Defect inspecting apparatus

Abstract

A defect inspecting apparatus of the invention solves a problem that in a defect inspecting apparatus, because of improving detection sensitivity of a microscopic defect by reducing a detection pixel size, a focal depth becomes shallow, a height of imaging is varied due to environmental change and the detection sensitivity of a defect becomes unstable. This apparatus comprises an XY stage, which carries a substrate to be inspected and scans in a predetermined direction, and a mechanism having a system of irradiating a defect on the inspected substrate at a slant and detecting the defect by a detection optical system disposed on the upper side, which corrects a height of imaging in real time for change in temperature and barometric pressure in order to keep the imaging in a best condition.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

FIG. 1 is view illustrating system configuration of a defect inspecting apparatus.

FIG. 2 is a view illustrating the configuration of a system according to the invention.

FIG. 3 is a graph showing relation between barometric pressure and the height of an inspected substrate in focus.

FIG. 4 is a view explaining that the height of an inspected substrate is varied by change in barometric pressure.

FIG. 5 is a graph of relation between temperature and barometric pressure and a correction amount for the height of an inspected substrate.

FIG. 6 is a view for explanation of a spot formed by illuminating a projection plane of an image sensor on an inspected substrate from three directions.

FIG. 7 is a view illustrating an inspected substrate on which memory LSIs, i.e. samples to be inspected, are arranged.

FIG. 8 is a view illustrating an inspected substrate on which LSIs such as microcomputers etc., i.e. samples to be inspected, are arranged.

FIG. 9 is a view illustrating an optical system, including an illumination lens of an illumination optical system, of the defect inspecting apparatus according to the invention.

FIG. 10 is a view illustrating the function of the illumination lens of the illumination optical system in the defect inspecting apparatus according to the invention.

FIG. 11 is a view for explanation of an illumination optical system.

FIG. 12 is a schematic view illustrating the principle of the invention that the height of a Z stage is corrected by using a coefficient of a conversion formula.

Claims

1. A defect inspecting apparatus, comprising: an XY stage carrying a substrate to be inspected and scanning in a predetermined direction;an autofocusing system having an illumination system irradiating a defect on the inspected substrate at a slant and an illumination path in a space which does not interfere with a detection lens, said autofocusing system being configured to illuminate the inspected substrate to provide dark-field illumination and to form an image of reflected light on an opposite position sensor; anda mechanism comprised of a detection optical system having a magnifying lens and disposed on an upper side, said detection optical system receiving light reflected from a defect with a high NA, magnifying and projecting the light on an image sensor, the image sensor, a measure for at least either temperature or barometric pressure, and a control system converting a deviation of at least either temperature or barometric pressure into a correction value for a height of an object surface or an image surface and positioning the object surface or the image surface, wherein the height of the object surface or the image surface is corrected in real time for change in at least either temperature or barometric pressure so that an image of the inspected substrate formed on the image sensor by the detection lens does not defocus.

2. The defect inspecting apparatus according to claim 1, wherein a temperature of an inspection lens and a barometric pressure near the inspection lens are measured.

3. The defect inspecting apparatus according to claim 1 further comprising either a Z mechanism moving up and down the image sensor to correct a height of the imaging, or a stage Z mechanism changing a height of the inspected substrate to correct the height of the object surface.

4. The defect inspecting apparatus according to claim 1 further comprising a means storing relation with a height of the object surface or the image surface at which imaging does not defocus in a particular temperature and barometric pressure, that is, a height of the object surface or the image surface at which maximal sensitivity is provided under a particular optical condition.

5. The defect inspecting apparatus according to claim 4 further comprising a means acquiring in advance data about relation between at least either temperature or barometric pressure, and a height of the object surface or the image surface in the defect inspecting apparatus, storing a result thereof in a data table etc., reading out a height of the object surface or the image surface at which the maximal sensitivity is provided at a temperature and barometric pressure measured before inspection from the data as acquired above, and performing inspection.