Characterization of process-induced lattice distortion in silicon by double-crystal x-ray topography using a curved collimator

Instead of the conventional flat collimator a curved collimator was used in double-crystal x-ray topography. The curvature of the collimator was adjus ted so that the Bragg condition for x-ray diffraction was uniformly satisfi ed over a wide area of the silicon wafer. The image area of the wafer was w ide enough to characterize the local lattice distortion induced by test ele ment groups of metal-oxide-semiconductor capacitors formed on the wafer. Th e lattice distortion was measured as variations in lattice plane spacing an d in lattice plane orientation using local angular deviations from the Brag g condition. These angular deviations were determined by fitting the x-ray intensities measured at the same point on a series of topographs taken arou nd the Bragg peak to the rocking curve of the sample. The lattice plane spa cing changed abruptly by 10(-6) at the boundary between the areas of gate o xide (11 nm thick) and the areas of field oxide (400 nm thick), and showed less variation within these areas. The lattice plane orientation changed mo notonically in each area, with an inclination of the order of 10(-5) rad wi thin the largest gate oxide area (5x5 mm(2)). (C) 2001 American Institute o f Physics.