Wafer-scale 3D shaping of high aspect ratio structures by multistep plasma etching and corner lithography

Shu Ni; Erwin J W Berenschot; Pieter J Westerik; Meint J de Boer; René Wolf; Hai Le-The; Han J G E Gardeniers; Niels R Tas

doi:10.1038/s41378-020-0134-6

Wafer-scale 3D shaping of high aspect ratio structures by multistep plasma etching and corner lithography

Microsyst Nanoeng. 2020 Mar 23:6:25. doi: 10.1038/s41378-020-0134-6. eCollection 2020.

Authors

Shu Ni^{1

2}, Erwin J W Berenschot¹, Pieter J Westerik¹, Meint J de Boer³, René Wolf³, Hai Le-The^{4

5}, Han J G E Gardeniers¹, Niels R Tas¹

Affiliations

¹ Mesoscale Chemical System Group, MESA+ Institute, University of Twente, 7522 NB Enschede, The Netherlands.
² Inorganic Materials Science Group, MESA+ Institute, University of Twente, 7522 NB Enschede, The Netherlands.
³ NanoLab Cleanroom, MESA+ Institute, University of Twente, 7522 NB Enschede, The Netherlands.
⁴ Physics of Fluids Group, MESA+ Institute & Max Planck Center for Complex Fluid Dynamics, University of Twente, 7522 NB Enschede, The Netherlands.
⁵ BIOS Lab-on-a-Chip Group, MESA+ Institute & Max Planck Center for Complex Fluid Dynamics, University of Twente, 7522 NB Enschede, The Netherlands.

Abstract

The current progress of system miniaturization relies extensively on the development of 3D machining techniques to increase the areal structure density. In this work, a wafer-scale out-of-plane 3D silicon (Si) shaping technology is reported, which combines a multistep plasma etching process with corner lithography. The multistep plasma etching procedure results in high aspect ratio structures with stacked semicircles etched deep into the sidewall and thereby introduces corners with a proper geometry for the subsequent corner lithography. Due to the geometrical contrast between the gaps and sidewall, residues are left only inside the gaps and form an inversion mask inside the semicircles. Using this mask, octahedra and donuts can be etched in a repeated manner into Si over the full wafer area, which demonstrates the potential of this technology for constructing high-density 3D structures with good dimensional control in the bulk of Si wafers.

Keywords: Engineering; Nanoscience and technology.