Advanced package substrate through hole detection device and method based on gray field edge diffraction

Abstract

The invention relates to an advanced packaging substrate through hole detection device and method based on gray field edge diffraction, and the device comprises a light source, a light beam shaping assembly, an upper objective lens 5, a lower objective lens 7, and a charge-coupled device 8. The light beam shaping assembly comprises an upper axicon lens 2 and a lower axicon lens 3. A light beam generated by the light source is shaped into an annular light beam through the light beam shaping assembly, the annular light beam penetrates through the upper objective lens 5 to be shaped into a spherical wave surface light beam, the spherical wave surface light beam penetrates through a through hole of a substrate to be detected to generate diffraction light waves, the lower objective lens 7 amplifies the diffraction light waves, and the diffraction light waves are amplified by the lower objective lens 7. And the charge-coupled device 8 receives the amplified diffraction light waves to obtain diffraction images of different through hole depths. According to the invention, the subtle change of the diffraction pattern in the imaging plane can be detected.

Description

Technical Field

[0001] The invention relates to the technical field of microelectronic packaging, and in particular to an advanced packaging substrate through-hole detection device and method based on gray field edge diffraction. Background Art

[0002] The substrate in advanced electronic packaging has a multi-layer structure, and the electrical signals between layers are coupled through micro-holes drilled in the insulating layer. Substrate through-holes can be made by laser drilling, mechanical drilling or chemical etching. These technologies require high precision and control. With the miniaturization of chips, the aperture of packaging substrates will be reduced to 5 microns and below in the future. In order to ensure that the size and shape of the holes meet the strict design requirements, through-hole detection is crucial. Commonly used methods include the use of non-destructive X-ray microscopes, scanning electron microscopes (SEM), scanning acoustic microscopes (SAM) and atomic force microscopes (AFM). However, the resolution of the X-ray microscope method is very limited, and the scanning acoustic microscope technology cannot effectively detect defects with small differences in acoustic impedance from the surrounding area. Atomic force microscopes are not suitable for rapid detection because only a small area can be detected at a time.

[0003] In optical inspection of substrate through-holes, in bright field, due to the high background brightness, some fine features of the through-holes may be difficult to distinguish, and glare and shadows may also be easily generated. In dark field, although the contrast of small samples can be enhanced, it may not provide sufficient contrast for the detailed information inside the sample, resulting in limited observation results. Therefore, bright field and dark field may lead to problems such as low resolution of through-hole morphological features and large noise interference.

[0004] In view of this, it is necessary to provide an advanced packaging substrate through-hole detection device and method based on gray field edge diffraction. Summary of the invention

[0005] The purpose of the present invention is to provide an advanced packaging substrate through-hole detection device and method based on gray field edge diffraction, which can detect subtle changes in the diffraction pattern in the imaging plane, and realize comprehensive 3D morphological characterization of the through-hole by superimposing diffraction images of different depths of the substrate through-hole.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] On the one hand, the present invention provides an advanced packaging substrate through-hole detection device based on gray field edge diffraction, comprising: a light source, a beam shaping component, an upper objective lens, a lower objective lens, and a charge coupled device;

[0008] The beam shaping assembly includes an upper axicon lens and a lower axicon lens;

[0009] The light beam generated by the light source is shaped into an annular light beam by the beam shaping component, the annular light beam is shaped into a spherical wave surface light beam through the upper objective lens, the spherical wave surface light beam passes through the through hole of the substrate to be inspected to generate a diffraction light wave, the lower objective lens amplifies the diffraction light wave, the charge coupled device receives the amplified diffraction light wave, and obtains diffraction images of different through hole depths.

[0010] Optionally, the light source is a laser, and the laser emits nano laser with a wavelength of 500-550nm.

[0011] Optionally, the conical surface of the upper axicon lens faces the incident direction of the light beam, and the conical surface of the lower axicon lens faces the emitting direction of the light beam.

[0012] Optionally, the lens entrance hole of the upper objective lens faces the incident direction of the light beam, the lens entrance hole of the lower objective lens faces the emitting direction of the light beam, and the upper objective lens moves along the direction of the light beam to scan the focal point of the light beam along the depth of the through hole of the substrate to be inspected.

[0013] Optionally, the device further comprises a neutral density filter, wherein the neutral density filter is used to receive the annular light beam output by the lower axicon lens and control the transmittance of the annular light beam.

[0014] Optionally, the device further comprises a flash lamp, and the flash lamp is used to increase the contrast of the diffraction image.

[0015] On the other hand, the present invention also provides a method for detecting through-holes in an advanced packaging substrate based on gray field edge diffraction, comprising:

[0016] The light source generates a light beam as an incident light source, and the incident light source is shaped into an annular light beam by an upper axicon lens and a lower axicon lens;

[0017] The annular beam is passed through an upper objective lens to shape the annular beam into a spherical wavefront beam;

[0018] The spherical wave surface light beam passes through the through hole of the substrate to be detected to generate a diffracted light wave, and the lower objective lens amplifies the diffracted light wave;

[0019] The charge coupled device receives the amplified diffracted light wave and obtains diffraction images of different through hole depths;

[0020] According to the diffraction image, a 3D morphology representation of the through hole of the substrate to be inspected is obtained to realize the inspection of the through hole of the inspection substrate.

[0021] Optionally, before allowing the annular light beam to pass through the upper objective lens, the method includes: allowing the annular light beam output by the lower axicon lens to pass through a neutral density filter to control the transmission amount of the annular light beam.

[0022] Optionally, after acquiring the diffraction images of different through-hole depths, the method further comprises: increasing the contrast of the diffraction images by using a flash lamp.

[0023] The beneficial effects of the present invention are as follows: Unlike conventional brightfield and darkfield microscopy, grayfield edge diffraction is characterized by a high sensitivity to scattered light, and is capable of detecting subtle changes in the diffraction pattern within the imaging plane. The stripes extracted from the grayfield edge diffraction show higher stripe intensity, providing higher image contrast and depth of focus, and enhancing image quality. As an effective non-destructive technology, the detection method of the present invention has the characteristics of ease of use and high efficiency; by superimposing diffraction images of different depths of substrate through-holes, a comprehensive 3D morphological characterization of the through-holes is achieved, and it is expected to achieve automatic optical inspection of various through-holes, including through-silicon vias (TSVs), through-glass vias (TGVs), and flexible printed circuit through-holes, for advanced electronic device packaging applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 This is a structural diagram of an advanced packaging substrate through-hole detection device based on gray field edge diffraction according to an embodiment of the present invention;

[0026] Figure 2 Schematic diagram of the gray field edge diffraction measurement principle of an embodiment of the present invention;

[0027] Figure 3 This is a flow chart of a method for detecting through-holes in an advanced packaging substrate based on gray field edge diffraction according to an embodiment of the present invention;

[0028] Among them, there are laser 1, upper axicon lens 2, lower axicon lens 3, neutral density filter 4, upper objective lens 5, substrate through hole 6, lower objective lens 7, charge coupled device 8, flash lamp 9, spherical wave surface beam 10, through hole edge 11, incident wave 12, reflected wave 13 and diffracted wave 14. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] Embodiment 1:

[0032] like Figure 1 As shown, this embodiment provides an advanced packaging substrate through-hole detection device based on gray field edge diffraction, including: a light source, a beam shaping component, an upper objective lens 5, a lower objective lens 7 and a charge coupled device 8;

[0033] The beam shaping assembly includes an upper axicon lens 2 and a lower axicon lens 3;

[0034] The light beam generated by the light source is shaped into an annular light beam by the beam shaping component. The annular light beam is shaped into a spherical wave surface beam through the upper objective lens 5. The spherical wave surface beam passes through the through hole of the substrate to be inspected to generate a diffraction light wave. The lower objective lens 7 amplifies the diffraction light wave. The charge coupled device 8 receives the amplified diffraction light wave to obtain diffraction images of different through hole depths.

[0035] Furthermore, the light source is a laser 1, which emits nano laser with a wavelength of 500-550nm.

[0036] In this embodiment, the laser wavelength output by the laser 1 is 530 nm.

[0037] Furthermore, the conical surface of the upper axicon lens 2 faces the incident direction of the light beam, and the conical surface of the lower axicon lens 3 faces the emitting direction of the light beam.

[0038] Furthermore, the lens entrance hole of the upper objective lens 5 faces the incident direction of the light beam, and the lens entrance hole of the lower objective lens 7 faces the emitting direction of the light beam, and the upper objective lens 5 moves along the direction of the light beam to scan the focal point of the light beam along the depth of the through hole of the substrate to be inspected.

[0039] In this embodiment, the upper objective lens 5 can be a 10-fold objective lens, and the lower objective lens 7 can be a 50-fold objective lens.

[0040] Furthermore, the device also includes a neutral density filter 4, which is used to receive the annular light beam output by the lower axicon lens 3 and control the transmittance of the annular light beam.

[0041] Furthermore, a charge coupled device 8 is fixed at the bottom of the device, and the device also includes a flash lamp 9, which is used to increase the contrast of the diffraction image.

[0042] Specifically, the flash lamp 9 is installed beside the charge coupled device 8 .

[0043] The following is a further description of a device placed perpendicular to a horizontal plane:

[0044] The invention discloses an advanced packaging substrate through-hole detection device based on gray field edge diffraction, comprising: a laser 1, which generates a light beam; a neutral density filter 4, which is used to reduce the amount of light beam transmitted; an upper axicon lens 2 and a lower axicon lens 3, which are installed between the laser 1 and the neutral density filter 4; a charge-coupled device 8, which is configured to receive diffracted light of the substrate through-hole; an upper objective lens 5, which is installed between the neutral density filter and the substrate through-hole; a lower objective lens 7, which is installed between the substrate through-hole 6 and the charge-coupled device 8; and a flash lamp 9, which is installed next to the charge-coupled device 8 and is used to reduce background noise on the imaging plane and enhance the contrast of the diffraction pattern.

[0045] The laser wavelength output by the laser 1 is 500-550nm.

[0046] The cone surface of the upper axicon lens 2 faces upward, and the cone surface of the lower axicon lens 3 faces downward.

[0047] The upper objective lens 5 may be a 10x objective lens, and the lower objective lens 7 may be a 50x objective lens.

[0048] The lens entrance hole of the upper objective lens 5 faces upward, and the lens entrance hole of the lower objective lens 7 faces downward.

[0049] The substrate through hole 6 is located between the upper objective lens 5 and the lower objective lens 7 .

[0050] Unlike conventional brightfield and darkfield microscopy, the grayfield edge diffraction measurement method can provide higher image contrast and focal depth, thereby improving image quality. Grayfield edge diffraction measurement is achieved by shaping the incident light profile into a ring beam shape, that is, the laser 1 emits a collimated laser as a light source, and two axicon lenses are installed under the laser 1 to shape the collimated laser into a collimated ring beam. The use of a neutral density filter 4 can avoid the intensity saturation of the CCD 8 imaging, and then the collimated ring beam is formed into a spherical wave surface through a 10x objective lens. When the light wave passes through the edge of the through hole, diffraction occurs. Through the 50x objective lens magnification process, the diffraction image (circular diffraction spot of light and dark ripples) at a selected height can be observed at the CCD 8. By observing and measuring the morphology and distribution of the diffraction fringes, the shape and size of the through hole and other information can be inferred.

[0051] Generation of diffraction images: This effect is explained by the Huygens-Fresnel principle, which states that every point on the wavefront is the origin of a new spherical wavelet. These wavelets add up and interfere with each other to form a diffraction pattern.

[0052] The measurement principle of gray field edge diffraction is as follows Figure 2As shown, when the spherical wavefront light beam 10 encounters the through-hole edge 11, an incident wave 12, a reflected wave 13 and a diffraction wave 14 are generated, thereby forming three boundaries: reflection, shadow and deep shadow. The diffraction patterns in these areas are affected by the geometry and roughness of the through-hole edge. The flash lamp 9 reduces the background noise on the diffraction pattern and enhances the contrast of the diffraction pattern, so that the through-hole edge features can be analyzed in detail.

[0053] The gray field edge diffractometer can also capture the diffraction image at each height and perform three-dimensional feature analysis of the through hole by adjusting the focus point of the CCD (charge coupled device 8) along the depth direction.

[0054] Embodiment 2:

[0055] The method for detecting through-holes in advanced packaging substrates based on gray field edge diffraction includes:

[0056] The light source generates a light beam as an incident light source, and the incident light source is shaped into an annular light beam by an upper axicon lens 2 and a lower axicon lens 3;

[0057] The annular beam is passed through the upper objective lens 5 to shape the annular beam into a spherical wavefront beam;

[0058] The spherical wave surface light beam passes through the through hole of the substrate to be inspected to generate diffracted light waves, and the lower objective lens 7 amplifies the diffracted light waves;

[0059] The charge coupled device 8 receives the amplified diffracted light waves and obtains diffraction images of different through-hole depths;

[0060] According to the diffraction image, the 3D morphology representation of the through hole of the substrate to be inspected is obtained to realize the inspection of the through hole of the substrate.

[0061] In this embodiment, the laser emitted by the laser 1 serves as the incident light source.

[0062] In this embodiment, the position of the upper objective lens 5 is adjusted to focus the light beam at different depths of the through hole 6 of the substrate. When the focused light beam interacts with the edge of the through hole, a circular diffraction spot is generated.

[0063] Furthermore, before the annular light beam is passed through the upper objective lens 5 , the method includes: passing the annular light beam output by the lower axicon lens 3 through the neutral density filter 4 to control the transmission amount of the annular light beam.

[0064] Further, after obtaining the diffraction images of different through-hole depths, the method further includes: increasing the contrast of the diffraction images by using a flash lamp 9 .

[0065] Specifically, the flash lamp 9, which is installed beside the charge coupled device 8, is used to reduce the background noise on the imaging plane and enhance the contrast of the diffraction pattern.

[0066] according to Figure 3The advanced packaging substrate through-hole detection method based on gray field edge diffraction is further explained:

[0067] like Figure 3 The advanced packaging substrate through-hole detection method based on gray field edge diffraction specifically includes the following steps:

[0068] 1) The laser emitted by laser 1 is used as the incident light source.

[0069] 2) The light beam is shaped into a circular ring-shaped beam profile by the upper axicon lens 2 and the lower axicon lens 3.

[0070] 3) Then the light passes through a neutral density filter 4 to control the amount of light transmitted.

[0071] 4) Adjust the position of the upper objective lens 5 so that the light beam is focused at different depths of the through hole of the substrate.

[0072] 5) The diffracted light waves are then amplified by the lower objective lens 7.

[0073] 6) By extracting diffraction images of different through-hole depths, the 3D morphology characterization of the through-hole is achieved.

[0074] Specifically, when light waves encounter the edge of the substrate through-hole contour, diffraction occurs, and the resulting circular diffraction pattern of light and dark ripples can be captured on the charge-coupled device 8. These fringe patterns on the plane are affected by the geometry and roughness of the through-hole contour edge, so the through-hole contour edge characteristics can be analyzed in detail.

[0075] The embodiments described above are only descriptions of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. An advanced packaging substrate through-hole detection device based on gray field edge diffraction, characterized in that: include: A light source, a beam shaping assembly, an upper objective lens (5), a lower objective lens (7) and a charge coupled device (8); The beam shaping assembly comprises an upper axicon lens (2) and a lower axicon lens (3); The light beam generated by the light source is shaped into an annular light beam by the beam shaping component, the annular light beam is shaped into a spherical wave surface light beam through the upper objective lens (5), the spherical wave surface light beam is transmitted through the through hole of the substrate to be detected to generate a diffracted light wave, the lower objective lens (7) amplifies the diffracted light wave, the charge coupled device (8) receives the amplified diffracted light wave, and obtains diffraction images of different through hole depths.

2. The advanced packaging substrate through-hole detection device based on gray field edge diffraction according to claim 1 is characterized in that: The light source is a laser (1), and the laser (1) emits nanometer laser with a wavelength of 500-550nm.

3. The advanced packaging substrate through-hole detection device based on gray field edge diffraction according to claim 1 is characterized in that: The conical surface of the upper axicon lens (2) faces the incident direction of the light beam, and the conical surface of the lower axicon lens (3) faces the emitting direction of the light beam.

4. The advanced packaging substrate through-hole detection device based on gray field edge diffraction according to claim 1 is characterized in that: The lens entrance hole of the upper objective lens (5) faces the incident direction of the light beam, the lens entrance hole of the lower objective lens (7) faces the emitting direction of the light beam, and the upper objective lens (5) moves along the direction of the light beam so that the light beam focal point scans along the depth of the through hole of the substrate to be inspected.

5. The advanced packaging substrate through-hole detection device based on gray field edge diffraction according to claim 1 is characterized in that: The device also includes a neutral density filter (4), which is used to receive the annular light beam output by the lower axicon lens (3) and control the transmittance of the annular light beam.

6. The advanced packaging substrate through-hole detection device based on gray field edge diffraction according to claim 1 is characterized in that: The device also includes a flash lamp (9), which is used to increase the contrast of the diffraction image.

7. The detection method of the advanced packaging substrate through-hole detection device based on gray field edge diffraction according to any one of claims 1 to 6, characterized in that: include: The light source generates a light beam as an incident light source, and the incident light source is shaped into an annular light beam by an upper axicon lens (2) and a lower axicon lens (3); The annular light beam is passed through an upper objective lens (5) to shape the annular light beam into a spherical wave surface light beam; The spherical wave surface light beam passes through the through hole of the substrate to be detected to generate a diffracted light wave, and the lower objective lens (7) amplifies the diffracted light wave; A charge coupled device (8) receives the amplified diffracted light waves to obtain diffraction images of different through-hole depths; According to the diffraction image, a 3D morphology representation of the through hole of the substrate to be inspected is obtained to realize the inspection of the through hole of the inspection substrate.

8. The method for detecting through-holes in advanced packaging substrates based on gray field edge diffraction according to claim 7, characterized in that: Before the annular light beam is passed through the upper objective lens (5), the method includes: passing the annular light beam output by the lower axicon lens (3) through a neutral density filter (4) to control the transmission amount of the annular light beam.

9. The method for detecting through-holes in advanced packaging substrates based on gray field edge diffraction according to claim 7, characterized in that: After obtaining the diffraction images of different through-hole depths, the method further comprises: increasing the contrast of the diffraction images by using a flash lamp (9).

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