| 摘要 |
PURPOSE:To facilitate the mask alignment, by constructing alignment marks such that a portion in a mark region or background region provided with a polysilicon layer is composed of first and second sections having different total thicknesses, with the difference being such that their reflectivity cycles are deviated from each other when monochromatic light is applied thereto. CONSTITUTION:A PSG layer is took as an example to be etched. The graph shows the relation between a thickness of the PSG layer and a reflectivity of mark portions 12R and 12L, taking the thicknesses on the axis of abscissa and the reflectivities on the axis of ordinate. The graph is made by computer simulation on the assumption that the thickness of a resist layer is 9500Angstrom and the wavelength is of G line of mercury (4358Angstrom ). If the difference in total thickness between the layers in the first mark section 12R and the layers in the second mark section 12L is approximately 900Angstrom , the phases of reflectivity on the G line of mercury are deviated from each other by a half wave-length. |
