Patent ID: 7471384
Filing Date: 2008-12-30
Classification: B23K,G01B

Abstract:
1. A via hole depth detector for detecting the depth of a via hole formed in a workpiece held on the holding surface of a chuck table, comprising: a first surface position detection means which comprises a first detection laser beam oscillation means for oscillating a first detection laser beam having a predetermined wavelength to a first optical path and detects the height position of an illuminated portion of the workpiece based on the reflected light of the first detection laser beam; a second surface position detection means which has a second detection laser beam oscillation means for oscillating a second detection laser beam having a wavelength different from the wavelength of the first detection laser beam to a second optical path and detects the height position of an illuminated portion of the workpiece based on the reflected light of the second detection laser beam; a synthetic beam splitter for guiding the first detection laser beam oscillated to the first optical path and the second detection laser beam oscillated to the second optical path to a third optical path; a condenser which is installed in the third optical path and converges the first detection laser beam and the second detection laser beam to apply them to the workpiece held on the chuck table; a focal point positioning means which is installed in the first or second optical path and changes the position of the focal point of the first detection laser beam or the second detection laser beam; and a control means for obtaining the depth of a via hole formed in the workpiece based on a detection value obtained by the first surface position detection means and a detection value obtained by the second surface position detection means.