Nano-Raman spectroscopy with metallized atomic force microscopy tips on strained silicon structures

Abstract

In this paper, intensity enhancements of the Raman signal from strained silicon films utilizing the tip enhanced Raman spectroscopy (TERS) effect are reported. Specially shaped metallized atomic force microscopy tips have been prepared by sputter deposition of thin silver films onto sharpened quartz tips and subsequent focused ion beam (FIB) modification. Raman signal enhancements of more than 20%, which are attributed to the strained silicon film of 70nm thickness only, have been obtained due to approaching the TERS tips the laser spot. On samples with patterned trench structures prepared by FIB milling, lateral sample scans have been performed. These scans revealed a resolution of strained silicon lines with center-to-center distances below 250nm, well below the classical optical diffraction limit. Based on an analysis of the stress state in the strained silicon structures, relaxation effects close to the trench edges have been investigated. The described approach of nano-Raman spectroscopy is promising for strain characterization in devices, e.g., in field-effect transistor structures.

Stress Measurements in Si and SiGe by Liquid-Immersion Raman Spectroscopy

“…Among them, Raman spectroscopy has the advantages such as high sensitive to local strain, submicron spatial resolution, nondestructive measurements, fast measurements, and ease of use. Consequently, Raman spectroscopy has been frequently used by many researchers to measure the strain in Si [3,[7][8][9][17][18][19][20][21]. However, conventional Raman spectroscopy fails to measure the complicated stress states in Si.…”

Detection of Carbon Nanotubes using Tip-Enhanced Raman Spectroscopy

“…b. TERS will be used in semiconductor inspection. It may be used in inspections for stress distribution and fission process in nanometer scale (Zhu et al, 2007a(Zhu et al, , 2007bGeorgi et al, 2007). The polarization control techniques may be used to reduce the far-field background to improve the contrast (Lee et al, 2007).…”

Perspectives for spatially resolved molecular spectroscopy – Raman on the nanometer scale

“…After the initial phase the TERS experiments were quickly extended to nanoscale systems like the new materials of single-walled carbon nanotubes (SWNTs) with a resolution of 15 nm down to a separated single molecule [32][33][34][35][36][37][38][39], semiconducting thin films [40,41], insulators [42,43] and organic molecules [44][45][46].…”