| 摘要 |
PURPOSE:To screen out only wafers with highly accurately flat surfaces and improve device characteristics such as the dielectric strength of an IC by a method wherein electron beams are applied to the surface of the semiconductor wafer with a certain inclination angle and electron beams reflected by Bragg reflection are focused to measure the variation of the height of the wafer surface by the gradation of the reflected electron beam density. CONSTITUTION:Electron beams are applied to the surface of a semiconductor wafer 5 with a certain inclination angle theta and electron beams reflected by Bragg reflection are focused. The variation of the height H of the surface of the wafer 5 is measured by the gradation of the reflected electron beam density and the wafers which show the variations of the heights not less a predetermined value, for instance 20 Angstrom , are screened out. For instance, when a transmitting type electron microscope is used, the wafer 5 is positioned with an inclination and moved while its position and angle are measured by a goniometer so as to make the electron beams applied with a plurality of incident angles theta and the electron beams reflected by Bragg reflection are projected onto a fluorescent screen 6. The height H is calculated from the width Wb of the part where the electron beam density is high and the width Wd of the part where the electron beam density is low.
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