JP2013044577A - Substrate inspection method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect, with high accuracy, a pin hole defect of a chromium film or the like of a mask substrate that is likely to warp greatly on a stage.SOLUTION: If there is a mask pattern such as a chromium film on a surface of a substrate, a light beam radiated on the surface of the substrate is scattered due to a shape or a defect of the mask pattern, scattered light is generated only around a surface side of the substrate, and therefore, there is no light beam transmitting to a rear surface of the substrate. Meanwhile, if there is a pin hole on the mask pattern, a portion of light scattered at an edge of the pin hole is generated as scattered light around the surface side of the substrate, is transmitted into the inside of the substrate via the pin hole, and therefore, is generated as scattered light around the rear surface of the substrate. By respectively receiving the scattered light detected on the surface and the rear surface of the substrate at scattered light receiving means arranged on the surface side and rear surface side of the substrate, a pin hole of a chromium film of a mask substrate that is likely to warp greatly on a stage is detected with high accuracy.

Description

  The present invention relates to a substrate inspection method and apparatus for detecting a defect of a transparent substrate such as glass or quartz used for an exposure mask or the like, and more particularly to a substrate inspection method and apparatus suitable for inspecting a pinhole defect of a mask. About.

  The manufacture of TFT (Thin Film Transistor) substrates, color filter substrates, plasma display panel substrates, organic EL (Electro Luminescence) display panel substrates, etc. for liquid crystal display devices used as display panels uses photomasks. The 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 mask 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.

  FIG. 1 is a perspective view showing a state of a substrate mounted on a conventional inspection table. The substrate 1 to be inspected is placed on the substrate support portions 5a and 5b of the inspection table. The inspection table includes two substrate support portions 5a and 5b extending in the horizontal direction of the drawing and arranged in parallel with each other in the drawing depth direction. The substrate support portions 5a and 5b have inclined surfaces 5c and 5d that contact the mask substrate 1 over the length in the longitudinal direction. When the substantially square mask substrate 1 is mounted on the substrate support portions 5a and 5b of the inspection table, the inclined surfaces 5c and 5d of the substrate support portions 5a and 5b are respectively located on the bottom sides of the two opposite sides of the mask substrate 1. It is designed to be held in contact. Therefore, the inspection table supports the substantially rectangular substrate 1 only on its two opposite sides.

  FIG. 2 is a diagram showing an outline of an optical system unit of a conventional substrate inspection apparatus. The optical system unit 40 includes an inspection light irradiation unit 41, a scattered light receiving unit 42, a scattering mirror unit 43, a transmitted light receiving unit 44, and a trap unit 45. As an example, the inspection light irradiation unit 41 includes a laser light source and a polygon mirror. The inspection light irradiation unit 41 reflects the laser light from the laser light source with a rotating polygon mirror, thereby inspecting the inspection light 41a having a predetermined width in the Y direction (the depth direction in the drawing) with a mask substrate mounted on the inspection table. 1 is irradiated. The width in the Y direction (the depth direction of the drawing) of the inspection light 41a irradiated onto the substrate 1 from the inspection light irradiation unit 41 is about 200 [mm].

  Most of the inspection light 41a irradiated to the chromium film 10 serving as the mask pattern portion of the mask substrate 1 is reflected as reflected light 41b by the chromium film 10, but a pinhole (not shown) is temporarily provided in the chromium film 10. When present, the inspection light 41a that has passed through the pinhole is transmitted to the back side of the mask substrate 1 as transmitted light 41d. Moreover, when the foreign material 40a exists on the surface of the chromium film 10 of the mask substrate 1, a part of the inspection light 41a is scattered by the foreign material 40a and becomes scattered light 41c. The scattered light receiving unit 42 includes a sensor having a predetermined detection width in the Y direction (the depth direction in the drawing), and receives the scattered light 41c from the mask substrate 1 (foreign matter 40a and the like). The scattering mirror unit 43 reflects the transmitted light 41 d transmitted through the mask substrate 1 to the transmitted light receiving unit 44. The transmitted light receiving unit 44 includes a sensor having a predetermined detection width in the Y direction (the depth direction in the drawing), and receives the reflected light 41 e that is transmitted through the mask substrate 1 and reflected by the scattering mirror unit 43. The trap unit 45 shields the transmitted light 41d from the inspection apparatus or reflected from the inspection apparatus and scattered light hitting other parts and entering the scattered light receiving unit 42 and the transmitted light receiving unit 44.

  As described above, when the pinhole of the chromium film 10 is inspected conventionally, the scattering mirror unit 43 and the transmitted light receiving unit 44 are used. However, as the mask substrate 1 increases in size, the thickness of the substrate also increases. When such a mask substrate is supported by only two sides on the inspection table, the amount of deflection is increased by the weight of the mask substrate 1 itself. When the bending of the mask substrate 1 is taken into consideration, as shown in FIG. 2, the mask substrate 1 has a thickness as if indicated by a dotted line. Therefore, assuming a substrate having a size as shown by the dotted line, the scattering mirror unit 43 for pinhole inspection and the transmitted light receiving unit 44 are sufficiently moved below the inspection table so as not to contact the mask substrate shown by the dotted line. As a result, the optical path length at the time of pinhole inspection also becomes longer, the refraction of the transmitted light increases due to the thick mask substrate 1, and the transmitted light 41d is efficiently reflected by the scattering mirror 43. It has become difficult to conduct pinhole inspection with high accuracy.

  The present invention has been made in view of the above-described points, and provides a substrate inspection method and apparatus capable of detecting pinhole defects such as a chromium film of a mask substrate that is greatly bent on a stage with high accuracy. For the purpose.

A first feature of the substrate inspection method according to the present invention is that the 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 substrate is scanned while moving the light beam while irradiating obliquely, and the scattered light, which is disposed on the surface side of the substrate and is scattered by the defect of the substrate, is used as the first scattered light receiving means. The second scattered light receiving means receives the scattered light, which is disposed on the back side of the substrate, and the light beam is scattered by the pinhole edge of the mask pattern formed on the substrate surface. The defect of the substrate is detected from a signal based on the scattered light received by the first and second scattered light receiving means.
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 Scan (inspect). At this time, if a mask pattern made of a chromium film exists on the surface of the substrate, the light beam irradiated to the surface of the substrate is scattered by the shape of the mask pattern and defects on the mask pattern, and scattered light around the surface side of the substrate Is generated, and there is no light beam transmitted to the back side of the substrate. On the other hand, if there is a pinhole in the mask pattern made of a chromium film, part of the light scattered near the edge of the pinhole is generated as scattered light around the surface of the substrate and the pinhole is formed inside the substrate. And is generated as scattered light around the back side of the substrate. The scattered light detected on the front surface and the back surface of the substrate is received by the first scattered light receiving device disposed on the front surface side of the substrate and the second scattered light receiving device disposed on the back surface side of the substrate, respectively. As a result, pinhole defects in the chromium film of the mask substrate that are greatly bent on the stage based on the received scattered light signals can be detected with high accuracy.

A second feature of the substrate inspection method according to the present invention is that in the substrate inspection method according to the first feature, the surface of the substrate is irradiated with a light beam containing a large amount of a predetermined polarization component, and only the light of the polarization component is irradiated. And a band-pass filter unit that allows only light in the vicinity of the frequency component of the light beam to pass through the front surface of the first and second scattered light receiving units.
This uses a polarizing plate means for passing only light of the polarized light component and a band pass filter for passing only light in the vicinity of the frequency component of the light, using a light containing a large amount of a predetermined polarized light component as a light beam irradiating the surface of the substrate By providing the means on the front surface of the scattered light receiving means, each scattered light also contains a lot of predetermined polarization components. Further, only scattered light containing a large amount of a predetermined polarization component passes through the polarizing means and the bandpass filter means and is taken into the scattered light receiving means. As a result, the influence of ambient light noise entering 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 first feature of the substrate inspection apparatus according to the present invention is that 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 projecting system means for scanning the substrate while moving the light beam while irradiating obliquely, and a light receiving system arranged on the surface side of the substrate to receive the scattered light scattered by the defect of the substrate. A first scattered light receiving means, and a second scattered light receiving means arranged on the back side of the substrate for receiving the scattered light scattered by the pinhole edge of the mask pattern formed on the substrate surface. And a defect detecting means for detecting a defect of the substrate from a signal based on the scattered light received by the first and second scattered light receiving means. This is an invention of a substrate inspection apparatus for realizing the first feature of the substrate inspection method.

  A second feature of the substrate inspection apparatus according to the present invention is that, in the substrate inspection device according to the first feature, the surface of the substrate is irradiated with a light beam containing a large amount of a predetermined polarization component, and only the light of the polarization component is irradiated. And a band-pass filter unit that allows only light in the vicinity of the frequency component of the light beam to pass through the front surface of the first and second scattered light receiving units. This is an invention of a substrate inspection apparatus for realizing the second feature of the substrate inspection method.

  According to the present invention, there is an effect that pinhole defects such as a chromium film of a mask substrate that is greatly bent on the stage can be detected with high accuracy.

It is a perspective view which shows the state of the board | substrate mounted in the conventional test | inspection table. It is a figure which shows the outline of the optical system unit of the conventional board | substrate inspection apparatus. It is a figure which shows schematic structure of the optical system unit of the board | substrate inspection apparatus by one embodiment of this invention. It is a figure which shows the detailed structure of the test | inspection light irradiation part of FIG. It is a figure which shows the operation example of an inspection apparatus in case the mask pattern of the chromium film | membrane is formed in the surface of a mask board | substrate, and a defect and a pinhole exist there. It is a figure which shows the operation example of an inspection apparatus in case only a defect exists in the mask pattern of the chromium film | membrane of the surface of the mask board | substrate 1. FIG. It is a figure which shows an example of the detection operation of the pinhole which exists in a mask pattern.

  FIG. 3 is a diagram showing a schematic configuration of the optical system unit of the substrate inspection apparatus according to the embodiment of the present invention. The optical system unit 400 of the substrate inspection apparatus according to the present invention includes an inspection light irradiation unit 41, a scattered light receiving unit 42, a trap unit 45, and a pinhole scattered light receiving unit 46. The substrate inspection apparatus of the present invention is different from that shown in FIG. 2 in that it receives light reflected from the edge portion of the pinhole existing in the mask pattern such as a chromium film on the back surface side of the mask substrate 1. The point 46 is provided. The pinhole scattered light receiving unit 46 is on the back side of the mask substrate 1, that is, on the side opposite to the position where the inspection light irradiation unit 41 is present, and is capable of directly receiving the scattered light 41f from the edge of the pinhole. Is arranged. Further, the pinhole scattered light receiving unit 46 has a mechanism for calculating the shift of the detection position based on the plate thickness and the refractive index and moving it as indicated by the double-ended arrows in the figure.

  As shown in FIG. 1, the mask substrate 1 to be inspected is placed on the substrate support portions 5a and 5b of the inspection table. In FIG. 3, the substrate support portions 5a and 5b are not shown. An inspection light irradiation unit 41 is disposed above the mask substrate 1. FIG. 4 is a diagram illustrating a detailed configuration of the inspection light irradiation unit in FIG. 3. As shown in FIG. 4, the inspection light irradiation unit 41 includes a laser light generation unit 11, a lens 12 a, an fθ lens 12 c, and a polygon mirror 13. The laser light generation unit 11 is a laser beam and mainly generates inspection light of an S-polarized component. The laser beam emitted from the laser beam generator 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 more sufficient than that of the P-polarized component. To be large. Note that the laser light generator 11 may emit only the S-polarized component. The lens 12 a condenses the laser beam generated from the laser beam generator 11 and converges so that the surface of the substrate 1 is focused. 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 irradiated obliquely onto the surface of the mask substrate 1 as inspection light 41a. At this time, when the polygon mirror 13 rotates in the direction of the arrow in FIG. 2, the inspection light 41a alternately moves in the depth direction of FIG. 3, and the surface of the mask substrate 1 is scanned with the inspection light 41a. In the present embodiment, as an example, this scanning range is about 200 [mm].

  In FIG. 3, a substrate movement control device that determines the inspection range of the mask substrate 1 and controls the movement range of the mask substrate 1 is mounted. The substrate movement control device is configured to include, for example, a linear motion motor and moves the substrate support portions 5a and 5b of the inspection table in the lateral direction of FIG. 3, but the detailed configuration is omitted in FIG. is there. When the substrate movement control device moves the substrate support portions 5a and 5b of the inspection table in the horizontal direction, the mask substrate 1 mounted on the substrate support portions 5a and 5b is moved in the substrate movement direction. The inspection light 41a is irradiated in the horizontal direction of the mask substrate 1 in the drawing. Accordingly, the substrate 1 is inspected by the width of the scanning range in the drawing depth direction by one movement of the substrate support portions 5a and 5b of the inspection table.

  The inspection light irradiation unit 41 is driven and controlled by a projection system control device. The light projection system control device is configured to include, for example, a linear motor, and controls the movement of the inspection light irradiation unit 41 in the depth direction of the drawing, but its detailed configuration is omitted in FIG. When the light projection system control device controls the movement of the inspection light irradiation unit 41, the scanning range of the mask substrate 1 by the inspection light 41a irradiated from the inspection light irradiation unit 41 is changed and controlled in the drawing depth direction. Then, the entire inspection range of the mask substrate 1 can be inspected by sequentially repeating the scanning of the mask substrate 1 by the inspection light 41a, the movement of the substrate support portions 5a and 5b of the inspection table, and the change of the scanning range. It can be done.

  When the inspection light irradiation unit 41 is controlled to move, the entire unit including the scattered light receiving unit 42, the trap unit 45, and the pinhole scattered light receiving unit 46 is synchronized with the movement of the inspection light irradiation unit 41. Move control. The light receiving system control device includes, for example, a linear motion motor, and controls movement of the scattered light receiving unit 42, the trap unit 45, and the pinhole scattered light receiving unit 46 in synchronization with the movement of the inspection light irradiation unit 41. .

  Instead of moving the substrate support portions 5a and 5b of the inspection table, the inspection light irradiation portion 41, the scattered light receiving portion 42, the trap portion 45, and the pinhole scattered light receiving portion 46 are moved in the horizontal direction of the drawing. The mask substrate 1 may be relatively moved in a direction (horizontal direction in the drawing) orthogonal to the scanning direction of the inspection light 41a. Further, the entire surface of the mask substrate 1 may be scanned by moving the substrate support portions 5a and 5b of the inspection table in the drawing depth direction and the drawing horizontal direction. That is, any configuration may be used as long as the moving direction of the light projecting system and the light receiving system and the moving direction of the mask substrate 1 are relatively movable.

  A part of the inspection light 41 a irradiated obliquely from the inspection light irradiation unit 41 to the mask substrate 1 is reflected by the surface of the mask substrate 1, and the rest is transmitted to the inside of the mask substrate 1. The inspection light 41 a transmitted to the inside of the mask substrate 1 spreads away from the surface of the mask substrate 1, a part of which is reflected on the back surface of the mask substrate 1, and the rest is out of the mask substrate 1 from the back surface of the mask substrate 1. To Penetrate. This is a case where the mask substrate 1 is an ideal flat transparent substrate.

  On the surface side of the mask substrate 1, a scattered light receiving unit 42 is disposed at a position off the optical axis of the reflected light 41 b of the inspection light 41 a reflected by the surface of the mask substrate 1. The scattered light receiving unit 42 includes an S polarizing plate, a band pass filter, a lens, a light receiving unit, a photomultiplier tube, and the like. As shown in FIG. 3, the inspection light 41a is controlled to be scanned in the scanning direction (the depth direction of the drawing), and is mostly composed of S-polarized light components. Is arranged so as to be directed to the scattered light receiver 42. The S-polarizing plate allows only the S-polarized light component to pass therethrough, and allows only the S-polarized light component of the scattered light 41c of the inspection light 41a scattered at the front surface, inside, back surface, and pinhole edge of the mask substrate 1 to pass therethrough. The band pass filter passes only light in the vicinity of the frequency component of the inspection light 41a emitted from the inspection light irradiation unit 41, that is, light in the vicinity of the wavelength component of the inspection light 41a, and light of other frequency components (wavelength components). Is to be removed. The lens collects only the light that has been scattered from the mask substrate 1 and has passed through the S-polarizing plate and the bandpass filter, and introduces it to the light receiving unit. The focal position of the lens matches the surface of the mask substrate 1. The light receiving unit is configured by bundling a plurality of optical fibers, receives the scattered light collected by the lens, and guides it to the light receiving surface of the photomultiplier tube. The photomultiplier tube outputs a detection signal corresponding to the intensity of scattered light received by the light receiving surface. The detection signal of the photomultiplier tube is amplified by an amplifier (not shown) and input to a defect detection device (not shown). In this way, by providing the S-polarizing plate and the bandpass filter on the front surface of the lens, it is the disturbance light from the surrounding environment of the apparatus, and the light other than the above-mentioned frequency component (wavelength component) and the light of the P polarization component Inspection light 41a effectively removed and obliquely irradiated from the light projecting system to the mask substrate 1 and only the S-polarized component light scattered at the front surface, inside, back surface, pinhole edge, etc. of the mask substrate 1 is scattered. It can be effectively introduced into the light receiving unit 42. If the disturbance light is sufficiently smaller than the signal, or if the detection defect size is large and the sensitivity is low, the S polarizing plate and the band pass filter may be omitted.

  When there is no mask pattern such as a chrome film on the surface of the mask substrate 1, the mask substrate 1 is equivalent to a transparent glass substrate. Therefore, when there is a defect on the surface of the mask substrate 1, the surface of the mask substrate 1 is irradiated. The inspection light 41a is scattered by the defect, and scattered light 41c is generated there. In addition, the inspection light 41a that is transmitted into the mask substrate 1 and reflected by the back surface of the mask substrate 1 and reaches the surface of the mask substrate 1 again is scattered by the defect, and scattered light is generated there. These scattered lights are received by the scattered light receiving unit 42 disposed on the surface side of the mask substrate 1. Further, when a defect exists in the mask substrate 1, the inspection light 41a transmitted to the inside of the mask substrate 1 is scattered by the defect, and scattered light is generated there, which is also transmitted to the inside of the mask substrate 1 to be masked. The inspection light 41a reflected from the back surface of the substrate 1 is scattered by defects inside the mask substrate 1, and scattered light is generated there. These scattered lights are received by the scattered light receiving unit 42 disposed on the surface side of the mask substrate 1. Since the scattered light 41c generated by the defect on the surface of the mask substrate 1 is received by the scattered light receiving unit 42 higher than the other scattered light generated by the defect inside the mask substrate 1, Surface defects can be easily detected.

  On the other hand, on the back surface side of the mask substrate 1, the pinhole scattered light receiving unit 46 is disposed at a position off the optical axis of the transmitted light 41 d transmitted through the back surface of the mask substrate 1. The pinhole scattered light receiving unit 46 includes an S polarizing plate, a bandpass filter, a lens, a light receiving unit, a photomultiplier tube, and the like. The scattered light receiving unit 46 for pinhole has scattered light scattered by defects existing on the front surface, inside, back surface, pinhole edge and the like of the mask substrate 1 and a mask pattern such as a chromium film on the surface of the mask substrate 1. In some cases, the scattered light scattered at the edge of the pinhole of the mask pattern is arranged to be incident. The S-polarizing plate transmits only the light of the S-polarized component and is scattered by the front surface, the inside, the back surface, the pinhole edge, etc. of the mask substrate 1, and the S-polarized light of the scattered light 41f that has passed through the mask substrate 1 Pass only ingredients. The band-pass filter passes only light in the vicinity of the frequency component of the inspection light 41a emitted from the inspection light irradiation unit 41, that is, light in the vicinity of the wavelength component of the outgoing inspection light 41a, and other frequency components (wavelength components). It removes light. The lens collects only light that has been scattered from the front surface, inside, back surface, pinhole edge, etc. of the mask substrate 1 and has passed through the S-polarizing plate and the bandpass filter, and the scattered light receiving unit 46 for pinholes. To introduce. The focal position of the lens coincides with the vicinity of the surface of the mask substrate 1.

  The light receiving unit of the pinhole scattered light receiving unit 46 is configured by bundling a plurality of optical fibers, receives the scattered light collected by the lens, and guides it to the light receiving surface of the photomultiplier tube. The photomultiplier tube outputs a detection signal corresponding to the intensity of scattered light received by the light receiving surface. The detection signal of the photomultiplier tube is amplified by an amplifier (not shown) and input to a defect detection device or the like. In this way, by providing an S-polarizing plate and a band-pass filter on the front surface of the lens, light other than the above-mentioned frequency component (wavelength component) and P-polarized component light that are disturbance light from the surrounding environment of the device are effective. Thus, only the scattered light of the S-polarized component scattered at the front surface, inside, back surface, pinhole edge, etc. of the mask substrate 1 can be introduced into the pinhole scattered light receiving unit 46.

  FIG. 5 is a diagram showing an operation example of the inspection apparatus when a mask pattern of a chromium film is formed on the surface of the mask substrate 1 and defects and pinholes are present there. As shown in FIG. 5, the mask pattern of the chromium film 10 is formed on the surface of the mask substrate 1, and there are foreign matter 40a and pinholes 40b that are defective. In this case, since the inspection light 41a irradiated on the surface of the mask substrate 1 is scattered by the foreign matter 40a and the pinhole 40b which become defects, scattered light 41c and 41f and transmitted light 41d are generated. Scattered light 41 c due to the foreign matter 40 a that becomes a defect on the surface of the mask substrate 1 is received by the scattered light receiving unit 42. The scattered light 41 f at the edge of the pin hole 40 b of the mask pattern of the chromium film 10 on the surface of the mask substrate 1 is transmitted through the mask substrate 1 and is disposed on the back side of the mask substrate 1 for the scattered light receiving unit 46 for pinholes. Is received. The transmitted light 41 d that has passed through the pinhole of the mask pattern of the chromium film 10 on the surface of the mask substrate 1 is trapped in the trap portion 45.

  The scattered light 41c and 41f are received by a light receiving unit in which a plurality of optical fibers constituting the scattered light receiving unit 42 and the pinhole scattered light receiving unit 46 are bundled, and as shown in FIGS. Are detected as a scattered signal S41c due to the foreign matter 40a which becomes the defect of FIG. 5 and a scattered signal S41f due to the edge of the pinhole 40b. That is, when the pinhole 40b exists in the chromium film 10 that is the mask pattern portion formed on the surface of the mask substrate 1, the inspection light 41a irradiated to the chromium film on the mask substrate 1 passes through the pinhole 40b. Then, the transmitted light 41d is trapped in the trap portion 45 on the lower side of the mask substrate 1. At this time, the scattered light receiving unit for pinhole 46 includes a sensor having a predetermined detection width in the Y direction (the depth direction in the drawing), and the inspection light 41a reflected near the edge of the pinhole in the chrome film 10. Of the light, that is, the scattered light 41f is received. Therefore, by detecting the scattered signals S41c and S41f as shown in FIG. 5, a defect (foreign matter 40a) exists on the surface of the mask substrate 1, and further, a pinhole 40b is formed in the mask pattern of the chromium film 10 on the mask substrate 1. It can be detected that it exists.

  FIG. 6 is a diagram illustrating an operation example of the inspection apparatus when only a defect exists in the mask pattern of the chromium film on the surface of the mask substrate 1. In FIG. 5, the pinhole 40b exists in the mask pattern of the chromium film together with the foreign matter 40a that becomes a defect, but in FIG. 6, the pinhole 40b does not exist in the mask pattern of the chromium film, and only the foreign matter 40a that becomes a defect exists. Indicates the presence of. In such a case, the scattered light 41c due to the foreign matter 40a that becomes a defect on the surface of the mask substrate 1 is received by the scattered light receiving unit 42, but the mask pattern of the chromium film 10 is formed on the surface of the mask substrate 1. Since it is formed, the light below the mask substrate 1 is shielded by this chromium film, and the scattered light does not reach the pinhole scattered light receiving portion 46 disposed on the back side of the mask substrate 1. .

  In the case of FIG. 6, the inspection light 41a irradiated to the chromium film on the mask substrate 1 is mostly reflected as reflected light 41b by the chromium film, but there is a foreign matter 40a that becomes a defect on the surface of the chromium film. A part of the inspection light 41a is scattered by the foreign matter 40a and is received by the scattered light receiving unit 42 as scattered light 41c. In FIG. 6, the scattered light 41c is received by a light receiving unit in which a plurality of optical fibers constituting the scattered light receiving unit 42 are bundled, and as shown in FIG. Detected. On the other hand, since the pinhole 40b does not exist in the chromium film 10 serving as the mask pattern portion on the surface of the mask substrate 1, the signal intensity does not change as shown in FIG. Therefore, in the case of FIG. 6, it can be detected that the foreign material 40 a that becomes a defect exists only on the surface of the mask substrate 1.

  FIG. 7 is a diagram illustrating an example of an operation for detecting a pinhole existing in the mask pattern of the chromium film. FIG. 7A schematically shows the positional relationship between the inspection light 41a and the pinhole 40b at a certain moment during raster scanning on the mask substrate 1 using the inspection light 41a, and FIG. The scattered signal S41f of the pinhole scattered light receiving unit 46 corresponding to the pinhole 40b at the moment 7 (A) is shown. As shown in FIG. 7A, the vicinity of the edge of the pinhole 40b is shown in a circular shape. When the inspection light 41a is positioned near the edge of the pinhole 40b (on the circular periphery), the scattered light 41f is detected by the pinhole scattered light receiving unit 46, but other locations (in the pinhole 40b) Scattered light 41f is not detected except on the circumference. Accordingly, the position where the pinhole edge is detected is mapped on the mesh of FIG. 7A corresponding to the raster scan position of the substrate inspection apparatus. In FIG. 7A, the raster scan position where the pinhole edge is detected is shown in gray. This makes it possible to recognize the size of the pinhole 40b based on the mapped shape of the raster scan position of the defect size of the pinhole 40b. For pinholes smaller than the beam diameter of the inspection light 41a, the pinhole size can be discriminated based on signal intensity and defect detection coordinates.

  In the above-described embodiment, by providing the S polarizing plate and the bandpass filter in the scattered light receiving unit 42 and the pinhole scattered light receiving unit 46, the disturbance light that enters the detection optical system from the surrounding environment of the substrate, that is, the laser This is inspection light 41a that effectively removes light other than the frequency component (wavelength component) of the light beam irradiated from the light source and P-polarized component light, and is irradiated obliquely onto the mask substrate 1 from the light projecting system. Only the S-polarized component light scattered at the front surface, inside, back surface, pinhole edge, etc. can be received, the influence of noise and the like can be eliminated, and the defect detection accuracy can be improved.

1 ... Mask substrate,
10 ... chrome film,
11 ... Laser light generator,
12a, 12c ... lenses,
13 ... Polygon mirror,
40, 400 ... optical system unit,
40a ... foreign matter,
40b ... pinhole,
41 ... inspection light irradiation unit,
41a ... Inspection light,
41b ... reflected light,
41c ... scattered light,
41d ... transmitted light,
41e ... reflected light,
41f ... scattered light,
42 ... scattered light receiving part,
43. Scattering mirror part,
44 ... transmitted light receiving part,
45 ... Trap part,
46: scattered light receiving part for pinhole,
S41c, S41f ... scattered signal,
5a, 5b ... substrate support part,
5c, 5d ... inclined surface

Claims (4)

The substrate is moved while moving the light beam while obliquely irradiating the light beam 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. Scan
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, is received by the first scattered light receiving means,
The second scattered light receiving means receives the scattered light that is disposed on the back side of the substrate and the light beam is scattered by the pinhole edge of the mask pattern formed on the substrate surface,
A substrate inspection method, comprising: detecting defects on the substrate from signals based on scattered light received by the first and second scattered light receiving means. The substrate inspection method according to claim 1,
Irradiating the surface of the substrate with a light beam containing a large amount of a predetermined polarized component
A polarizing plate means for passing only the light of the polarization component and a band pass filter means for passing only light in the vicinity of the frequency component of the light beam are provided on the front surface of the first and second scattered light receiving means. Substrate inspection method. The substrate is moved while moving the light beam while obliquely irradiating the light beam 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
A first scattered light receiving means arranged on the surface side of the substrate and receiving the scattered light scattered by the defect of the substrate;
A second scattered light receiving means disposed on the back side of the substrate and receiving the scattered light scattered by the pinhole edge of the mask pattern formed on the substrate surface;
A substrate inspection apparatus comprising: defect detection means for detecting defects on the substrate from signals based on scattered light received by the first and second scattered light receiving means. The substrate inspection apparatus according to claim 2,
Irradiating the surface of the substrate with a light beam containing a large amount of a predetermined polarized component
A polarizing plate means for passing only the light of the polarization component and a band pass filter means for passing only light in the vicinity of the frequency component of the light beam are provided on the front surface of the first and second scattered light receiving means. Substrate inspection device.

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