Hiding E-beam exposure fields by deterministic aperiodic 2D patterning

Result code in IS VaVaI

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Result on the web

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DOI - Digital Object Identifier

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Result language

angličtina

Original language name

Hiding E-beam exposure fields by deterministic aperiodic 2D patterning

Original language description

The high stability and good current homogeneity in the spot of the e-beam writer is crucial to the exposure quality, particularly in the case of large-area structures when gray-scale lithography is used. Even though the deflection field distortion is calibrated regularly and beam focus and beam astigmatism is dynamically corrected over the entire deflection field [1], [2], we can observe disturbances in the exposed relief. Recently, we presented a method that makes use of e–beam exposure imperfection by introducing marginally visible high–frequency diffraction gratings of variable pitch that fill in separate orthogonal exposure fields [3]. The actually presented approach follows up our research on aperiodic arrangements of optical primitives [4], especially on the phyllotactic–like arrangement of sub–micron relief optical elements. This approach is extended from the diffraction element arrangement to the higher level of exposure fields arrangements. The benchmarking DOVID (Diffractive Optically Variable Image Device), presented here as an example (Figure 1), makes use of the aperiodic arrangement at three different hierarchical levels. First, at the visual level, it consists of small visible planar objects (referenced hereafter as seeds), that are considered to be separated exposure fields (there is a movement of the patterning system stage between exposures of two adjacent seeds). This imposes an interesting task of the exposure field sequencing, as discussed below. Second, at the microscopic level, the aperiodic arrangement is used to determine two complementary areas filled in with a different diffractive patterns. Third, at the sub–micron level, the phyllotactic arrangement of diffractive elements is filling selected areas of the benchmarking image device (Figure 2). The seeds in the arrangement are ordered along a primary spiral (cf. the coordinates model in [5], [6]); this is, by the way, the ordering used by the Nature. However, plants grow up slowly into this arrangement within an appropriate time span. The use of this sequencing while trying to mimic the final state of the arrangement seems to be quite inefficient. The summary path (which is related to the length of the primary spiral) linking all the seeds, depends not only on the number of seeds but also on the diameter of the arrangement. Schematically, this is illustrated in Figure 3 (left), denoted as 1D sequencing (as the ordering depends just on one independent variable, the primary angle in this case). One can imagine several approaches to decrease the discussed path that would make it possibly to be related only to the number of seeds. Actually, we are studying various approaches and we are trying to evaluate their tradeoff attributes. Here, we propose just one of them: a simple sequencing along the secondary (or derived) spirals that are visible in the arrangements of a medium size (approximately in the order of 10e2–10e4). This type of sequencing is denoted as a 2D sequencing, because the order of seeds goes along the first selected spiral from a selected secondary spiral set, then continuing along the second spiral of the mentioned set and so on, until all the seeds are ordered. Schematically, this 2D sequencing approach (with oversampling ration of 8:1) is depicted in the Figure 3 (right). In this simple example arrangement of 90 seeds, the full path is 18.2c and 4.0c in the case of 1D and 2D sequencing algorithm, respectively (c being the scale parameter of the aperiodic arrangement).

Czech name

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Czech description

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Type

D - Article in proceedings

CEP classification

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OECD FORD branch

21002 - Nano-processes (applications on nano-scale); (biomaterials to be 2.9)

Project

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Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2018

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Article name in the collection

Recent Trends in Charged Particle Optics and Surface Physics Instrumentation

ISBN

978-80-87441-23-7

ISSN

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e-ISSN

neuvedeno

Number of pages

1

Pages from-to

36

Publisher name

Czech Academy of Science, Institute of Scientific Instruments

Place of publication

Praha

Event location

Brno

Event date

Jun 4, 2018

Type of event by nationality

WRD - Celosvětová akce

UT code for WoS article

000450591400012