| 摘要 |
PURPOSE:To enable to measure thickness of a dielectric insulating isolation substrate having high precision simply and speedily by a method wherein the Michelson infrared interference method is applied to measure thickness of a single crystal island of the dielectric insulating isolation substrate. CONSTITUTION:Near-infrared rays having large transmissivity to Si, for example, is made to be injected having the angle of incidence theta from the surface on the single crystal wafer 1 side of the dielectric insulating isolation substrate 8 prior to completion of abrassion work. Reflected light L1 from the surface and reflected light L2 from the boundary between the wafer 1 and an SiO2 film 3 are introduced to a Michelson interferometer 9. Delay of wave (the difference between the optical paths x) corresponding to a round trip of optical thickness to be generated by thickness (t) of the wafer is generated between rays L1,L2. At this time, with regard to interference of light, because the relation between the refractive index eta of Si, the incidence theta, thickness of the island (t), the difference (x) between the optical paths can be formulated, thickness (t) can be obtained by measuring (x) when eta, theta are known. Namely, when merely transferred distance (x) of a transferrable reflector Mb corresponding to the difference between the optical paths (x) is measured precisely, thickness (t) can be obtained. |
