The growth of 3D VA-CNTs stacks by predefining multilayered Al/Fe catalyst films for MEMS fabrication

This study presents a novel approach to fabricate highly-structured 3D vertically-aligned carbon nanotubes (VA-CNTs) architectures, and further integrates 3D VA-CNTs with MEMS surface micromachining to fabricate suspended 3D CNTs structures. The merits of presented approach are as follows: (1) highly-structured 3D VA-CNTs stacks can be achieved by predefining multilayered Al/Fe catalyst films; (2) only single run of the pyrolysis CVD process is required to grow multilayered 3D VA-CNTs stacks; (3) the design flexibility of the microstructure in out-of-plane direction can be increased by the variation layers of CNTs stacks. Preliminary fabrication results implement various 3D VA-CNTs architectures. Furthermore, 3D CNTs stacks have been integrated with MEMS surface micromachining to demonstrate different thickness of 3D CNTs suspended cantilevers and probe. The out-of-plane resonant frequency has also been calibrated to characterize different stiffness of the 3D CNTs suspended devices.