AVS 49th International Symposium
    Electronic Materials and Devices Tuesday Sessions
       Session EL+SC-TuM

Paper EL+SC-TuM9
Observation of a Long-range Strain Field under SiO@sub 2@/Si Interface by using Multi-wave X-ray Diffraction

Tuesday, November 5, 2002, 11:00 am, Room C-107

Session: Heterojunctions
Presenter: W. Yashiro, National Institute of Advanced Industrial Science and Technology (AIST), Japan
Authors: W. Yashiro, National Institute of Advanced Industrial Science and Technology (AIST), Japan
K. Sumitani, The University of Tokyo, Japan
T. Takahashi, The University of Tokyo, Japan
Y. Yoda, Japan Synchrotoron Radiation Research Institute (JASRI)
K. Takahashi, Musashi Institute of Technology, Japan
T. Hattori, Musashi Institute of Technology, Japan
Correspondent: Click to Email
In order to further improve the speed of VLSI circuits, new materials and device structures are being proposed in recent year. In particular there has been considerable interest in strained Si because it can lead to high-performance metal-semiconductor (MOS) devices. Transmission electron microscopy (TEM) is a technique to investigate local strains, e.g. around a dislocation at a phase boundary. In contrast with TEM, x-ray diffraction is powerful to investigate long-range ordered structures in crystals. In the present paper, we propose a new method that is sensitive to very small and long-range strains near surfaces of crystals by using multi-wave x-ray diffraction technique. To date, the Bragg reflection of x-ray diffraction is used to investigate such long-range strain fields. Recently Emoto et al. have indicated using the Bragg reflection that there exist very small strain fields on the side of the Si substrates if even ultra-thin layers are formed on them.@footnote 1@ Our method is also a method using the Bragg reflection, but with the important distinction that we use a phenomenon, intensity modulation of the CTR scattering under a Bragg condition. This makes it possible to determine total displacements due to small lattice distortions, rather than local lattice spacing. The method was applied to a Si(001) wafer whose surface is covered with an oxide layer about 5 nm thick formed by microwave-excited high density Kr/O@sub 2@ plasma oxidation. We found that the total displacement of -0.18 Å in the direction normal to the surface exists under the interface between the oxide layer and the substrate. @FootnoteText@ @footnote 1@Emoto et al. Surf. Sci. 493 (2001) 221-226.