Strain stability in nanoscale patterned strained silicon-on-insulator
Nowadays, strain engineering plays a key role in boosting the performance of Si-based nanoelectronics. So far a tremendous progress has been made in establishing methods for strain manipulation in Si nanodevices. This has brought up further challenges in terms of development of reliable probes to characterize the strain on the nanoscale. In this paper, we discuss strain imaging using multi-wavelength micro-Raman spectroscopy. As a model system, we investigate the strain behavior upon nanoscale patterning of ultrathin strained silicon-on-insulator (SSOI). We show that valuable details on the strain depth distribution can be obtained by combining deep UV and visible Raman microprobes. Additionally, we also demonstrate that strain mapping with high lateral resolution can be achieved using UV-Raman with glycerin-immersed high numerical aperture objective lens. Results from nano-beam electron diffraction and peak-pairs analysis of high-angle annular dark field images are also presented. Detailed 3D finite element simulations of edge-induced strain relaxation in SSOI nanostructures augment our experimental studies.