JP2009244091A - Substrate inspection apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a detection precision of defects by eliminating the influence of noise at the peripheral section of a substrate in an inspection of defects in the transparent substrate have a large plate thickness. <P>SOLUTION: An inspection table 5 supports the square, transparent substrate 1 only by the two opposing sides. A light projection system obliquely irradiates the surface of the substrate 1 with rays, moves the rays by a prescribed distance in a direction vertical to the two supported sides of the substrate 1, and scans the substrate 1 with the rays. A CPU 60 excludes the irradiation range of rays that are scattered by a taper of the edge of the substrate 1 and generates scattered light to the surface of the substrate 1 and the irradiation range of rays that are scattered by the inspection table 5 and generate scattered light onto the surface of the substrate 1, determines the inspection range of the substrate 1, detects a position on the surface of the substrate 1 irradiated with rays, and detects the position of a defect detected by defect detection circuits 25, 35. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a substrate inspection apparatus and a substrate inspection method for detecting a defect in a substrate having a large thickness such as a glass substrate or a quartz substrate used for an exposure mask or the like, and particularly suitable for inspecting a transparent substrate. The present invention relates to an inspection apparatus and a substrate inspection method.

  Manufacturing of TFT (Thin Film Transistor) substrates, color filter substrates, plasma display panel substrates, organic EL (Electroluminescence) display panel substrates, etc. of liquid crystal display devices used as display panels is performed by using an exposure apparatus and a photomask. This pattern is transferred to a panel substrate such as a glass substrate or a plastic substrate. A photomask is manufactured by forming a chromium film or the like that blocks light other than a pattern portion on the surface of a mask substrate such as a glass substrate or a quartz substrate. If a defect such as a scratch or a foreign substance exists on the mask substrate, the formation of the chromium film or the like and the transfer of the pattern are not performed satisfactorily, causing a defect. For this reason, a defect inspection of a mask substrate is performed using a substrate inspection apparatus.

In the inspection of the mask substrate by the conventional substrate inspection apparatus, the inspection is performed while supporting the four sides or the four corners of the rectangular mask substrate so as not to contact the mask substrate as much as possible. However, when supporting the four sides or the four corners of the substrate as in the conventional case, if the back surface of the substrate is not supported at all, the substrate bends in a mortar shape due to its own weight, and the amount of deflection increases especially as the substrate becomes larger. For this reason, in order to adjust the focal position of the optical system to the substrate with a conventional substrate inspection apparatus, a complicated calculation is performed to analyze the deflection of the substrate, or the height of the surface of the substrate using an autofocus mechanism or the like. It was necessary to actually move the substrate or the optical system up and down according to the complicated deflection of the substrate. On the other hand, in Patent Document 1, the substrate is supported by only two sides facing each other, and the substrate support means or the optical system is moved up and down in accordance with the deflection of the supported substrate, so that the focal position of the optical system is determined. A technique for easily performing the adjustment is disclosed.
JP 2007-107884 A

  The substrate inspection apparatus described in Patent Document 1 inspects a mask substrate with a film on which a pattern is formed by a chromium film or the like for defects such as foreign matter and chromium film pinholes. The inspection light applied to the chromium film portion of the mask substrate is reflected by the chromium film, and if there is a pinhole in the chromium film, the inspection light is transmitted only at the pinhole. Therefore, in the peripheral portion of the mask substrate covered with the chromium film, the inspection light did not pass through the inside of the mask substrate unless there was a pinhole in the chromium film.

  Using the technique described in Patent Document 1, when the inspection of the transparent mask substrate was performed on the entire surface without the chromium film, the inspection light transmitted to the inside of the mask substrate at the periphery of the mask substrate was Scattered by the edge taper or the substrate support that supports the substrate, scattered light is generated, and these are detected as noise.

  An object of the present invention is to eliminate the influence of noise around the periphery of a substrate in a defect inspection of a transparent substrate having a large plate thickness and to improve the defect detection accuracy.

  The substrate inspection apparatus according to the present invention includes an inspection table that supports a rectangular transparent substrate only on two sides facing each other, and a light beam that is perpendicular to the two sides supported by the substrate while obliquely irradiating the surface of the substrate with the light beam. A light receiving system that moves a predetermined distance in the direction and scans the substrate, and a light receiving unit that bundles a lens and a plurality of optical fibers, and receives the scattered light that is scattered by the defect of the substrate. A first moving means for relatively moving the system, the inspection table, the light projecting system and the light receiving system in a direction parallel to the two sides supported by the substrate; and a first control for controlling the first moving means. A second moving means for moving the inspection table, the light projecting system and the light receiving system relative to each other in a direction perpendicular to the two sides supported by the substrate to change the scanning range of the substrate by the light beam; The second control means for controlling the two moving means and the light receiving system Detection means for detecting a defect of the substrate from the scattered light, and determining the inspection range of the substrate and instructing the first control means and the second control means to detect the position on the surface of the substrate irradiated with the light beam And processing means for detecting the position of the defect detected by the detection means, and the processing means irradiates the surface of the substrate with a light beam scattered by the edge taper of the substrate and generates scattered light, and inspection. The inspection range of the substrate is determined by excluding the irradiation range of the light beam scattered by the table and generating scattered light on the surface of the substrate.

  In the substrate inspection method of the present invention, a rectangular transparent substrate is supported by only two opposite sides by the inspection table, and the light beam scattered by the taper of the edge of the substrate to generate scattered light is applied to the surface of the substrate. Exclude the irradiation range and the irradiation range to the substrate surface of the light beam scattered by the inspection table to generate scattered light, determine the inspection range of the substrate, and irradiate the light beam obliquely from the light projection system to the surface of the substrate While moving the light beam by a predetermined distance in the direction perpendicular to the two sides supported by the substrate, the substrate is scanned, and the inspection table, the light projecting system and the light receiving system are relatively supported by the substrate. Move in the direction parallel to the two sides, move the inspection table, the light projecting system and the light receiving system in a direction relatively perpendicular to the two sides supported by the substrate, change the scanning range of the substrate by the light beam, Repeat these steps to apply light to the entire inspection range. The substrate is scanned, the scattered light scattered by the defects on the substrate is received by the light receiving system, the defect on the surface of the substrate is detected from the received scattered light, and the surface of the substrate irradiated with the light is detected. The position of the detected defect is detected by detecting the position.

  The inspection table supports a rectangular transparent substrate only on its two opposite sides, and irradiates light rays from the light projecting system obliquely onto the surface of the substrate, while irradiating the light rays in a direction perpendicular to the two supported sides of the substrate. The distance between the inspection table, the light projecting system, and the light receiving system is relatively moved in a direction parallel to the two sides supported by the substrate. And the light receiving system is moved in a direction perpendicular to the two sides supported by the substrate, the scanning range of the substrate by the light beam is changed, and these steps are repeated to scan the substrate by the light beam over the entire inspection range. . At this time, when the entire substrate is set as the inspection range, the light beam directly irradiated to the taper at the edge of the substrate is scattered by the taper at the edge of the substrate in the peripheral portion of the substrate, and scattered light is generated. In addition, light rays that have been transmitted into the substrate, reflected by the back surface of the substrate, and applied to the taper at the edge of the substrate are scattered by the taper at the edge of the substrate, generating scattered light. In the direction perpendicular to the two supported sides of the substrate, the light beam that has passed through the substrate, is emitted from the back surface of the substrate, and is irradiated onto the inspection table is scattered by the inspection table to generate scattered light. . And these scattered lights are detected as noise, and the detection accuracy of a defect falls. In the present invention, the irradiation range of the light beam scattered by the edge of the substrate and generating scattered light to the surface of the substrate, and the irradiation range of the light beam scattered by the inspection table and generating the scattered light to the surface of the substrate. Since the inspection range of the substrate is determined by excluding it, the influence of noise around the substrate is eliminated, and the defect detection accuracy is improved.

  Further, in the substrate inspection apparatus of the present invention, the inspection table has a substrate support portion having an inclined surface that contacts the bottoms of the two opposite sides of the substrate, and the processing means is transmitted to the inside of the substrate and on the back surface of the substrate. The light beam reflected and irradiated to the taper corner of the edge of the substrate passes from the irradiation position on the surface of the substrate to the edge of the substrate, passes through the inside of the substrate and is emitted from the back surface of the substrate to the corner of the substrate support section. The inspection range in the direction perpendicular to the two supported sides of the substrate is determined by excluding the irradiation position of the irradiated light from the surface of the substrate to the edge of the substrate. In the substrate inspection method of the present invention, the inspection table is provided with a substrate support portion having an inclined surface that contacts the bottoms of the two opposite sides of the substrate, and is transmitted to the inside of the substrate and reflected by the back surface of the substrate. From the irradiation position on the front surface of the substrate to the edge of the substrate from the irradiation position of the light beam to the corner of the edge taper, the light beam transmitted to the inside of the substrate and emitted from the back surface of the substrate and irradiated to the corner of the substrate support section The inspection range in the direction perpendicular to the two supported sides of the substrate is determined by excluding from the irradiation position on the surface of the substrate to the edge of the substrate.

  In the direction perpendicular to the two sides supported by the substrate, the light beam is moved by a predetermined distance, the substrate is scanned by the light beam, and the inspection table, the light projecting system and the light receiving system are relatively supported by the substrate. Moving in the direction perpendicular to the two sides, the scanning range of the substrate by the light beam is changed. At this time, assuming that the entire width in the direction perpendicular to the two supported sides of the substrate is the inspection range, the light beam directly irradiated to the taper corner of the edge of the substrate in the peripheral portion of the two supported sides of the substrate, and Light rays that are transmitted into the substrate, reflected by the back surface of the substrate, and applied to the taper corner of the substrate edge are scattered by the taper corner of the substrate edge, and scattered light is generated. In addition, light rays that have been transmitted through the substrate and emitted from the back surface of the substrate and applied to the corners of the substrate support portion of the inspection table are scattered by the corners of the substrate support portion, and scattered light is generated. The irradiation position of the light beam that is transmitted into the substrate and reflected by the back surface of the substrate and applied to the taper corner of the substrate edge on the surface of the substrate is the position of the light beam directly applied to the taper corner of the substrate edge. It is inside the substrate with respect to the irradiation position on the surface of the substrate, and changes according to the thickness of the substrate. The irradiation position on the surface of the substrate of the light beam that is transmitted into the substrate and emitted from the back surface of the substrate and irradiated on the corners of the substrate support portion also changes according to the thickness of the substrate. Therefore, the light beam that is transmitted to the inside of the substrate, reflected from the back surface of the substrate, and irradiated to the taper corner of the substrate edge is transmitted from the irradiation position to the substrate edge to the inside of the substrate. Inspection range in the direction perpendicular to the two supported sides of the substrate, excluding from the irradiation position on the surface of the substrate to the edge of the substrate, which is emitted from the back surface of the substrate and irradiated to the corner of the substrate support section To decide. In the direction perpendicular to the two supported sides of the substrate, the irradiation range of the light beam that is scattered by the taper at the edge of the substrate and generates scattered light, and the light beam that is scattered by the inspection table and generates scattered light The irradiation range on the surface of the substrate is surely excluded from the inspection range.

  Further, in the substrate inspection apparatus of the present invention, the processing means transmits the light beam directly irradiated onto the taper corner of the substrate edge from the irradiation position to the edge of the substrate to the edge of the substrate and passes through the inside of the substrate. Inspection in a direction parallel to the two supported sides of the substrate, excluding from the irradiation position on the surface of the substrate to the edge of the substrate, which is reflected from the back surface of the substrate and irradiated to the taper corner of the substrate edge The range is determined. Further, the substrate inspection method of the present invention transmits the light beam directly irradiated to the taper corner of the substrate edge from the irradiation position to the substrate edge to the inside of the substrate and reflects on the back surface of the substrate. The inspection range in the direction parallel to the two supported sides of the substrate is determined by excluding from the irradiation position of the light beam applied to the taper corner of the substrate edge to the edge of the substrate. Is.

  In the direction parallel to the two sides supported by the substrate, the inspection table, the light projecting system, and the light receiving system are relatively moved, and the substrate is scanned with the light beam. At this time, if the entire width in the direction parallel to the two supported sides of the substrate is the inspection range, the light beam is obliquely applied to the surface of the substrate, so one side perpendicular to the two supported sides of the substrate In the peripheral portion, only the light beam directly irradiated to the taper corner of the substrate edge is scattered by the taper corner of the substrate edge to generate scattered light. At the periphery of the other side perpendicular to the two supported sides of the substrate, the light beam transmitted to the inside of the substrate, reflected by the back surface of the substrate and irradiated to the taper corner of the substrate edge, and the edge of the substrate Light rays directly applied to the taper corner are scattered by the taper corner of the edge of the substrate, and scattered light is generated. Therefore, the light beam directly radiated onto the taper corner of the substrate is transmitted from the irradiation position on the surface of the substrate to the edge of the substrate and transmitted to the inside of the substrate and reflected by the back surface of the substrate, and the taper of the edge of the substrate is reflected. The inspection range in the direction parallel to the two supported sides of the substrate is determined by excluding from the irradiation position of the light beam irradiated to the corner to the edge of the substrate. In the direction parallel to the two supported sides of the substrate, the irradiation range on the surface of the substrate that is scattered by the taper of the edge of the substrate and generates scattered light is reliably excluded from the inspection range.

  According to the present invention, the irradiation range of the light beam scattered by the edge taper of the substrate to generate the scattered light on the surface of the substrate, and the irradiation of the light beam scattered by the inspection table to generate the scattered light to the surface of the substrate. By excluding the range and determining the inspection range of the substrate, in the inspection of the defect of the transparent substrate having a large thickness, it is possible to eliminate the influence of the noise in the peripheral portion of the substrate and improve the detection accuracy of the defect. .

  Further, according to the present invention, the inspection table is provided with a substrate support portion having an inclined surface that contacts the bottoms of the two opposite sides of the substrate, transmitted to the inside of the substrate and reflected by the back surface of the substrate, and From the irradiation position of the light beam irradiated to the corner of the taper to the edge of the substrate to the edge of the substrate, the light beam irradiated to the corner of the substrate support part through the inside of the substrate and emitted from the back surface of the substrate The substrate in the direction perpendicular to the two supported sides of the substrate is determined by determining the inspection range in the direction perpendicular to the two supported sides of the substrate, excluding from the irradiation position on the surface to the edge of the substrate. The irradiation range of the light beam scattered by the edge taper to generate the scattered light on the surface of the substrate and the irradiation range of the light beam scattered by the inspection table to generate the scattered light from the inspection range are surely confirmed. Can be excluded.

  Further, according to the present invention, the light beam directly radiated to the taper corner of the substrate edge is transmitted from the irradiation position on the substrate surface to the edge of the substrate and is reflected from the back surface of the substrate. By determining the inspection range in the direction parallel to the two supported sides of the substrate, excluding from the irradiation position of the light beam irradiated to the taper corner of the substrate edge to the edge of the substrate The irradiation range of the light beam that is scattered by the taper of the edge of the substrate and generates scattered light in the direction parallel to the two supported sides of the substrate can be reliably excluded from the inspection range.

  FIG. 1 is a diagram showing a schematic configuration of a substrate inspection apparatus according to an embodiment of the present invention. The substrate inspection apparatus includes an inspection table 5, a light projection system, an angle detector 15, an upper light receiving system 20, a lower light receiving system 30, amplifiers 24 and 34, defect detection circuits 25 and 35, a focus adjustment mechanism 40, and a focus adjustment control circuit 41. , Substrate movement mechanism 50, substrate movement control circuit 51, light projection system movement mechanism 52, light projection system movement control circuit 53, upper light reception system movement mechanism 54, upper light reception system movement control circuit 55, lower light reception system movement mechanism 56, lower The light receiving system movement control circuit 57, the CPU 60, and the memory 70 are included.

  A transparent substrate 1 to be inspected is mounted on an inspection table 5. On the inspection table 5, two substrate support portions extending in the horizontal direction of the drawing are arranged in parallel in the depth direction of the drawing. FIG. 2 is a perspective view of the substrate mounted on the inspection table. Each board | substrate support part 5a has the inclined surface 5b which contacts the board | substrate 1 over the length of the longitudinal direction. When the square substrate 1 is mounted on the inspection table 5, the inclined surface 5b of the substrate support portion 5a comes into contact with the bottoms of the two opposite sides of the substrate 1, and the inspection table 5 holds the square substrate 1 only on the two opposite sides. To support.

  In FIG. 1, a light projection system including a scanning unit 10 and a mirror 14 is disposed above the substrate 1 mounted on the inspection table 5. FIG. 3 is a top view of the scanning unit. The scanning unit 10 includes a laser light source 11, a lens 12a, an fθ lens 12c, and a polygon mirror 13. The laser light source 11 generates a laser beam as inspection light. The lens 12 a condenses the laser beam generated from the laser light source 11 and converges so as to be focused on the surface of the substrate 1. The laser beam condensed by the lens 12a is reflected by the polygon mirror 13 and enters the fθ lens 12c. The fθ lens 12c aligns the focal plane of the laser beam shaken by the rotation of the polygon mirror 13 with the planar position. The laser beam transmitted through the fθ lens 12c is applied to the mirror 14 in FIG. The mirror 14 obliquely irradiates the surface of the substrate 1 with the laser beam emitted from the scanning unit 10. At this time, when the polygon mirror 13 rotates in the direction of the arrow in FIG. 3, the laser beam irradiated from the mirror 14 to the surface of the substrate 1 moves in the depth direction of FIG. 1 to scan the substrate 1 with the laser beam. Is called. In the present embodiment, as an example, the scanning range is 200 mm.

  In FIG. 1, the CPU 60 determines the inspection range of the substrate 1 as described later, and instructs the substrate movement control circuit 51 to move the substrate 1. The substrate movement control circuit 51 drives the substrate movement mechanism 50 according to an instruction from the CPU 60. The substrate moving mechanism 50 includes, for example, a linear motor, and moves the inspection table 5 in the lateral direction of the drawing. When the substrate moving mechanism 50 moves the inspection table 5, the substrate 1 mounted on the inspection table 5 is moved in the substrate moving direction indicated by the arrow, and the laser beam from the light projecting system has a length in the horizontal direction of the substrate 1 in the drawing. Irradiated over. Therefore, the substrate 1 is inspected by the width of the scanning range in the drawing depth direction by one movement of the inspection table 5.

  Subsequently, the CPU 60 instructs the projection system movement control circuit 53 to change the scanning range. The light projecting system movement control circuit 53 drives the light projecting system moving mechanism 52 according to an instruction from the CPU 60. The light projection system moving mechanism 52 includes, for example, a linear motor, and moves the light projection system in the drawing depth direction. When the light projection system moving mechanism 52 moves in the light projection system, the scanning range of the substrate 1 by the laser beam from the light projection system is changed in the drawing depth direction. Then, the entire inspection range of the substrate 1 is inspected by repeatedly scanning the substrate 1 with the laser beam, moving the inspection table 5, and changing the scanning range.

  When moving the light projecting system in the depth direction of the drawing, the upper light receiving system 20 and the lower light receiving system 30 are moved as much as the light projecting system. The CPU 60 instructs the upper light receiving system movement control circuit 55 and the lower light receiving system movement control circuit 57 to move. The upper light reception system movement control circuit 55 and the lower light reception system movement control circuit 57 drive the upper light reception system movement mechanism 54 and the lower light reception system movement mechanism 56, respectively, according to instructions from the CPU 60. The upper light receiving system moving mechanism 54 and the lower light receiving system moving mechanism 56 are configured to include, for example, a linear motor, and move the upper light receiving system 20 and the lower light receiving system 30 as much as the light projecting system.

  Instead of moving the inspection stage 5, the substrate 1 and the light projecting system may be relatively moved in a direction orthogonal to the scanning direction of the laser beam by moving the light projecting system in the lateral direction of the drawing. In that case, the upper light receiving system and the lower light receiving system are moved together with the light projecting system. Further, instead of moving the light projecting system, the inspection stage 5 is moved in the depth direction of the drawing, so that the substrate 1 and the light projecting system are moved relatively in the laser beam scanning direction, thereby scanning the substrate by the laser beam. May be changed.

  A part of the laser beam irradiated obliquely onto the substrate 1 is reflected by the surface of the substrate 1 and a part of the laser beam is transmitted into the substrate 1. The laser beam transmitted to the inside of the substrate 1 spreads away from the surface of the substrate 1, a part of which is reflected by the back surface of the substrate 1, and a part is emitted from the back surface of the substrate 1 to the outside of the substrate 1.

  On the surface side of the substrate 1, the upper light receiving system 20 is disposed at a position off the optical axis of the laser beam reflected by the surface of the substrate 1. The upper light receiving system 20 includes a lens 21, a light receiving unit 22, and a photomultiplier tube 23. FIG. 4 is a top view of the upper light receiving system. The lens 21 collects scattered light from the substrate 1 and irradiates the light receiving unit 22. The focal position of the lens 21 matches the surface of the substrate 1. The light receiving unit 22 is configured by bundling a plurality of optical fibers 22 a, receives scattered light collected by the lens 21, and guides it to the light receiving surface of the photomultiplier tube 23. The photomultiplier tube 23 outputs a detection signal corresponding to the intensity of scattered light received by the light receiving surface. In FIG. 1, the detection signal of the photomultiplier tube 23 is amplified by an amplifier 24 and input to the defect detection circuit 25.

  When a defect exists on the surface of the substrate 1, the laser beam irradiated on the surface of the substrate 1 is scattered by the defect, and scattered light is generated. Further, the laser beam that has been transmitted into the substrate 1 and reflected by the back surface of the substrate 1 and has reached the surface of the substrate 1 again is scattered by defects, and scattered light is generated. These scattered lights are received by the upper light receiving system 20 disposed on the surface side of the substrate 1. When a defect exists inside the substrate 1, the laser beam transmitted to the inside of the substrate 1 is scattered by the defect, and scattered light is generated. Further, the laser beam that has passed through the inside of the substrate 1 and has been reflected by the back surface of the substrate 1 is scattered by the defect, and scattered light is generated. These scattered lights pass through the substrate 1 and are received by the upper light receiving system 20 disposed on the surface side of the substrate 1. Scattered light generated due to defects on the surface of the substrate 1 has a higher intensity received by the light receiving unit 22 of the upper light receiving system 20 than scattered light generated due to defects inside the substrate 1. The defect detection circuit 25 detects a defect on the surface of the substrate 1 from the intensity of the detection signal amplified by the amplifier 24.

  On the back side of the substrate 1, the lower light receiving system 30 is disposed at a position off the optical axis of the laser beam emitted from the back surface of the substrate 1 to the outside of the substrate 1. The lower light receiving system 30 includes a lens 31, a light receiving unit 32, and a photomultiplier tube 33. The CPU 60 instructs the focus adjustment control circuit 41 to adjust the focus position of the lower light receiving system 30. The focus adjustment control circuit 41 drives the focus adjustment mechanism 40 according to an instruction from the CPU 60. The focus adjustment mechanism 40 includes, for example, a pulse motor, and moves the lens 31 and the light receiving unit 32 up and down. When the focus adjustment mechanism 40 moves the lens 31 and the light receiving unit 32 up and down, the focus position of the lower light receiving system 30 is adjusted so as to match the inside of the substrate 1.

  FIG. 5 is a side view of the lower light receiving system. The lens 31 collects scattered light from the substrate 1 and irradiates the light receiving unit 32. The light receiving unit 32 is configured by bundling a plurality of optical fibers 32 a, receives the scattered light collected by the lens 31, and guides it to the light receiving surface of the photomultiplier tube 33. The photomultiplier tube 33 outputs a detection signal corresponding to the intensity of scattered light received by the light receiving surface. In FIG. 1, the detection signal of the photomultiplier tube 33 is amplified by an amplifier 34 and input to a defect detection circuit 35.

  When a defect exists on the surface of the substrate 1, the laser beam irradiated on the surface of the substrate 1 is scattered by the defect, and scattered light is generated. The scattered light passes through the substrate 1 and is received by the lower light receiving system 30 disposed on the back side of the substrate 1. Scattered light received by the light receiving unit 32 in which a plurality of optical fibers 32a are bundled has a shape that substantially represents the shape of the defect. Further, the laser beam that has been transmitted into the substrate 1 and reflected by the back surface of the substrate 1 and has reached the surface of the substrate 1 again is scattered by defects, and scattered light is generated. When the thickness of the substrate 1 is large, this scattered light is generated at a position far from the position where the surface of the substrate 1 is irradiated with the laser beam. When the light receiving area by the lens 31 of the lower light receiving system 30 is set to the optimum position, the scattered light is not received by the lower light receiving system 30.

  When a defect exists inside the substrate 1, the laser beam transmitted to the inside of the substrate 1 is scattered by the defect, and scattered light is generated. Further, the laser beam that has passed through the inside of the substrate 1 and has been reflected by the back surface of the substrate 1 is scattered by the defect, and scattered light is generated. These scattered lights pass through the substrate 1 and are received by the lower light receiving system 30 disposed on the back side of the substrate 1. Scattered light received by the light receiving unit 32 in which a plurality of optical fibers 32a are bundled has a cross shape that spreads vertically and horizontally regardless of the shape of the defect. The defect detection circuit 35 detects a defect inside the substrate 1 from the shape characteristic of the scattered light. The scattered light transmitted through the substrate 1 is received by the lower light receiving system 30 disposed on the back side of the substrate 1, so that not only the defect near the surface of the substrate 1 but also the defect located at a deep position away from the surface of the substrate 1 Is also detected.

  The angle detector 15 detects the rotation angle of the polygon mirror 13 of the scanning unit 10. The substrate movement control circuit 51 grasps the position in the drawing horizontal direction of the inspection table 5 from the drive signal to the substrate movement mechanism 50. The CPU 60 detects the position on the surface of the substrate 1 irradiated with the laser beam based on the position of the projection system in the drawing depth direction, the detection result of the angle detector 15 and the position information from the substrate movement control circuit 51. Then, the CPU 60 sets the position on the surface of the substrate 1 irradiated with the laser beam when the defect detection circuits 25 and 35 detect the defect as a defect position in the memory 70 together with the detection result of the defect detection circuits 25 and 35. Remember.

  Hereinafter, a method for determining the inspection range of the substrate 1 by the CPU 60 will be described. Note that the XY directions in the embodiments described below are examples, and the X direction and the Y direction may be interchanged.

  FIG. 6 is a diagram illustrating the relationship between incident light, reflected light, transmitted light, and emitted light. The incident light irradiated on the surface of the substrate 1 is IA, the incident light IA is reflected light reflected by the surface of the substrate 1, IR0, the transmitted light transmitted through the incident light IA into the substrate 1 is IA0, and the transmitted light IA0 is The emitted light emitted from the back surface of the substrate 1 is IS1, the transmitted light IA0 is reflected light reflected from the back surface of the substrate 1, IA1, the reflected light IA1 is emitted light emitted from the surface of the substrate 1, IR1, and the reflected light IA1. Is reflected light IA2 reflected from the surface of the substrate 1, IS2 is reflected light IA2 emitted from the back surface of the substrate 1, IA3 is reflected light reflected from the back surface of the substrate 1 IA3, reflected light The emitted light emitted from the surface of the substrate 1 by the IA 3 is defined as IR2.

As an example, when the reflectance of the laser beam from the projection system on the front and back surfaces of the substrate 1 is 5%, and the absorption rate of the laser beam inside the substrate 1 is 0%, when the amount of incident light IA is 100, The light amounts of the reflected light IR0, the transmitted light IA0, the emitted light IS1, the reflected light IA1, the emitted light IR1, the reflected light IA2, the emitted light IS2, the reflected light IA3, and the emitted light IR2 are as follows.
IR0 = 5
IA0 = 95
IS1 = 90.25
IA1 = 4.75
IR1 = 4.5125
IA2 = 0.375
IS2 = 0.256625
IA3 = 0.011875
IR2 = 0.0112812

  Among these, the reflected light IR0 reflected from the surface of the substrate 1 and the emitted lights IR1 and IR2 emitted from the surface of the substrate 1 are not scattered by the edge of the substrate 1 or the inspection table 5. Further, the light amounts of the reflected light IA2, the emitted light IS2, and the reflected light IA3 are as small as 0.3% or less with respect to the light amount of the incident light IA. Therefore, in the present embodiment, noise due to scattered light generated by the incident light IA, the transmitted light IA0, the emitted light IS1, and the reflected light IA1 being scattered by the edge of the substrate 1 or the substrate support portion 5a of the inspection table 5 is detected. Considering this, the inspection range of the substrate 1 is determined. When the thickness of the substrate is T, the refractive index of air is N1, the refractive index of the substrate is N2, the incident angle of the laser beam is I, and the refractive angle is R, the irradiation position of the incident light IA on the surface of the substrate 1 and the reflection The irradiation position of the light IA1 on the surface of the substrate 1 is separated by a distance D calculated by the equation shown in the drawing.

  7 to 11 are diagrams for explaining scattered light generated at the taper of the edge of the substrate in scanning in the X direction of the substrate with a laser beam when the entire substrate is set as the inspection range. 7 to 11, a taper is formed on the edge of the surface of the substrate 1. When the laser beam from the light projecting system moves from the edge of the substrate 1 toward the center of the substrate in the left direction in the drawing, first, as shown in FIG. Irradiated to the corner 1a surrounded by the broken line of the taper and scattered by the corner 1a, scattered light is generated.

  Subsequently, when the incident light IA is moved in the left direction of the drawing, as shown in FIG. 8, the incident light IA is irradiated to the corner 1b surrounded by the broken line of the taper on the surface of the substrate 1, and is scattered by the corner 1b. Scattered light is generated. At this time, the distance X1 between the irradiation position of the incident light IA on the surface of the substrate 1 and the edge of the substrate 1 depends on the size of the taper.

  Further, when the incident light IA is moved in the left direction of the drawing, as shown in FIG. 9, the transmitted light IAO is irradiated to the corner 1c surrounded by the broken line on the back surface of the substrate 1, and scattered by the corner 1c. Light is generated. At this time, the distance X2 between the irradiation position of the incident light IA on the surface of the substrate 1 and the edge of the substrate 1 is larger than the distance X1 in FIG. 8 and changes according to the thickness of the substrate 1.

  Further, when the incident light IA is moved in the left direction of the drawing, as shown in FIG. 10, the reflected light IA1 is irradiated to the corner 1a surrounded by the broken line of the taper at the edge of the surface of the substrate 1 and scattered by the corner 1a. , Scattered light is generated. At this time, the distance X3 between the irradiation position of the incident light IA on the surface of the substrate 1 and the edge of the substrate 1 is larger than the distance X2 in FIG. 9 and changes according to the thickness of the substrate 1.

  Further, when the incident light IA is moved in the left direction of the drawing, as shown in FIG. 11, the reflected light IA1 is irradiated to the corner 1b surrounded by the broken line of the taper on the surface of the substrate 1, and is scattered by the corner 1b. , Scattered light is generated. At this time, the distance X4 between the irradiation position of the incident light IA on the surface of the substrate 1 and the edge of the substrate 1 is larger than the distance X3 in FIG. 10 and changes according to the thickness of the substrate 1.

  FIG. 12 and FIG. 13 are diagrams for explaining scattered light generated at the substrate support portion when scanning the substrate in the X direction with a laser beam when the entire substrate is in the inspection range. When the laser beam from the light projecting system moves from the edge of the substrate 1 toward the center of the substrate in the left direction in the drawing, first, as shown in FIG. 12, the emitted light IS1 is emitted from the inclined surface of the substrate support portion 5a. Irradiated to the corner 5c surrounded by the broken line 5b and scattered by the corner 5c to generate scattered light. At this time, the distance X5 between the irradiation position of the incident light IA on the surface of the substrate 1 and the edge of the substrate 1 changes according to the thickness of the substrate 1.

  Further, when the incident light IA is moved in the left direction of the drawing, as shown in FIG. 13, the emitted light IS1 is irradiated to the corner 5d surrounded by the broken line of the substrate support portion 5a, and is scattered by the corner 5d. appear. At this time, the distance X6 between the irradiation position of the incident light IA on the surface of the substrate 1 and the edge of the substrate 1 is larger than the distance X5 in FIG. 12 and changes according to the thickness of the substrate 1. In the present embodiment, a surface 5e parallel to the emission light IS1 is formed in the lower portion of the substrate support portion 5a. For this reason, even if the incident light IA is further moved in the left direction of the drawing, the emitted light IS1 is not irradiated and scattered on the portion below the corner 5d of the substrate support portion 5a.

  When the CPU 60 determines the inspection range of the substrate 1, the laser beam transmitted to the inside of the substrate 1, reflected by the back surface of the substrate 1, and irradiated to the taper corner 1 b of the edge of the substrate 1 is applied to the surface of the substrate 1. From the irradiation position to the edge of the substrate 1 (distance X4 in FIG. 11), the surface of the substrate 1 of the laser beam that is transmitted into the substrate 1 and emitted from the back surface of the substrate 1 and irradiated to the corner 5d of the substrate support 5 Excluding from the irradiation position to the edge of the substrate 1 (distance X6 in FIG. 13), the inspection range in the X direction of the substrate 1 is determined. In the X direction perpendicular to the two supported sides of the substrate 1, the irradiation range of the laser beam that is scattered by the taper of the edge of the substrate 1 to generate scattered light and the surface of the substrate 1 is scattered and scattered by the inspection table 5. The irradiation range of the laser beam that generates light to the surface of the substrate 1 is reliably excluded from the inspection range.

  14 to 20 are diagrams for explaining scattered light generated by the taper of the edge of the substrate when the inspection table moves in the Y direction when the entire substrate is set as the inspection range. 14 to 20, a taper is formed at the edge of the surface of the substrate 1. When the inspection table 5 is moved in the right direction in the drawing, first, as shown in FIG. 14, the incident light IA is irradiated to the corner 1a surrounded by the dashed broken line at the edge of the surface of the substrate 1 and scattered by the corner 1a. Scattered light is generated.

  Subsequently, when the inspection table 5 is moved to the right in the drawing, as shown in FIG. 15, the incident light IA is irradiated to the corner 1b surrounded by the broken line of the taper at the edge of the surface of the substrate 1, and is scattered by the corner 1b. Scattered light is generated. At this time, the distance Y1 between the irradiation position of the incident light IA on the surface of the substrate 1 and the edge of the substrate 1 depends on the taper size.

  Further, when the inspection table 5 is moved to the right in the drawing and the inspection is continued, the reflected light IA1 is surrounded by a tapered broken line at the edge of the surface of the substrate 1, as shown in FIG. Irradiated to the corner 1b and scattered by the corner 1b to generate scattered light. At this time, the distance Y2 between the irradiation position of the incident light IA on the surface of the substrate 1 and the edge of the substrate 1 changes according to the thickness of the substrate 1.

  Further, when the inspection table 5 is moved to the right in the drawing, as shown in FIG. 17, the reflected light IA1 is irradiated to the corner 1a surrounded by the broken line of the taper on the edge of the substrate 1, and is scattered by the corner 1a. , Scattered light is generated. At this time, the distance Y3 between the irradiation position of the incident light IA on the surface of the substrate 1 and the edge of the substrate 1 is smaller than the distance Y2 in FIG. 16 and changes according to the thickness of the substrate 1.

  Further, when the inspection table 5 is moved to the right in the drawing, as shown in FIG. 18, the transmitted light IAO is irradiated to the corner 1c surrounded by the broken line on the edge of the back surface of the substrate 1, and scattered by the corner 1c. Light is generated. At this time, the distance Y4 between the irradiation position of the incident light IA on the surface of the substrate 1 and the edge of the substrate 1 is smaller than the distance Y3 in FIG. 17 and changes according to the thickness of the substrate 1.

  Further, when the inspection table 5 is moved to the right in the drawing, as shown in FIG. 19, the incident light IA is irradiated to the corner 1b surrounded by the broken line of the taper at the edge of the surface of the substrate 1 and scattered by the corner 1b. , Scattered light is generated. At this time, the distance Y1 between the irradiation position of the incident light IA on the surface of the substrate 1 and the edge of the substrate 1 is smaller than the distance Y4 in FIG. 18 and depends on the taper size.

  Further, when the inspection table 5 is moved to the right in the drawing, as shown in FIG. 20, the incident light IA is irradiated to the corner 1a surrounded by the broken line of the taper at the edge of the surface of the substrate 1 and scattered by the corner 1a. , Scattered light is generated.

  When the CPU 60 determines the inspection range of the substrate 1, from the irradiation position on the surface of the substrate 1 of the laser beam directly applied to the taper corner 1b of the edge of the substrate 1 to the edge of the substrate 1 (distance Y1 in FIG. 15). From the irradiation position on the surface of the substrate 1 to the edge of the substrate 1 that is transmitted to the inside of the substrate 1 and reflected on the back surface of the substrate 1 and irradiated to the taper corner 1b of the edge of the substrate 1 (FIG. 16). And the inspection range in the Y direction of the substrate 1 is determined. In the Y direction parallel to the two supported sides of the substrate 1, the irradiation range of the laser beam that is scattered by the taper of the edge of the substrate 1 and generates scattered light is reliably excluded from the inspection range. .

  According to the embodiment described above, the laser beam that is scattered by the taper at the edge of the substrate 1 to generate scattered light and the laser beam that is scattered by the inspection table 5 and generates scattered light. By eliminating the irradiation range on the surface of the substrate 1 and determining the inspection range of the substrate 1, in the inspection of the defect of the transparent substrate having a large plate thickness, the influence of noise around the substrate is eliminated, and the defect Detection accuracy can be improved.

  Furthermore, according to the embodiment described above, the inspection table 5 is provided with the substrate support portion 5a having the inclined surface 5b that contacts the bottoms of the two opposite sides of the substrate 1, and penetrates into the substrate 1 to transmit the substrate 1 From the irradiation position on the surface of the substrate 1 to the edge of the substrate 1 through the inside of the substrate 1 and from the back surface of the substrate 1. Inspection in the direction perpendicular to the two supported sides of the substrate 1 excluding from the irradiation position on the surface of the substrate 1 to the edge of the substrate 1 of the light beam emitted and irradiated onto the corner 5d of the substrate support 5a By determining the range, in the direction perpendicular to the two supported sides of the substrate 1, the irradiation range on the surface of the substrate 1 that is scattered by the taper of the edge of the substrate 1 to generate scattered light, and the inspection table A substrate of light rays scattered by 5 to generate scattered light Irradiation range to the surface, can be excluded securely from the inspection range.

  Furthermore, according to the embodiment described above, the light beam directly irradiated onto the taper corner 1b of the edge of the substrate 1 is transmitted from the irradiation position on the surface of the substrate 1 to the edge of the substrate 1 and into the inside of the substrate 1. Then, the substrate 1 is supported by excluding from the irradiation position on the surface of the substrate 1 to the edge of the substrate 1 that is reflected from the back surface of the substrate 1 and applied to the taper corner 1b of the edge of the substrate 1. By determining the inspection range in the direction parallel to the two sides, the light beam that is scattered by the taper of the edge of the substrate 1 and generates scattered light in the direction parallel to the two sides supported by the substrate 1 is obtained. The irradiation range on the surface can be reliably excluded from the inspection range.

It is a figure which shows schematic structure of the board | substrate inspection apparatus by one embodiment of this invention. It is a perspective view of the board | substrate mounted in the test | inspection table. It is a top view of a scanning part. It is the figure which looked at the upper light-receiving system from the top. It is the figure which looked at the lower light-receiving system from the side. It is a figure explaining the relationship between incident light, reflected light, transmitted light, and emitted light. It is a figure explaining the scattered light which generate | occur | produces in the taper of the edge of a board | substrate in the scanning of the X direction of a board | substrate by a laser beam when the whole board | substrate is made into the inspection range. It is a figure explaining the scattered light which generate | occur | produces in the taper of the edge of a board | substrate in the scanning of the X direction of a board | substrate by a laser beam when the whole board | substrate is made into the inspection range. It is a figure explaining the scattered light which generate | occur | produces in the taper of the edge of a board | substrate in the scanning of the X direction of a board | substrate by a laser beam when the whole board | substrate is made into the inspection range. It is a figure explaining the scattered light which generate | occur | produces in the taper of the edge of a board | substrate in the scanning of the X direction of a board | substrate by a laser beam when the whole board | substrate is made into the inspection range. It is a figure explaining the scattered light which generate | occur | produces in the taper of the edge of a board | substrate in the scanning of the X direction of a board | substrate by a laser beam when the whole board | substrate is made into the inspection range. It is a figure explaining the scattered light which generate | occur | produces in a board | substrate support part in the scanning of the X direction of a board | substrate by a laser beam when the whole board | substrate is made into the inspection range. It is a figure explaining the scattered light which generate | occur | produces in a board | substrate support part in the scanning of the X direction of a board | substrate by a laser beam when the whole board | substrate is made into the inspection range. It is a figure explaining the scattered light which generate | occur | produces with the taper of the edge of a board | substrate in the movement to the Y direction of an inspection table, when the whole board | substrate is made into the inspection range. It is a figure explaining the scattered light which generate | occur | produces with the taper of the edge of a board | substrate in the movement to the Y direction of an inspection table, when the whole board | substrate is made into the inspection range. It is a figure explaining the scattered light which generate | occur | produces with the taper of the edge of a board | substrate in the movement to the Y direction of an inspection table, when the whole board | substrate is made into the inspection range. It is a figure explaining the scattered light which generate | occur | produces with the taper of the edge of a board | substrate in the movement to the Y direction of an inspection table, when the whole board | substrate is made into the inspection range. It is a figure explaining the scattered light which generate | occur | produces with the taper of the edge of a board | substrate in the movement to the Y direction of an inspection table, when the whole board | substrate is made into the inspection range. It is a figure explaining the scattered light which generate | occur | produces with the taper of the edge of a board | substrate in the movement to the Y direction of an inspection table, when the whole board | substrate is made into the inspection range. It is a figure explaining the scattered light which generate | occur | produces with the taper of the edge of a board | substrate in the movement to the Y direction of an inspection table, when the whole board | substrate is made into the inspection range.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate 5 Inspection table 5a Board | substrate support part 10 Scanning part 11 Laser light source 12a Lens 12c f (theta) lens 13 Polygon mirror 14 Mirror 15 Angle detector 20 Upper light receiving system 30 Lower light receiving system 21, 31 Lens 22, 32 Light receiving part 22a, 32a Optical fiber 23, 33 Photomultiplier tubes 24, 34 Amplifiers 25, 35 Defect detection circuit 40 Focus adjustment mechanism 41 Focus adjustment control circuit 50 Substrate movement mechanism 51 Substrate movement control circuit 52 Projection system movement mechanism 53 Projection system movement control circuit 54 System movement mechanism 55 Upper light reception system movement control circuit 56 Lower light reception system movement mechanism 57 Lower light reception system movement control circuit 60 CPU
70 memory

Claims (6)

An inspection table that supports a rectangular transparent substrate only on its two opposite sides;
A light projecting system that scans the substrate by irradiating the surface of the substrate obliquely while moving the light beam by a predetermined distance in a direction perpendicular to the two sides supported by the substrate;
A light receiving system including a lens and a light receiving unit in which a plurality of optical fibers are bundled, and a light receiving system that receives scattered light in which a light beam is scattered by a defect in the substrate;
First moving means for moving the inspection table, the light projecting system, and the light receiving system in a direction that is relatively parallel to the two sides supported by the substrate;
First control means for controlling the first moving means;
A second moving means for moving the inspection table, the light projecting system, and the light receiving system in a direction that is relatively perpendicular to two sides supported by the substrate, and changing a scanning range of the substrate by the light beam;
Second control means for controlling the second moving means;
Detecting means for detecting a defect of the substrate from the scattered light received by the light receiving system;
The inspection range of the substrate is determined, the first control unit and the second control unit are instructed, the position on the surface of the substrate irradiated with the light beam is detected, and the defect detected by the detection unit is detected. Processing means for detecting the position,
The processing means irradiates the surface of the substrate with light rays scattered by the edge taper of the substrate and generates scattered light, and irradiates the surface of the substrate with light rays scattered by the inspection table and generating scattered light. A substrate inspection apparatus that determines a substrate inspection range by excluding the range. The inspection table has a substrate support portion having an inclined surface that contacts bottoms of two opposite sides of the substrate,
The processing means passes from the irradiation position on the surface of the substrate to the edge of the substrate from the irradiation position of the light beam transmitted to the inside of the substrate, reflected on the back surface of the substrate and irradiated to the taper corner of the substrate edge, and into the substrate inside. Except from the irradiation position on the surface of the substrate to the edge of the substrate, the light beam that is transmitted and emitted from the back surface of the substrate and irradiated to the corner of the substrate support portion is perpendicular to the two supported sides of the substrate. The substrate inspection apparatus according to claim 1, wherein a direction inspection range is determined.   The processing means transmits the light beam directly irradiated to the taper corner of the substrate edge from the irradiation position on the substrate surface to the substrate edge, and is transmitted to the inside of the substrate and reflected on the back surface of the substrate to be reflected on the substrate edge. The inspection range in the direction parallel to the two supported sides of the substrate is determined by excluding from the irradiation position of the light beam irradiated to the taper corner of the substrate to the edge of the substrate. The board | substrate inspection apparatus of Claim 1 or Claim 2. The inspection table supports a rectangular transparent substrate only on its two opposite sides,
Excluding the irradiation range on the surface of the substrate of the light beam scattered by the edge taper of the substrate and the irradiation range of the light beam scattered by the inspection table and generating the scattered light on the surface of the substrate, Determine the inspection range of the board,
While obliquely irradiating the surface of the substrate with light rays from the light projecting system, the light rays are moved by a predetermined distance in a direction perpendicular to the two supported sides of the substrate, and the substrate is scanned.
The inspection table, the light projecting system and the light receiving system are moved in a direction parallel to the two sides relatively supported by the substrate, and the inspection table, the light projecting system and the light receiving system are relatively moved by the two sides supported by the substrate. The scanning range of the substrate with the light beam is changed, and these steps are repeated to scan the substrate with the light beam over the entire inspection range,
The light receiving system receives the scattered light scattered by the defects on the substrate,
Detect defects on the surface of the substrate from the received scattered light,
A substrate inspection method, comprising: detecting a position of a detected defect by detecting a position on a surface of a substrate irradiated with a light beam. The inspection table is provided with a substrate support having an inclined surface that contacts the bottoms of the two opposite sides of the substrate,
From the irradiation position on the surface of the substrate to the edge of the substrate, the light beam that is transmitted to the inside of the substrate and reflected from the back surface of the substrate and irradiated to the taper corner of the substrate is transmitted to the inside of the substrate and transmitted to the inside of the substrate. Excludes from the irradiation position on the surface of the substrate to the edge of the substrate, which is emitted from the back surface and irradiated to the corner of the substrate support part, and determines the inspection range in the direction perpendicular to the two supported sides of the substrate The substrate inspection method according to claim 4, wherein:   From the irradiation position of the light beam directly applied to the taper corner of the substrate edge to the edge of the substrate from the irradiation position to the substrate edge, it is transmitted to the inside of the substrate and reflected by the back surface of the substrate to the taper corner of the substrate edge 5. The inspection range in a direction parallel to the two supported sides of the substrate is determined by excluding the irradiation position of the irradiated light beam on the surface of the substrate to the edge of the substrate. Item 6. The substrate inspection method according to Item 5.

Images