Patent ID: 8069008

Claim:
A depth measurement apparatus having a sample observation mode for outputting two-dimensional image information of a sample surface and a depth measurement mode for outputting depth information of a recess formed on the sample surface, the depth measurement apparatus comprising: a white light source for generating white illumination light; a first slit having an elongate opening portion extending in a first direction, receiving the illumination light and emitting a line shaped illumination beam extending in the first direction; a vibrating minor which, in the sample observation mode, deflects the line shaped illumination beam in a direction perpendicular to its extending direction and, in the depth measurement mode, remains stationary; a second slit which has an elongate opening portion extending in a direction perpendicular to the first direction and, in the depth measurement mode, is selectively disposed in an optical path; an objective lens for focusing the light beam deflected by the vibrating mirror to project it onto the sample surface; a line sensor which has a plurality of light receiving elements arranged in a direction corresponding to the first direction and receives reflected light from the sample surface through the objective lens and the vibrating mirror; a beam splitter arranged in the optical path between the vibrating minor and the objective lens and for dividing the light beam deflected by the vibrating minor into a measurement beam and a reference beam; a reference mirror for reflecting the reference beam to advance it along the optical path; fringe scanning means for continuously changing a relative optical path length difference between an optical path length of the measurement beam and an optical path length of the reference beam; beam combining means for combining the reflected light from the sample and the reflected light from the reference mirror to form an interference beam; a drive mechanism for changing a relative distance between the objective lens and the sample; position detecting means for detecting a relative position between the objective lens and the sample; and signal processing means which, in the sample observation mode, outputs two-dimensional image information of the sample surface based on an output signal from the line sensor, and, in the depth measurement mode, outputs the depth information of the recess based on displacement information calculated with an interference signal outputted from the line sensor and the relative position information outputted from the position detecting means.