Fabrication of SiN_x Nanopore Filters Using Combined Process of Nanoimprint and Dual‐Side Aligned Photolithography for Purified Cs₃MnBr₅ Green Phosphors

Abstract

A combined process of nanoimprint lithography and dual‐side aligned photolithography to address misalignment of subsequent layers for the fabrication of SiNx nanoporous membrane filters (SiNx nanofilter) is suggested. Here, in one process, 21 SiNx nanofilter chips are fabricated on a 6 inch Si wafer by aligning nanopore area of nanofilter and template area of nanofilter chip. An SiNx nanofilter chip‐integrated fluidic device is used to test the purification ability of the nanofilter in terms of its pore size and surface hydrophobicity or hydrophilicity. This is the first attempt at separating unnecessary chemical residues from a mixed reactant solution by nanoscale purification process using the tremendous number of nanoholes in the nanofilter. After purification by the nanofilter, high efficiency and narrow‐band Cs3MnBr5 phosphor is synthesized by evaporative crystallization. Here, the photoluminescent quantum yield (PLQY) of the purified Cs3MnBr5 phosphor is monitored to evaluate the purification ability of the SiNx nanofilter. The highest PLQY (53%) of Cs3MnBr5 green phosphors is obtained by purification of reactant solution using nanofilter with 50 nm nanopore diameter and hydrophilic surface. This combined process proves its potential for scalable manufacturing of complex designed SiNx nanofilter chips for chemical species sieving and other applications.

Synthesis of Cs3MnBr5 Green Phosphors Using an Eco-Friendly Evaporative Crystallization Process

“…XRD patterns having enhanced major peaks, indexed by (114), (213), and (204) planes of the 200 nm syringe-filtered Cs 3 MnBr 5 phosphors, indicate that Cs 3 MnBr 5 powder is better crystallized, with the tetragonal phase, than are unfiltered Cs 3 MnBr 5 phosphors. 22 However, small amounts of certain residual phases remain after the optimum evaporative crystallization process (at 150 °C for 2 h) of the purified reactant solutions. In terms of improving the PLQY or crystal quality of the synthesized Cs 3 MnBr 5 powder phosphors, it will be necessary to further remove remaining impurities via the pre-filtration process before evaporative crystallization.…”

“…Because oxygen is also detected in very small amounts in the filtered solids, these impurities might be amorphous mixtures of Mn- and/or Cs-related oxides or hydroxides, as well as bromide, with average agglomerated size larger than the pore size of the syringe filter. 22 When a 200 nm syringe filter is used, oxygen impurities in the phosphor can be minimized.…”

“…We reported PLQYs of Cs 3 MnBr 5 green phosphors up to 53%. 22 However, our previous report did not focus on evaporative crystallization for Cs 3 MnBr 5 G phosphors, but mainly on the fabrication of the SiN x membrane nanofilter and the ultrafiltration process. We introduced Cs 3 MbBr 5 phosphor synthesis only as a good example of ultrafiltration by the SiN x membrane nanofilter.…”

Isolation of Bovine Milk Exosome Using Electrophoretic Oscillation Assisted Tangential Flow Filtration with Antifouling of Micro-ultrafiltration Membrane Filters

“…After finishing the front side patterning of the LSN wafer, a 200 nm layer of Cr, a hard mask of Si, was deposited on the back side of the LSN wafer to fabricate the back side of the micro-ultrafiltration SiN x membrane filter. Dual-side aligned photolithography was then carried out using a negative PR for manufacturing the back side of the micro-ultrafiltration SiN x membrane filter, as previously reported . The patterned Cr mask was etched by a Cr etchant (ETCR-400, APCT), and both SiO 2 and LSN were etched by inductively coupled plasma (ICP; PlasmaPro 100 Cobra, Oxford instruments).…”

“…The antifouling effect on the micro-ultrafiltration SiN x membrane filter of EP oscillation (EPO) of large bioparticles can improve the purity and collected amounts of isolated bovine milk exosomes over long-term TF-UF operation. Recently, we fabricated SiN x nanoporous membrane filters using a combined process of nanoimprint lithography and dual-side aligned photolithography . This successful development of SiN x membrane filters with various nanopore sizes helped us present an EP oscillation (EPO)-assisted TF (EPOTF) system with two different pore-sized membrane filters.…”