| 摘要 |
<p>PURPOSE:To accurately align by detecting the optical intensity of moire fringes presented by the operation of an interference foire formed by positive primary and negative primary diffracted lights and a first diffraction grating, and relatively moving the first and second diffraction gratings in response to the optical intensity. CONSTITUTION:A first diffraction grating 27 is formed on the side of a mask 22, and a second diffraction grating 28 is provided at a position facing the first grating 27 of the face opposite to the mask 22 of a wafer 21. A laser light 30 oscillated from a laser oscillator 29 is reflected on a mirror 31 to be irradiated to the grating 28 through an objective lens 26. Optical parallel glasses 32, 33 superpose the optical paths of positive and negative primary diffracted lights 34, 35 from the grating 28 on a wafer 22. A photosensor 36 detects the intensities of moire fringes due to the operations of an interference foire formed of the lights 34, 35 and the operation of the grating 27, and transmits it to a servo controller 37. The controller 37 aligns the mask 22 and the wafer 21 at predetermined positions on the basis of the intensity of the moire foire.</p> |
