| 摘要 |
<p>first position detection means for detecting a position on a wafer surface at the laser beam incident point; second position detection means for detecting in advance a position on the wafer surface; and a control section for controlling the position of the collective point in the thickness direction in the wafer. When scanning the laser beam from the wafer peripheral outside to the wafer peripheral inside, the position of the collective point at the wafer periphery is controlled according to the data obtained in advance by the second position detection means and after scanning a predetermined distance, the control is switched to control based on the data obtained by the first position detection means. Thus, when scanning the wafer by applying the laser beam from the wafer surface, it is possible to perform position control of the laser beam collective point even at the wafer periphery and to form a refined region by absorption of plenty of photons at a predetermined position in the wafer.</p> |
