Chip-scale pattern modification method for equalizing residual layer thickness in nanoimprint lithography

Abstract

A software program for modifying a mold design to obtain a uniform residual layer thickness (RLT) distribution has been developed and its validity was verified by UV-nanoimprint lithography (UV-NIL) simulation. First, the effects of granularity (G) on both residual layer uniformity and filling characteristics were characterized. For a constant complementary pattern depth and a granularity that was sufficiently larger than the minimum pattern width, filling time decreased with the decrease in granularity. For a pattern design with a wide density range and an irregular distribution, the choice of a small granularity was not always a good strategy since the etching depth required for a complementary pattern occasionally exceptionally increased with the decrease in granularity. On basis of the results obtained, the automated method was applied to a chip-scale pattern modification. Simulation results showed a marked improvement in residual layer thickness uniformity for a capacity-equalized (CE) mold. For the given conditions, the standard deviation of RLT decreased in the range from 1/3 to 1/5 in accordance with pattern designs.

Multilevel nanoimprint lithography with a binary mould for plasmonic colour printing

“…The variation in imprint depth (and the resulting value of g, where g ¼ h i À t) is mainly affected by the nanouidic channelling behaviour of the resist during the NIL process. 25,31,36 There are two major factors that inuence the nanouidic dynamics of the resist: (i) the architecture of the mould and (ii) the physical properties of the resist. For a given resist, the details of the mould architecture can be used to tune the behaviour of the gap size across the imprinted structure.…”

“…Several approaches have been proposed to reduce the global variation of imprint depth such as increasing the applied pressure, 42 increasing the imprinting time, 31,43 introducing additional microcavities or protrusions in proximity to the original design 33 and utilising a cavity-equalized mould. 36 To address this issue, we propose the addition of a novel mesh-like microcavity architecture to the multi-density mould to facilitate resist ow. The structure considered here has microcavities with a width, s micro ¼ 5 mm and periodicity of 25 mm (schematic shown in Fig.…”