JP2014081255A - Method for visual inspection of substrate and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for the visual inspection of a substrate where a vibration piece including an electrode is formed and to provide an imaging apparatus.SOLUTION: The method for the visual inspection of the substrate comprises irradiating the substrate having a first reflecting object on one of a first main surface and a second main surface being the back side of the first main surface and having optical transmittance with first light from the side of the first main surface in a direction crossing the first main surface, to receive the reflection component of the first light reflected by the first reflecting object by first receiving means and for irradiating the substrate with second light from the side of the second main surface in the direction crossing the first main surface, to receive the transmission component of the second light transmitted through the substrate by the first receiving means, to perform the visual inspection of the substrate.

Description

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

Although the resonator element is formed from a substrate, even if the substrate has a slight scratch, the resonator element becomes defective. Therefore, detection of a substrate scratch is very important.
Until now, an operator visually inspected the scratch on the substrate with a microscope. However, since it relied on visual observation, it was very difficult to detect a scratch (etching defect) of several μm or less. Moreover, since work is performed continuously for a long time, it is a burden on the worker. In order to solve such a problem, in Patent Document 1, light is irradiated perpendicularly to a substrate having a resonator element formed by etching, a reflection component reflected on the substrate is photographed, and a reflection component in the photographed image is captured. An etching defect inspection method and inspection system for detecting a low-intensity region as an etching defect formed in a substrate are disclosed. As a result, the reflection component from the scratch existing on the surface of the object to be inspected is emphasized and clearly appears on the image, and the presence of the scratch is determined by image processing, so that the burden on the operator can be reduced.

JP 2010-85225 A

  However, in the case of a substrate having a resonator element on which an electrode is formed, in a region where the electrode is formed and a region where there is no electrode, when the same amount of light is irradiated perpendicularly to the substrate, Since the strength is greatly different, there is a problem that it is impossible to simultaneously detect a scratch (etching defect) generated in a region where an electrode is formed and a region where no electrode is present.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 In the substrate appearance inspection method according to this application example, a first reflector is provided on one surface of the first main surface or the second main surface which is the back side of the first main surface. Of the first light reflected on the first reflector by irradiating the first light-transmitting substrate with the first light in the direction intersecting the first main surface from the first main surface side. A reflection component and a second light transmission component transmitted through the substrate by irradiating the substrate with the second light from the second main surface side in a direction intersecting the first main surface; And a step of inspecting the appearance of the substrate by receiving light with one light receiving means.

  According to this application example, even if the substrate is a light transmissive substrate in which an electrode serving as a reflector is formed on the first major surface or the second major surface on the back side of the substrate, an electrode serving as a reflector is formed. When the first region is irradiated with the first light, the light is scattered in the region having the etching defect, and the intensity of the reflection component is smaller than that in the region without the etching defect. Etching defects can be detected by receiving light with the means. Further, in the light-transmitting region where the electrode is not formed, when the second light is irradiated from the second main surface side which is the back surface of the substrate, the light is scattered in the region where there is an etching defect, and the intensity of the transmitted component Is smaller than a region having no etching defect, so that the etching defect can be detected by receiving the second transmission component by the first light receiving means. Therefore, there is an effect that etching defects generated in the light-transmitting substrate on which the electrode serving as the reflector is formed can be detected simultaneously without being limited to the presence or absence of the electrode.

  Application Example 2 In the substrate appearance inspection method according to the application example described above, the substrate includes a second reflector on the other surface, and third light is emitted from the second main surface side to the second light. In the direction intersecting with the first main surface, the fourth light component from the first main surface side is reflected from the reflection component of the third light irradiated in the direction intersecting the main surface and reflected by the second reflector. And a step of inspecting the appearance of the substrate by receiving the transmitted light component of the fourth light that has been irradiated and transmitted through the substrate with a second light receiving means.

  According to this application example, the third light is transmitted from the second main surface side of the substrate to the second main surface of the light transmissive substrate from the second main surface side of the substrate. 4 is irradiated from the first main surface side of the substrate, so that light is scattered in a region where there is an etching defect. Therefore, the intensity of the third reflection component and the fourth transmission component depending on the presence or absence of the etching defect. By receiving the difference with the second light receiving means, it is possible to detect etching defects generated in the region where the electrode of the second main surface is formed and the light-transmitting region where the electrode is not formed. effective.

  Application Example 3 In the substrate appearance inspection method according to the application example described above, the substrate is made of quartz.

  According to this application example, since quartz is a light-transmitting material, it is possible to simultaneously detect etching defects generated in a quartz substrate on which an electrode serving as a reflector is formed, regardless of the presence or absence of the electrode. effective.

  Application Example 4 In the substrate appearance inspection method according to the application example, the appearance inspection is an etching defect inspection.

  According to this application example, it is possible to easily detect an etching defect of several μm or less, which is very difficult by visual inspection by an operator, and it is possible to improve detection accuracy.

  Application Example 5 In the substrate appearance inspection method according to the application example, the reflection component of the first light is received by the first light receiving unit.

  According to this application example, in the region where the electrode of the substrate is formed, the first light is scattered in the region having the etching defect and the intensity of the reflection component is reduced. By receiving the intensity difference with the first light receiving means, there is an effect that it is possible to detect an etching defect generated in the region where the electrode of the substrate is formed.

  Application Example 6 In the substrate appearance inspection method according to the application example described above, the transmission component of the second light is received by the first light receiving unit.

  According to this application example, in the region where the electrode of the substrate is not formed, the second light is scattered in the region having the etching defect and the intensity of the transmission component is reduced. By receiving the difference in intensity by the first light receiving means, there is an effect that it is possible to detect an etching defect generated in a region where the electrode of the substrate is not formed.

  Application Example 7 In the substrate appearance inspection method according to the application example described above, the substrate is irradiated with the first light and the second light along a normal direction of the first main surface. It is characterized by.

  According to this application example, by irradiating the first light and the second light perpendicularly to the first main surface of the substrate, it is possible to reduce scattered light from the edge of the substrate or the edge of the vibrating piece. There is. Further, the contrast between the first reflection component and the second transmission component having a low intensity due to the etching defect and the first reflection component and the second transmission component having a high intensity of the etching defect without the etching defect are expressed as follows. There is an effect that the etching defects in both regions can be simultaneously and accurately detected.

  Application Example 8 In the substrate appearance inspection method according to the application example described above, the light amount of the second light source that emits the second light is greater than the light amount of the first light source that emits the first light. It exists in the range of 1.5 times or more and 2.5 times or less.

  According to this application example, the electrode of the first light is formed by setting the light amount of the second light source in the range of 1.5 to 2.5 times the light amount of the first light source. The intensity of the reflection component in the region and the intensity of the transmission component in the region where the electrode is not formed by the second light are approximately the same, and the etching defect generated in the region where the electrode is formed and the region where the electrode is not formed The light intensity difference depending on the presence or absence of the region can be detected, and the etching defect generated on the light-transmitting substrate on which the electrode serving as the reflector is formed can be detected simultaneously without being limited to the presence or absence of the electrode. is there.

  Application Example 9 In the substrate appearance inspection method according to the application example described above, the appearance of the substrate is inspected by receiving the first reflection component and the second transmission component by the first light receiving unit. And the step of inspecting the appearance of the substrate by receiving the third reflection component and the fourth transmission component by the second light receiving unit, and transporting the substrate by the transport unit. It is characterized by doing.

  According to this application example, in the visual inspection of the substrate in which the electrode serving as the reflector is formed on the first main surface and the second main surface of the light-transmitting substrate, the first light receiving unit performs the first main light receiving unit. After inspecting the etching defect generated in the electrode region of the surface, the second light receiving means inspects the etching defect generated in the electrode region of the second main surface, and when performing the appearance inspection of both main surfaces of the substrate, Since the substrate can be transferred from the first light receiving means installation position to the second light receiving means installation position by the transfer means, the appearance inspection of both main surfaces of the substrate can be performed in a short time without inverting the main surface of the substrate. Can be performed, which has a great effect on cost reduction.

  Application Example 10 In an imaging apparatus according to this application example, the first light source has an optical axis that is at least partially overlapped with the first light source and is optically opposed, and the amount of light is the first light source. A second light source in a range of 1.5 times to 2.5 times the light source, and a light receiving means disposed on the optical axis and the optical axis opposite to the second light source. And.

  According to this application example, the second light source is disposed at a position where the light receiving unit, the first light source, and the second light source overlap on the optical axis and facing the light receiving unit and the first light source. By irradiating the light of the 1st light source and the light of the 2nd light source to the to-be-inspected object installed between the 1st light source and the 2nd light source, it reflected on the main surface of the to-be-inspected object The light receiving means can receive the reflection component of the first light source and the transmission component of the second light source that has passed through the inspection object. In addition, by setting the light amount of the second light source in the range of 1.5 times to 2.5 times that of the first light source, the reflected light component of the first light source and the light of the second light source can be reduced. The intensity with a certain transmission component can be made comparable. Therefore, the difference in light intensity due to the presence or absence of etching defects can be detected in the region where the reflection component of the inspection object is generated and the region where the transmission component is generated. An imaging device capable of detecting at the same time can be provided.

1 is a schematic diagram of a substrate visual inspection method and an imaging apparatus according to a first embodiment of the present invention. The figure for demonstrating the relationship between the crystal substrate which is a board | substrate to be examined, and a crystal axis. The schematic diagram of the board | substrate to be examined. It is a schematic diagram of the vibration piece formed in the board | substrate of a test object, (a) is a top view, (b) is AA sectional drawing. Process drawing which shows an example of the manufacturing process of the board | substrate of the test object in which the vibration piece was formed. FIG. 5 is a schematic cross-sectional view of a substrate (vibrating piece) showing an outer shape forming process of a substrate to be inspected on which a vibrating piece is formed, and a diagram showing a process in which a defect portion grows into an etching defect. FIG. 4 is a schematic cross-sectional view of a substrate (vibration piece) showing a mesa formation process of a substrate to be inspected on which a vibration piece is formed, and a diagram showing a process in which a defect portion or an etch channel grows into an etching defect. The schematic sectional drawing of the board | substrate (vibration piece) which shows the electrode formation process of the board | substrate of the test object in which the vibration piece was formed. The figure which shows the detection rate of the etching defect resulting from the various factors with respect to the light quantity ratio of the 1st light source and the 2nd light source. It is a figure explaining the method to irradiate light to a board | substrate, and to detect an etching defect, (a) is a schematic diagram which shows the cross section of a board | substrate, (b) is a schematic diagram of the image seen from a light-receiving means. It is a schematic diagram of an image process, (a) is a figure which shows the division | segmentation plane before a process, (b) is a figure which shows the division | segmentation plane after a process. The schematic diagram of the external appearance inspection method and imaging device of a board concerning a 2nd embodiment of the present invention. The schematic diagram of the external appearance inspection method and imaging device of a substrate concerning a 3rd embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram showing a substrate visual inspection method according to a first embodiment of the present invention and an imaging apparatus embodying the method.
In the visual inspection method for the substrate 10 on which the electrode 14 is formed, the first light 38 a of the first light source 32 is reflected by the total reflection mirror 36 in the region where the electrode 14 is formed on the substrate 10. Is irradiated perpendicularly to the substrate 10. Thereafter, the first reflection component 38b reflected by the electrode 14 of the substrate 10 and transmitted through the total reflection mirror 36 is photographed, and the low-intensity region of the first reflection component 38b in the photographed image is captured in the substrate 10. This is detected as an etching defect 92 generated in step (b). Further, in the region where the electrode 14 of the substrate 10 is not formed, the second light 48a of the second light source 42 is reflected by the total reflection mirror 46, and the second light 48a is irradiated to the substrate 10 perpendicularly. . Thereafter, the second transmissive component 48c that was transmitted through the substrate 10 and transmitted through the total reflection mirror 36 was photographed, and a region having a low intensity of the second transmissive component 48c in the photographed image was generated in the substrate 10. This is detected as an etching defect 92.

  And the imaging device 1 which inspects the external appearance of the board | substrate 10 which embodies this is light reception which is imaging means, such as the lens-barrel 20, the 1st light source 32, the 2nd light source 42, the total reflection mirrors 36 and 46, and a camera. The inspection target is the substrate 10 including the means 50, the detection unit 60 serving as the detection means, and the sample stage 70, on which the electrode 14 is formed. As will be described later, the etching defect 92 is a concave surface on the surface of the substrate generated during etching of the substrate due to dust, scratches in the corrosion-resistant film, etch channels of the substrate material, and the like in the manufacturing process of the substrate on which the resonator element is formed. It is a defect or a through hole inside the substrate.

Next, a substrate to be inspected in the appearance inspection method according to the first embodiment of the present invention will be described.
FIG. 2 is a diagram illustrating a relationship between a crystal substrate as an example of the substrate 10 and a crystal axis. As shown in FIG. 2, the substrate 10 has a rectangular shape, has crystal axes X, Y, and Z orthogonal to each other, and is along a plane obtained by rotating the XZ plane by a predetermined angle θ around the X axis. This is a cut out Y-cut quartz crystal substrate.
When the angle θ of the rotated Y-cut quartz substrate is 35.25 ° (35 ° 15 ′), it is called an AT-cut quartz substrate and has excellent frequency temperature characteristics. Here, the AT-cut quartz substrate has crystal axes X, Y ′, and Z ′ that are orthogonal to each other, the thickness direction is the Y′-axis, and the surface that includes the X-axis and the Z′-axis orthogonal to the Y′-axis is the main. A thickness-shear vibration is excited as a main vibration on the main surface.

Here, the etch channel generated in the quartz substrate will be described.
Etch channels extending in the Z-axis direction are formed in the quartz crystal with the Z-axis as the crystal growth direction. This is because the crystal growth rate in the direction perpendicular to the Z-axis direction is slower than the crystal growth rate in the Z-axis direction. This etch channel can be detected even at the stage of the rough or the base plate cut out from it, but it is difficult to detect the exact position because of visual inspection. However, this etch channel has a higher etching rate than a defect-free region because the etchant enters from the region where the etch channel is exposed on the surface of the substrate in the wet etching process in which the mesa portion is formed in the subsequent vibrating piece. The fast etch channel region is etched to increase the inner diameter, and appears as an etching defect 92 (see FIG. 7H) having a shape like a through hole. Therefore, it is desirable to use a quartz substrate cut out from a quartz crystal with few etch channels.

  FIG. 3 is a schematic view of a substrate to be inspected according to the present invention. 4A and 4B are schematic views of a resonator element formed on a substrate to be inspected. FIG. 4A is a plan view, and FIG. 4B is a cross-sectional view taken along line AA in FIG. In the following description, for convenience of description, the plane in the + Y′-axis direction will be described as the upper surface and the −Y′-axis direction surface in the plan view when viewed from the Y′-axis direction.

  A plurality of vibrating pieces 12 are formed on the substrate 10 to be inspected by a wet etching process. The resonator element 12 has a mesa portion 16 formed by a wet etching process at the center of the substrate 10, and electrodes 14 are provided on the upper and lower surfaces 10 a and 10 b of the mesa portion 16. Further, a pad electrode 15 is provided at the end of the substrate 10 for supporting / fixing and conducting to a package internal terminal (not shown). The provision of the mesa portion 16 in the resonator element 12 is for confining the vibration energy under the electrode 14 and preventing the vibration energy leaking to the outside, and the effect of reducing the CI (crystal impedance) value of the resonator element 12. There is.

Next, a process in which an etching defect occurs in a substrate when an AT cut quartz substrate is used will be described with reference to FIGS.
FIG. 5 is a process diagram illustrating an example of a manufacturing process of a substrate to be inspected on which a resonator element is formed. FIG. 6 is a schematic cross-sectional view of a substrate (vibration piece) showing the outer shape forming step of FIG. 5 and a process of growing a defect portion into an etching defect. FIG. 7 is a schematic cross-sectional view of a substrate (vibration piece) showing the mesa formation process of FIG. 5 and a process of growing a defect portion or an etch channel into an etching defect. FIG. 8 is a schematic cross-sectional view of the substrate (vibration piece) showing the electrode forming step of FIG.

  The manufacturing process of the vibrating element 12 formed on the substrate 10 includes an outer shape forming process for forming the outer shape of the vibrating element 12, and a mesa forming process for forming the mesa portion 16 on the upper and lower surfaces 10a and 10b of the vibrating element 12. And an electrode forming process for forming electrodes 14 on the upper and lower surfaces 10a and 10b of the resonator element 12, and is performed using a photolithography technique.

In the outer shape forming step of FIG. 6, first, the substrate 10 is washed with pure water (ST1), and then a corrosion-resistant film 80 (for example, chromium (Cr) as a base film is formed on the upper and lower surfaces 10a and 10b of the substrate 10). (Au)) is deposited using a vapor deposition device or a sputtering device, and then a resist 82 is applied to the entire surface of the corrosion-resistant film 80 (ST2).
Thereafter, exposure / development is performed to form an outer shape forming mask of the resonator element 12 on the substrate 10 (ST3).
Subsequently, the corrosion-resistant film 80 exposed from the mask opening is etched (gold (Au) uses, for example, a potassium iodide solution, and then chromium (Cr) as a base film uses a ceric ammonium nitrate solution), For example, in the case of a quartz substrate, the substrate 10 exposed from the mask opening is etched using an ammonium fluoride solution or the like as an etching solution (ST4).
Further, the resist 10 and the corrosion-resistant film 80 that is the outer shape forming mask are peeled off (ST5), whereby the substrate 10 on which the resonator element 12 is formed is completed.

Here, dust (for example, broken substrate pieces, metal pieces, organic matter) adheres to the surface of the substrate 10, the corrosion-resistant film 80 is formed thereon, and the corrosion-resistant film 80 in the region where the dust adheres is lost. A process in which the defect portion 91 grows into the etching defect 92 will be described.
In FIG. 6B, if there is a defect 91 in the corrosion-resistant film 80 generated by dust when the corrosion-resistant film 80 is formed, the outer shape of the resonator element 12 is penetrated in the substrate etching of FIG. 6D. During the etching, the etching solution penetrates the resist 82 and reaches the defect portion 91, whereby the surface of the substrate 10 is etched and grows into a concave etching defect 92. Note that the etching defect 92 due to dust adhesion may occur not only in the outer shape forming process but also in the mesa forming process.

Next, in the mesa forming step of FIG. 7, as in the outer shape forming step of FIG. 6, the corrosion-resistant film 80 is deposited on the upper and lower surfaces 10a, 10b of the substrate 10 on which the outer shape of the resonator element 12 has been applied. A film is formed using an apparatus or the like, and then a resist 82 is applied to the entire surface of the corrosion-resistant film 80 (ST6).
Thereafter, a mesa forming mask is formed on the vibrating piece 12 by exposure and development (ST7).
Subsequently, the corrosion-resistant film 80 exposed from the mask opening is etched, and the substrate 10 exposed from the mask opening is etched with an etchant (ST8).
Further, the resist 10 and the corrosion-resistant film 80 that is a mesa formation mask are peeled off (ST9), whereby the substrate 10 on which the resonator element 12 having the mesa portion 16 is formed is completed.

Here, a process in which scratches are generated on the surface of the corrosion-resistant film 80 and the corrosion-resistant film 80 is lost, so that a defect 91 grows into an etching defect 92 and a process in which the etching channel 90 of the substrate 10 causes the etching defect 92 to grow. Will be described.
In FIG. 7F, if there is a defect 91 in the corrosion-resistant film 80 due to scratches on the surface of the corrosion-resistant film 80, the mesa formation etching in the mesa formation etching of FIG. During the application, the etching solution penetrates the resist 82 and reaches the defect portion 91, whereby the surface of the substrate 10 is etched and grows into a concave etching defect 92. The etching defect 92 due to scratches may occur not only in the mesa formation process but also in the outer shape formation process, and the size of the etching defect 92 varies depending on the etching time for forming the mesa portion 16. Since it is shorter than the etching time for forming the outer shape of the piece 12, it is relatively small compared to that generated during the outer shape formation.

  In FIGS. 6A and 7F, the etch channel 90 of the substrate 10 is considered to have a structure in which glass (amorphous in a broad sense) is embedded in the crystal, and is etched more than the surrounding crystal. The rate is high. Therefore, in FIG. 7H, when the corrosion resistant film 80 is etched after the mesa formation mask is formed, the etch channel 90 is exposed. Thereafter, during the mesa formation etching, the glass of the etch channel 90 is etched by the etchant, and the inner diameter increases after the penetration, and grows into an etching defect 92 such as a through hole. On the other hand, the etch channel 90 covered with the anticorrosion film 80 is not eroded by the etchant and maintains a state where the glass is buried.

  The above-described etching defect 92 generated in the resonator element 12 causes attenuation of vibration energy and generation of unnecessary spurious vibration, and causes a decrease in the CI value of the resonator element 12 and a defective frequency jump. In addition, the etching defect 92 such as a through hole becomes a location where stress is concentrated, the strength is lowered, and causes a defect due to cracking or chipping. Therefore, it is necessary to detect the etching defect 92 by visual inspection before the resonator element 12 is detached from the substrate 10 and mounted on a package or the like. Accordingly, it is very important to detect the etching defect 92 generated on the substrate 10 in order to reduce characteristic defects and breakage defects.

Next, in the electrode formation process of FIG. 8, the electrode film 13 (for example, chromium (Cr) as a base material is used as the base film on the upper and lower surfaces 10a and 10b of the substrate 10 on which the resonator element 12 having the mesa portion 16 is formed. The gold (Au)) is deposited using a vapor deposition device or a sputtering device, and then a resist 82 is applied to the entire surface of the electrode film 13 (ST10).
Thereafter, an electrode formation mask is formed on the vibrating piece 12 having the mesa portion 16 by exposure and development (ST11).
Subsequently, the electrode film 13 exposed from the mask opening is etched (ST12).
Further, the resist 82 is peeled off (ST13), whereby the substrate 10 on which the resonator element 12 having the mesa portion 16 provided with the electrode 14 is formed is completed.

Next, a method for inspecting the appearance of a substrate having a resonator element on which an electrode is formed will be described in detail.
In FIG. 1, the lens barrel 20 holds a first light source 32, a total reflection mirror 36, and a light receiving means 50. The lens barrel 20 has a cylindrical shape as a whole, and the inner wall is treated so as to be able to absorb light by matte coating or the like in order to prevent irregular reflection of light. Further, the lens barrel 20 is set up vertically and fixed by the sample stage 70 or a predetermined member (not shown) outside the system.

  The opening 22 at the upper end and the opening 24 at the lower end of the lens barrel 20 are formed at positions that overlap each other in plan view. The light receiving means 50 is attached to the opening 22 at the upper end, and the opening 24 at the lower end is directed to the sample stage 70. A branch tube 30 is attached to the central portion of the lens barrel 20 in the horizontal direction, and a first light source 32 that generates first light 38 a is attached to the tip of the branch tube 30.

  The total reflection mirror 36 is mounted on the line (optical axis C) connecting the opening 22 and the center of the opening 24 of the lens barrel 20 and at the same height as the branch tube 30. The total reflection mirror 36 is attached to the inner wall of the lens barrel 20 with the mirror surface inclined at an angle of approximately 45 ° from the vertical direction toward the branch tube 30.

  As the first light source 32, a light source having a frequency band that can be detected by the light receiving unit 50 and is not absorbed by the total reflection mirror 36 and the substrate 10 is used. In addition, a lens 34 is disposed after the first light source 32 so that the first light 38a can be emitted as parallel light. The first light source 32 may be a light having a spectrum spread in a predetermined frequency band (white light), but is preferably monochromatic light in consideration of chromatic aberration of the lens 34. By making the first light 38a parallel light, it is possible to prevent the first light 38a from diffusing on the optical path and reducing the intensity of the first reflection component 38b reaching the light receiving means 50. Further, since all of the first light 38 a that reaches the substrate 10 is incident perpendicularly to the main surface (upper surface 10 a) of the substrate 10, scattered light from the edge of the substrate 10 or the edge of the vibrating piece 12 enters the light receiving means 50. Mixing as stray light can be prevented, and a reduction in contrast described later can be prevented.

  A sample table 70 on which the substrate 10 is placed is disposed below the lens barrel 20. The sample stage 70 has a hollow opening 72 formed therein. The opening 72 is formed at a position (on the optical axis C) overlapping the openings 22 and 24 of the lens barrel 20 in plan view. The substrate 10 is placed so as to close the opening 72.

Further, a light source unit 40 to which a second light source 42 is attached is disposed below the sample stage 70. The light source unit 40 includes a second light source 42, a lens 44, and a total reflection mirror 46.
The total reflection mirror 46 is attached on a line (optical axis C) connecting the centers of the openings 22 and 24 of the lens barrel 20. The total reflection mirror 46 is attached to the inside of the light source unit 40 with the mirror surface tilted at about 45 ° from the vertical direction to the second light source 42 side.

  As the second light source 42, a light source having a frequency band that can be detected by the light receiving unit 50 and is not absorbed by the total reflection mirror 46 and the substrate 10 is used. In addition, a lens 44 is disposed following the second light source 42 so that the second light 48a can be emitted as parallel light. The second light source 42 may be one having a spectrum spread in a predetermined frequency band (white light), but considering the chromatic aberration of the lens 44, monochromatic light is desirable. By making the second light 48a parallel light, it is possible to prevent the second light 48a from diffusing along the optical path and preventing the intensity of the second transmissive component 48c reaching the light receiving means 50 from being reduced. Since all the second light 48a reaching 10 is incident perpendicularly on the lower surface 10b of the substrate 10, it is possible to prevent scattered light from the edge of the substrate 10 and the edge of the resonator element 12 from entering the light receiving means 50 as stray light. Therefore, it is possible to prevent a decrease in contrast described later.

  The light receiving means 50 attached to the opening 22 at the upper end of the lens barrel 20 is formed with the first reflection component 38b reflected by the upper surface 14a of the electrode 14 formed on the substrate 10 and the electrode 14 of the substrate 10. The second transmissive component 48c that has passed through the unoccupied region is photographed. The light receiving means 50 is formed by a lens 56 and an image sensor 52. The optical axis C of the light receiving means 50 is vertical and coincides with a line connecting the centers of the circular openings 22 and 24 of the lens barrel 20. Similarly, the optical axis C also passes through the central portions of the total reflection mirrors 36 and 46. By the optical system described above, the first light 38a emitted from the first light source 32 is reflected vertically downward by the total reflection mirror 36 in the state of parallel light, reflected by the substrate 10 vertically upward, and totally reflected mirror. The first reflection component 38 b that has passed through 36 is obtained. The second light 48 a emitted from the second light source 42 is reflected vertically upward by the total reflection mirror 46 in the state of parallel light, passes through the substrate 10, and passes through the total reflection mirror 36. It becomes the transmission component 48c. Then, the first reflection component 38b and the second transmission component 48c reach the light receiving means 50 while maintaining the state of parallel light.

  In the imaging device 52 of the light receiving means 50, the normal line of the imaging surface 54 coincides with the optical axis C. Since the focus of the light receiving means 50 is about 1 μm at the maximum, the position of the lens 56 is adjusted so as to match the upper surface 10 a of the substrate 10. Therefore, the image sensor 52 can capture an image focused on the upper surface 10 a of the substrate 10. The light receiving means 50 is focused on the top surface 10a of the substrate 10 because the image of the etching defect 92 near the focused top surface 10a and the image of the etching defect 92 near the focused bottom surface 10b are aligned. In comparison, the image of the etching defect 92 near the upper surface 10a looks sharper and easier to focus. Further, in the case of the substrate 10 on which the mesa portion 16 is formed, the etching defect 92 due to the etch channel 90 occurs, and the mesa portion 16 is not formed in order to detect the etching defect 92 having a small size without mistake. It is desirable to focus on the upper surface 10a of the substrate 10.

Next, the relationship between the light quantity ratio of the two light sources and the etching defect detection rate will be described.
FIG. 9 is a diagram showing a detection rate of etching defects caused by various factors with respect to the light amount ratio between the first light source and the second light source. 10A and 10B are diagrams for explaining a method of detecting etching defects by irradiating the substrate with light. FIG. 10A is a schematic view showing a cross section of the substrate, and FIG. 10B is a schematic view of an image seen from the light receiving means. FIG.

  From FIG. 9, the etching defect 92 is detected in the electrode region and the non-electrode region of the substrate 10 in the range where the light quantity ratio between the first light source 32 and the second light source 42 is 1.5 times or more and 2.5 times or less. It is possible. However, the detection rate does not become 100% in the electrodeless region, and the etching defect 92 due to dust and scratches has a detection rate of 70% or more. In addition, the etching defect 92 due to the etch channel is greatly deteriorated to a detection rate of 30% or more. This is because the size of the etching defect 92 caused by the etch channel is about 3 μm, which is very small compared to the size of the etching defect 92 caused by dust or scratches of 10 μm or more. Therefore, in order to obtain a detection rate of 100% in the electrode region and the non-electrode region, it is desirable to make the light amount ratio approximately twice.

  The reason for this is that, as shown in FIG. 10A, in the electrode region of the substrate 10, the first light 38a of the first light source 32 is reflected by the upper surface 14a of the electrode 14, and the intensity of the first light 38a is increased. Almost 100% reaches the light receiving means 50. On the other hand, the second light 48a of the second light source 42 is divided into a second transmissive component 48c that is transmitted through the substrate 10 and a second reflective component 48b that is reflected from the lower surface 10b of the substrate 10, so that it receives light. The intensity of the second transmission component 48c reaching the means 50 is halved to about 50% of the intensity of the second light 48a. Therefore, the intensity of the first reflection component 38b reaching the light receiving means 50 is about twice the intensity of the second transmission component 48c, and the first reflection component 38b and the second transmission component 48c due to scattering of the etching defect 92 are obtained. Since the intensity difference between the first reflection component 38b and the second transmission component 48c is larger than the intensity decrease, the etching defect 92 between the electrode region and the non-electrode region cannot be detected at the same time. Therefore, by making the light amount of the second light source 42 about twice the light amount of the first light source 32, the intensity of the first reflection component 38b reflected by the electrode region and the second light transmitted through the non-electrode region are obtained. The intensity of the transmitted component 48c can be made substantially equal. Therefore, the etching defect 92 in the electrode region and the non-electrode region can be detected at the same time.

  FIG. 10B is a schematic diagram of an image of the etching defect caused by the etch channel of FIG. The image sensor 52 can obtain the etching defect 92 in a plan view as a negative image. In FIG. 10B, the low intensity areas of the first reflection component 38b and the second transmission component 48c are drawn in black, and the high areas are drawn in white.

Image data 62 obtained by the image sensor 52 is output to the detection unit 60. The image data 62 has, for example, planar coordinates that form the same plane as the imaging surface 54 of the imaging element 52, and the imaging plane that configures the imaging element 52 with the center (optical axis C) of the imaging element 52 as the origin of the planar coordinates. The interval between the light receiving elements (not shown) arranged in 54 is defined as the plane resolution, and has the intensity of the reflection component and the transmission component for each coordinate position of the plane coordinates of each light receiving element.
The detection unit 60 detects the etching defect 92 by extracting a region that is equal to or less than a predetermined threshold from the intensity distribution of the reflection component and the transmission component indicated by the image data 62.

  11A and 11B are schematic diagrams of image processing. FIG. 11A is a diagram illustrating a divided plane before processing, and FIG. 11B is a diagram illustrating a divided plane after processing. In the image processing in the detection unit 60, for example, as shown in FIG. 11A, the plane coordinates indicated by the image data 62 are divided into divided planes 64 having a predetermined size. At this time, the minimum unit of the dividing plane 64 is an area (pixel area) of a light receiving element (not shown). Then, for each divided plane 64, the reflection component intensity is simplified to, for example, an intensity level of 256 steps. If there are a predetermined number of dividing planes 64 having an intensity level of 100 or less (three in FIG. 11B), it is determined that there is an etching defect 92 in that region, and a detection signal is output. Output to the outside. As described above, the detection unit 60 can detect the etching defect 92 in the substrate 10 by appropriately setting the size of the division plane 64, the number of steps of the intensity level, and the threshold of the intensity level.

  As described above, a method for inspecting the appearance of a substrate having a vibrating piece on which an electrode is formed, and an imaging apparatus that embodies the substrate are an AT-cut quartz substrate on which a vibrating piece 12 having a mesa portion 16 provided with an electrode 14 is formed. As described above, the substrate to be inspected is not particularly limited, and is an AT-cut quartz crystal substrate, a tuning-fork type vibration piece, and a gyro vibration formed with a vibrating piece having a flat plate or an inverted mesa portion provided with electrodes. A Z-cut quartz substrate on which a piece is formed may be used.

Next, a substrate visual inspection method and an imaging apparatus according to a second embodiment of the present invention will be described.
FIG. 12 is a schematic view showing a substrate visual inspection method according to a second embodiment of the present invention and an imaging apparatus that embodies the substrate visual inspection method.
As illustrated in FIG. 12, the imaging apparatus 1 a according to the second embodiment includes a first inspection system having the same configuration as the imaging apparatus 1 according to the first embodiment, and the imaging apparatus 1 according to the first embodiment. Is composed of a second inspection system that is vertically inverted and a transport unit 74 that transports the sample stage 70 on which the substrate 10 is installed.

  In the first inspection system, the lens barrel 20 holding the branch tube 30 to which the first light source 32 is attached and the first light receiving means 50 to which the detection unit 60 is connected is installed above the transport unit 74. A light source unit 40 to which the second light source 42 is attached is disposed below the transport unit 74. Further, in the second inspection system, the light source unit 40a to which the fourth light source 42a is attached is arranged above the transport unit 74, and the branch to which the third light source 32a is attached below the transport unit 74. A lens barrel 20a holding the tube 30a and the second light receiving means 50a to which the detector 60a is connected is installed.

  In the first inspection system, the substrate 10 is placed on the optical axis C line, and the first light is emitted from the first light source 32 reflected from the region where the electrode 14 is formed on the upper surface 10a of the substrate 10. And the second transmissive component of the second light emitted from the second light source 42 that has passed through the region where the electrode 14 of the substrate 10 is not formed is photographed by the first light receiving means 50, Etching defect 92 is detected. Thereafter, the substrate 10 placed on the optical axis Ca line of the second inspection system by the transport unit 74 is reflected by the second inspection system in the region where the electrode 14 on the lower surface 10b of the substrate 10 is formed. The third reflection component by the third light emitted from the light source 32a and the fourth transmission by the fourth light emitted from the fourth light source 42a that has passed through the region where the electrode 14 of the substrate 10 is not formed. The component is photographed by the second light receiving means 50a, and the etching defect 92 is detected.

  With such a configuration, even if the substrate 10 has the electrodes 14 formed on the upper and lower surfaces 10a and 10b of the substrate 10, the substrate 10 is generated on the upper and lower surfaces 10a and 10b without being turned upside down during the inspection. The etching defect 92 can be detected regardless of the presence or absence of the electrode 14, and the visual inspection time is shortened, which has a great effect on cost reduction.

Next, a substrate visual inspection method and an imaging apparatus according to a third embodiment of the present invention will be described.
FIG. 13 is a schematic diagram illustrating a substrate visual inspection method according to a third embodiment of the present invention and an imaging apparatus that embodies the substrate visual inspection method.
As shown in FIG. 13, the imaging apparatus 1b according to the third embodiment includes a branch tube 30b to which a first light source 32b is attached and a branch to which a fourth light source 42c is attached above a sample stage 70. The lens barrel 20b holding the tube 40c and the first light receiving means 50b to which the detection unit 60b is connected is installed. Also, below the sample stage 70, the second light receiving means to which the branch tube 30c to which the third light source 32c is attached, the branch tube 40b to which the second light source 42b is attached, and the detector 60c are connected. A lens barrel 20c holding 50c is installed. The light receiving means 50b and 50c, the lens barrels 20b and 20c, and the sample stage 70 are installed on the optical axis Cb line.

  The substrate 10 on which the electrodes 14 are formed on the upper and lower surfaces 10a, 10b of the substrate 10 is placed on the optical axis Cb line via the sample stage 70, and is reflected by the region where the electrode 14 on the upper surface 10a of the substrate 10 is formed. The first reflection component by the first light emitted from the first light source 32b and the second by the second light emitted from the second light source 42b that has passed through the region where the electrode 14 of the substrate 10 is not formed. The transmitted light component is photographed by the first light receiving means 50b, and the etching defect 92 is detected. Further, the third reflection component by the third light emitted from the third light source 32c reflected in the region where the electrode 14 on the lower surface 10b of the substrate 10 is formed, and the region where the electrode 14 of the substrate 10 is not formed. The fourth light-transmitting component of the fourth light emitted from the fourth light source 42c that has passed through is photographed by the second light receiving means 50c, and the etching defect 92 is detected.

  With such a configuration, even if the substrate 10 has the electrodes 14 formed on the upper and lower surfaces 10a and 10b of the substrate 10, the substrate is not turned upside down during the inspection, and the substrate 10 is not transported. Etching defects 92 generated on the upper and lower surfaces 10a and 10b 10 can be detected regardless of the presence or absence of the electrode 14, and the visual inspection time can be greatly shortened, and the cost can be greatly reduced.

  As described above, according to the appearance inspection method for the substrate 10 on which the electrode 14 according to the embodiment of the present invention is formed and the imaging measure embodying the method, the first light 38a from the first light source 32 is provided. The first light receiving means 50 generates the first reflection component 38b reflected by the electrode 14 of the substrate 10 and the second transmission component 48c transmitted through the substrate 10 by the second light 48a from the second light source 42. Take a picture. Thereafter, a low-intensity region of the first reflection component 38 b and the second transmission component 48 c in the photographed image is detected as an etching defect 92 generated in the substrate 10. Here, since the first light 38a and the second light 48a are scattered in the region where the etching defect 92 is present, the intensity of the first reflection component 38b and the second transmission component 48c is reduced in that region. Therefore, the etching defect 92 can be detected as a shape in plan view in a region where the reflection component intensity is small in the reflection component intensity distribution indicated by the image data 62 shown as an image.

  Further, by setting the light quantity ratio between the first light source 32 and the second light source 42 in the range of 1.5 times or more and 2.5 times or less, the first reflection component 38b reflected on the electrode 14 of the substrate 10 and The strength of the second transmissive component 48c transmitted through the region where the electrode 14 of the substrate 10 is not formed can be made substantially equal. Therefore, even in the substrate 10 on which the electrode 14 that has been impossible is formed, the etching defect 92 generated in the substrate 10 can be detected regardless of the presence or absence of the electrode 14.

  Furthermore, since the first light 38 a and the second light 48 a are irradiated perpendicularly to the main surface of the substrate 10, scattered light from the edge of the substrate 10 or the edge of the resonator element 12 can be reduced. Further, the intensity of the first reflection component 38b and the second transmission component 48c in the region where the first reflection component 38b and the second transmission component 48c due to the etching defect 92 are low and the region where the etching defect 92 is not present. The contrast with a large region can be improved, and the etching defects 92 in both regions can be detected simultaneously with high accuracy.

  Note that the etching defect 92 generated in the resonator element 12 causes attenuation of vibration energy and generation of unnecessary spurious vibration, and causes a decrease in the CI value of the resonator element 12 and a frequency jump failure. In addition, the etching defect 92 such as a through hole becomes a location where stress is concentrated, the strength is lowered, and causes a defect due to cracking or chipping. Therefore, the resonator element 12 having such an etching defect 92 is reliably selected to reduce the characteristic failure of the vibrator and oscillator formed thereafter and the oscillation defect due to the resonator element breakage, thereby improving the yield and reducing the cost. Can be achieved.

  DESCRIPTION OF SYMBOLS 1 ... Imaging device, 10 ... Board | substrate, 10a, 14a ... Upper surface, 10b ... Lower surface, 12 ... Vibrating piece, 13 ... Electrode film, 14 ... Electrode, 15 ... Pad electrode, 16 ... Mesa part, 20 ... Lens tube, 22, 24, 72 ... opening, 30 ... branch tube, 32 ... first light source, 34, 44, 56 ... lens, 36, 46 ... total reflection mirror, 38a ... first light, 38b ... first reflection component, DESCRIPTION OF SYMBOLS 40 ... Light source part, 42 ... 2nd light source, 48a ... 2nd light, 48c ... 2nd transmissive component, 50 ... Light-receiving means, 52 ... Imaging element, 54 ... Imaging surface, 60 ... Detection part, 62 ... Image Data: 64 ... Dividing plane, 70 ... Sample stage, 74 ... Conveying section, 80 ... Corrosion resistant film, 82 ... Resist, 90 ... Etch channel, 91 ... Defect, 92 ... Etching defect.

Claims (10)

The first main surface side of the first main surface or a light transmissive substrate provided with a first reflector on one surface of the second main surface which is the back side of the first main surface. The first light is reflected in the first reflector and the first light is reflected in the direction intersecting the first main surface,
Irradiating the substrate with the second light from the second principal surface side in a direction intersecting the first principal surface and transmitting the second light component transmitted through the substrate;
A step of inspecting the appearance of the substrate by receiving light by the first light receiving means,
A method for inspecting the appearance of a substrate, comprising: The substrate includes a second reflector on the other surface;
A reflection component of the third light reflected from the second reflector by irradiating the third light from the second main surface side in a direction intersecting the second main surface;
A transmission component of the fourth light transmitted through the substrate by irradiating the fourth light from the first main surface side in a direction intersecting the first main surface;
A step of inspecting the appearance of the substrate by receiving the light by the second light receiving means,
The substrate visual inspection method according to claim 1, further comprising:   3. The method of inspecting a substrate according to claim 1, wherein the substrate is made of quartz.   The substrate appearance inspection method according to claim 1, wherein the appearance inspection is an etching defect inspection.   The substrate visual inspection method according to claim 1, wherein the reflection component of the first light is received by the first light receiving unit.   6. The substrate visual inspection method according to claim 1, wherein the second light transmission component is received by the first light receiving unit.   The substrate according to any one of claims 1 to 6, wherein the substrate is irradiated with the first light and the second light along a normal direction of the first main surface. Visual inspection method.   The light quantity of the second light source that emits the second light is in the range of 1.5 to 2.5 times the light quantity of the first light source that emits the first light. The method for inspecting the appearance of a substrate according to any one of claims 1 to 7. Between the step of inspecting the appearance of the substrate by receiving light with the first light receiving means and the step of inspecting the appearance of the substrate by receiving light with the second light receiving means,
9. The method of inspecting a substrate according to claim 2, wherein the substrate is transported by a transport unit. A first light source;
A second optical axis is at least partially overlapped with the first light source and is optically opposed, and the amount of light is in a range of 1.5 to 2.5 times that of the first light source. A light source;
A light receiving means arranged on the optical axis and at a position optically facing the second light source;
An imaging apparatus comprising:

Images