| 摘要 |
PURPOSE: To accurately measure the overlapping dimension deviation of the pattern of an LSI wafer with a high step difference by forming each of light images from two patterns onto the image sensor of a detection optical system by applying light to a region on a sample. CONSTITUTION: A lighting optical system 2 is provided with a light source 1, and a detection optical system 8 is provided with an objective lens system 3, a branch optical system 4, relay optical systems 5a and 5b of different light path lengths with a plurality of focusing positions, a plurality of image sensors 6a and 6b corresponding to each light path, and an automatic focusing system 7. A stage system 11 is provided with a traveling stage 9 and a sample stand 10 for placing a sample 13. Then, a control system 12 drives and controls the Z stage of the stage system 11 based on the automatic focusing information on the surface of the sample 13 for the objective lens system 3 obtained from the automatic focusing system 7, and finely moves the surface of the sample 13 to a proper focusing distance to position the sample 13 in Z-axis direction, thus detecting the signals at different focusing positions simultaneously with the sensors 6a and 6b, since the light path length each of the relay optical systems 5a and 5b is different from each other. |
