| 摘要 |
PURPOSE:To improve the transfer of fine circuit pattern by a method wherein slits limiting the passage of illumination light are reflected halfway of optical path on a detected surface to detect the position of the slit image for processing the slippage from the focus surface. CONSTITUTION:The signal waveforms of slit images 13a, 13b formed through optical paths 6, 7 reflecting on the surface 1 detected through a linear sensor 18 of an optical system A are taken in a controller 20. Likewise, the other waveforms of the other slit images 13a', 13b' formed through the other optical paths 6', 7' reflecting on the surface 1 detected through the other linear sensor 18' of another optical system B are taken in the controller 20 to be compared with the reference signal waveforms of slit image correct in focus. Finally, the tilt of detected surface 1 is processed from the positional flucturation to drive a tilt stage 27 by this signal while the signal of tilt elements 24-26 are transferred to driving circuits 21-23 to correct the signal in the focus by a reduction projection lens 2 for driving the stage 27 so as to correct the stage 27 for letting the detected surface 1 in the focus. |
