Double-sided masking and stress-release etching for the fabrication of high-aspect-ratio graphene micro-cantilever

Abstract

Well-shaped micro/nano-structured suspended graphene is a versatile building block for micro/nano-electromechanical (MEMS/NEMS) devices. Directly ‘sculpting’ the suspended graphene membrane using an accelerated energetic electron/ion beam to form micro/nano-structured graphene possesses the merits of high resolution and well-processed flexibility. However, both the residual and process-induced stress in the membrane still challenge the obtaining of non-distorted freestanding graphene patterns. We report a featured double-sided masking and stress-release etching method to fabricate well-defined suspended graphene micro-ribbon. We demonstrated that the one-step low-energy (10 keV) electron beam induced the deposition of amorphous carbon (a-C) on both sides of the suspended graphene. The a-C layers were precisely self-aligned, not only allowing its use as reliable masks for the following plasma etch of suspended graphene, but showing potential for future applications of effectively ‘writing’ circuits/devices directly on both sides of a suspended 2D atomic-layered platform. A stress-release plasma etching process and its ‘self-crumpling’ mechanism were demonstrated. High-aspect-ratio micro-structured graphene (bridge and cantilever) with a good shape was obtained. This provides a promising and universal processing method for making suspended structures of 2D materials with in-plane flatness for potential MEMS/NEMS applications.

Layer-by-layer thinning of two-dimensional materials

“…To achieve precise control over the layer numbers or attain a specific micro-nano structure of 2D materials, the dry thinning technique is regarded as the most effective method due to its high precision and cleanliness. 48,49 Vinoth Kumar Ponnusamy is a Full Professor in the Department of Medicinal and Applied Chemistry, and also a research faculty at the Research Center for Precision Environmental Medicine Kaohsiung Medical University (KMU), Kaohsiung City, Taiwan, leading the Nano and Green Analytical Technology (NGAT) research laboratory since 2016 (https://kumarslab.wixsite.com/ kumarslab). He also serves as a joint professor in the Department of Chemistry at National Sun Yat-sen University (NSYSU), Kaohsiung, Taiwan.…”

“…To achieve precise control over the layer numbers or attain a specific micro-nano structure of 2D materials, the dry thinning technique is regarded as the most effective method due to its high precision and cleanliness. 48,49…”