Channel strain analysis in damascene-gate p-metal-oxide-semiconductor field effect transistors (pMOSFETs) with a compressive stress liner and embedded SiGe after the dummy gate removal was studied using micro-Raman spectroscopy with a UV laser (λ=363.8 nm) and a quasiline excitation source. Using a quasiline excitation source, we obtained spatial and energy information simultaneously with a high spatial resolution in the one-dimensional strain profile. For Lgate>210 nm samples, we performed laser exposure for 10 min to measure the channel strain. However, the channel strain for Lgate<210 nm samples was impossible to evaluate due to the limitation of the spatial resolution. Therefore, we increased the laser exposure time to 40 min for Lgate<210 nm samples. Super invar metal with an extremely low thermal coefficient was installed in the monochromator, which achieved a very long measurement. Finally, we found an extremely large stress of −2.4 GPa in the channel of Lgate=30 nm samples. These results demonstrated good agreement with a stress simulation. We found that the large stress in the channel significantly enhanced the drivability in the damascene-gate pMOSFET.

We demonstrate the results of strain (stress) evaluation obtained from electron backscattering pattern (EBSP) measurement for samples of a strained Si-on-insulator (SSOI) and a Si substrate with a patterned SiN film. Two-dimensional stress distributions were obtained in 40×40 µm2 areas of the SSOI. The biaxial stress state was also obtained in the SSOI. Furthermore, clear cross-hatch contrast was observed, especially in the distribution of shear stress S x y , in contrast to with the other distributions of normal stress S x x and S y y . One- and two-dimensional stress distributions in the Si substrate with the patterned SiN film were also obtained from EBSP measurement. Moreover, the results were compared with those of UV-Raman measurement and edge force model calculation, and were found to have a good correlation with each other. EBSP measurement was used to measure the complicated biaxial stress including the shear stress in a sample with a 150-nm-wide space pattern. We can conclude that EBSP measurement is a useful method for precisely measuring stress with high spatial resolution.

We evaluated density and chemical bonding states of the CVD SiO2 film with and without plasma treatment to clarify an effect of the plasma treatment. It was found that the chemical bonding states were homogenized by the plasma treatment from the results of X-ray photoelectron spectroscopy. In addition, an increase of the film density was also observed. These results indicate the densification of SiO2 film, suppression of bond-angle fluctuation, and decrease of impurities (e.g. Hydrogen, Nitrogen and so on) in the SiO2 film. These results can well explain the improvement of the electrical properties by the plasma treatment. Furthermore, UV-Raman measurement was performed to evaluate the modification of Si stress and crystal quality at the SiO2/Si interface.

Strain induction was studied on a sample that had a dummy gate tetraethyl orthosilicate–silicon dioxide (TEOS–SiO2) and SiN film by UV-Raman spectroscopy with high spatial and high wave-number resolution. The UV laser penetrated through the dummy gate that was transparent to UV light, which enabled us to evaluate strain in the channel of the metal–oxide–semiconductor field-effect transistor (MOSFET) model. Furthermore, we compared stress profiles obtained by finite element (FE) calculations with those obtained by UV-Raman measurements. There was a difference between the stress profiles in the line-and-space pattern sample and in the dummy-gate sample; large compressive (tensile) strains were concentrated at the channel edges in the dummy-gate sample with the compressive (tensile) stress liner, although both tensile and compressive strains existed at the channel edge in the line-and-space pattern sample. The results from UV-Raman spectroscopy were consistent with those obtained by the FE calculation.

Global and local strained-Si samples, namely strained-Si on insulator (SSOI) wafer and a Si substrate with a patterned SiN film were each evaluated by electron backscattering pattern (EBSP). In the EBSP measurements for SSOI, biaxial tensile stresses (biaxial tensile strains and compressive strain perpendicular to the surface) were obtained, whose values were consistent with those obtained by UV-Raman spectroscopy. One-dimensional stress distributions in the Si substrate with the patterned SiN film were obtained by EBSP, UV-Raman spectroscopy with a deconvolution method, and edge force model calculation. The results were well consistent with each other. EBSP allows us to measure stress and strain in the patterned SiN sample with 150-nm wide space. Furthermore, anisotropic biaxial stress including shear stress was also obtained by EBSP.

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.

We investigated the suppression mechanism of volume shrinkage for a spin on glass (SOG) film by plasma treatment using hard X-ray photoelectron spectroscopy, X-ray reflectometry (XRR), and UV-Raman spectroscopy. The suppression of the SOG film shrinkage was attributed to the control of N out-diffusion from the SOG film and O in-diffusion into the SOG film, which was due to the plasma treatment prior to the conventional cure annealing process. It was also confirmed from the XRR measurements that the SOG film was densified by the plasma treatment. Moreover, UV-Raman measurements were performed to evaluate the Si stress at the SiO2/Si interface that was induced during the gap filling process. The stress was controlled by the appropriate plasma treatment. Thus, we concluded that the plasma treatment was effective for the suppressions of SOG film shrinkage and stress induction and for the SOG film densification.

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