JP2011257304A - Substrate inspection method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily determine whether a defect left on a mask substrate after cleaning processing is carried out on the mask substrate is caused by the cleaning processing process or an internal defect of the mask substrate itself.SOLUTION: Since defects present on both surfaces (a top and a reverse surface) of the substrate can be detected based upon scattered light received by first and second light reception means, presence positions of the defects on both the surfaces before and after the cleaning processing on the substrate are compared with each other respectively to easily determine whether the defects present on both the surfaces of the substrate are removed through the cleaning processing. Namely, when a predetermined number of defects are not removed from the substrate through the cleaning processing on the substrate, the possibility that a defect is present in the mask substrate is high, so detection processing for the defect in the substrate is carried out. Based upon a result thereof, it can easily be determined whether a defect which cannot be removed through the cleaning processing is the defect in the substrate or caused owing to a problem of the cleaning processing process.

Description

  The present invention relates to a substrate inspection method and apparatus 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. And an apparatus.

  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 well, causing a defect. For this reason, a defect inspection of a mask substrate is performed using a substrate inspection apparatus. As such a substrate inspection apparatus, the thing of patent document 1 and patent document 2 is known, for example.

Japanese Patent Laid-Open No. 11-52552 JP 2005-156924 A

  In recent years, in the inspection of a mask substrate by a substrate inspection apparatus, there is a demand for acquiring an image of a detected defect by an image acquisition apparatus such as a camera and observing the defect in detail. In order to execute this, an observation system including an image acquisition device such as a camera is accurately moved above the defect based on the coordinates of the position of the defect detected by inspection. Even when defects are observed on the surface of the mask substrate or the like, the defects can be removed by cleaning the mask substrate. However, when there is a problem in the cleaning process of the mask substrate, it has been difficult to remove the defect. Furthermore, even when a defect exists inside the mask substrate, it is difficult to remove the defect only by cleaning the front and back surfaces of the mask substrate. Conventionally, when the mask substrate was cleaned in this way, the defect could not be removed due to a problem in the cleaning process, or the defect could not be removed because there was a defect inside the mask substrate. It was not possible to determine which of the problems caused the defect to be removed.

  The present invention has been made in view of the above points, and whether the defect remaining in the mask substrate after the cleaning process when the mask substrate is cleaned is caused by the cleaning process, or the inside of the mask substrate itself. It is an object of the present invention to provide a substrate inspection method and apparatus that can easily determine whether it is due to a defect or a processing process such as a scratch.

A first feature of the substrate inspection method according to the present invention is that the light beam is obliquely incident on the surface of the substrate at an angle such that a part of the light beam is reflected on the surface of the substrate and the remaining light beam is transmitted into the substrate. The substrate is scanned while moving the light beam, and the scattered light, which is disposed on the surface side of the substrate and is scattered by the defect of the substrate, is collected by the first lens means. Received by the first light receiving means, arranged on the back side of the substrate, and the scattered light scattered by the defect of the substrate is condensed by the second lens means to the second light receiving means. And detecting the position of the defect on the substrate from the signal based on the scattered light received by the first and second light receiving systems, and detecting the detected position of the defect in the cleaning process of the substrate. Compare the board before and after, and recycle the board according to the comparison result. It is to determine whether to Kiyoshi processing.
By moving the light beam while obliquely irradiating the surface of the substrate at an angle such that a part of the light beam irradiated to the surface of the substrate is reflected by the surface of the substrate and the rest is transmitted to the inside of the substrate A scanning inspection is performed. When there is a defect on the surface of the substrate, the light beam irradiated on the surface of the substrate is scattered by the defect on the surface of the substrate, and scattered light is generated around it. In addition, when a defect exists inside the substrate, the light beam transmitted to the inside of the substrate is scattered by the defect inside the substrate, and scattered light is generated around it. Further, when there is a defect on the back surface of the substrate, light rays that are transmitted into the substrate and emitted from the back surface of the substrate are scattered by the defects on the back surface of the substrate, and scattered light is generated around the light. These scattered lights are respectively received by the first light receiving means arranged on the front surface side of the substrate and the second light receiving means arranged on the back surface side of the substrate.
Since defects existing on both surfaces (front and back surfaces) of the substrate can be detected based on the scattered light received by the first and second light receiving means, the presence positions of the defects on both surfaces before and after the substrate cleaning process. By comparing each of these, it is possible to easily determine whether or not the defects existing on both surfaces of the substrate have been removed by the cleaning process. That is, when a predetermined number of defects are not removed from the substrate by the substrate cleaning process, there is a high possibility that a defect exists in the mask substrate. Based on the result, it is possible to easily determine whether the defect that could not be removed by the cleaning process is a defect inside the substrate or a problem of the cleaning process.

  A second feature of the substrate inspection method according to the present invention is that the first light beam is reflected on the surface of the substrate at an angle such that a part of the light beam is reflected on the surface of the substrate and the remaining light beam is transmitted into the substrate. The first polarizing plate means that scans the substrate while moving the light beam while obliquely irradiating the light beam containing a large amount of the polarization component, and passes only the light of the first polarization component, and the vicinity of the frequency component of the light beam A band-pass filter means for allowing only the first light to pass therethrough, and receiving light received by the first light-receiving means by condensing the light that has passed through the first polarizing plate means and the band-pass filter means by the lens means. System means, which is disposed on the surface side of the substrate, and the scattered light is scattered by a defect of the substrate, the first polarizing means, the first bandpass filter means and the first Through the lens means Second polarizing plate means for receiving only light of the first polarization component and second band-pass filter means for passing only light in the vicinity of the frequency component of the light beam received by the first light receiving means; A light receiving system means that is provided on the front surface and that condenses light that has passed through the second polarizing plate means and the second bandpass filter means by the second lens means and is received by the second light receiving means; The scattered light, which is disposed on the back surface side of the substrate and is scattered by the defect of the substrate, passes through the second polarizing plate means, the second bandpass filter means, and the second lens means. The defect position of the substrate is detected from a signal based on the scattered light received by the first and second light-receiving units and received by the first and second light-receiving units, and the detected defect position is detected. Compare before and after cleaning of the substrate Is to determine whether to re-cleaning process of the substrate according to the comparison result. In the present invention, a light beam that includes a large amount of the first polarization component is used as a light beam that irradiates the surface of the substrate. A polarization device that allows only the first polarization component to pass therethrough before each light receiving device and a frequency component of the light beam. Bandpass filter means for passing only light is provided. Since the irradiation light includes a large amount of the first polarization component, each scattered light also includes a large amount of the first polarization component. Further, only the scattered light containing a large amount of the first polarization component passes through the polarization means and the bandpass filter means and is taken into the light receiving means. As a result, the influence of ambient light noise that attempts to enter the detection optical system from the environment around the substrate is reduced as much as possible, and the defect detection accuracy can be improved.

  A third feature of the substrate inspection method according to the present invention is the substrate inspection method according to the first or second feature, wherein after the re-cleaning process, the position of the defect and the re-cleaning before and after the cleaning process. It is to compare the existence positions of the defects after processing and determine whether or not to detect defects inside the substrate according to the comparison result. If removal of defects is insufficient after the cleaning process, a re-cleaning process may be performed. In this case, based on three types of data, that is, pre-cleaning data indicating the position of the substrate defect before the first cleaning process, post-cleaning data (pre-cleaning data), and post-cleaning data, that is, Based on one of the comparison results between the data before cleaning and the data after re-cleaning processing, the comparison result between the data after cleaning processing (data before re-cleaning) and the data after re-cleaning processing, or both comparison results It is determined whether or not to detect internal defects.

  According to a fourth aspect of the substrate inspection method of the present invention, in the substrate inspection method according to the first, second, or third feature, a measurement condition for detecting the presence position of the defect is given to the substrate. It is to read from a barcode or the like. The mask substrate is provided with a barcode, QR code, etc. for specifying the mask substrate. In this invention, the barcode, QR code, etc. are read to determine measurement conditions for defect inspection. Yes. As a result, there is no risk of erroneous inspection by manual input, and defect inspection can be quickly performed under measurement conditions corresponding to the mask substrate.

  According to a fifth aspect of the substrate inspection method of the present invention, in the substrate inspection method according to the first, second, third, or fourth feature, the focal positions of the first and second light receiving units are set as the focus positions. In accordance with the inside of the substrate, a defect inside the substrate is detected based on the shape characteristic of the scattered light received by the first and second light receiving means. When a defect exists in the substrate, when the light beam is moved and the substrate is scanned by the light beam, the light beam transmitted to the inside of the substrate is scattered by the defect, and scattered light is generated. Further, the light beam that has been transmitted into the substrate and reflected by the back surface of the substrate is scattered by the defect, and scattered light is generated. These scattered lights are transmitted through the substrate and received by a light receiving system disposed on the back side of the substrate. Scattered light received by a light receiving unit in which a plurality of optical fibers are bundled has a cross shape that spreads vertically and horizontally regardless of the shape of the defect. In the present invention, defects inside the substrate are detected from the shape characteristics of the scattered light. Since the scattered light transmitted through the substrate is received by the light receiving system arranged on the back side of the substrate, not only the defects near the surface of the substrate but also the defects at a deep position away from the surface of the substrate are detected.

  A first feature of the substrate inspection apparatus according to the present invention is that the light beam is obliquely incident on the surface of the substrate at an angle such that a part of the light beam is reflected on the surface of the substrate and the remaining light beam is transmitted into the substrate. A projection system means for scanning the substrate while moving the light beam while irradiating the light beam, and a first lens that is disposed on the surface side of the substrate, and the scattered light is scattered by the defect of the substrate. A first light receiving system configured to collect light by the first light receiving unit and receive light by the first light receiving unit; and scattered light that is disposed on the back side of the substrate and in which the light beam is scattered by a defect in the substrate On the basis of the second light receiving system means configured to collect the light by the second lens means and receive the light by the second light receiving means, and the scattered light received by the first and second light receiving system means Defect detection means for detecting the position of the defect on the substrate from the detected signal A control means for comparing the presence position of the defect detected by the defect detection means before and after the cleaning process of the substrate and determining whether or not to re-clean the substrate according to the comparison result; Be prepared. This is an invention of a substrate inspection apparatus for realizing the substrate inspection method described in the first feature.

  A second feature of the substrate inspection apparatus according to the present invention is that the first part of the light beam is reflected to the surface of the substrate at an angle such that a part of the light beam is reflected by the surface of the substrate and the remaining light beam is transmitted into the substrate. A light projection system means for scanning the substrate while moving the light beam obliquely while irradiating a light beam containing a large amount of a polarization component, a first polarizing plate means for passing only the light of the first polarization component, and the Band pass filter means for allowing only light in the vicinity of the frequency component of the light beam to pass therethrough is provided on the front surface, and light passing through the first polarizing plate means and the band pass filter means is condensed by the lens means, and the first light receiving means. A light receiving system means for receiving light scattered by the first polarizing plate means and the first band-pass filter means arranged on the surface side of the substrate, and the scattered light scattered by the defects of the substrate. And the first lens A first light receiving system configured to receive light by the first light receiving unit through a stage, a second polarizing plate unit that passes only light of the first polarization component, and a frequency of the light beam Second band-pass filter means for allowing only light in the vicinity of the component to pass therethrough is provided on the front surface, and light passing through the second polarizing plate means and the second band-pass filter means is condensed by the second lens means. A light receiving system means for receiving light by the second light receiving means, and disposed on the back side of the substrate, and the scattered light scattered by the defect of the substrate by the second polarizing plate means, A second light receiving system means configured to receive light by the second light receiving means via two band pass filter means and the second lens means, and the first and second light receiving system means, From the signal based on the received scattered light, the substrate The defect detection means for detecting the presence position of the defect and the presence position of the defect detected by the defect detection means are compared before and after the substrate cleaning process, and the substrate is re-cleaned according to the comparison result. And a control means for determining whether or not to perform. This is an invention of a substrate inspection apparatus for realizing the substrate inspection method described in the second feature.

  According to a third aspect of the substrate inspection apparatus of the present invention, in the substrate inspection apparatus according to the first or second aspect, the control means includes the presence of the defect before and after the cleaning process after the re-cleaning process. The position and the existence position of the defect after the re-cleaning process are respectively compared, and it is determined whether or not to detect the defect inside the substrate according to the comparison result. This is an invention of a substrate inspection apparatus for realizing the substrate inspection method described in the third feature.

  According to a fourth aspect of the substrate inspection apparatus of the present invention, in the substrate inspection apparatus according to the first, second, or third feature, the measurement is performed when the defect detection unit detects the position of the defect. The condition is to read from a barcode or the like given to the substrate. This is an invention of a substrate inspection apparatus for realizing the substrate inspection method according to the fourth feature.

  According to a fifth aspect of the substrate inspection apparatus of the present invention, in the substrate inspection apparatus according to the first, second, third, or fourth feature, the defect detection unit includes the first and second light receiving elements. The focus position of the means is adjusted to the inside of the substrate, and a defect inside the substrate is detected based on the shape characteristic of the scattered light received by the first and second light receiving means. This is an invention of a substrate inspection apparatus for realizing the substrate inspection method according to the fifth feature.

  According to the present invention, whether the defect remaining on the mask substrate after the cleaning process when the mask substrate is cleaned is due to the cleaning process, the internal defect of the mask substrate itself, or a process such as a scratch It can be easily determined whether it is due to the process.

It is a figure which shows schematic structure of the board | substrate inspection apparatus which concerns on one embodiment of this invention. It is a perspective view which shows the state of the board | substrate 1 mounted in the test | inspection table of FIG. It is a figure which shows the detail of the scanning part of FIG. It is a figure which shows schematic structure of the upper light reception system of FIG. 1, and is the top view seen from the light projection system side. It is a figure which shows schematic structure of the lower light-receiving system of FIG. 1, and is the side view seen from the left side of FIG. It is a figure which shows an example of the test result of the board | substrate test | inspection method of this invention. It is a figure which shows an example of the 1st test | inspection process of a board | substrate test | inspection method. It is a figure which shows an example of the process after mask substrate cleaning process used as the 2nd test | inspection process of a board | substrate inspection method. It is a figure which shows an example of the process after a mask substrate re-cleaning process used as the 3rd test | inspection process of a board | substrate inspection method. It is a figure which shows an example of the internal defect inspection process of the mask board | substrate used as the 4th inspection process of a board | substrate inspection method.

  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 projecting system, an angle detector 15, an upper light receiving system 20, a lower light receiving system 30, amplifiers 27 and 37, defect detection circuits 28 and 38, 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 A light receiving system movement control circuit 57, a control unit (CPU) 60, and a memory 70 are included.

  FIG. 2 is a perspective view showing a state of the substrate 1 mounted on the inspection table 5. A mask substrate 1 to be inspected is placed on an inspection table 5. On the inspection table 5, two substrate support portions 5a extending in the horizontal direction of the drawing are arranged in parallel to each other in the depth direction of the drawing. On each opposing side of each substrate support 5a, an inclined surface 5b that contacts the substrate 1 is formed in the longitudinal direction. The substantially rectangular substrate 1 is mounted on the inspection table 5 (on the inclined surface 5b). As a result, the substrate 1 is held such that the bottom surfaces of the two opposite sides of the substrate 1 are in contact with the inclined surface 5b of the substrate support portion 5a. In other words, the inspection table 5 supports the rectangular substrate 1 only on its two opposite sides.

  In FIG. 1, a light projecting system including a scanning unit 10, an angle detector 15, and a mirror 14 is disposed above the substrate 1 mounted on the inspection table 5. FIG. 3 is a diagram illustrating details of the scanning unit 10. 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 is a laser beam and mainly generates inspection light having an S-polarized component. The laser beam emitted from the laser light source 11 is mainly composed of an S-polarized component, but may contain some P-polarized component, and the proportion of the S-polarized component is sufficiently larger than that of the P-polarized component. Shall. The laser light source 11 may emit only the S-polarized component. 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 12 c matches the focal plane of the laser beam shaken by the rotation of the polygon mirror 13 with the planar position of the substrate 1. 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. 2, the laser beam irradiated from the mirror 14 to the surface of the substrate 1 alternately moves in the depth direction of FIG. Done. In the present embodiment, as an example, this scanning range is about 200 [mm].

  In FIG. 1, the CPU 60 serving as the control unit determines the inspection range of the substrate 1 as will be described later, and instructs the substrate movement control circuit 51 to move the substrate 1. The substrate movement control circuit 51 drives and controls the substrate movement mechanism 50 in accordance with an instruction from the CPU 60. The substrate moving mechanism 50 includes, for example, a linear motion motor and moves the inspection table 5 in the horizontal direction of the drawing, but its detailed configuration is omitted in FIG. When the substrate moving mechanism 50 moves the entire inspection table 5 in the horizontal direction, 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 is lateral to the drawing of the substrate 1. Irradiate over the length of the direction. Accordingly, 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 projection system movement control circuit 53 drives and controls the light projection system movement mechanism 52 in accordance with an instruction from the CPU 60. The light projecting system moving mechanism 52 includes, for example, a linear motion motor and moves the light projecting system in the depth direction of the drawing, but the detailed configuration is omitted in FIG. When the light projecting system moving mechanism 52 moves the entire light projecting system, the scanning range of the substrate 1 by the laser beam irradiated from the light projecting system is controlled to be changed in the drawing depth direction. The entire inspection range of the substrate 1 can be inspected by sequentially repeating the scanning of the substrate 1 by the laser beam, the movement of the inspection table 5 and the change of the scanning range.

  In the case where movement control of the light projecting system is performed as described above, the CPU 60 controls movement of the entire system including the upper light receiving system 20 and the lower light receiving system 30 in synchronization with the movement of the light projecting system. That is, the CPU 60 instructs the upper light receiving system movement control circuit 55 and the lower light receiving system movement control circuit 57 to control the movement. The upper light receiving system movement control circuit 55 and the lower light receiving system movement control circuit 57 respectively drive and control the upper light receiving system moving mechanism 54 and the lower light receiving system moving mechanism 56 in accordance with a movement instruction 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 and control the upper light receiving system 20 and the lower light receiving system 30 in synchronization with the light projecting system.

  Instead of moving the inspection table 5, the substrate 1 and the light projecting system may be relatively moved in a direction perpendicular to the scanning direction of the laser beam by moving the light projecting system in the horizontal direction of the drawing. In this 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 table 5 is moved in the drawing depth direction, so that the substrate 1 and the light projecting system are relatively moved in the laser beam scanning direction, thereby scanning the substrate by the laser beam. May be changed. That is, the light projecting system and the light receiving system and the substrate 1 may be configured to be relatively movable.

  A part of the laser beam irradiated obliquely from the light projecting system to the substrate 1 is reflected by the surface of the substrate 1 and the rest is transmitted to the inside of 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 the rest is transmitted from the back surface of the substrate 1 to the outside of the substrate 1. This is the case where the substrate 1 is an ideal flat transparent substrate.

  On the surface side of the substrate 1, an 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 an upper light receiver 21 and a photomultiplier tube 26. The upper light receiving element 21 includes an S polarizing plate 22, a band pass filter 23, a lens 24, and a light receiving unit 25. FIG. 4 is a diagram showing a schematic configuration of the upper light receiving system 20, and is a top view seen from the light projecting system side. In FIG. 4, the laser beam emitted from the laser light source 11 is reflected from the mirror 14. This laser beam is scan-controlled in the scanning direction as shown in the figure, and is mostly composed of an S-polarized component. What is scattered on the front surface, inside, back surface, etc. of the substrate 1 is directed to the light receiving portion 25 of the upper light receiving element 21. It is arranged as follows. The S-polarizing plate 22 allows only the S-polarized light component to pass through, and allows only the S-polarized light component of the laser beam (scattered light) scattered on the front surface, inside, and back surface of the substrate 1 to pass therethrough. The bandpass filter 23 passes only light in the vicinity of the frequency component of the laser beam emitted from the laser light source 11, that is, passes light in the vicinity of the wavelength component of the emitted laser beam, and removes light of other frequency components (wavelength components). It is. The lens 24 collects only the light scattered from the substrate 1 and passed through the S-polarizing plate 22 and the bandpass filter 23 and introduces it to the light receiving unit 25. The focal position of the lens 24 matches the surface of the substrate 1. The light receiving unit 25 is configured by bundling a plurality of optical fibers 25 a, receives the scattered light collected by the lens 24, and guides it to the light receiving surface of the photomultiplier tube 26. The photomultiplier tube 26 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 26 is amplified by an amplifier 27 and input to the defect detection circuit 28. As described above, by providing the S polarizing plate 22 and the band pass filter 23 on the front surface of the lens 24, the light is disturbing light from the surrounding environment of the apparatus and includes light other than the above-described frequency component (wavelength component) and P-polarized light component. The lens 24 and the light receiving unit 25 are the laser beams that are effectively removed from the light projecting system and obliquely applied to the substrate 1 from the light projecting system, and only the S-polarized component light scattered on the front surface, inside, back surface, etc. Can be introduced effectively.

  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 to generate scattered light. Further, the laser beam that has been transmitted into the substrate 1 and 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 by defects on the surface of the substrate 1 has a higher intensity received by the light receiving unit 25 of the upper light receiving system 20 than scattered light generated by defects inside the substrate 1. The defect detection circuit 28 detects a defect on the surface of the substrate 1 from the intensity of the detection signal amplified by the amplifier 27.

  On the back surface side of the substrate 1, a lower light receiving system 30 is disposed at a position off the optical axis of the laser beam transmitted from the back surface of the substrate 1. The lower light receiving system 30 includes a lower light receiver 31 and a photomultiplier tube 36. The lower light receiving element 31 includes an S polarizing plate 32, a band pass filter 33, a lens 34, and a light receiving unit 35. 5 is a diagram showing a schematic configuration of the lower light receiving system 30, and is a side view seen from the left side of FIG. In FIG. 5, the laser beam emitted from the laser light source 11 is reflected from the mirror 14. This laser beam is scan-controlled in the scanning direction as shown in the figure, and is mostly composed of S-polarized light, which is scattered on the surface, inside, back surface, etc. of the substrate 1 It arrange | positions so that it may go to the light-receiving part 35 of the lower light receiving element 31. FIG. The S-polarizing plate 32 allows only the S-polarized light component to pass through, is scattered on the front surface, inside, back surface, and the like of the substrate 1 and passes only the S-polarized light component of the laser beam that has passed through the substrate 1. The band-pass filter 33 passes only light in the vicinity of the frequency component of the laser beam emitted from the laser light source 11, that is, light in the vicinity of the wavelength component of the emitted laser beam, and removes light of other frequency components (wavelength components). It is. The lens 34 collects only light that has been scattered from the front surface, inside, and back surface of the substrate 1 and has passed through the S-polarizing plate 32 and the band-pass filter 33, and introduces it to the light receiving unit 35. The focal position of the lens 34 matches the back surface of the substrate 1. The light receiving unit 35 is configured by bundling a plurality of optical fibers 35 a, receives the scattered light collected by the lens 34, and guides it to the light receiving surface of the photomultiplier tube 36. The photomultiplier tube 36 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 36 is amplified by an amplifier 37 and input to a defect detection circuit 38. As described above, by providing the S polarizing plate 32 and the band pass filter 33 on the front surface of the lens 34, the light is a disturbance light from the surrounding environment of the apparatus, and the light other than the frequency component (wavelength component) and the P polarization component. The lens 34 and the light receiving unit 35 receive only the light of the S-polarized component, which is a laser beam that is effectively removed from the light emitting system and is obliquely irradiated to the substrate 1 from the light projecting system and scattered on the front surface, inside, and back surface of the substrate 1. Can be introduced.

  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 35 in which a plurality of optical fibers 35a are bundled has a shape that directly 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 34 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 to generate scattered light. Further, the laser beam that has been transmitted into the substrate 1 and 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. When the scattered light received by the light receiving unit 35 in which a plurality of optical fibers 35a are bundled is superimposed on a map scanned in the Z direction (substrate thickness direction), a cross spreads vertically and horizontally depending on the laser scanning direction regardless of the shape of the defect. It becomes a shape. The defect detection circuit 38 selectively 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 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 lower light receiving element 31 up and down. When the focus adjusting mechanism 40 moves the lower light receiving element 31 up and down, the focus position of the lower light receiving system 30 is adjusted so as to be matched with the inside of the substrate 1.

  According to the embodiment described above, in the inspection of a defect on a transparent substrate having a large thickness, the disturbance light entering the detection optical system from the surrounding environment of the substrate, that is, the frequency component (wavelength component) of the light emitted from the laser light source. The light other than the light and the P-polarized component light is effectively removed, and only the S-polarized component light scattered obliquely from the projection system to the substrate 1 and scattered on the front surface, inside, back surface, etc. of the substrate 1 is obtained. It can be introduced into the lens 34 and the light receiving unit 35, and the influence of noise or the like can be eliminated, and the defect detection accuracy can be improved.

  FIG. 6 is a diagram showing an example of the inspection result of the substrate inspection method of the present invention. FIG. 6 shows the distribution of defects such as scratches and foreign matter on the front and back surfaces of the mask substrate, and FIG. 6 (A) shows the defect distribution as the inspection result before the mask substrate cleaning process, FIG. 6B shows a defect distribution state as an inspection result after the cleaning process of the mask substrate, and FIG. 6C shows the defect distribution before the cleaning process in FIG. This is a subtraction of the defect distribution after the cleaning process, that is, the distribution of defects and scratches removed by the cleaning process. By observing the distribution state of FIG. 6C, it can be understood that how many scratches and foreign matters are removed by the cleaning process, and the front and back surfaces of the mask substrate are cleaned cleanly. . If the distribution of defects such as scratches and foreign matter removed by the cleaning process is extremely small as shown in FIG. 6C, understand that there is a problem with the cleaning process. Can do. In the present invention, the quality of the process is judged using the distribution state of FIG.

  FIG. 7 is a diagram illustrating an example of a first inspection process of the substrate inspection method. An example of processing of the substrate inspection method of the present invention will be described with reference to this flowchart. In this inspection process, first, a predetermined inspection is performed on the mask substrate 1 using the substrate inspection apparatus shown in FIG. In the first step S71, the recipe number (measurement conditions and the like) and the work number of the mask substrate 1 are read from the barcode, QR code or the like given to the mask substrate 1. In step S72, the pre-cleaning substrate inspection A is performed on the mask substrate 1 according to the recipe number read first. In step S73, since the substrate inspection A is completed, the mask substrate 1 is discharged, the processing is ended, and the preparation for the next mask substrate is prepared. The result of the substrate inspection A is an inspection result A (defect distribution) as shown in FIG.

  FIG. 8 is a diagram illustrating an example of a post-mask substrate cleaning process that is a second inspection process of the substrate inspection method. In accordance with the result of the pre-cleaning substrate inspection A in FIG. 7, the mask substrate is subjected to a cleaning processing for removing defects such as scratches and foreign matters. In FIG. 8, the same inspection as described above is performed on the mask substrate after the cleaning process using the substrate inspection apparatus of FIG. First, in step S81, the recipe number (measurement conditions, etc.) and the work number of the mask substrate 1 and the work number are read from the bar code, QR code, etc. given to the mask substrate 1. In step S82, the post-cleaning substrate inspection B is performed on the mask substrate 1 according to the recipe number. In step S83, since the substrate inspection B is completed, the mask substrate 1 is discharged. The result of the substrate inspection B becomes an inspection result B (defect distribution) as shown in FIG. 6B and is stored in the memory 70. In step S84, the inspection result A is subtracted from the inspection result B. That is, the defect distribution (FIG. 6A) of the mask substrate before the cleaning processing is subtracted from the defect distribution (FIG. 6B) of the mask substrate after the cleaning processing. As shown in FIG. 6C, the subtraction result is obtained by subtracting the defect distribution of FIG. 6B from the defect distribution of FIG. 6A.

  The defect distribution in FIG. 6C indicates the defect distribution removed by the cleaning process of the mask substrate. Therefore, in the next step S85, it is determined whether or not the value indicating the subtraction result (subtraction value) is larger than the predetermined value. If the value is larger than the predetermined value (yes), the process proceeds to step S86, and the predetermined value or less. In the case of (no), the process proceeds to step S87. In step S86, the fact that the subtracted value is larger than the predetermined value means that defects such as scratches and foreign matter have been removed from the mask substrate by the cleaning processing of the mask substrate. Instruct the administrator or the like to finish the process. On the other hand, in step S87, the subtraction value being equal to or less than the predetermined value means that the predetermined number of defects have not been removed from the mask substrate by the cleaning processing of the mask substrate. Is instructed to the administrator or the like to end the process.

  FIG. 9 is a diagram illustrating an example of a post-mask substrate re-cleaning process that is a third inspection process of the substrate inspection method. In accordance with the determination result in step S85 in FIG. 8, a second cleaning process (recleaning process) is performed on the mask substrate in order to remove defects such as scratches and foreign matters. In FIG. 9, the same inspection as in FIG. 8 is performed on the mask substrate after the re-cleaning processing using the substrate inspection apparatus in FIG. First, in step S91, the recipe number (measurement conditions, etc.) and the work number of the mask substrate 1 and the work number are read from the barcode, QR code, or the like given to the mask substrate 1. In step S92, the substrate inspection C after the re-cleaning process is performed on the mask substrate 1 according to the recipe number. In step S93, since the substrate inspection C is completed, the mask substrate 1 is discharged. In step S94, the inspection result B of FIG. 8 is subtracted from the current inspection result C. That is, the defect distribution (FIG. 6B) of the mask substrate before the recleaning process (after the first cleaning process) is subtracted from the defect distribution (not shown) of the mask substrate after the recleaning process. The result of this subtraction processing indicates the defect distribution removed by the re-cleaning processing of the mask substrate, and is stored in the memory 70. Therefore, in the next step S95, it is determined whether or not the value indicating the subtraction result (subtraction value) is larger than the predetermined value. If the value is larger than the predetermined value (yes), the process proceeds to step S96, and the value is equal to or smaller than the predetermined value. In the case of (no), the process proceeds to step S97. In step S96, the fact that the subtraction value is larger than the predetermined value means that a predetermined amount of defects such as scratches and foreign matter has been removed from the mask substrate by the re-cleaning processing of the mask substrate. The process is terminated by instructing the administrator or the like to complete the process (re-cleaning unnecessary). On the other hand, in step S97, the subtraction value being equal to or less than the predetermined value means that the predetermined number of defects such as scratches and foreign matters have not been removed from the mask substrate by the re-cleaning processing of the mask substrate. Since there is a high possibility that a defect such as a scratch or a foreign substance exists inside the mask substrate, an instruction is given to the administrator or the like to perform an internal defect inspection, and the process is terminated.

  FIG. 10 is a diagram illustrating an example of the internal defect inspection process of the mask substrate which is the fourth inspection process of the substrate inspection method. According to the result of the determination in step S95 in FIG. 9, a defect inspection process is performed on the inside of the mask substrate. In FIG. 10, processing for selectively detecting defects such as scratches and foreign matters inside the mask substrate 1 is performed based on the shape characteristics of the scattered light. First, in step S101, the recipe number (measurement conditions, etc.) and the work number of the mask substrate 1 and the work number are read from a barcode, QR code, or the like given to the mask substrate 1. In step S102, the internal defect inspection D is performed on the mask substrate 1 according to the recipe number. In step S103, since the internal defect inspection D is completed, the mask substrate 1 is discharged. In step S104, process determination is performed based on the result D of the current internal defect inspection, and the process ends.

In the above-described embodiment, the case where the inspection result B is subtracted from the inspection result C in step S94 has been described. However, the inspection result A may be subtracted from the inspection result C. Further, in the above-described embodiment, the re-cleaning process or the re-cleaning process is determined based on the subtraction value, but may be determined based on whether the value of the inspection result B or C is equal to or less than a predetermined value. However, the determination may be made based on a combination of this and the subtraction value.
In the above-described embodiment, as a method of aligning the substrate 1 on the inspection table 5, the end of the substrate 1 in the Y-axis direction is pushed to a positioning pin or the like while the substrate 1 is placed as shown in FIG. Position the contact. In this case, at least two positioning pins may be provided at the end of the substrate 1 in the Y-axis direction.

DESCRIPTION OF SYMBOLS 1 ... Mask board | substrate 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 21 ... Upper light receiver 22, 32 ... S polarizing plate 23, 33 ... Band-pass filters 24, 34 ... Lenses 25, 35 ... Light receivers 25a, 35a ... Optical fibers 26, 36 ... Photomultiplier tubes 27, 37 ... Amplifiers 28, 38 ... Defect detection circuit 30 ... Lower light receiving system 31 ... Lower light receiver 40 ... Focus adjustment mechanism 41 ... Focus adjustment control circuit 5 ... Inspection table 50 ... Substrate movement mechanism 51 ... Substrate movement control circuit 52 ... Light projection system movement mechanism 53 ... Light projection system movement control circuit 54 ... Upper light reception system movement mechanism 55 ... Upper light receiving system movement control circuit 56 ... Lower light receiving system moving mechanism 57 ... Lower light receiving system movement control circuit 5a ... Substrate support part 5b ... Inclined surface 60 ... Control part (CPU)
70: Memory

Claims (10)

While irradiating the surface of the substrate obliquely at an angle such that a part of the light beam is reflected by the surface of the substrate and the remaining light beam is transmitted to the inside of the substrate, the light beam is moved while moving the light beam. Scan,
The first lens unit condenses the scattered light, which is disposed on the surface side of the substrate, and the light beam is scattered by the defect of the substrate, and is received by the first light receiving unit,
Disposed on the back side of the substrate, and the scattered light scattered by the defects of the substrate is collected by the second lens means and received by the second light receiving means,
Detecting the presence position of the defect on the substrate from the signal based on the scattered light received by the first and second light receiving system means;
A substrate inspection method comprising: comparing the detected positions of the detected defects before and after cleaning the substrate; and determining whether or not to reclean the substrate according to the comparison result. While obliquely irradiating the surface of the substrate with a large amount of the first polarization component at an angle such that a part of the light beam is reflected by the surface of the substrate and the remaining light beam is transmitted to the inside of the substrate, Scanning the substrate while moving the light beam,
A first polarizing plate means that allows only light of the first polarization component to pass through and a band-pass filter means that passes only light in the vicinity of the frequency component of the light beam are provided on the front surface, and the first polarizing plate means and the band pass are provided. Light receiving system means for condensing the light that has passed through the filter means by the lens means and receiving the light by the first light receiving means, which is disposed on the surface side of the substrate, and the light beam is scattered by the defect of the substrate Scattered light is received by the first light receiving means via the first polarizing plate means, the first band pass filter means and the first lens means,
The second polarizing plate means includes a second polarizing plate means for allowing only light of the first polarization component to pass therethrough and a second band pass filter means for allowing only light in the vicinity of the frequency component of the light ray to pass therethrough, and the second polarizing plate means. And light receiving system means for condensing the light that has passed through the second bandpass filter means by the second lens means and receiving the light by the second light receiving means, disposed on the back side of the substrate, Light scattered by the defect of the substrate is received by the second light receiving means through the second polarizing plate means, the second bandpass filter means and the second lens means,
Detecting the presence position of the defect on the substrate from the signal based on the scattered light received by the first and second light receiving system means;
A substrate inspection method comprising: comparing the detected positions of the detected defects before and after cleaning the substrate; and determining whether or not to reclean the substrate according to the comparison result. The substrate inspection method according to claim 1 or 2,
Whether the defect existing position before and after the cleaning process and the defect existing position after the re-cleaning process are compared after the re-cleaning process, and the defect inside the substrate is detected according to the comparison result. A substrate inspection method characterized by determining whether or not. In the board | substrate inspection method of Claim 1, 2, or 3,
A substrate inspection method, wherein a measurement condition for detecting the presence position of the defect is read from a barcode or the like given to the substrate. In the board | substrate inspection method of Claim 1, 2, 3 or 4,
The focal positions of the first and second light receiving means are aligned with the inside of the substrate, and a defect inside the substrate is detected based on the shape characteristics of the scattered light received by the first and second light receiving means. A method for inspecting a substrate. While irradiating the surface of the substrate obliquely at an angle such that a part of the light beam is reflected by the surface of the substrate and the remaining light beam is transmitted to the inside of the substrate, the light beam is moved while moving the light beam. A light projection system means for scanning;
A first lens arranged on the surface side of the substrate and configured to collect the scattered light scattered by the defect of the substrate by the first lens means and receive the light by the first light receiving means; Light receiving means;
A second arrangement is arranged on the back side of the substrate, and is configured to collect the scattered light, which is scattered by the defect of the substrate, by the second lens means and receive it by the second light receiving means. Light receiving means;
A defect detection means for detecting a position of a defect on the substrate from a signal based on scattered light received by the first and second light receiving system means;
Control means for comparing the presence positions of the defects detected by the defect detection means before and after cleaning the substrate, and determining whether or not to re-clean the substrate according to the comparison result. A board inspection apparatus characterized by that. While obliquely irradiating the surface of the substrate with a large amount of the first polarization component at an angle such that a part of the light beam is reflected by the surface of the substrate and the remaining light beam is transmitted to the inside of the substrate, Projection system means for scanning the substrate while moving the light beam;
A first polarizing plate means that allows only light of the first polarization component to pass through and a band-pass filter means that passes only light in the vicinity of the frequency component of the light beam are provided on the front surface, and the first polarizing plate means and the band pass are provided. Light receiving system means for condensing the light that has passed through the filter means by the lens means and receiving the light by the first light receiving means, which is disposed on the surface side of the substrate, and the light beam is scattered by the defect of the substrate First light-receiving system means configured to receive the scattered light at the first light-receiving means via the first polarizing plate means, the first band-pass filter means, and the first lens means. When,
The second polarizing plate means includes a second polarizing plate means for allowing only light of the first polarization component to pass therethrough and a second band pass filter means for allowing only light in the vicinity of the frequency component of the light ray to pass therethrough, and the second polarizing plate means. And light receiving system means for condensing the light that has passed through the second bandpass filter means by the second lens means and receiving the light by the second light receiving means, disposed on the back side of the substrate, The second light receiving means receives the scattered light, which is scattered by the defect of the substrate, through the second polarizing plate means, the second bandpass filter means, and the second lens means. A second light receiving system configured in
A defect detection means for detecting a position of a defect on the substrate from a signal based on scattered light received by the first and second light receiving system means;
Control means for comparing the presence positions of the defects detected by the defect detection means before and after cleaning the substrate, and determining whether or not to re-clean the substrate according to the comparison result. A board inspection apparatus characterized by that. In the board | substrate inspection apparatus of Claim 6 or 7,
The control means, after the re-cleaning process, compares the position of the defect before and after the cleaning process and the position of the defect after the re-cleaning process, respectively, and according to the comparison result, the defect inside the substrate A substrate inspection apparatus that determines whether or not to perform detection. The board inspection apparatus according to claim 6, 7 or 8,
The substrate inspection apparatus, wherein the defect detection means reads a measurement condition for detecting the presence position of the defect from a barcode or the like given to the substrate. The substrate inspection apparatus according to claim 6, 7, 8 or 9,
The defect detecting means adjusts the focal positions of the first and second light receiving means to the inside of the substrate, and based on the geometric characteristics of the scattered light received by the first and second light receiving means. A substrate inspection apparatus for detecting an internal defect.

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