JP2016057180A - Substrate inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical inspection device capable of inspecting which side (front surface side or rear surface side) of the substrate to be inspected a foreign matter adheres to even when the substrate gets thinned.SOLUTION: A substrate inspection device comprises: a substrate holding unit; an illumination unit; an imaging unit; a polarization unit which changes a vibration direction of illumination light; a polarization direction switching unit which switches the polarization unit to an S polarization state or a P polarization state; and a foreign matter inspection unit. The foreign matter inspection unit further includes a foreign matter adherence surface determination unit which determines that the foreign matter adheres to the first surface side of the substrate to be inspected when scattered light intensity in the S polarization state is higher than scattered light intensity in the P polarization state, and determines that the foreign matter adheres to the second surface side of the substrate to be inspected when the scattered light intensity in the P polarization state is higher than scattered light intensity in the S polarization state.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an apparatus for optically inspecting the presence or absence of defects such as foreign matter and scratches attached to the front surface side or the back surface side of a transparent body (so-called substrate) such as a glass substrate.

  In the conventional surface defect inspection of a liquid crystal panel, detection optical systems are symmetrically arranged on the front surface side and the back surface side of the substrate, respectively, and the front surface defect and the back surface defect are inspected separately. (For example, patent document 1).

  In addition, the illumination light is irradiated to the inspection target substrate from the oblique direction, and an imaging optical system having a focal depth smaller than the thickness of the inspection target substrate is disposed at a light receiving angle of 90 degrees with respect to the substrate surface, A technique capable of inspecting at a time without confusing the front side and the back side of the substrate to be inspected has been put into practical use (for example, Patent Document 2).

  FIG. 10 is an external view showing an example of a conventional substrate inspection apparatus. The conventional substrate inspection apparatus 1z irradiates the illumination light 32 from the illumination unit 3 toward the inspection target region Rz of the substrate Wz to be inspected, and the scattered light emitted from the inspection target region Rz is located above the substrate Wz. Imaging is performed using the imaging camera 42z of the imaging unit 4z provided, and inspection is performed based on the captured image. The substrate Wz is held on the substrate mounting table 20, and the substrate mounting table 20 is mounted on the X-axis stage 61 and the Y-axis stage 62 mounted on the apparatus frame 11z. It can move in a direction at a predetermined speed and stop at a predetermined position. In addition, the imaging camera 42z has the apparatus frame 11z via the connecting member 15z so that the normal line of the inspection target region Rz of the substrate Wz coincides with the optical axis direction (that is, in the direction perpendicular to the surface of the substrate Wz). Is attached. Therefore, imaging / inspection can be performed with the substrate Wz and the imaging unit 4z facing each other (that is, by repeating the operation of dividing the entire substrate Wz into a plurality of portions in the X direction and performing a scanning operation in the Y direction at a constant speed).

Japanese Patent Laid-Open No. 3-189491 Japanese Patent No. 4104924

  When it is desired to quickly inspect for defects such as foreign matter and scratches attached to the front surface side and the back surface side of the substrate to be inspected, as shown in Patent Document 1, optical systems for inspection are provided on the front surface side and back surface side of the substrate. In the device configuration in which two sets are arranged, the cost and size of the inspection device itself are increased.

  On the other hand, as shown in Patent Document 2, even if an inspection optical system is used and an apparatus that can inspect the front side and the back side of the inspection target substrate separately is used, the inspection target substrate becomes thinner and thinner ( When the thickness is less than 0.4 mm), it becomes difficult to separate the front surface side and the back surface side of the substrate (that is, separation between the front and back surfaces).

  FIG. 11 is a conceptual diagram showing a state in which the front and back surfaces of a substrate are inspected using a conventional substrate inspection apparatus. Scattering diffusely reflected by foreign matter adhering to the substrate by irradiating illumination light 32z onto the substrate Wz to be inspected. The state in which light is imaged and the intensity of scattered light from the foreign matter X1, X2 imaged by the imaging unit are illustrated in a composite manner. FIG. 11A shows a state in which a substrate Wz (thickness tz: 0.5 to 0.7 mm) that has been conventionally inspected is inspected, and FIG. A state of inspecting a thin substrate W (thickness t: 0.4 mm or less) is shown. The illumination light 32z emitted from the illumination unit is irregularly reflected on the surface of the foreign matter X1 attached to the front side of the substrates Wz and W and the surface of the foreign matter X2 attached to the back side of the substrates Wz and W, and the scattered light is imaged. The image passes through the lens 43z of the unit 4z, forms an image, and is imaged by the imaging camera 42z.

  In the case of the conventional substrate Wz, the scattered light of the foreign substance X1 on the front surface side and the foreign substance X2 on the rear surface side forms images at separate positions, and thus can be detected in a separated state. However, in the case of a substrate W thinner than the conventional one, the scattered light of the foreign matter X1 on the front surface side and the foreign matter X2 on the back surface side overlap, so that it cannot be detected separately, and it is difficult to maintain inspection accuracy.

  Therefore, the present invention provides an optical inspection apparatus capable of inspecting whether the foreign matter attached to the substrate is attached to the front side or the back side separately even when the inspection target substrate is thin. Objective.

In order to solve the above problems, the form of the first aspect according to the present invention is:
A substrate holding unit for holding a substrate to be inspected;
An illumination unit that irradiates illumination light toward the inspection target region set on the substrate;
An imaging unit for imaging scattered light emitted from the inspection target region;
A polarizing section that changes a vibration direction of the illumination light;
A polarization direction switching unit that switches the polarization unit to an S polarization state or a P polarization state;
A foreign matter inspection unit that inspects the position and size of foreign matter attached to the front or back side of the substrate to be inspected based on the image captured by the imaging unit,
In the foreign matter inspection section,
An S-polarization inspection result output unit that outputs a result of imaging and inspection by switching the polarization unit to an S-polarization state;
A P-polarization inspection result output unit for switching the polarization unit to a P-polarization state and outputting a result of imaging and inspection;
An inspection result comparison unit for comparing inspection results output from the S polarization inspection result output unit and the P polarization inspection result output unit;
As a result of comparing the scattered light intensity at the same position on the substrate to be inspected by the inspection result comparison unit,
If “scattered light intensity in S-polarized state> scattered light intensity in P-polarized state”, it is determined that foreign matter is attached to the surface side of the substrate to be inspected.
If “scattering light intensity in the P-polarized state> scattered light intensity in the S-polarized state”, a foreign matter attachment surface determination unit is provided that determines that foreign matter is attached to the back side of the substrate to be inspected.
It is a substrate inspection apparatus.

  According to this configuration, the surface side of the substrate to be inspected and the back side thereof are imaged in the S-polarized state and the P-polarized state, and the surface where the scattered light is emitted from the substrate is strong if the S-polarized component is strong. If there is a foreign substance on the side and the P-polarized light component is strong, it can be determined that there is a foreign substance on the back side. By doing so, it can be stably determined whether the foreign matter has adhered to the front surface side or the back surface side of the substrate.

The form of the second aspect according to the present invention is as follows.
A substrate holding unit for holding a substrate to be inspected;
An illumination unit that irradiates illumination light toward the inspection target region set on the substrate;
An imaging unit for imaging scattered light emitted from the inspection target region;
A polarizing section that changes a vibration direction of the illumination light;
A polarization direction switching unit that switches the polarization unit to an S polarization state or a P polarization state;
A foreign matter inspection unit that inspects the position and size of foreign matter attached to the front or back side of the substrate to be inspected based on the image captured by the imaging unit,
In the foreign matter inspection section,
An S-polarization inspection result output unit that outputs a result of imaging and inspection by switching the polarization unit to an S-polarization state;
A P-polarization inspection result output unit for switching the polarization unit to a P-polarization state and outputting a result of imaging and inspection;
An inspection result comparison unit that multiplies and compares at least one of the inspection result output from the S polarization inspection result output unit and the inspection result output from the P polarization inspection result output unit;
As a result of comparing the scattered light intensity at the same position on the substrate to be inspected by the inspection result comparison unit,
If “scattered light intensity in the S-polarized state ÷ scattered light intensity in the P-polarized state> k (k is a constant)”, it is determined that foreign matter is attached to the surface side of the substrate to be inspected.
If “scattered light intensity in S-polarized state ÷ scattered light intensity in P-polarized state <k (k is a constant)”, it is determined that foreign matter is attached to the back side of the substrate to be inspected. It is a board | substrate inspection apparatus provided with the determination part.

According to this configuration, the surface k and the back side of the substrate to be inspected are imaged in the S-polarized state and the P-polarized state, and the coefficient k is a constant ratio for each place where scattered light is emitted from the substrate. Can be determined as to whether the foreign substance is on the front surface side or the back surface side of the substrate. By doing so, it becomes possible to inspect substrates of various materials and thicknesses.

  Even if the substrate to be inspected becomes thinner, it is possible to inspect whether the foreign matter attached to the substrate is attached to the front side or the back side separately.

The perspective view which shows an example of the form which embodies this invention. The front view which shows the principal part of an example of the form which embodies this invention. The front view which shows the principal part of another example of the form which embodies this invention. The perspective view explaining the polarization direction in this invention. The flowchart which shows the inspection process in an example of the form which embodies this invention in time series. The top view which shows an example of the board | substrate made into a test object in an example of the form which embodies this invention. The image figure which shows an example of each result examined in an example of the form which embodies the present invention. The correlation diagram which shows the relationship between the setting direction of a polarizing plate used for realization of this invention, and scattered light intensity | strength. The correlation diagram which compared the scattered light intensity from the foreign material adhering to the front and back of a board | substrate by applying this invention. The external view which shows an example of the conventional board | substrate inspection apparatus. The conceptual diagram which shows a mode that the front and back of a board | substrate is test | inspected using the conventional board | substrate inspection apparatus.

DESCRIPTION OF EMBODIMENTS Embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is an external view showing an example of a form embodying the present invention.
FIG. 1 is a composite view of a perspective view of each component device and a block diagram of a configuration necessary for acquiring and inspecting an image of a substrate inspection apparatus 1 that performs an optical inspection based on an image obtained by imaging a substrate. Has been. In each figure, the three axes of the orthogonal coordinate system are X, Y, and Z, the XY plane is the horizontal plane, and the Z direction is the vertical direction. In particular, in the Z direction, the direction of the arrow is represented as the top, and the opposite direction is represented as the bottom. Further, the substrate W to be inspected has a first main surface S1 and a second main surface S2 in which the first main surface S1 is in a front-back relationship. In the present application, the first main surface S1 side is referred to as a first main surface side or a front surface side, and the second main surface S2 side in a front-back relationship with the first main surface S1 side is referred to as a second main surface side or back surface side. Further, among the inspection target regions R set on the substrate W, the first main surface side is referred to as a first main surface side inspection target region R1, and the second main surface side is referred to as a second main surface side inspection target region R2.

  A substrate inspection apparatus 1 according to an example embodying the present invention includes a substrate holding unit 2, an illumination unit 3, an imaging unit 4, a polarization unit 5, a polarization direction switching unit 6, and a foreign substance inspection unit 7. It is prepared for. The substrate inspection apparatus 1 irradiates illumination light from the illumination unit 3 toward the inspection target region R set on the substrate W held by the substrate holding unit 2, and from the foreign matter in the inspection target region R. The scattered light is imaged by the imaging unit 4. At that time, the illumination light is switched to the S wave or the P wave by the polarization unit 5 and the polarization direction switching unit 6, the captured images are respectively acquired, and the foreign material inspection unit 7 extracts the foreign material. Further, the foreign matter inspection unit 7 compares the scattered light intensity when the S wave is irradiated with the scattered light intensity when the P wave is irradiated with respect to the extracted foreign matters, and the foreign matter is the substrate W from the magnitude relationship. It is determined whether it is on the first main surface S1 side (that is, the front surface side) or the second main surface S2 side (that is, the back surface side). In addition, the board | substrate inspection apparatus 1 is good also as a structure provided with the relative movement part 8 as needed.

The substrate holding unit 2 holds the substrate W to be inspected.
Specifically, the substrate holding unit 2 can be configured by the substrate mounting table 20. The substrate mounting table 20 has a cross-sectional shape that is slightly inside the outer dimension of the substrate W and is hollow or recessed outside the portion that becomes the inspection target region of the substrate W. The substrate mounting table 20 is provided with positioning reference pins 21 slightly outside the outer dimensions of the substrate W. Alternatively, the configuration shown in FIG. 5 and described later may be used.

  FIG. 2 is a diagram showing the main part of an example embodying the present invention and the scattered light intensity captured. FIG. 2 conceptually shows a state in which the front and back surfaces of a substrate thinner than the conventional one are inspected using the substrate inspection apparatus embodying the present invention, and the substrate W to be inspected is irradiated with illumination light. A state in which scattered light irregularly reflected by the foreign matters X1 and X2 attached to the substrate W and an intensity of the scattered light from the foreign matters X1 and X2 captured by the imaging unit are illustrated in a composite manner.

  The illumination light 52 used for the inspection irradiated from the illuminating unit 3 and passed through the polarizing unit 5 includes the surface of the foreign material X1 attached to the first main surface side of the substrate W and the foreign material attached to the second main surface side of the substrate W. The light is irregularly reflected on the surface of X2 (that is, the interface with the second main surface side of the substrate W), and the scattered light is imaged by the imaging camera 42 of the imaging unit 4.

  At this time, as will be described in detail later, if the illumination light 52 used for the inspection is in the S-polarized state, the intensity distribution of the scattered light imaged by the imaging camera 42 is shown by a solid line, and the illumination light 52 used for the inspection. Is a P-polarized state, the intensity distribution of the scattered light imaged by the imaging camera 42 is indicated by a broken line.

  The illumination unit 3 irradiates the illumination light 32 toward the inspection target region R set on the substrate W. Further, the illuminating unit 3 is arranged so as to irradiate the illumination light 32 in the direction of the arrow 33 at a predetermined angle θ1 with respect to the normal H1 of the first main surface S1 of the substrate W. In other words, the illumination light 32 is applied to the first main surface S1 of the substrate W from an obliquely upward direction.

  Specifically, the illumination unit 4 can be exemplified by a semiconductor laser, an LED, a lamp light source, or the like, and the illumination light is irradiated toward the inspection target region through a lens, a mirror, or the like. More specifically, in the case of using a semiconductor laser, a configuration in which light is irradiated as light sheet-like illumination light through a cylindrical lens or the like can be exemplified. More specifically, the light sheet-like illumination light 32 is exemplified by light traveling in the clockwise direction as indicated by the arrow 34 (that is, circularly polarized light) when traveling in the direction of the arrow 33. it can.

  In addition, as shown in FIGS. 1 and 2, the illumination light emitted from the illumination unit 4 may be directly irradiated to the inspection target region R through the polarization unit 5 described later. As illustrated in FIG. 3, the inspection target region R may be irradiated with the illumination light 53 used for the inspection after the reflection mirror 35 or the like is disposed in the middle of the optical path and reflected.

FIG. 3 is a front view showing a main part of another example of a form embodying the present invention.
In FIG. 3, the illumination unit 3B different from the configuration shown in FIG. 2 and the light irradiated from the irradiation unit 3B are polarized by the polarization unit 5 and irradiated to the inspection target region R of the substrate W, and foreign matter X1, X2 A state in which the image of the scattered light from the image pickup unit 4 is seen from the arrow side in the X direction is shown.

  The irradiation unit 3B includes a light sheet illumination unit 31 disposed so as to irradiate light sheet-like illumination light 32 substantially downward in the vertical direction, and a reflection mirror 35. The reflection mirror 35 changes the direction of the light that has passed through the polarization unit 5 that polarizes the light sheet-like illumination light 32. Details of the polarization unit 5 will be described later.

  The imaging unit 4 images the inspection target region R. Specifically, the imaging unit 4 includes the first main surface side inspection target region R1 set on the first main surface S1 side of the substrate W or the second main surface set on the second main surface S2 side of the substrate W. The side inspection target region R2 is imaged from the first main surface S1 side. And the imaging part 4 is arrange | positioned so that predetermined angle (theta) 2 may be made with respect to 1st main surface S1 of the board | substrate W, and 1st main surface side test object area | region R1 may be imaged. That is, the inspection target region is imaged from the obliquely upward direction with respect to the first main surface S1 of the substrate W.

  Specifically, the imaging unit 4 includes an imaging camera 42 and a lens 43. More specifically, the imaging camera 42 can be exemplified by a line sensor using a CCD or CMOS as the imaging element 44. The imaging camera 42 outputs a video signal and image data corresponding to the image received by the imaging element 44 to the outside.

  Note that the imaging camera 42 is not limited to a line sensor, and may be a TDI sensor. Alternatively, the imaging camera 42 may employ an area sensor.

  When the depth of field of the lens 43 is shallower than the thickness of the substrate W, the imaging unit 4 performs imaging while focusing on either the first main surface S1 of the substrate W or the second main surface of the substrate W. Keep it in configuration. For example, the imaging unit 4 is configured to be attached to the apparatus frame 11 in a state where the distance from the substrate W is fixed. By doing so, the imaging unit 4 can inspect either the first main surface S1 of the substrate W or the second main surface of the substrate W.

  Alternatively, the imaging unit 4 may be configured to be attached to the apparatus frame 15 via a mechanism (for example, a camera position changing unit) that changes the imaging position. In this case, the camera position changing unit shifts the difference in the optical path calculated from the thickness of the substrate W, the refractive index of the substrate W, and the predetermined angle θ2 where the imaging camera 42 is attached obliquely to the normal line H1. It is set as the structure which can be performed. The direction of this shift movement is the thickness of the substrate W, the refractive index of the substrate W, the predetermined angle θ2 at which the imaging camera 42 is mounted obliquely with respect to the normal H1, and the working distance of the lens 43 of the imaging unit 4 Calculated by (so-called working distance).

  As a specific configuration of the camera position changing unit, a manual actuator including a guide rail extending in the shift movement direction, a ball screw, and a handwheel handle, or an electric motor including a rotation motor instead of the handwheel handle is provided. An actuator etc. can be illustrated. The actuator described above is not only a mechanism that moves only in the shift movement direction (that is, the uniaxial direction), but also in a direction (X direction) parallel to the surface of the substrate W and a thickness direction (the Z direction) (that is, It may be a mechanism that moves in two axial directions.

  Since the imaging unit 4 is attached via the camera position changing unit having such a configuration, the first main surface S1 or the second main surface S2 of the substrate W is selected by changeover, and one of the inspections is performed. Inspection can be performed with a focus on the target area.

  If the depth of field of the lens 43 is equal to or greater than the thickness of the substrate W, both the first main surface S1 and the second main surface S2 are placed in focus in advance and the working distance is fixed. good.

  The polarizing unit 5 polarizes the vibration direction of the illumination light. Specifically, an optical element called a phase plate 50 that changes the vibration direction of light incident from one side (that is, polarizes) and emits from the other side is used for the polarizing unit 5. Then, by rotating the phase plate 50 around the optical axis and changing the setting angle, the light sheet-shaped light irradiated with circularly polarized light (or elliptically polarized light) from the light sheet illumination unit 31 of the illumination unit 3 is converted into S A polarized light sheet or a P-polarized light is irradiated in the direction of an arrow 53 as polarized light sheet-like light (that is, illumination light used for inspection) 51. More specifically, if the light emitted from the light sheet illumination unit 31 is circularly polarized light, a so-called λ / 4 plate (that gives a phase difference of 90 degrees) can be used for the phase plate 50. .

FIG. 4 is a perspective view illustrating the polarization direction of the light that has passed through the polarization unit.
The S-polarized light here means light traveling in the direction of the arrow 53 while oscillating in the horizontal direction (that is, the X direction) like a curve SW indicated by a solid line in the drawing. On the other hand, the P-polarized light vibrates in the horizontal direction (that is, the X direction) and the direction orthogonal to the arrow 53 (that is, the combined direction of the X direction and the Y direction) as indicated by a curved line PW indicated by a broken line in the figure. However, it means light traveling in the direction of the arrow 53.

  The S-polarized state here is preferably a state in which only the light of the S-polarized component is completely obtained (that is, the phase plate is 45 degrees), but is not limited to this state, and the light of the S-polarized component. Is a main component, and the set angle of the phase plate 50 is within a range of 45 ° ± 20 °. Similarly, the P-polarization state referred to here is preferably a state in which only the light of the P-polarization component is completely obtained (that is, the phase plate is 0 degree). This means a state in which light is a main component, and the setting angle of the phase plate 50 is within a range of 0 ° ± 20 °.

The polarization direction switching unit 6 switches the polarization unit to the S polarization state or the P polarization state.
Specifically, the polarization direction switching unit 6 includes a hollow holder 60 to which the phase plate 50 is attached and a rotating mechanism 61 that rotates the hollow holder 60. The imaging camera 42, the lens 43, and the phase plate 50 are attached to the hollow holder 60 in a state where their optical axes coincide with each other, and their optical axes and the rotation center axes of the hollow holder 60 also coincide with each other. Therefore, the polarization direction switching unit 6 can switch the S polarization state or the P polarization state by rotating the phase plate 60 of the polarization unit 5 around the optical axis by controlling the rotation mechanism 61 with a signal from an external device. it can.

  The foreign object inspection unit 7 is based on the image captured by the image capturing unit 4 and the position and size of the foreign material attached to the first main surface S1 side (that is, the front surface side) and the second main surface S2 side (that is, the back surface side) of the substrate W. It is to check the thickness. Further, the foreign matter inspection unit 7 will be described in detail later. Whether the detected foreign matter is on the first main surface S1 side (that is, the front surface side) or the second main surface S2 side (that is, the back surface side) of the substrate W is individually determined. It is to be judged.

The foreign matter inspection unit 7 includes an S polarization inspection result output unit, a P polarization inspection result output unit, an inspection result comparison unit, and a foreign matter adhesion surface determination unit.
The S-polarized light inspection result output unit outputs a result obtained by switching and imaging the polarizing unit 5 to the S-polarized state.
The P-polarization inspection result output unit outputs a result of imaging and inspection by switching the polarization unit 5 to the P-polarization state.
The inspection result comparison unit compares inspection results output from the S-polarization inspection result output unit and the P-polarization inspection result output unit.
As a result of comparing the scattered light intensity at the same position on the substrate to be inspected by the inspection result comparison unit,
If “scattered light intensity in S-polarized state> scattered light intensity in P-polarized state”, it is determined that foreign matter is attached to the surface side of the substrate to be inspected.
If “scattered light intensity in the P-polarized state> scattered light intensity in the S-polarized state”, it is determined that foreign matter is attached to the back side of the substrate to be inspected.

  More specifically, the foreign matter inspection unit 7 can be configured by a so-called image processing apparatus IM (hardware) and an image processing program (software). Then, after the video signal and image data output from the imaging camera 42 and the imaging camera 47 are input to the image processing apparatus IM, the foreign substance inspection unit 7 performs predetermined image processing and sets a predetermined inspection standard. Inspection based on

  As specific image processing in the foreign matter inspection unit 7, the bright spot included in the image is detected, the particle size as the foreign matter is determined from the brightness information of each bright spot, the number of occupied pixels, etc., and the coordinates in the imaging field of view An example is a form in which labeling is performed while being linked to information, and inspection is performed to determine how many foreign particles having a particle size exist on the substrate (so-called foreign matter detection inspection). In this foreign object detection inspection, the illumination light 53 used for the inspection is switched between the S-polarized state and the P-polarized state, the inspection results are output, and the inspection results are compared. It is judged whether it adheres to.

[Processing flow at the foreign substance inspection unit]
FIG. 5 is a flowchart showing the inspection process in an example of the embodiment of the present invention in time series, and shows an example of the inspection process in the foreign substance inspection unit according to the present invention.

  First, the substrate W to be inspected is placed on the substrate platform 20 (step s10).

Then, signal control is performed on the rotation mechanism 61 of the polarization direction switching unit 6 to rotate the hollow holder 60, and the phase plate 50 of the polarization unit 5 is switched to the S polarization state. In this state, the imaging camera 42 of the imaging unit 4 captures an image of the inspection target region R (step s11).
Then, an image captured in the S-polarized state is acquired by the image processing apparatus IM, and an inspection result (referred to as “S-polarized inspection result” for convenience) is acquired based on this image (step s12).

  Next, signal control is performed on the rotation mechanism 61 of the polarization direction switching unit 6 to rotate the hollow holder 60 to switch the phase plate 50 of the polarization unit 5 to the P polarization state. In this state, the imaging camera 42 of the imaging unit 4 captures an image of the inspection target region R (step s13).

  Then, an image captured in the P-polarized state is acquired by the image processing apparatus IM, and an inspection result (referred to as “P-polarized inspection result” for convenience) is acquired based on this image (step s14).

  Then, the S polarization inspection result and the P polarization inspection result are compared in the image processing apparatus IM (step s15). At this time, since the imaging camera 42 of the imaging unit 4 is disposed at an angle θ2 with respect to the normal line of the substrate W, the position information of the detected foreign matter is attributed to the thickness of the substrate W. Position correction is performed in a coordinate system in plan view of the substrate W so that no deviation occurs between the first main surface S1 side (that is, the front surface side) and the second main surface S2 side (that is, the back surface side).

Then, a comparison process is performed on the foreign matter at the same position in the coordinate system in plan view of the substrate W,
If “scattered light intensity in S-polarized state> scattered light intensity in P-polarized state”, on the surface side of the substrate,
If “scattered light intensity in the P-polarized state> scattered light intensity in the S-polarized state”, it is determined that foreign matter is attached to the back side of the substrate (step s16).

Note that the order of steps s11 to s12 and s13 to 14 described above may be reversed.
[Examples of inspection targets and inspection results]
FIG. 6 is a plan view showing an example of a substrate to be inspected in an example of a form embodying the present invention. FIG. 6 shows a large foreign matter X1 and a small foreign matter X2 on the first main surface S1 side (that is, the front surface side) of the substrate W to be inspected, and a large foreign matter on the second main surface S2 side (that is, the back surface side) of the substrate W. A state in which X3 and a small foreign matter X4 are attached is shown.
FIG. 7 is an image diagram showing an example of each result inspected in an example of a form embodying the present invention. FIG. 7A shows a captured image in the above-described step s11 (that is, the S-polarized state), and FIG. 7B shows a captured image in the above-described step s13 (that is, the P-polarized state). Yes.

In FIG. 7C, a large foreign matter X1 and a small foreign matter X3 are attached as the inspection result on the first main surface S1 side (that is, the front side) of the substrate W output in step s17. It is shown.
Further, in FIG. 7D, a large foreign matter X2 and a small foreign matter X4 are attached as the inspection result on the second main surface S2 side (that is, the back side) of the substrate W output in step s17 described above. The situation is shown.

  As an output example of the inspection result, FIGS. 7C and 7D illustrate a form in which the foreign substances X1 to X4 are plotted on the XY coordinates of the substrate W. However, the present invention is not limited to this form. Alternatively, the output may be in the form of numerical data.

  The relative movement unit 8 moves the illumination unit 3 and the imaging unit 4 relative to the substrate W to be inspected. The relative movement unit 8 uses the illumination unit 3 and the imaging unit 4 configured to capture only a part of the area of the substrate W, and performs all of the inspection target areas set on the substrate W by a scanning operation and a step-and-repeat operation. It enables imaging.

  Specifically, the relative movement unit 8 can be realized using a so-called XY stage, and is attached on the apparatus frame 11 to move the slider in the X direction at a predetermined speed and to stop at a predetermined position. An axis stage 81 and a Y-axis stage 82 that is mounted on the slider of the X-axis stage 81 and moves the slider in the Y direction at a predetermined speed and stops at a predetermined position are configured. On the slider of the Y-axis stage 82, the substrate mounting table 20 is attached. By doing so, the illumination unit 3 and the imaging unit 4 can be moved relative to the substrate W placed on the substrate mounting table 20, and the entire substrate W is imaged and inspected by being divided and scanned a plurality of times. be able to.

  Further, if necessary, a configuration in which a rotary table mechanism is provided between the slider of the Y-axis stage 82 and the substrate mounting table 20 may be adopted. By doing so, it is possible to change the angle of the substrate W, correct the positional deviation of the substrate W, and change the direction of imaging / inspection and receipt / delivery of the substrate to 90 degrees, 180 degrees, and 270 degrees. Can be.

  In applying the present invention, in the above description, the configuration in which the substrate W is continuously moved while illuminating the light sheet-like illumination light from the illumination unit 3 and the line sensor of the imaging unit 4 captures an image is shown. With such a configuration, it is possible to perform imaging while continuously moving in the Y direction, so that time can be shortened and no special optical correction is required, so that a quick inspection is possible.

  However, the present invention is not limited to such a configuration, and the relative movement unit moves and stops the substrate W by a step-and-repeat method, the illumination unit includes a surface illumination, the imaging unit includes an area sensor, and is intermittent. Alternatively, the inspection target region R set on the substrate W may be divided and imaged.

  Note that when imaging is performed by the step-and-repeat method or the collective imaging method, the imaging unit 4 is inclined with respect to the normal H1 of the inspection target region R set on the substrate W at a predetermined angle θ2, so that the trapezoidal shape. What is necessary is just to correct | amend the image imaged above to the rectangle, or to image using a tilt correction lens.

  Further, instead of performing the divided imaging as described above, the entire surface of the substrate W may be set as the inspection target region R, and a configuration of a collective imaging method in which illumination light irradiation and imaging are performed at a time may be employed.

[Setting the polarization direction]
FIG. 8 is a correlation diagram showing the relationship between the setting direction of the polarizing plate used to embody the present invention and the scattered light intensity.
FIG. 8 shows scattered light from a foreign substance imaged by the imaging camera 42 of the imaging unit 4 when the set angle of the phase plate 50 of the polarizing unit 5 (that is, the polarization direction of the illumination light 51 used for inspection) is changed. Intensity is indicated. At this time, the substrate W was made of transparent non-alkali glass having a thickness t of 0.3 mm. Then, with respect to the normal line H1 of the first main surface S1 of the substrate W, the angle θ1 of the light 53 that is polarized by the polarization unit 5 and is applied to the inspection target region R is within 80 degrees ± 5 degrees. The devices of the illumination unit 3, the imaging unit 4, and the polarization unit 5 are arranged so that the imaging angle θ2 is within 45 ° ± 5 °.

  FIG. 8 shows a case where standard particles having a particle size of 1 μm are attached as foreign matter to the surface S1 side of the substrate W, and a case where standard particles having a particle size of 10 μm are attached as foreign matter to the back surface S2 side of the substrate W. Is shown in combination. Referring to FIG. 8, for the foreign matter attached to the surface side of the substrate (that is, the first main surface S1 side of the substrate W), the setting angle of the phase plate 50 is preferably 25 to 45 degrees (that is, the S-polarized state). Is 45 degrees (perfect S-polarized light), the setting angle of the phase plate 50 is 0 to 20 degrees (that is, P-polarized state), and preferably the scattered light intensity is stronger than 0 degree (perfect P-polarized light). I understand that. On the other hand, for the foreign matter attached to the back surface side of the substrate (that is, the second main surface S2 side of the substrate W), the set angle of the phase plate 50 is 0 to 20 degrees (that is, the P polarization state), preferably 0 degrees ( In the case of complete P-polarized light, the scattered light intensity is stronger than the setting angle of the phase plate 50 of 25 to 45 degrees (that is, S-polarized state), preferably 45 degrees (complete S-polarized light).

  Therefore, in the substrate inspection apparatus 1 embodying the present invention, imaging / inspection is performed with the set angle of the phase plate 50 set to the S-polarization state and the P-polarization state, and the inspection results are compared. When foreign matter is detected at the same position on the substrate W, the result of inspection in the S-polarized state is compared with the result of inspection in the P-polarized state, and the S-polarized scattered light intensity is higher than the P-polarized scattered light intensity. For example, it is determined that foreign matter is attached to the front surface S1 side of the substrate W, and it is determined that foreign matter is attached to the rear surface S2 side of the substrate W if the P-polarized scattered light intensity is higher than the S-polarized scattered light intensity.

  FIG. 9 is a correlation diagram comparing intensities of scattered light from foreign matters adhering to the front and back surfaces of the substrate by applying the present invention. In FIG. 9A, standard particles having different particle diameters as foreign substances are attached only to the surface S1 side of the substrate W, and the illumination light 51 used for inspection is switched between the S-polarized state and the P-polarized state and irradiated. The scattered light intensity in the state is shown. On the other hand, in FIG. 9B, standard particles having different particle diameters as foreign matters are attached only to the back surface S2 side of the substrate W, and illumination light 51 used for inspection is irradiated while switching between the S-polarized state and the P-polarized state, The scattered light intensity in each state is shown. At this time, with respect to the normal H1 of the first main surface S1 of the substrate W, the angle θ1 of the light 53 that is polarized by the polarizing unit 5 and is applied to the inspection target region R is within 80 ° ± 5 °, and the imaging camera 42 The illumination unit 3, the imaging unit 4, and the polarization unit 5 are arranged so that the angle θ <b> 2 for imaging at 45 ° ± 5 ° or less.

  9A and 9B, the scattered light intensity in the S-polarized state is the scattered light in the P-polarized state if the foreign matter adheres to the surface S1 side of the substrate W even though the particle diameters are different. It turns out that it is stronger than strength. On the other hand, even if the particle sizes are different, it can be seen that if the foreign matter adheres to the back surface S2 side of the substrate W, the scattered light intensity in the P-polarized state is stronger than the scattered light intensity in the S-polarized state.

  Since the substrate inspection apparatus 1 according to the present invention has such a configuration, the position and size of the foreign matter attached to the inspection target region R set on the substrate W is detected, and each foreign matter is detected on the substrate W. It can be accurately determined whether the surface is attached to the front surface S1 side or the back surface S2 side. Even when the substrate to be inspected becomes thin, it is possible to inspect whether the foreign matter attached to the substrate is attached to the front side or the back side of the substrate.

[Illumination light and imaging angle setting]
In the above description, the angle θ1 of the light 53 that is polarized by the polarizing unit 5 and is applied to the inspection target region R with respect to the normal line H1 of the first main surface S1 of the substrate W is within 80 ° ± 5 °. The configuration in which the illumination unit 3, the imaging unit 4, and the polarization unit 5 are arranged so that the angle θ2 captured by the camera 42 is within 45 ° ± 5 ° is illustrated.

  In general, the intensity of the scattered light from the foreign material X varies depending on the angle, and the difference in strength varies depending on the particle size of the foreign material. However, it has been found that if the angles θ1 and θ2 are set as described above, the present invention can be applied to foreign matters having various particle sizes.

  Further, it has been found that the same result can be obtained if the angle formed by these angles θ1 and θ2 (that is, θ1 + θ2) is within 125 ° ± 10 °.

[Other angles of illumination light and imaging]
Further, when it is desired to know the distribution tendency of the foreign matter, when the strictness is not required, or when the particle size of the foreign matter to be inspected is known in advance, it is not limited to the above-described conditions, and is shown below. It was also found that the present invention can be applied under conditions.

  That is, with respect to the normal H1 of the first main surface S1 of the substrate W, the angle θ1 of the light 53 that is polarized by the polarizing unit 5 and is applied to the inspection target region R is in the range of 40 to 85 degrees, The devices of the illumination unit 3, the imaging unit 4, and the polarization unit 5 are arranged so that the angle θ2 captured by the imaging camera 42 is in the range of 0 to 60.

  In addition, although the above-mentioned board | substrate W illustrated about the case where the non-alkali glass whose thickness t is 0.3 mm was used, this invention is applicable even if it is non-alkali glass of other thickness. Furthermore, even if a thin film such as ITO or SiO2 is coated on the front surface S1 side or the back surface S2 side of the substrate W, the present invention can be applied as long as the scattered light intensity from the foreign matter is not affected. it can.

In addition, the condition of the angles θ1 and θ2 as described above, the material and the thickness of the substrate W are not limited, and the foreign matter adhered to the surface S1 side of the substrate is “in the S-polarized state” even under other conditions. Scattered light intensity> scattered light intensity in the P-polarized state ", and the relationship of" scattered light intensity in the P-polarized state> scattered light intensity in the S-polarized state "is established for the foreign matter attached to the back surface S2 side of the substrate. Then, like the above-mentioned determination procedure,
If “scattered light intensity in the S-polarized state> scattered light intensity in the P-polarized state”, foreign matter is attached to the surface side of the substrate, and “scattered light intensity in the P-polarized state> scattered light intensity in the S-polarized state” ", It is possible to apply the present invention by determining that foreign matter is attached to the back side of the substrate.

[Application to second aspect]
In the above description, the mode of simply comparing the scattered light intensity in the S-polarized state and the scattered light intensity in the P-polarized state (that is, the first aspect) has been described.

  However, the present invention is not limited to such a form, and after multiplying either the scattered light intensity in the S-polarized state or the scattered light intensity in the P-polarized state by the magnification factor, the comparison is made by the inspection result comparison unit of the foreign matter inspection unit. May be. Alternatively, the scattered light intensity in the S-polarized state and the scattered light intensity in the P-polarized state may be multiplied by different magnification factors and then compared by the inspection result comparison unit of the foreign matter inspection unit.

And in the foreign substance adhesion surface judgment part of a foreign substance inspection part,
As a result of comparing the scattered light intensity at the same position on the substrate to be inspected by the inspection result comparison unit of the foreign substance inspection unit,
If the condition is “scattered light intensity in the S-polarized state ÷ scattered light intensity in the P-polarized state> k (k is a constant)”, it is determined that foreign matter is attached to the surface side of the substrate to be inspected,
If the condition is “scattered light intensity in the S-polarized state ÷ scattered light intensity in the P-polarized state <k (k is a constant)”, it is determined that the foreign matter is attached to the back side of the substrate to be inspected.

  In this case, with respect to the magnification coefficient and the value of the constant k serving as a determination criterion, the standard particles are scattered on the front surface S1 or the back surface S2 of the substrate W, and the scattered light intensity in the S-polarized state and the scattering in the P-polarized state. The light intensity is measured and set in the foreign matter inspection section after grasping in advance.

  By doing so, it is possible to inspect whether the foreign matter attached to the substrate is attached to the front side or the back side, even if the scattered light intensity is not compared in the first aspect. it can. As a result, the present invention can be applied to substrates of various materials and thicknesses.

[Another form]
In the above description, the relative movement unit 6 that moves the illumination unit 3 and the imaging unit 4 relative to the substrate to be inspected is provided.
The imaging unit 4 includes a line sensor having a predetermined length in a direction orthogonal to the direction of relative movement,
The illumination unit 3 has been described with respect to a configuration that irradiates a light sheet-like illumination light onto an inspection target region imaged by a line sensor.

  If it is this structure, since it can test | inspect using a line sensor with high resolution and can minimize the irradiation range of an illumination light beam, cost reduction and size reduction become easy. Furthermore, the scattered light from other foreign substances existing on the same surface (first main surface when inspecting the first main surface) or on the opposite side (second main surface when inspecting the first main surface) is simultaneously imaged. Therefore, it is possible to prevent a problem that a desired inspection result cannot be obtained correctly.

  However, in order to embody the present invention, the present invention is not limited to this configuration, and the following configuration may be used. That is, an area sensor is used for the imaging unit 4, and the illumination unit 3 is configured to irradiate illumination light to a range including an inspection target region imaged by the area sensor. In this case, the illumination unit 3 and the imaging unit 4 are relatively moved with respect to the substrate W to be inspected, and the illumination light is stroboscopically emitted to repeat imaging (so-called divided imaging), or the illumination light is continuously irradiated. However, the configuration is such that imaging is performed intermittently (also a type of divided imaging). Alternatively, the relative movement unit 8 may be omitted, and the inspection target region R may be collectively imaged using an area sensor camera.

  The relative movement unit 8 is not limited to the above-described configuration, but is configured to transfer the substrate W using a rotating roller (so-called conveyor transfer), or configured to transfer using a walking beam and a gripping unit ( So-called shuttle transport) may be used.

DESCRIPTION OF SYMBOLS 1 Board | substrate inspection apparatus 2 Board | substrate holding part 3 Illumination part 4 Imaging part 5 Polarization part 6 Polarization direction switching part 7 Foreign material inspection part 8 Relative movement part 11 Apparatus frame 15 Connecting member 20 Substrate mounting base 21 Positioning reference pin 31 Light sheet illumination unit 32 Light sheet-like illumination light 32t Light sheet-like illumination light thickness 33 Arrow (light traveling direction)
34 Arrow (light polarization direction)
41 substrate first main surface side imaging unit 42 imaging camera 42z imaging camera 43 lens 43z lens 44 imaging device 50 phase plate 51 illumination light on polarized light sheet (illumination light used for inspection)
53 Arrow (direction of light travel)
60 Hollow holder

R Inspection target area R1 Inspection target area (first main surface side)
R2 Inspection target area (second main surface side)
W substrate S1 first main surface of substrate (surface of substrate)
S2 Second main surface of substrate (back surface of substrate)
θ1 Predetermined angle (angle of polarized illumination light)
θ2 Predetermined angle (angle of imaging camera)
X Foreign matter X1 Foreign matter X2 Foreign matter X3 Foreign matter X4 Foreign matter

Claims (6)

A substrate holding unit for holding a substrate to be inspected;
An illumination unit that irradiates illumination light toward the inspection target region set on the substrate;
An imaging unit for imaging scattered light emitted from the inspection target region;
A polarizing section that changes a vibration direction of the illumination light;
A polarization direction switching unit that switches the polarization unit to an S polarization state or a P polarization state;
A foreign matter inspection unit that inspects the position and size of foreign matter attached to the front or back side of the substrate to be inspected based on the image captured by the imaging unit,
In the foreign matter inspection section,
An S-polarization inspection result output unit that outputs a result of imaging and inspection by switching the polarization unit to an S-polarization state;
A P-polarization inspection result output unit for switching the polarization unit to a P-polarization state and outputting a result of imaging and inspection;
An inspection result comparison unit for comparing inspection results output from the S polarization inspection result output unit and the P polarization inspection result output unit;
As a result of comparing the scattered light intensity at the same position on the substrate to be inspected by the inspection result comparison unit,
If “scattered light intensity in S-polarized state> scattered light intensity in P-polarized state”, it is determined that foreign matter is attached to the surface side of the substrate to be inspected.
If “scattering light intensity in the P-polarized state> scattered light intensity in the S-polarized state”, a foreign matter attachment surface determination unit is provided that determines that foreign matter is attached to the back side of the substrate to be inspected.
Board inspection equipment. A substrate holding unit for holding a substrate to be inspected;
An illumination unit that irradiates illumination light toward the inspection target region set on the substrate;
An imaging unit for imaging scattered light emitted from the inspection target region;
A polarizing section that changes a vibration direction of the illumination light;
A polarization direction switching unit that switches the polarization unit to an S polarization state or a P polarization state;
A foreign matter inspection unit that inspects the position and size of foreign matter attached to the front or back side of the substrate to be inspected based on the image captured by the imaging unit,
In the foreign matter inspection section,
An S-polarization inspection result output unit that outputs a result of imaging and inspection by switching the polarization unit to an S-polarization state;
A P-polarization inspection result output unit for switching the polarization unit to a P-polarization state and outputting a result of imaging and inspection;
An inspection result comparison unit that multiplies and compares at least one of the inspection result output from the S polarization inspection result output unit and the inspection result output from the P polarization inspection result output unit;
As a result of comparing the scattered light intensity at the same position on the substrate to be inspected by the inspection result comparison unit,
If “scattered light intensity in the S-polarized state ÷ scattered light intensity in the P-polarized state> k (k is a constant)”, it is determined that foreign matter is attached to the surface side of the substrate to be inspected.
If “scattered light intensity in S-polarized state ÷ scattered light intensity in P-polarized state <k (k is a constant)”, it is determined that foreign matter is attached to the back side of the substrate to be inspected. A substrate inspection apparatus provided with a determination unit. The substrate to be inspected is a transparent glass substrate,
The light that is polarized by the polarizing unit and is irradiated toward the inspection target region is disposed so as to be irradiated at an angle of 40 to 85 degrees with respect to the normal line of the inspection target region.
The said imaging part is arrange | positioned so that the said test object area | region may be observed at an angle of 0 to 60 degree | times with respect to the normal line of the said test object area | region, The Claim 1 or Claim 2 characterized by the above-mentioned. Board inspection equipment. The substrate to be inspected is a transparent glass substrate,
The light that is polarized by the polarizing unit and is emitted toward the inspection target region and the scattered light that is imaged by the imaging unit are within 125 ° ± 10 ° across the normal of the inspection target region. The board inspection apparatus according to claim 1, wherein the board inspection apparatus is set. The substrate to be inspected is a transparent glass substrate,
The light that is polarized by the polarizing unit and is irradiated toward the inspection target region is arranged so as to be irradiated at an incident angle within 80 degrees ± 5 degrees with respect to the normal line of the inspection target region.
5. The substrate according to claim 4, wherein the imaging unit is arranged to image the inspection target region at an angle within 45 degrees ± 5 degrees with respect to a normal line of the inspection target region. Inspection device. A relative movement unit that moves the illumination unit and the imaging unit relative to the substrate in a direction parallel to the inspection target region;
The illumination unit irradiates a light sheet-shaped illumination light having a predetermined length in a direction orthogonal to the relatively moving direction toward the inspection target region,
The substrate inspection apparatus according to claim 1, wherein the imaging unit is a line sensor arranged in a direction aligned with a longitudinal direction of the illumination light applied to the inspection target region. .