Method for making a single-step etch mask for 3D monolithic nanostructures

Current nanostructure fabrication by etching is usually limited to planar structures as they are defined by a planar mask. The realization of three-dimensional (3D) nanostructures by etching requires technologies beyond planar masks. We present a method for fabricating a 3D mask that allows one to e...

Full description

Saved in:
Bibliographic Details
Published in:Nanotechnology 2015-12, Vol.26 (50), p.505302-10
Main Authors: Grishina, D A, Harteveld, C A M, Woldering, L A, Vos, W L
Format: Article
Language:English
Subjects:
Alignment
Crystals
etch mask
Etching
integrated circuits
Masks
nanofabrication
Nanostructure
nanotechnology
photonic band gap crystals
Silicon
silicon photonics
Three dimensional
three-dimensional nanostructures
Two dimensional
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Current nanostructure fabrication by etching is usually limited to planar structures as they are defined by a planar mask. The realization of three-dimensional (3D) nanostructures by etching requires technologies beyond planar masks. We present a method for fabricating a 3D mask that allows one to etch three-dimensional monolithic nanostructures using only CMOS-compatible processes. The mask is written in a hard-mask layer that is deposited on two adjacent inclined surfaces of a Si wafer. By projecting in a single step two different 2D patterns within one 3D mask on the two inclined surfaces, the mutual alignment between the patterns is ensured. Thereby after the mask pattern is defined, the etching of deep pores in two oblique directions yields a three-dimensional structure in Si. As a proof of concept we demonstrate 3D mask fabrication for three-dimensional diamond-like photonic band gap crystals in silicon. The fabricated crystals reveal a broad stop gap in optical reflectivity measurements. We propose how 3D nanostructures with five different Bravais lattices can be realized, namely cubic, tetragonal, orthorhombic, monoclinic and hexagonal, and demonstrate a mask for a 3D hexagonal crystal. We also demonstrate the mask for a diamond-structure crystal with a 3D array of cavities. In general, the 2D patterns on the different surfaces can be completely independently structured and still be in perfect mutual alignment. Indeed, we observe an alignment accuracy of better than 3.0 nm between the 2D mask patterns on the inclined surfaces, which permits one to etch well-defined monolithic 3D nanostructures.
ISSN:0957-4484
1361-6528
DOI:10.1088/0957-4484/26/50/505302