Evaluation of Anisotropic Biaxial Stress by Raman Spectroscopy with a High Numerical Aperture Immersion Objective Lens

Abstract

It is expected to be necessary to measure the stress tensors in Si because the stress field in the channels of metal–oxide–semiconductor field-effect transistors is remarkably complicated. Raman spectroscopy enables us to evaluate the stress precisely, nondestructively, and with relatively high spatial resolution, although its standard implementation fails to resolve the stress tensor. The goal of this study is to establish a procedure for measuring an unknown plane-stress state. In this study, the anisotropic biaxial stress in Si induced by a SiN film was evaluated by Raman spectroscopy with an immersion objective lens with a high numerical aperture.

Evaluation of Anisotropic Strain Relaxation in Strained Silicon-on-Insulator Nanostructure by Oil-Immersion Raman Spectroscopy

“…As a result, the TO phonon modes in Si can be effectively excited by z-polarization even under the (001) Si backscattering geometry; on the other hand, exciting the TO phonon modes is difficult in conventional Raman measurements, e.g., the aperture angle is 9.8 in the case of using NA ¼ 0:7 objective. [7][8][9] We selectively obtained each optical phonon mode in Si by controlling incident and scattered electrical fields using polarizers and by sample rotation, which was based on the Raman polarization selection rules. 39) Figure 2 shows the various configurations in oil-immersion Raman measurements.…”

“…8) It is possible to evaluate the anisotropic stress state in Si using the TO phonon modes. 9) In our previous study, the strain relaxation in transmission electron microscopy (TEM) samples of strained Si-oninsulator (SSOI) substrates was evaluated by oil-immersion Raman spectroscopy. 7) Our purpose was to distinguish the stress in the long direction from that in the short direction in the TEM samples of SSOI.…”

Quantitative Analysis of Stress Relaxation in Transmission Electron Microscopy Samples by Raman Spectroscopy with a High-Numerical Aperture Lens

“…14) We consider that the z polarization can be accomplished using a high-NA lens. 2,3) Actually, the very large aperture angle of 70.8 can be obtained using an objective with an NA of 1.7, while the aperture angle is 44.4 in the case of using a conventional objective (NA ¼ 0:7). However, it is difficult to obtain the z polarization even using the high-NA lens, because the refraction index of Si is relatively high, 4.1 at 532 nm.…”

“…We have already demonstrated the excitation of the transverse optical (TO) phonon mode under backscattering geometry from a (001)-oriented Si substrate, which is conventionally the forbidden mode, using a high-numerical aperture (NA) oil-immersion lens. 2,3) The TO phonon mode allows us to evaluate the stress tensor in Si. [4][5][6][7][8] In this study, we performed quantitative analysis of stress relaxation in TEM samples using Raman spectroscopy with a high-NA oil-immersion lens.…”

Tensor Evaluation of Anisotropic Stress Relaxation in Mesa-Shaped SiGe Layer on Si Substrate by Electron Back-Scattering Pattern Measurement: Comparison between Raman Measurement and Finite Element Method Simulation

“…[11][12][13][14][15][16] Raman spectroscopy is also useful for evaluating anisotropic biaxial stress with high stress sensitivity. 3,4,[11][12][13][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] In this study, we evaluated the anisotropic stress relaxation in mesa-shaped strained SiGe layers on Si substrates by EBSP measurement. Moreover, we compared the results of EBSP measurement with those of Raman spectroscopy and finite element method (FEM) simulation.…”