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

• Published in: Journal of micromechanics and microengineering 2018-08, Vol.28 (8), p.85001
• Main Authors: Li, Shasha, Zeng, Miaoxuan, Huang, Yifeng, Zhan, Runze, Chen, Jun, Xu, Ningsheng, She, Juncong, Deng, Shaozhi
• Format: Article
• Language: English
• Subjects: electron beam-induced deposition; micro-cantilever; oxygen plasma; stress-induced distortion; suspended graphene
• ISSN: 0960-1317; 1361-6439
• DOI: 10.1088/1361-6439/aabd44

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.