| 摘要 |
<p>PURPOSE: To make it possible to shorten remarkedly the working time to take for an autofocus of a dicer by a method wherein information on the thickness of a wafer is previously registered in a CPU, the focal point of a microscope is moved at a stretch from its initial position to a position to reach the error range of an irregularity in thickness and after that, the autofocus is accurately performed. CONSTITUTION: Previously registered information on the thickness (t1 ) of a wafer (In the case where the wafer is adhered on an adhesive tape, the thickness (t1 ) includes the thickness of the tape.) is outputted from a CPU to an alignment means 7, the focal point P of a microscope 7a is moved at a stretch from its initial position to the vicinity of the surface of the wafer W and after that, is step-fed at a resolution of about 2μm, for example, and each time the focal point is step-fed, a differential processing for finding the maximum value of the contrast of an image and the like are conducted on the basis of an image imaged by a CCD camera, whereby the time to take for an autofocus of a dicer is remarkedly shortened and the improvement of the productivity of the dicer can be contrived.</p> |
