Real- and Q-space travelling: multi-dimensional distribution maps of crystal-lattice strain (∊044) and tilt of suspended monolithic silicon nanowire structures.

Simone Dolabella,Tobias U Schulli,Yusuf Leblebici,Ruggero Frison,B Erdem Alaca,Gilbert A Chahine,Alex Dommann,Zuhal Tasdemir,Antonia Neels,Carsten Richter

doi:10.1107/s1600576719015504

Abstract

Silicon nanowire-based sensors find many applications in micro- and nano-electromechanical systems, thanks to their unique characteristics of flexibility and strength that emerge at the nanoscale. This work is the first study of this class of micro- and nano-fabricated silicon-based structures adopting the scanning X-ray diffraction microscopy technique for mapping the in-plane crystalline strain (∊044) and tilt of a device which includes pillars with suspended nanowires on a substrate. It is shown how the micro- and nanostructures of this new type of nanowire system are influenced by critical steps of the fabrication process, such as electron-beam lithography and deep reactive ion etching. X-ray analysis performed on the 044 reflection shows a very low level of lattice strain (<0.00025 Δd/d) but a significant degree of lattice tilt (up to 0.214°). This work imparts new insights into the crystal structure of micro- and nanomaterial-based sensors, and their relationship with critical steps of the fabrication process.

Highlights

In the past few decades, the wide field of applications of electronic devices and the miniaturization of materials have enabled the study and development of devices such as microand nano-electromechanical systems (MEMS and NEMS)
The structural features discussed are derived from the NEMS design and the related critical steps of the fabrication process, such as electron-beam lithography and deep reactive ion etching
Through measurements by means of scanning X-ray diffraction microscopy, we were able to access the structural properties of the silicon-based suspended NWs

Summary

Introduction

In the past few decades, the wide field of applications of electronic devices and the miniaturization of materials have enabled the study and development of devices such as microand nano-electromechanical systems (MEMS and NEMS). Typical manufacturing process steps, such as electron-beam lithography, deep reactive ion etching (DRIE), thermal annealing, dicing and bonding, could favour failure as well (Schifferle et al, 2017). Such critical steps have a direct impact on the mechanical properties, reducing significantly the lifetime of such devices (Jadaan et al, 2003). The characterization of the atomic structure of MEMS and NEMS is extremely important, as very small defects may affect the long-term reliability of devices under working conditions (Fitzgerald et al, 2009; Neels, Dommann et al, 2008)

Methods

Results

Conclusion