Abstract
Directed self-assembly of block copolymers is a bottom-up approach to nanofabrication that has attracted high interest in recent years due to its inherent simplicity, high throughput, low cost and potential for sub-10 nm resolution. In this paper, we review the main principles of directed self-assembly of block copolymers and give a brief overview of some of the most extended applications. We present a novel fabrication route based on the introduction of directed self-assembly of block copolymers as a patterning option for the fabrication of nanoelectromechanical systems. As a proof of concept, we demonstrate the fabrication of suspended silicon membranes clamped by dense arrays of single-crystal silicon nanowires of sub-10 nm diameter. Resulting devices can be further developed for building up high-sensitive mass sensors based on nanomechanical resonators.
Highlights
In standard micro/nanofabrication, structures and devices are created by depositing a variety of thin films, followed by pattern definition by lithography and etching to remove undesired regions of material
In this work we have introduced the opportunities that microphase separation of block copolymers (BCPs) offers for patterning at the nanoscale
We have discussed how BCP microdomains placement and alignment can be directed by directed self-assembly (DSA) methods, such as chemoepitaxy and graphoepitaxy, and demonstrated a process flow based on the latter for the fabrication of nanomechanical functional structures
Summary
In standard micro/nanofabrication, structures and devices are created by depositing a variety of thin films, followed by pattern definition by lithography and etching to remove undesired regions of material. As EUV and its combination with multiple patterning presents exponentially increased costs due to its extreme complexity, research in other less conventional lithographic techniques still remains of great interest It is in this scenario where DSA is considered as an attractive alternative for the fabrication of nanoscale structures, thanks to its high resolution, low cost, ease of integration and scalability [12,13,14]. Due to the dis-affinity and repulsion forces between these blocks, and in order to present minimal free energy, BCPs segregate into microdomains after a thermally-driven phase separation process They generate self-assembled patterns within the nano/microscale [23], which facilitates their use in high-resolution nanopatterning [24]. DSA has been incorporated into conventional 300-mm pilot lines with existing tracks for logic applications [26,27,28], and in a variety of other applications, such as non-volatile memory, sensors, photovoltaics, solar cells, graphene patterning or liquid separation membranes [29,30,31]
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