Nanoscale stress analysis of strained-Si metal-oxide-semiconductor field-effect transistors by quantitative electron diffraction contrast imaging

A technique that uses quantitative electron diffraction contrast imaging (EDCI) to measure stress with a spatial resolution on the order of 10 nm and sensitivity on the order of tens of MPa is applied to strained-Si metal-oxide-semiconductor field-effect transistors. This is accomplished by utilizing transmission electron microscopy and focused ion beam micromachining in conjunction with finite element modeling and electron diffraction contrast simulations. Our techniques enable quantitative interpretation of EDCI intensity, as a function of the magnitude of the local stress field. Analysis shows that the stress distribution in the strained-Si channel is very sensitive to the stress state of the surrounding materials, especially Ti Si2, which can modify the stress distribution in the channel by well over 100 MPa.