Beyond 100 nm resolution in 3D laser lithography — Post processing solutions

Abstract

Laser polymerization has emerged as a direct writing technique allowing the fabrication of complex 3D structures with microscale resolution. The technique provides rapid prototyping capabilities for a broad range of applications, but to meet the growing interest in 3D nanoscale structures the resolution limits need to be pushed beyond the 100 nm benchmark, which is challenging in practical implementations. As a possible path towards this goal, a post processing of laser polymerized structures is presented. Precise control of the cross-sectional dimensions of structural elements as well as tuning of an overall size of the entire 3D structure was achieved by combining isotropic plasma etching and pyrolysis. The smallest obtainable feature sizes are mostly limited by the mechanical properties of the polymerized resist and the geometry of 3D structure. Thus the demonstrated post processing steps open new avenues to explore free form 3D structures at the nanoscale.

It's in the Fine Print: Erasable Three‐Dimensional Laser‐Printed Micro‐ and Nanostructures

“…First, we briefly introduce DLWw ith an emphasis on non-cleavable photoresists and the resulting material properties.T he major part of the Minireview covers existing photoresists with labile bonds that are cleavable by specific triggers such as light, additives,o re nzymes.N ote that decomposition processes,s uch as plasma etching and pyrolysis,which provide little control over the cleavage process,are beyond the scope of this Minireview,b ut there are several examples that can be found elsewhere. [15] Finally,weshare our vision for the future of cleavable photoresists in DLWwhich we believe will have significant impact in adaptive 3D microand nanoprinting for future applications in cell biology, microfluidics,a nd micro-optics.…”

Es ist im Kleingedruckten: Löschbare dreidimensionale lasergedruckte Mikro‐ und Nanostrukturen

“…Ein derzeit aktives Forschungsgebiet konzentriert sich auf spaltbare Materialien, die nach dem Druck kontrolliert entfernt werden kçnnen. Obwohl es keinen Konsens über die Definition gibt, wird die kontrollierte Entfernung mit spaltbaren Photolacken heute oft als subtraktive Fertigung bezeichnet, um sie von der ad- [15] Schließlich teilen wir unsere Vision fürd ie Zukunft der spaltbaren Photolacke beim DLW, von denen wir glauben, dass sie einen wesentlichen Einfluss auf den adaptiven 3D-Mikrodruck und -Nanodruck fürz ukünftige Anwendungen in der Zellbiologie, Mikrofluidik und Mikrooptik haben werden. DLW, auch bekannt als direkte Laserlithographie,3 D-Laserlithographie oder 3D-Laserdruck, wurde 1997 von Maruo et al eingeführt und bietet die mit Abstand hçchste Auflçsung aller lichtbasierten 3D-Druckverfahren.…”

Additive Manufacturing of Nanostructures That Are Delicate, Complex, and Smaller than Ever

“…In particular, new photoresist chemistries that allow for chemically selective removal of one type of photoresist from another through a wet process have been developed, enabling the fabrication of more delicate structures . Moreover, the use of oxygen‐plasma etching and pyrolysis has been recently proposed to reduce the dimensions of structures fabricated with TPP, demonstrating that the minor diameter of elliptical struts in a wire‐like structure can be reduced to around 25 nm. However, the use of oxygen‐plasma etching for fabrication has been confined to the case of a structure where the local geometry is arbitrarily determined by the spheroidal voxel shape that is natural to TPP .…”