Motohiro Tomita

Although the strain technology has been realized in the advanced LSI as a booster technology in the post scaling era, the mechanism for the strain introduction and performance acceleration has not been completely clarified. In this study channel strain in the nano scale pMOSFETs with compressive SiN film and embedded SiGe were evaluated by Raman spectroscopy. We performed Raman measurement for the sample after the dummy gate removal process. For fine-gate length, we analyzed by a long measurement and peak extraction. We succeeded in obtaining strain down to the 30nm gate length. The channel strain was effectively introduced as decreasing gate length, and the huge stress of -2.4GPa was detected in the channel of Lg=30nm. The induced strain, however, was expected rather complicated including share strain than simple uni-axial or symmetric bi-axial ones. It has been impossible to evaluate such strain using Raman spectroscopy, because TO phonon mode has been difficult to be excited for Si(100) substrate due to the Raman selection rule. In this study we have succeeded in exciting TO phonon mode using high-NA immersion lens. This allows us to perform asymmetric bi-axial strain analysis.