thickness contrast in the polymer material, which can be further transferred through the resist layer via an O2 plasma-based anisotropic etching process. Nanoimprint has the capability of patterning sub-10 nm features, " yet only entails simple equipment setup and easy processing. This is the key reason that NIL attracted wide attention within only a few years after its inception. 

Mold in nanoimprint technique plays the same role as photomask in photolithography. Both NIL and S-FIL utilize hard molds to replicate patterns, which distinguish... 

On the other hand, the high temperature and pressure required for the nanoimprinting of thermal plastic materials limit the throughput and the application scope of the NIL technique. In addition, the thermal expansion mismatch between the mold and the substrate frequently incurred often presents an obstacle for pattern alignment over large substrates. Although various means have been attempted to make the thermoplastics imprintable at a temperature close to room... 

Komuro, M. Hiroshima, H. Kobayashi, K. Miyazaki, T. Ohyi, H. Preparation of diamond mold using electron beam lithography for application to nanoimprint lithography. Jpn. J. Appl. Phys. 1 (Regular Papers Short Notes Review Papers) 2000, 39 (12B), 7070-7074. 

Nanoimprint lithography Molding of pattern Parallel, fast, no resist, solvents, etc. Large structures, residual chemicals Smaller structures, improved pattern transfer... 

FIGURE 5.5.32 Schematic of nanoimprint hthography (NIL). (1) A rigid mold is pressed into a thermoplastic resist, heated above its glass transition temperature, to create an imprint. (2) The mold is removed, leaving behind the patterned resist. (3) An anisotropic etch removes the residual resist and transfers the pattern into the substrate. (From S. Y. Chou et al., J. Vac. Sci. Technol, B, 14, 4129, 1996.)... 

Nanoimprint lithography (NIL) is a relatively new technique designed to produce precisely defined nanoscale features in a parallel, efficient, and cost-effective manner [3,4]. In a typical NIL process, a prepatterned mold is used to press against a resist layer which can go through a thermal plastic transition at an elevated temperature or can be permanently... 

In contrast to the nanolithography techniques that employ radiation to create patterns, nanoimprint uses a mechanical mold to delineate features, as illustrated in Figure 1.3. This technique generates nanoscale patterns by physically deforming a material and, therefore, can be used for the direct imprint of functional materials. 

The nanoimprint was first developed by Chou and colleagues.Their process is called thermal nanoimprint, which is shown in Figure 4.1. The transfer layer on a Si wafer is thermal plasticity polymethylmethacrylate (PMMA) (Tg = 105°C). A mold of Si02 is produced by electron beam writing. 

It has been reported that with thermal nanoimprint it is possible to achieve resolutions of less than 10 nm in pattern transfer. It has been confirmed that no resolution limit exists in nanoimprint, and resolution is controlled by the accuracy of mold fabrication. It is possible to produce fine patterns similar to photolithography without high-cost equipment in nanoimprint. PMMA is superior for thermal plasticity polymers because of its stability in division. 

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