JP6618354B2 - Defect inspection method and defect inspection apparatus - Google Patents

Description

  The present invention relates to a method and a defect inspection apparatus for inspecting a defect of an inspection object. In particular, the present invention relates to a method and an apparatus for inspecting a defect of an object to be inspected without applying mechanical stress by directly applying a stress applying means to the object to be inspected.

  There are a destructive inspection method and a non-destructive inspection method as methods for inspecting extremely small defects such as defects on a wafer. However, the destructive inspection method represented by etching has a problem that the inspection object cannot be used after the inspection, and therefore the non-destructive inspection method is preferably used. On the other hand, non-destructive inspection methods that do not perform such destructive processing include, for example, electrical methods, methods using light, and ultrasonic waves (Patent Documents 1 to 3).

  In order to inspect defects such as wafers that could not be sufficiently inspected even by non-destructive inspection methods as disclosed in Patent Documents 1 to 3, etc., the inventors give stress to the object to be inspected. A method for inspecting fine defects and various defects by obtaining an intensity ratio of polarized scattered light irradiated to an object to be inspected before and after the inspection is proposed (Patent Documents 4 to 6). The techniques disclosed in these patent documents have been proposed as techniques suitable for substrates for optical functional elements, superlattice structures, MEMS structures, glass, reticles, etc., particularly with the above-described wafer as the center. .

  In Patent Document 4, light polarized by a polarizer is incident on an object to be inspected, and the presence or absence of a defect is detected from the scattered light intensity difference between before and after applying an ultrasonic wave to the object to be inspected. The method etc. to perform are disclosed.

  Patent Document 5 discloses a method of detecting by detecting the presence or absence of a defect based on a difference in scattered light intensity before and after applying stress to an object to be inspected with incident light polarized by a polarizer. To do. Further, Patent Document 6 discloses a stress due to a mechanical static load such as a tensile static load as an even more preferable method for this stress, and further discloses a quality control method for a wafer or a semiconductor element.

Japanese Patent Laid-Open No. 62-177447 JP 2002-188999 A Japanese Patent No. 3664134 Japanese Patent No. 463002 Japanese Patent No. 5007979 Japanese Patent No. 5713264

  The present inventors further examined the inspection technique that has been studied on the inspected object centered on the wafer by the stress such as mechanical static load and ultrasonic wave disclosed in Patent Documents 4 to 6. . As a result, for the inspected object having a complicated shape or a thin shape, the adjustment of the inspection method is required to be very delicate control only by the techniques disclosed in Patent Documents 4 to 6. And I found a problem that it might not be enough.

  More specifically, when the object to be inspected is a transparent body, scattered light from a means for applying mechanical stress such as a pressing member that presses the object to be inspected is generated, and this is a large noise at the time of scattered light analysis. Thus, it may be difficult to set a threshold value during defect inspection. Further, in the case where a material to be inspected is a material that is vulnerable to mechanical stress such as a very thin material, there is a possibility that the material may be destroyed when mechanical stress is applied, and stress control suitable for inspection may be difficult. In addition, when applying stress by ultrasonic waves, it may be difficult to find a suitable setting for the object to be inspected, and it may be difficult to apply sufficient stress, or erroneous detection may occur depending on the shape of the object to be inspected There was also. Furthermore, there are cases where it is required to inspect the object being inspected continuously, and a method of applying stress mechanically by contact, or setting ultrasonic waves according to the object to be inspected. The method may not be adopted.

  Under such circumstances, it is an object of the present invention to provide an inspection method and an inspection apparatus suitable for inspection of defects of an object to be inspected that are difficult to inspect by a conventionally known mechanical static load or stress such as ultrasonic waves. To do.

  The present inventors use a stress applying means that applies stress to the object to be inspected in a non-contact manner in order to inspect a material that is not suitable for mechanical stress, such as a transparent body as described above or a thin material. Has been found to be suitable for the present invention.

  The present invention detects the scattered light by irradiating the surface of the inspection object with light having a wavelength that can penetrate the inspection object in a state where no stress is applied to the inspection object and a state where stress is applied. A method for inspecting a defect of an inspection object by irradiating light obliquely with respect to the surface at a position on the surface of the inspection object without applying stress to the inspection object. The intensity of the scattered light generated thereby is obtained, and the light is applied in a state where the stress is applied to the inspected object by a non-contact stress applying means to the inspected part of the inspected object. Irradiating light obliquely with respect to the surface at the same position on the surface of the inspected object as that irradiated, obtaining the intensity of scattered light generated thereby, and applying stress to the inspected object The intensity of scattered light obtained in the absence of the To a method for inspecting defects characterized by having a possible to detect the defect by comparing the intensity of scattered light obtained in a state of applying a stress to a predetermined threshold.

  Further, the present invention is a stress applying means for applying stress to the support portion of the object to be inspected and the object to be inspected placed on the support portion. The stress applying means to be applied; a light source device that irradiates light of a wavelength capable of penetrating into the inspected surface onto the surface of the inspected object supported by the support portion; Light receiving means for detecting scattered light of light irradiated obliquely with respect to the surface of the inspection object, and light detected by the light receiving means in a state where stress is applied to the inspection object and a state where stress is not applied to the inspection object, respectively. The present invention relates to a defect inspection apparatus comprising: an arithmetic processing unit that detects a defect in the inspection object by comparing an intensity with a predetermined threshold value.

  According to the present invention, when there is a difference in scattered light intensity measured before and after stress application, it is possible to detect defects such as micron-sized cracks based on the difference in scattered light intensity. Further, since the stress applying means of the present invention is a non-contact stress applying means to the object to be inspected, there is very little variation in the position of the object to be inspected before and after applying the stress when the non-inspecting pair is stopped.

  In the inspection of the defect that is the subject of the present invention, in order to confirm the defect in detail, the application of stress at a place where the apparatus configuration is limited, such as under a microscope, was examined. When inspecting in such a narrow range while performing microscopic observation etc., if stress is applied in such a way that it directly contacts the object to be inspected, the position of the object to be inspected may fluctuate. Many. When the position varies, the focus of the microscope shifts, and inspection cannot be performed while observing the defect.

  The present invention irradiates the surface of the inspection object with light having a wavelength that can penetrate into the inspection object in a state where stress is not applied to the inspection object and a state where stress is applied. This is a method for inspecting a defect of an object to be inspected by detecting it. The defects detected by the present invention are small defects such as micron-sized cracks, which are defects whose scattered light intensity changes before and after stress application. A micron-sized crack is a defect having a size of about several hundred nm to several tens of μm, and is a defect having a shape that is difficult to confirm from the surface of the object to be inspected, which exists as a crack. Various technologies have been developed to inspect defects by irradiating the object with light and measuring the scattered light, but defects such as micron-sized cracks are irradiated without applying stress. In this case, the scattered light intensity at this time is not detected or is about the noise level, so that it is often not recognized as a defect.

  In the present invention, the light irradiated to the object to be inspected is light having a wavelength that can penetrate into the object to be inspected. This light is irradiated using a light source device that can irradiate the surface to be inspected of the inspection object with light having a wavelength that can penetrate into the inspection object. Since scattered light cannot be obtained from the light absorbed by the object to be inspected, it is difficult to inspect the defect. Further, when the light is reflected from the surface of the object to be inspected, it is difficult to inspect the defect because light does not pass through and does not scatter up to a micron-sized crack generated as a crack inside the object to be inspected. The light irradiated in the present invention includes light from the wavelength in the ultraviolet region to the wavelength in the near infrared region. The light to be irradiated is appropriately selected from the wavelengths in this range in consideration of each object to be inspected, measurement environment, ease of detection, and the like.

  As the irradiating light, various kinds of light capable of obtaining the scattered light intensity of the object to be inspected can be selected and used.

  For example, the light to be irradiated may be a spectroscopic light having a specific wavelength. If the light is split, whether the light of that wavelength is easy to detect penetration and scattering intensity on the object, on the other hand, examine the characteristics of the object, such as the influence of absorption and reflection, There is an advantage that the measurement can be easily performed at the optimum wavelength.

  In addition, it is preferable to use laser light as the irradiation light. The greater the intensity of the irradiated light, the greater the intensity of the scattered light and the more easily detectable the light intensity, and the laser light can easily achieve a light intensity suitable for such detection. When irradiating with laser light, it is possible to perform line irradiation of pseudo parallel irradiation light or area irradiation of pseudo surface irradiation light by appropriately combining known optical elements such as a collimator lens.

  Moreover, LED may be used for the light to irradiate and monochromatic light emission LED may be used. Further, it is more preferable to use a high-brightness one. Also for this LED, since the intensity of scattered light increases as the intensity of irradiated light increases, and it becomes easier to detect, it is preferable to set the intensity of irradiated light high.

  Further, linearly polarized light or elliptically polarized light may be used as the irradiation light. If polarized light is used, it may be easy to classify the types of defects by performing an analysis that combines the polarization state of irradiation light and the polarization state of scattered light. On the other hand, since the irradiation light intensity generally decreases when polarized, the scattered light tends to decrease, and the detection sensitivity may decrease.

  Scattered light is detected by a configuration capable of detection corresponding to the light. The intensity of the scattered light is detected by the light receiving means and stored in a storage unit or the like for comparison with the scattered light intensity obtained when stress is separately obtained. The scattered light is detected by a line sensor as one-dimensional linear information or an area as two-dimensional planar information so that the position of the scattered light in the inspection object can be specified. You may detect with a sensor. For example, when the scattered light is in the range of visible light or the like, it can be detected by a CCD camera or the like. In order to reduce the variation in the detection sensitivity of the scattered light intensity, it is preferable to detect the scattered light intensity a plurality of times and obtain the scattered light intensity as an integrated value thereof.

  The light to be irradiated is irradiated in various directions to detect a defect from the intensity of scattered light, and the light to be irradiated is irradiated from an oblique direction to the surface to be inspected of the inspection object. The angle for irradiating light and the angle for detecting scattered light are appropriately set. For example, the angle for irradiating light is 10 to 70 °, preferably 30 to 60 °, when the vertical to the surface is 0 °. Irradiate at an angle that makes it easy to detect scattered light. On the other hand, the scattered light is detected at an angle deviating from the reflection angle corresponding to the incident angle because there is a possibility of overlooking the light intensity at the defect level when the reflected light is also detected. For example, the detection may be performed by checking the incident angle and tilting it in a range perpendicular to the surface (0 °) or in any direction within 30 °.

  In the present invention, with respect to the inspected part of the same inspected object, the irradiation light is obliquely applied to the inspected part in a state where stress is applied to the inspected object and in a state where the stress is not applied. The scattered light intensity is measured. Thereby, since it is possible to obtain the intensity of scattered light obtained in a state where no stress is applied to the object to be inspected and the intensity of scattered light obtained in a state where stress is applied to the object to be inspected, Based on these ratios, a defect is detected by comparing with a predetermined threshold. The comparison with the predetermined threshold is performed by the arithmetic processing unit.

  The predetermined threshold value used for the determination of the defect is set according to the size of the defect to be detected, the material of the inspection object, the intensity of the irradiated / scattered light, and the like. The object to be inspected which is the main object of the present invention has high homogeneity. Scattering hardly occurs even when light is applied to such an object to be inspected without applying stress, and scattering occurs only when foreign matter or the like is present. In addition, defects such as micron-sized cracks often have little scattering when no stress is applied. However, large scattering occurs when stress is applied when micron-sized cracks are present. Therefore, when the scattered light intensity ratio is taken before and after stress application when the scattered light intensity is within the range of noise assumed when scattered light is detected, or when there is an obvious foreign object, the ratio is about 1. It becomes the range. On the other hand, if micron-sized cracks exist, large scattering occurs when stress is applied as described above. Therefore, the ratio of scattered light intensity before and after stress application is expressed as “scattered light intensity after stress application / scattered light intensity before stress application”. ", The value exceeds 1 and becomes a large value. Therefore, a range in which this ratio is assumed as a noise level may be set as a threshold value.

  The present invention is characterized in that stress applying means for applying stress in a state where the stress is applied is stress applying means that is not in contact with the object to be inspected. Non-contact with the inspected portion of the object to be inspected is determined by whether the means for applying the stress is in direct mechanical contact with the inspected portion and its surroundings, and a non-contacting stress applying means is applied. . Here, the stress applied to the object to be inspected is set according to the size of the defect to be detected, the material of the object to be inspected, the intensity of light to be irradiated / scattered, and the like, specifically a stress of about several MPa.

  In practicing the present invention, the entire object to be inspected is supported by some kind of support portion, for example, by holding both ends of the non-inspection object with fasteners. At this time, the method of directly contacting the inspected part in order to apply the stress is easier to apply the stress because it is easier to apply the stress because it is easier to apply the stress. Such a method may be a cause of disturbance. Specific examples of stress applying means that do not contact the object to be inspected include stress applying means using thermal stress, and means using sound waves.

  The stress applying means of the present invention is preferably a heating means and / or a cooling means that is not in contact with the part to be inspected of the object to be inspected. Such heating means and / or cooling means may be described simply as stress applying means by thermal stress because both heating and cooling are related to stress due to temperature gradient in the subject. Such a stress applying means using thermal stress is a technique that can be easily adopted as one of methods for applying stress without contact. In the present invention, since the stress applying means is a means that is not in contact with the part to be inspected, a heating stage or the like that is in direct contact is not suitable.

  The heating means and / or cooling means of the present invention is preferably one that heats and / or cools by applying a heated and / or cooled gas to an object to be inspected. That is, it is preferable to apply a stress by applying a gas having a temperature higher than that of the object to be inspected or a gas having a cold temperature to the object to be inspected. The gas applied to the object to be inspected is easy to adjust by applying the gas to the object to be inspected so that the change in the position and shape of the object to be inspected is small, and is suitable as the stress applying means by the thermal stress of the present invention.

  The heating means of the present invention is preferably one that heats the object to be inspected by irradiating it with infrared rays. The object can be heated by irradiating the object with an infrared ray suitable for each object to be inspected, but it is easy to adjust the infrared ray so that the position and shape of the object to be examined are small. It is suitable as a means for applying stress by heating in the invention.

  It is preferable that the heating means and / or the cooling means partially heat and / or cool a part to be inspected of the object to be inspected. If the object to be inspected is partially heated / cooled, stress suitable for inspection is likely to be generated in the entire object to be inspected, particularly in the inspected part. As described above, heating / cooling with gas and application of stress by infrared rays facilitate such partial heating / cooling by adjusting the structure of the air blowing port so that the gas falls in a narrow range. In addition, heating by infrared rays can be easily performed by irradiating a so-called heat beam so that a position where the infrared rays are irradiated becomes partial.

  It is preferable that the temperature gradient generated in the body to be inspected by the heating means and / or the cooling means of the present invention is a temperature gradient having a temperature difference of 5 ° C. or more in the body to be inspected. The range in which this temperature difference occurs may be a more limited range. For example, the temperature difference may be within a range of 10 mm to 30 mm, preferably 10 mm to 20 mm, with the portion to be inspected as the center. Or it is good also as a temperature difference of the surface and a back surface in the to-be-inspected part of a to-be-inspected object. By heating / cooling the inspection object so as to generate such a temperature difference, a stress suitable for the inspection of the present invention is generated. In order to generate such a temperature difference, it is preferable to partially heat / cool the object to be inspected, and the above-described method of partially applying gas or infrared rays is suitable.

  The stress applying means of the present invention may be a stress applying means for forcibly vibrating the object to be inspected by sound waves. Specifically, it is preferable to use a sound wave having a natural frequency depending on the thickness of the subject, particularly a sound wave having a frequency in the range of about 1 Hz to 1000 Hz, and it is preferable to use a sound wave having a frequency corresponding to the primary mode. By irradiating the subject with forced vibration by a sound wave corresponding to, for example, the primary mode in such a range, stress accompanying it is also generated in the same cycle, and thus stress suitable for the examination of the present invention is generated. In particular, a sound wave having a frequency in this range is likely to apply a greater stress than an ultrasonic wave.

  When applying stress due to this sound wave, such as the frequency corresponding to this primary mode, it is possible to provide a more sensitive detection technique by detecting the intensity of the periodically changing scattered light using a signal processing device or the like. . When applying stress by sound waves, sound waves having directivity may be used. Or you may arrange | position a to-be-inspected part etc. in a soundproof structure.

  The inspected part of the inspected object of the present invention is preferably transparent to the light to be irradiated. In the present invention, a defect is detected using light, but when inspecting a material transparent to the irradiated light, in the case of a stress applying means that mechanically contacts the vicinity of the part to be inspected, the stress applying means However, according to the configuration of the present invention, it is easy to detect such a defect in the transparent body. When the object to be inspected is transparent, the advantage of non-contact inspection according to the present invention is that light having a wavelength that can pass through the object to be inspected is preferably used.

  In the present invention, the object to be inspected may be an inspection target. For this reason, the inspection method of the present invention can include a step of conveying an object to be inspected. Moreover, the apparatus for inspecting of the present invention may have a transport means for transporting the object to be inspected. This conveyance may be carried continuously. Even in such a case, the present invention can inspect micron-sized cracks in-line during conveyance because of non-contact stress application.

  When inspecting the object to be inspected during transportation, it is preferable to irradiate the surface of the object to be inspected in a direction orthogonal to the transport direction, and to detect at least the light irradiated with the line with a line sensor. Further, by acquiring and processing this information continuously over time, the inspection result of the surface of the object to be inspected can be obtained.

  In the present invention, observation using a microscope may be performed. For this reason, it can be set as the test | inspection method which has the expansion observation process which expands and observes the to-be-inspected part of a to-be-inspected object. Moreover, it can be set as the inspection apparatus provided with the microscope which observes the to-be-inspected part of the said to-be-inspected object. Here, a microscope refers to a configuration in which a minute object can be visually magnified and observed by using an optical or electronic technique. For example, the configuration may be such that the information of the scattered light can be observed with the naked eye via a magnifying lens or the like, or may be detected by a CCD camera or the like to form an image. The present invention relates to a technique that can be equipped with such a microscope, and a part that is determined to be defective by having a microscope can be appropriately and promptly observed, and only as information on scattered light intensity. Instead, the defect can be determined from the enlarged observation image.

  Due to the non-contact type stress application method, it is easy to apply stress to various test objects (particularly transparent and thin). Further, it is possible to detect a defect even in an inspection object for which it is difficult to detect the defect by the conventional method.

It is a schematic diagram showing a first embodiment of a defect inspection apparatus of the present invention. It is a flowchart which shows the flow of defect inspection method S1 which concerns on the inspection method of this invention. It is a figure which shows the temperature distribution before applying stress to the to-be-inspected object which test | inspects a defect by this invention. It is a figure which shows the temperature distribution of the said to-be-inspected object when stress is applied to the to-be-inspected object concerning FIG. 3A by a heating means. It is a figure which shows the result of the ratio of the scattered light intensity when the to-be-inspected object to which the stress by the heating means concerning FIG. 3B was applied is defect-inspected by this invention. It is a figure which shows the defect observed when the part with a high scattered light intensity ratio in FIG. 3C was expanded and observed with the optical microscope.

  FIG. 1 is a schematic diagram showing a first embodiment of the defect inspection apparatus of the present invention. The defect inspection apparatus 1 is an apparatus for inspecting a defect of the inspected object 10 supported by the support unit 11, and includes a light source device 20, scattered light detection means 30 including an objective lens 31, stress application means 40, It is an apparatus for inspecting a defect including an arithmetic processing unit 50, a display unit 60, and a magnification observation processing unit 70.

  The light source device 20 irradiates the surface of the inspection object 10 supported by the support portion 11 with light having a wavelength that can penetrate into the inspection object 10 in an oblique direction with respect to the surface. The stress applying unit 40 applies stress to the object to be inspected 10 placed on the support unit 11 and applies stress to the part to be inspected of the object to be inspected 10 without contact. As the stress applying means 40 for applying a stress to the part to be inspected in a non-contact manner, a heating and / or cooling means, a stress applying means for forcibly vibrating the object to be inspected by sound waves, or the like is appropriately used. it can.

  The scattered light detection means 30 detects the scattered light of the light irradiated in an oblique direction with respect to the surface of the inspection object 10. This is because the light of the light source device 20 in a state where no stress is applied at the same position on the surface of the inspection object 10 as the light of the light source device 20 irradiated with the stress is applied. Irradiation is performed obliquely with respect to the surface, and the scattered light generated thereby can be detected. At this time, the information input to the scattered light detection means 30 is an image appropriately enlarged by the objective lens 31. The objective lens 31 can change its magnification appropriately.

  The arithmetic processing unit 50 compares the intensity of light detected by the scattered light detection means 30 in a state where stress is applied to the inspection object 10 and a state where no stress is applied, with a predetermined threshold value to thereby detect defects in the inspection object 10. Detection is performed. The result of inspecting this defect can be output so that the result can be easily recognized as appropriate, and is displayed on a monitor which is the display unit 60 in this embodiment. This apparatus is particularly suitable for an object to be inspected such as a transparent body, and can detect a defect more stably than using a stress applying means that makes mechanical contact.

  The enlarged observation processing unit 70 performs processing for obtaining an observation image in which the inspected part is enlarged based on the scattered light intensity detected by the scattered light detecting means 30. By performing this process, an image can be obtained as a microscope. In order to make this observation easier, the light of the light source device 20 may be appropriately changed to light or the like different from the light for inspecting the defect. In addition, it is possible to change the magnification of the objective lens 31 and observe only the defective portion detected as a result of calculation by the calculation processing unit 50 in more detail.

  FIG. 2 is a diagram showing a flow of the defect inspection method S1 using the defect inspection apparatus 1 of FIG. 1 of the inspection method of the present invention. The defect inspection method S1 includes a step S10 for determining the scattered light intensity of the inspected portion of the inspection object without applying stress, and the inspection of the inspection portion of the inspection object with the application of stress (a state in which stress is applied to the inspection object). This is an inspection method including a step S11 for obtaining scattered light intensity and a step S30 for detecting a defect from the results of the steps S10 and S11. This defect inspection method S1 can be performed using the defect inspection apparatus 1 according to the first embodiment.

Step S10 has a step S11 of irradiating light obliquely with respect to the surface at a position on the surface of the inspection object in a state where no stress is applied to the inspection object, and the scattered light generated thereby. It is a process which has process S12 which calculates | requires the intensity | strength of. This light is light having a wavelength that can penetrate into the body to be inspected, and the surface of the body to be inspected is a surface to be inspected (usually the surface side of the body to be inspected).
In step S20, light is irradiated at the same position on the surface of the object to be inspected as that irradiated with light in step S11 in a state where stress is applied to the object to be inspected by a non-contact stress applying means on the inspected part of the object. This step includes a step S21 of irradiating the surface in an oblique direction, and a step S22 for obtaining the intensity of scattered light generated thereby.
In step S30, the intensity of the scattered light obtained in the state where no stress is applied to the object to be inspected in step S10 and the intensity of the scattered light obtained in the state in which the stress is applied to the object to be inspected in step S20. The step S31 includes a step S31 for comparing the values obtained by the step S31 and a step S32 for comparing the compared value obtained in the step S31 with a predetermined threshold value, and includes a step S33 for determining a defect from the result of the step S32. Thereby, defects that are difficult to detect without applying stress, such as micron-sized cracks, can be detected separately from noise and foreign matter. In this defect inspection method S1, the stress applying means in the step S20 is a stress applying means that is not in contact with the inspection object (part to be inspected).

Details of an example in which a micron-sized crack was detected according to the present invention using glass as an object to be inspected will be described below.
As an apparatus corresponding to the defect inspection apparatus of the first embodiment shown in FIG. 1 (however, the enlarged observation processing unit 70 is omitted), an experiment was performed with the following configuration and process.

Light source device: Visible laser (wavelength 532 nm) Area irradiation (by collimator lens)
Object to be inspected: Cover glass with micron-sized cracks (18 mm square (thickness 0.12 mm))
Supporting part: Clamp that holds one end (about 2 mm) of the cover glass Stress applying means: Dryer that blows hot air with high directivity by adjusting the air outlet to Φ3 mm Objective lens: CCTV lens (focal length 50 mm)
Scattered light detection means: CCD camera Arithmetic processor: Scattered light intensity ratio (scattered light intensity after applying stress / scattered light intensity before applying stress) was used as surface image information. It should be noted that a point having a change ratio of 1.2 or more was emphasized as a portion having a possibility of a defect, and a point exceeding 1.5 was particularly emphasized.
Display unit: The calculation result of the calculation processing unit is displayed on the monitor.

FIG. 3A shows the result of measuring the temperature distribution of the object to be inspected before applying stress when inspecting with this configuration. FIG. 3B shows the result of measuring the actual temperature distribution when a thermal stress is applied to the object to be inspected.
Since this test object is a test object with very few foreign matters and high homogeneity, there were almost no parts judged to be defective before stress application. On the other hand, if there is a part where the intensity of scattered light increases when stress is applied, the contrast value of that part naturally increases when comparing before and after stress application. The presence or absence of defects can be determined. Here, the ratio of scattered light intensity (scattered light intensity after application of stress / scattered light intensity before application of stress) of 1.2 or more was used as a threshold value, and defect discrimination was performed.
Further, FIG. 3C shows the result of detecting the scattered light intensity after applying stress by enlarging the 1000 μm square centering on the X axis 10 mm and the Y axis 10 mm in FIG. 3B. As shown in FIG. 3 (C), a portion having a high scattered light intensity is observed only when stress is applied in the vicinity of the X axis of 300 μm and the Y axis of 500 μm, and it is determined that micron-sized cracks exist.

  FIG. 3D shows an image of the defect confirmed as a result of observing this part with an erecting optical microscope in order to confirm the defect in the part where this defect was detected. As is clear from this microscopic observation image, the defect at this portion was about 60 μm in size, and crack-like micron-sized cracks were confirmed.

  INDUSTRIAL APPLICABILITY The inspection method and inspection apparatus according to the present invention can be used for detecting defects in an inspection object centering on a transparent body such as a glass substrate, which has been difficult to inspect by a conventional method.

DESCRIPTION OF SYMBOLS 1 Defect inspection apparatus 10 Inspected object 11 Support part 20 Light source apparatus 30 Scattered light detection means 31 Objective lens 40 Stress application means 50 Arithmetic processing part 60 Display part 70 Magnification observation processing part S1 Defect inspection method

Claims (12)

Inspected by irradiating the surface of the inspection object with light having a wavelength that can penetrate into the inspection object in a state where stress is not applied to the inspection object and in a state where stress is applied. A method for inspecting a body defect,
Irradiating light obliquely with respect to the surface at a position on the surface of the inspection object in a state in which no stress is applied to the inspection object, and determining the intensity of the scattered light generated thereby;
The same surface of the object to be inspected as the object to be inspected is irradiated with light in a state where the stress is not applied to the inspected part of the object to be inspected by a non-contact stress applying means. Irradiating light at an upper position in an oblique direction with respect to the surface, and determining the intensity of scattered light generated thereby;
A defect is obtained by comparing the intensity of scattered light obtained in a state where no stress is applied to the object to be inspected and the intensity of scattered light obtained in a state where stress is applied to the object to be inspected with a predetermined threshold value. possess and performing the detection,
The stress applying means is a heating means and / or a cooling means for applying a stress by heating and / or cooling a part to be inspected of an object to be inspected;
A method for inspecting a defect characterized by inspecting a micron-sized crack inside an object to be inspected .   2. The inspection method according to claim 1, wherein the temperature gradient generated in the body to be inspected by the heating means and / or the cooling means is a temperature gradient having a temperature difference of 5 ° C. or more in the body to be inspected. Wherein said heating means and / or cooling means, inspected according to claim 1 or 2, wherein the heating and / or cooled gas is intended for heating and / or cooling by exposure to the test subject . Wherein said heating means is inspected according to claim 1 or 2, wherein the infrared is to heat by irradiating the object to be inspected. Wherein said heating means and / or cooling means, to inspect according to claim 1-4 in which characterized in that the partially heated and / or cooled to be inspected portion of the object to be inspected. The method for light to be inspected portion of the object to be inspected is irradiated, inspected according to any one of claims 1 to 5, characterized in that it is transparent. The method of light of a wavelength that can penetrate into the test subject is inspected according to any one of claims 1 to 6, characterized in that a laser beam.   The inspection method according to claim 1, further comprising a magnification observation step of magnifying and observing a portion to be inspected of the inspection object.   The inspection method according to claim 1, wherein the inspection is performed in a state where the inspection target is being conveyed.   The said to-be-inspected object is glass, The method to test | inspect in any one of Claims 1-9. A support portion of the object to be inspected;
Stress applying means for applying stress to the object to be inspected placed on the support part, the stress applying means for applying stress in a non-contact manner to the inspected part of the object to be inspected;
A light source device that irradiates light of a wavelength capable of penetrating into the surface of the test object supported by the support portion in an oblique direction with respect to the surface;
A light receiving means for detecting scattered light of light irradiated in an oblique direction with respect to the surface of the inspection object;
An arithmetic processing unit that detects a defect in the inspection object by comparing the intensity of light detected by the light receiving means with a predetermined threshold value in a state where stress is applied to the inspection object and a state where stress is not applied to the inspection object; ,
Ri name with a,
The stress applying means is a heating means and / or a cooling means for applying a stress by heating and / or cooling a part to be inspected of an object to be inspected;
Defect inspection apparatus according to claim der Rukoto intended to inspect the interior of the crack micron size of the device under test.   The defect inspection apparatus according to claim 11, further comprising a microscope for observing an inspection portion of the inspection object.