Improvement of Spatial Resolution in Raman Spectroscopy Selecting Measurement Area by Opaque Material Deposition

Abstract

We have succeeded in the strain analysis beyond the spatial resolution in conventional Raman measurements, which can be achieved by selecting the strain-induced measurement area by an opaque material. Tungsten (W) film deposited by electron beam (EB)-assisted deposition was used for the opaque material in this study. The EB-W film has the properties of a relatively high absorption coefficient and a low density. These features give rise to shading of the excitation light without stress induction into Si. As a result, the wave number shift of 0.86 cm -1 was obtained in the Si substrate with 100-nm-wide space SiN pattern, whose value was higher than that obtained in conventional Raman measurements, 0.3–0.4 cm -1 . Furthermore, the spatial resolution of Raman spectroscopy with the W film deposition was better than that of Raman spectroscopy with an immersion lens. We can say that the methodology is a promising candidate to measure strain in fine structures.