Method and apparatus for inspecting defects on transparent substrate
A method of inspecting defects of a transparent substrate may include: illuminating a transparent substrate; calculating an incidence angle range of light so that a first region where the light meets a first surface of the transparent substrate and a second region where light meets a second surface being opposite the first surface of the transparent substrate do not overlap each other; adjusting an incidence angle according to the incidence angle range; adjusting a position of a first detector so that a first field-of-view of the first detector covers the first region and does not cover the second region; adjusting a position of a second detector so that a second field-of-view of the second detector covers the second region and does not cover the first region; and obtaining a first image of the first region and a second image of the second region from the first and second detector, respectively.
1. A method of inspecting defects of a transparent substrate, the method comprising:
illuminating the transparent substrate by emitting light from an illumination optical system;
calculating an incidence angle range of light emitted from the illumination optical system and incident on the transparent substrate so that a first region where the light meets a first surface of the transparent substrate and a second region where light transmitted through the transparent substrate meets a second surface of the transparent substrate do not overlap each other in a direction normal to the transparent substrate, the second surface being opposite to the first surface;
adjusting an incidence angle of the light according to the calculated incidence angle range;
adjusting a position of a first detector so that a first field-of-view of the first detector covers the first region and does not cover the second region;
adjusting a position of a second detector so that a second field-of-view of the second detector covers the second region and does not cover the first region;
obtaining a first image of the first region from the first detector and obtaining a second image of the second region from the second detector;
after the obtaining of the first and second images obtaining a first surface image and a second surface image by using the first and second images;
extracting a first position component of defects detected on the first image and a second position component of defects detected on the second image;
generating defect position data comprising the first and second position components;
comparing a light intensity of each position component of the defect position data on the first image with a light intensity of each position component of the defect position data on the second image; and
obtaining the first surface image of the transparent substrate by removing, from the first image, defects on positions with a greater light intensity on the second image than a light intensity on the first image.
2. The method of claim 1 , wherein calculating the incidence angle range comprises determining a horizontal separation distance between opposite edges of the first region and the second region.
3. The method of claim 2 , wherein calculating the incidence angle range comprises utilizing the equation:
D
R
1
R
2
=
T
·
tan
(
sin
-
1
(
sin
θ
1
n
)
)
-
W
L
cos
θ
1
≥
0
where D R1R2 is a separation distance between the first region and the second region, T is a thickness of the transparent substrate, θ 1 is the incidence angle, n is a refractive index of the transparent substrate, and W 1 is a beam width of the incident light.
4. The method of claim 1 , further comprising adjusting a field-of-view width of the first detector and a field-of-view width of the second detector so that the first field-of-view and the second field-of-view do not overlap each other.
5. The method of claim 1 , further comprising adjusting at least one of a beam width of the illumination optical system and field-of-view widths of the first and second detectors so that the widths of the first field-of-view and the first region are matched to each other and the widths of the second field-of-view and the second region are matched to each other.
6. The method of claim 1 , further comprising moving the transparent substrate mounted on a stage,
wherein the illuminating of the transparent substrate and the obtaining of the first and second images are simultaneously performed while the transparent substrate is moved.
7. The method of claim 1 , further comprising obtaining the second surface image of the transparent substrate by removing, from the second image, defects on positions with a greater light intensity on the first image than a light intensity on the second image.
8. The method of claim 1 , further comprising, after the adjusting of the incidence angle of the incident light, adjusting a gradient of a detection optical system comprising the first detector and the second detector so that each of optical axes of the first and second detectors has a detection angle that is equal to or less than the incidence angle.
9. The method of claim 8 , wherein a position of at least one of the first and second detectors is adjusted according to the following equation:
D R1R2′ ≥D F1F2 ≥≥0
where D F1F2 n is a separation distance between the first field-of-view and the second field-of-view, D R1R2 , is a separation distance between the first region and a 2′nd region, the 2′nd region is a region through which the second region is exposed to the first surface of the transparent substrate when the second region is seen at the detection angle, and D R1R2 , is determined by the following equation:
D
R
1
R
2
′
=
T
·
tan
(
sin
-
1
(
sin
θ
1
n
)
)
-
W
L
cos
θ
1
+
T
·
tan
(
sin
-
1
(
sin
θ
2
n
)
)
where T is a thickness of the transparent substrate, 1 is the incidence angle, 02 is the detection angle, n is a refractive index of the transparent substrate, and W L is a beam width of the incident light.
10. A method of inspecting defects of a transparent substrate, the method comprising:
illuminating the transparent substrate by emitting light from an illumination optical system;
calculating an incidence angle range of light emitted from the illumination optical system and incident on the transparent substrate so that a first region where the light meets a first surface of the transparent substrate and a second region where light transmitted through the transparent substrate meets a second surface of the transparent substrate do not overlap each other in a direction normal to the transparent substrate, the second surface being opposite to the first surface;
adjusting an incidence angle of the light according to the calculated incidence angle range;
adjusting a position of a first detector so that a first field-of-view of the first detector covers the first region and does not cover the second region;
adjusting a position of a second detector so that a second field-of-view of the second detector covers the second region and does not cover the first region;
obtaining a first image of the first region from the first detector and obtaining a second image of the second region from the second detector; and
after the adjusting of the incidence angle of the incident light, adjusting a gradient of a detection optical system comprising the first detector and the second detector so that each of optical axes of the first and second detectors has a detection angle that is equal to or less than the incidence angle,
wherein a position of at least one of the first and second detectors is adjusted according to the following equation:
D R1R2′ ≥D F1F2 ≥0
where D F1F2 is a separation distance between the first field-of-view and the second field-of-view, D R1R2 , is a separation distance between the first region and a 2′nd region, the 2′nd region is a region through which the second region is exposed to the first surface of the transparent substrate when the second region is seen at the detection angle, and D R1R2 , is determined by the following equation:
D
R
1
R
2
′
=
T
·
tan
(
sin
-
1
(
sin
θ
1
n
)
)
-
W
L
cos
θ
1
+
T
·
tan
(
sin
-
1
(
sin
θ
2
n
)
)
where T is a thickness of the transparent substrate, θ 1 is the incidence angle, θ 2 is the detection angle, n is a refractive index of the transparent substrate, and W L is a beam width of the incident light.
11. The method of claim 10 , wherein calculating the incidence angle range comprises determining a horizontal separation distance between opposite edges of the first region and the second region.
12. The method of claim 10 , further comprising adjusting a field-of-view width of the first detector and a field-of-view width of the second detector so that the first field-of-view and the second field-of-view do not overlap each other.
13. The method of claim 10 , further comprising adjusting at least one of a beam width of the illumination optical system and field-of-view widths of the first and second detectors so that the widths of the first field-of-view and the first region are matched to each other and the widths of the second field-of-view and the second region are matched to each other.
14. The method of claim 10 , further comprising moving the transparent substrate mounted on a stage,
wherein the illuminating of the transparent substrate and the obtaining of the first and second images are simultaneously performed while the transparent substrate is moved.