| 摘要 |
PURPOSE:To make it possible to detect smaller defects and foreign matters at the upper part and the lower part of a pattern by changing the position of focal points for the surface of a substrate by two or more steps, photographing the images, and utilizing the image data obtained by integrating the images. CONSTITUTION:A foreign matter 14 on a circuit pattern 12 formed on a wafer 11 and a foreign matter 13 which is attached to the wafer 11 have the different heights. The image of the foreign matter 13 on the wafer is not picked up in the image which is obtained at a first focal-point position 15. The foreign matter 14 on the circuit pattern 12 is not transferred on the image obtained at a third focal-point position 17. The image of the foreign matter 14 and the foreign matter 13 are both picked up in the image (c) obtained at a second focal-point position 16 because the position is located just at the intermediate point. In the image obtained by integrating these images, both images of the foreign matter 14 and the foreign matter 13 are very clearly displayed as a result. |
