Photolithographic nanoseeding method for selective synthesis of metal-catalysed nanostructures

Abstract

In this work we present a general method for the selective synthesis by photolithography of localised nanostructures in planar geometries. The methodology relies on the previous concept of photo-patternable metallic nanoparticle (NP)/polymer nanocomposites, which can provide a range of NP sizes, polydispersity and densities. First, a photoresist containing metallic ions is patterned by photolithography. Silver NPs are synthesised in situ after the exposure and development of the patterned thin film via the thermal-induced reduction of ions embedded in its structure. Gentle plasma ashing is used to selectively remove the polymer, which leaves NPs on the patterned areas. These NPs are used as seeds for subsequent processes. In order to demonstrate the flexibility of the method, its use to selectively produce localised nanostructures through different processes is shown here. Following a top-down approach, high aspect-ratio silicon nanograss has been produced by reactive ion etching and masking by the NPs. In a bottom-up approach, 280 nm copper clusters have been selectively grown in arrays. This method can be easily extrapolated to other metals and it provides a quick way to selectively generate hierarchical nanostructures in large planar areas that can be used for different applications, such as the fabrication of nanostructured sensor arrays.

Direct metallisation of polyetherimide substrates by activation with different metals

“…The application of KCl to an ion exchanged Ag-PEI substrate causes the formation of photosensitive compound AgCl, which can then be photoreduced to silver (Ag) metal by visible light (450 nm), as confirmed by EDX and XRD, respectively, in previous work [5]. The selective production of metallic nanoparticles via m + reduction can be achieved by either using light, heat [7,8], chemistry [9], or by high energy radiation [10,11]. Chemical reduction is popular due to its relative simplicity and low cost [9].…”

A rapid technique for the direct metallization of PDMS substrates for flexible and stretchable electronics applications

“…The formation and growth of Ag NPs inside the polymer matrix occurs by thermal induced reduction of Ag(I) to Ag(0) at high temperatures [12]. The Ag NPs act as seeding catalysts for copper ions adsorption during the electroless copper metallization step [13]. Electroless copper plating for 10 minutes resulted in copper thickness of 0.44 ± 0.05 µm.…”

Selective Electroless Copper Deposition by Using Photolithographic Polymer/Ag Nanocomposite

“…The seed layer could be fabricated using a photolithographic approach, where metal NPs are synthesized inside a photosensitive polymer matrix, as reported by Marques-Hueso et al [8], [9]. Metal NPs embedded inside the polymer can be used for further processing, such as nanostructure precursors [10], and it is viable that they could act as seeding sites for metal ions adsorption and continuous electrode formation.…”