Photopatterning of PMMA Films with Gold Nanoparticles: Diffusion of AuCl₄⁻ Ions

Abstract

Photopatterning of poly(methyl methacrylate) (PMMA) films is performed by UV irradiation of the polymer films containing uniformly distributed AuCl 4 -ions. The process reduces the gold ions and leads to production of Au nanoparticles in the irradiated regions at room temperature (RT). Resulting films are investigated with scanning electron microscopy, which revealed, in addition to regions with gold nanoparticles, the presence of "ion-depleted regions". These regions are formed at RT and within the rigid polymer matrix by diffusion of gold ions toward the irradiated regions, ending up with no or very little gold moieties, which are important for prevention of delayed processes for postgeneration of unwanted features, if and when such materials are utilized for device production. Further investigations performed by fluorescence and Raman measurements and XPS mapping give additional evidence supporting the existence of such regions. Similar regions are also observed within the poly(vinyl alcohol) (PVAL) films. The ion-depleted regions are about 10 µm wide, which is a significant length for the metal ions to travel through a rigid matrix like PMMA (or PVAL) at room temperature and raises important questions as to the diffusion mechanism(s) of the metal ions and to the nature of the driving force(s).

Optical Properties of Complex Plasmonic Materials Studied with Extended Effective Medium Theories Combined with RCWA

“…From the fabrication point of view, it is likely that the localization of gold occurs during the irradiation process. As the gold ions experience the light intensity gradient of the interference pattern, they migrate toward the bright fringes and are photo-reduced near the surface of the films [43]. This would explain why the localization is more pronounced in the case of GNGs than for HFs, for which the irradiation is homogenous (no gradient).…”

Plasmon-enhanced diffraction in nanoparticle gratings fabricated by in situ photo-reduction of gold chloride doped polymer thin films by laser interference patterning

“…5(b). In addition, some ion diffusion may also occur, leading to a homogenization of the ionic concentration 28 . Finally, the gold atom distribution becomes almost uniform as all gold ions are reduced and the diffraction goes to a minimum after 40 min of irradiation.…”

Inorganic Nanomaterials with a Highly Fluorinated Polymer Ligand Dispersed in Fluorous Solvents

“…특히 전자공학의 발전에 따 라 보다 작으면서도 더욱 높은 집적도를 지닌 전자소자, 우 수한 표시성능을 가진 디스플레이 등이 요구되고 있으며, 이 를 위해 나노 복합재료에 추가적으로 포토패터닝 성능을 부 여하는 시도가 활발이 진행되고 있다. [11][12][13][14][15] Marques-Hueso 그 룹에서는 전통적인 포지티브 감광재료인 2-diazo-2H-naphthalen-1-one(DNQ)-novolac에 금 입자 혹은 은 나노입자를 첨가한 후 마이크로 포토패터닝을 진행하여 나노입자 크기에 따른 광학적 특성 변화에 대해 확인하였으며, 특정 화학물질에 대 한 센서로 기능을 확인하였다. 11 Jiguet 그룹에서는 네거티브 감광재료인 SU-8을 적용, 실리카 입자가 분산된 에폭시 고분 자-나노입자 복합재료의 패턴 형성을 진행하여 부착성 및 민 폴리머, 제41권 제5호, 2017년 감도가 증가된 10 μm급 패턴이 형성됨을 확인한 바 있다.…”