Raman spectroscopy capabilities for advanced semiconductor technology devices

Abstract

In semiconductor processing and metrology, Raman spectroscopy is a valuable characterization tool because of its nondestructive nature, high throughput, and versatility in terms of parameter sensitivity. However, with the miniaturization of semiconductor devices, the inherent diffraction limit of the optical technique becomes a roadblock. In order to re-enable the strengths of Raman spectroscopy at the nanometer scale, we exploit polarization-induced enhancement effects that focus the excitation light into the region of interest, without the need for external probes or particles. This allows the detection of structures with dimensions far smaller than the excitation wavelength, unlocking the strengths of Raman spectroscopy at the nanoscale for, e.g., stress and composition measurements. Moreover, under these conditions the experiment probes the totality of the materials stack and we show how this transforms the technique into a volumetric and geometric measurement. The result is a completely new application domain for Raman spectroscopy as a critical dimensional metrology toolkit for a wide variety of semiconducting and metallic materials.