| 摘要 |
PURPOSE:To increase the resolution of an alignment pattern for a very accurate alignment by illuminating an alignment mark on a projection substrate with light of a wide wavelength width through a projection lens and by correcting a chromatic aberration caused by the projection lens at the time of detecting the alignment mark. CONSTITUTION:Light of a wide wavelength width which is emitted from an illumination light source 11 is led through an optical fiber 12 to illuminate an alignment mark 31 on a wafer 3 through an achromatic lens 13, a beam splitter 14, a bending mirror 15 and a reduction projection lens 2. An image of the alignment mark 31 is formed on an image sensing element 5 by means of an achromatic lens 41 and a holographic lens 42. The holographic lens 42 corrects a chromatic aberration of the reduction projection lens 2. By this method, the distance between the wafer and the image sensing surface can be shortened and thereby mounting can be done easily and the resolution as a detecting system can also be enhanced and eventually a very accurate alignment is available. |
