Defect inspection device and defect inspection method

Patent metadata

Field	Value
Publication number	US-10317368-B2
Application number	US-201415528013-A
Country	US
Kind code	B2
Filing date	Nov 28, 2014
Priority date	Nov 28, 2014
Publication date	Jun 11, 2019
Grant date	Jun 11, 2019

Abstract

A defect inspection device configured to measure a surface shape of an inspection target using light applied to the inspection target via a spatial light phase modulator based on an interference state of reflected light from the inspection target obtained via the spatial light phase modulator, to measure magnetic field distribution of a surface of the inspection target magnetized by an excitation device for magnetizing the inspection target using light applied to the inspection target via the spatial light phase modulator based on an interference state of reflected light from the inspection target obtained via the spatial light phase modulator, and to separate data of a magnetic field specific portion which exists on the surface of the inspection target from magnetic field distribution data which is a measurement result of magnetic field distribution of the inspection target based on surface shape data which is a measurement result of the surface shape of the inspection target, to suppress deterioration of measurement accuracy of magnetic field distribution generated by the surface shape of the inspection target and to improve defect detection accuracy.

First claim

The invention claimed is:

1. A defect inspection device comprising:
a surface shape measurement unit which measures a surface shape of an inspection target using light applied to the inspection target via a spatial light phase modulator based on an interference state of reflected light from the inspection target obtained via the spatial light phase modulator;
a magnetic field distribution measurement unit which measures magnetic field distribution of a surface of the inspection target magnetized by an excitation device for magnetizing the inspection target using light applied to the inspection target via the spatial light phase modulator based on an interference state of reflected light from the inspection target obtained via the spatial light phase modulator; and
a data separation unit which separates data of a magnetic field specific portion which exists on the surface of the inspection target from magnetic field distribution data which is a measurement result of magnetic field distribution of the inspection target obtained by the magnetic field distribution measurement unit based on surface shape data which is a measurement result of the surface shape of the inspection target obtained by the surface shape measurement unit,
wherein the surface shape measurement unit includes
a laser light source;
a spatial filter for shaping light emitted from the laser light source;
a collimator lens for adjusting light from the spatial filter to parallel light;
a ¼ wavelength plate for converting the parallel light from the collimator lens to a circular polarized light beam;
a beam splitter for splitting incident light into transmitted light and reflected light;
a spatial light phase modulator for modulating spatial distribution of a phase of the incident circular polarized light beam transmitted through the beam splitter from the ¼ wavelength plate;
a camera for imaging light, which is reflected light from the inspection target of light applied to the inspection target via the spatial light phase modulator, reflected by the beam splitter via the spatial light phase modulator; and
a surface shape data generating unit for generating surface shape data of the surface of the inspection target based on an interference state of reflected light obtained as luminance data of an image captured by the camera.

2. The defect inspection device according to claim 1 ,
wherein the data separation unit includes
a surface shape data storage unit for storing the surface shape data of the inspection target obtained by the surface shape measurement unit,
a magnetic field distribution data storage unit for storing the magnetic field distribution data of the inspection target obtained by the magnetic field distribution measurement unit, and
a difference calculation unit for performing difference calculation between the magnetic field distribution data and the surface shape data.

3. The defect inspection device according to claim 1 ,
wherein the magnetic field distribution measurement unit and the surface shape measurement unit include
the beam splitter for splitting light, which is incident via the collimator lens for adjusting light from the light source to parallel light and the ¼ wavelength plate for converting the parallel light to the circular polarized light beam, into transmitted light and reflected light,
the spatial light phase modulator for modulating spatial distribution of the phase of the incident circular polarized light beam transmitted through the beam splitter from the ¼ wavelength plate, and
the camera for imaging light, which is reflected light as object light and reference light from the inspection target of light applied to the inspection target via the spatial light phase modulator, reflected by the beam splitter via the spatial light phase modulator,
wherein the surface shape measurement unit and the magnetic field distribution measurement unit measure the surface shape and the magnetic field distribution of the inspection target based on an interference state of the object light and the reference light from the inspection target.

4. The defect inspection device according to claim 1 , further comprising:
a modulation switching control unit which controls the spatial light phase modulator and switches presence or absence of modulation of light applied to the inspection target; and
a distance measurement function which obtains a position of an optical axis direction of the inspection target by irradiation of light to the inspection target in a state in which modulation of light is not performed by the spatial light phase modulator.

5. A defect inspection device comprising:
a surface shape measurement unit which measures a surface shape of an inspection target using light applied to the inspection target via a spatial light phase modulator based on an interference state of reflected light from the inspection target obtained via the spatial light phase modulator;
a magnetic field distribution measurement unit which measures magnetic field distribution of a surface of the inspection target magnetized by an excitation device for magnetizing the inspection target using light applied to the inspection target via the spatial light phase modulator based on an interference state of reflected light from the inspection target obtained via the spatial light phase modulator; and
a data separation unit which separates data of a magnetic field specific portion which exists on the surface of the inspection target from magnetic field distribution data which is a measurement result of magnetic field distribution of the inspection target obtained by the magnetic field distribution measurement unit based on surface shape data which is a measurement result of the surface shape of the inspection target obtained by the surface shape measurement unit,
wherein the surface shape measurement unit includes
a laser light source;
a spatial filter for shaping light emitted from the laser light source;
a collimator lens for adjusting light from the spatial filter to parallel light;
a ¼ wavelength plate for converting the parallel light from the collimator lens to a circular polarized light beam;
a beam splitter for splitting incident light into transmitted light and reflected light;
a spatial light phase modulator for modulating spatial distribution of a phase of the incident circular polarized light beam transmitted through the beam splitter from the ¼ wavelength plate;
a camera for imaging light, which is reflected light from the inspection target of light applied to the inspection target via the spatial light phase modulator, reflected by the beam splitter via the spatial light phase modulator; and
a surface shape data generating unit for generating surface shape data of the surface of the inspection target based on an interference state of reflected light obtained as luminance data of an image captured by the camera, and

wherein the magnetic field distribution measurement unit includes
the laser light source;
the spatial filter for shaping light emitted from the laser light source;
the collimator lens for adjusting light from the spatial filter to parallel light;
the ¼ wavelength plate for converting the parallel light from the collimator lens to the circular polarized light beam;
the beam splitter for splitting incident light into transmitted light and reflected light;
the spatial light phase modulator for modulating spatial distribution of the phase of the incident circular polarized light beam transmitted through the beam splitter from the ¼ wavelength plate;
the camera for imaging light, which is reflected light from the inspection target of light applied to the inspection target via the spatial light phase modulator, reflected by the beam splitter via the spatial light phase modulator;
an excitation

Assignees

• Hitachi Ltd

Inventors

• Endou Hisashi
• Takagi Hiroyuki
• Goto Taichi
• Inoue Mitsuteru

Classifications

• G01N27/9046 Primary

  by analysing electrical signals · CPC title

• G01N27/83

  by investigating stray magnetic fields · CPC title

• G01R33/0325 Primary

  using the Kerr effect · CPC title

• G01B11/2441

  using interferometry · CPC title