微小角入射X線トポグラフィによる(100)Si表面の格子歪の観察と評価

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Since electric devices become easy to be influenced by local stress with improvementin the degree of accumulation of very large scale integration, the quality of the siliconsurfaces on which they are made becomes more and more important. Therefore, it isimportant to detect minute lattice distortion near the silicon surface with sufficientaccuracy. X-ray topography under the condition of simultaneous specular and Braggreflections is effective for imaging a strain of shallow domain near the surface.In the present study, reflection X-ray topography by Berg-Barrett method using theextremely asymmetric X-ray diffraction and double-crystal arrangement of (+,+) and(+,-) parallel setting of the 311 reflection with CuKαl radiation have been applied toobservation of lattice strains in near surface of silicon crystals and silicon epitaxial layeron the silicon substrate. For silicon wafers with 4.6 nm-thick oxide film, and 18 nm-thickaluminum film, local variation in the orientation of the lattice plane occurring at theboundary were observed. Lattice distortion images near the surface produced by themechanochemical polishing and low-energy N+ ion implantation were clearly visualized.For a wafer with near (100)-oriented surface, and 18 μm thickness epitaxial film grownon <100> silicon substrate, lattice distortions of faint wrinkle-like pattern and shortstreaks running horizontally were also observed.
宮崎大学の論文