Optical detection equipment and operation method thereof

Abstract

The optical detection apparatus includes a projection optical system, a digital microscope system, and a calculation unit. The projection optical system is configured to obtain oblique projection images of a plurality of through hole structures in the substrate. The digital microscope system is configured to acquire a 2D interference image. The calculation unit is electrically connected with the projection optical system and the digital microscope system. The calculation unit is configured to analyze the 2D interference image to obtain stereo image information and analyze the oblique projection image to obtain a plurality of parameters of the through hole structure. The optical detection device is a non-contact and non-destructive detection method, thereby providing feedback in real time. The plurality of through hole structures can be detected at the same time, and the time for scanning the substrate can be shortened. The shape and contour of the whole through hole structure can pass through an oblique projection image of the projection optical system and a 2D interference image of the digital microscope system.

Description

TECHNICAL FIELD

[0001] The present invention relates to the technical field of optical detection, and in particular to an optical detection apparatus and a method of operating the same. BACKGROUND

[0002] In the field of semiconductor detection, common detection methods such as laser confocal microscopy, chromatic confocal microscopy or white light scanning technology are used. However, these methods cannot simultaneously detect multiple through holes, and are time-consuming. For example, the conventional SEM scanning method takes about 30 minutes in the early stage. In addition, the current detection method cannot analyze the side wall taper angle of the corner of the through hole. However, as the critical dimension of the metal electroplating process becomes smaller and smaller, the side wall taper angle at the corner of the through hole is crucial to the metal electroplating process.

[0003] Therefore, how to shorten the processing time (for example, to several seconds or so) and how to provide an optical detection apparatus and a method of operating the same for through holes are still one of the goals to be developed. SUMMARY

[0004] One of the purposes of the present invention is to provide an optical detection apparatus and a method of operating the same to solve the problem of long detection processing time and difficulty in simultaneously detecting multiple through holes.

[0005] The technical solution of the present invention is an optical detection apparatus.

[0006] In an embodiment, the optical detection apparatus comprises a projection optical system, a digital microscope system and a computing unit. The projection optical system is configured to obtain oblique projection images of multiple through hole structures in a substrate. The digital microscope system is configured to obtain 2D interference images. The computing unit is electrically connected to the projection optical system and the digital microscope system. The computing unit is configured to analyze the 2D interference images to obtain stereoscopic image information and analyze the oblique projection images to obtain multiple parameters of the through hole structures.

[0007] In an embodiment, the projection optical system further comprises a light source, a projection lens and an image sensor. The light source is configured to illuminate the back surface of the substrate. The projection lens is located on the front surface of the substrate, wherein the projection lens is configured to obtain oblique projection images of the through hole structures of the substrate. The image sensor is configured to record the images from the projection lens.

[0008] In an embodiment, the projection lens of the projection optical system is a telecentric lens.

[0009] In an embodiment, the computing unit is configured to perform a depth of field extension algorithm or a full depth of field algorithm to obtain the parameters of the through hole structures.

[0010] In one embodiment, the through-hole structure is an etched hole, and the parameters include the upper critical dimension, the middle critical dimension, the lower critical dimension, the sidewall cone angle, the spacing, the diameter, the roughness, the height, and the central axis.

[0011] In one embodiment, the through-hole structure is a region after laser modification, and the parameters include depth, angle, spacing, density, linewidth, and internal cracks.

[0012] In one embodiment, the digital microscope system further includes a laser source and an image sensor. The laser source is configured to emit incident light toward the substrate. The image sensor is configured to record a 2D interference image formed after the incident light passes through the via structure.

[0013] In one embodiment, the optical inspection device further includes a stage. A substrate is disposed on the stage, and the distance between the stage and the image sensor is adjustable.

[0014] In one embodiment, the computing unit is configured to perform a back-propagation reconstruction algorithm on the 2D interferometric image to obtain a 3D image stack of the via structure.

[0015] In one embodiment, the computing unit is configured to perform a twin image elimination algorithm on the stack of 3D images.

[0016] In one embodiment, the computing unit is configured to perform a super-resolution algorithm on the stack of 3D images.

[0017] In one embodiment, the through-hole structure is an etched hole, and the stereoscopic image information includes the upper key dimension, the middle key dimension, the lower key dimension, the sidewall cone angle, the upper arc degree, the lower arc degree, the spacing, the diameter, the height, the axis, the surface roughness, the cross-sectional view, and the map scan.

[0018] In one embodiment, the through-hole structure is the region after laser modification, and the stereoscopic image information includes the accuracy of laser modification and map scanning.

[0019] Another technical solution of the present invention is an operation method for an optical detection device.

[0020] In one embodiment, the operation method of the optical inspection device includes forming a plurality of etched holes in a substrate; obtaining a first oblique projection image of the etched holes through a projection system; obtaining a first 2D interference image of the etched holes through a digital microscope system; and analyzing the oblique projection image through a computing unit to obtain a plurality of parameters and analyzing the first 2D interference image to obtain stereoscopic image information.

[0021] In one embodiment, before forming etched holes in the substrate, a calculation unit calculates a first spacing based on a preset diameter of the etched holes and the thickness of the substrate.

[0022] In one embodiment, obtaining a first oblique projection image of the etched holes via a projection system further includes illuminating the back side of the substrate with a light source; obtaining a first oblique projection image of the etched holes of the substrate via a projection lens; and recording the image from the projection lens via an image sensor.

[0023] In one embodiment, obtaining a first 2D interferometric image of the etched hole using a digital microscope system further includes emitting incident light through a laser source to illuminate the substrate; and recording an image of the incident light passing through the etched hole using an image sensor.

[0024] In one embodiment, the substrate is laser-modified to form a plurality of laser-modified regions before the etched holes are formed in the substrate.

[0025] In one embodiment, before performing laser modification on the substrate to form the laser-modified region, a calculation unit calculates a first spacing based on the default linewidth of the laser-modified region and the thickness of the substrate.

[0026] In one embodiment, the operation method of the optical detection device further includes obtaining a second oblique projection image of the laser-modified region through a projection system and obtaining a second 2D interference image of the laser-modified region through a digital microscope system.

[0027] In the above embodiments, the optical inspection equipment is a non-contact and non-destructive inspection method, thereby providing feedback in real time. The shape and contour of the entire via structure can be obtained through oblique projection images from a projection optics system and 2D interference images from a digital microscope system. Furthermore, multiple via structures can be inspected simultaneously, reducing the time required to scan the substrate. The sidewall cone angles of the via structures can be detected, allowing metal plating processes to be performed to form vias (metal conductors) with smaller critical dimensions. Before performing laser modification or etching processes, the optimal spacing of the via structures can be calculated according to a first spacing equation to avoid overlap. Attached Figure Description

[0028] FIG. 1AThis is a schematic diagram of an optical inspection device according to an embodiment of the present invention.

[0029] FIG. 1B This is a schematic diagram of a projection optical system according to an embodiment of the present invention.

[0030] FIG. 1C This is a schematic diagram of a digital microscope system according to an embodiment of the present invention.

[0031] FIG. 2 A schematic diagram of an image obtained by a projection optical system.

[0032] FIGS. 3A-3D An image of a laser-modified substrate obtained by a projection optics system.

[0033] FIG. 4 An image of the etched holes obtained by a projection optics system.

[0034] FIG. 5 An image of the etched holes obtained by a projection optics system.

[0035] FIG. 6 2D contour analysis of images acquired by a projection optical system.

[0036] FIG. 7 This is a schematic diagram of the analysis parameters for an image acquired by a projection optical system.

[0037] FIG. 8 A schematic diagram of roughness profile analysis of an image obtained by a projection optical system.

[0038] FIG. 9 This is a schematic diagram of generating a 2D interferometric image according to an embodiment of the present invention.

[0039] FIG. 10 for FIG. 9 2D interferometric images obtained by a digital microscope system.

[0040] FIG. 11 for FIG. 9 3D image stacking obtained by a digital microscope system.

[0041] FIG. 12 for FIG. 11 A stereoscopic image reconstructed by stacking 3D images.

[0042] FIG. 13 An image of a laser-modified substrate is obtained using a digital microscope system according to an embodiment of the present invention.

[0043] FIGS. 14A-14E An image of the etched hole was obtained using a digital microscope system according to an embodiment of the present invention.

[0044] FIG. 15 A schematic diagram of 3D point cloud data for reconstructing a through-hole structure.

[0045] FIG. 16A This is a schematic diagram of the detection angle according to an embodiment of the present invention.

[0046] FIG. 16B To pass FIG. 16A A schematic diagram of the detection image obtained from the detection angle.

[0047] FIG. 17A and FIG. 17B This is a schematic diagram of the detection image of an overlapping through-hole structure.

[0048] FIG. 18 This is a schematic diagram of the rotation angle according to an embodiment of the present invention.

[0049] FIG. 19 This is a chart with minimum spacing obtained according to the minimum spacing formula.

[0050] FIG. 20 This is a schematic diagram of a detection image of a laser-modified substrate according to an embodiment of the present invention.

[0051] FIG. 21 This is a flowchart of the operation method for optical inspection equipment.

[0052] Explanation of icon numbers

[0053] 10: Optical inspection equipment

[0054] 100: Projection Optical System

[0055] 110: Light source

[0056] 120: Projection lens

[0057] 130: Image sensor

[0058] 200: Digital Microscope System

[0059] 210: Laser source

[0060] 212: Incident light

[0061] 214: Uninterrupted light

[0062] 216: Interference Light

[0063] 230: Image sensor

[0064] 300: Computing Unit

[0065] 400: Support Platform

[0066] 500,500a,500b,500d:Substrate

[0067] 502: Back

[0068] 504: Front

[0069] 510, 510a, 510b, 510c: Through-hole structure

[0070] 510, 510d: Regions after laser modification

[0071] 510, 510b: Etched holes

[0072] 600: Operating Instructions for Optical Inspection Equipment

[0073] AX1: First optical axis

[0074] AX2: Second optical axis

[0075] IM1, IM2, IM3: Oblique projection images

[0076] IM4: Processed image

[0077] IM5: 2D Interferometric Image

[0078] IM6: 3D Image Stacking

[0079] IM7: Stereoscopic Image

[0080] IC: Internal crack

[0081] P1: Dense Part

[0082] P2: Sparse portion

[0083] DP: Depth

[0084] LW: Line width

[0085] AN: Angle

[0086] LP: Left side outline

[0087] RP: Right side profile

[0088] LW: Left-side wavy line

[0089] RW: Right side wavy line

[0090] CL: Central Axis

[0091] TCD: Upper Critical Dimension

[0092] MCD: Central Critical Dimension

[0093] BCD: Lower critical dimensions

[0094] NCD: Narrowest Key Dimension

[0095] H1: First Height

[0096] H2: Second Altitude

[0097] CTA: Central tilt angle

[0098] LTA: Upper Left Cone Angle

[0099] RTA: Upper right cone angle

[0100] LBA: Lower Left Cone Angle

[0101] RBA: Lower right cone angle

[0102] LR: Roughness on the left side

[0103] RR: Roughness on the right side

[0104] DS: Dual Launch

[0105] PCD: Point Cloud Data

[0106] α: Detection angle

[0107] ψ: Rotation angle

[0108] p: Spacing

[0109] t: thickness

[0110] d: diameter

[0111] S1~S10: Steps Detailed Implementation

[0112] Several embodiments of the present invention will be disclosed below with reference to the accompanying drawings. For clarity, many practical details will be described in the following description. However, it should be understood that these practical details are not intended to limit the invention.

[0113] FIG. 1A This is a schematic diagram of an optical inspection device 10 according to an embodiment of the present invention. The optical inspection device 10 includes a projection optical system 100, a digital microscope system 200, a computing unit 300, and a stage 400. The substrate 500 to be inspected is placed on the stage 400. The substrate 500 is transparent or translucent, such as a glass substrate, an acrylic substrate, or a silicon substrate. In this embodiment, the projection optical system 100 is a non-orthogonal projection optical system, but the present invention is not limited thereto.

[0114] A projection optics system 100 and a digital microscope system 200 are configured to detect a plurality of via structures 510 located in a substrate 500. Before the etching process and after the laser modification process, the via structures 510 are the laser-modified areas. After the etching process, the via structures 510 are etched holes formed in the laser-modified areas. The etched holes are essentially filled with metal in a subsequent metal plating process to form vias (metal conductors).

[0115] A projection optics system 100 is configured to acquire an oblique projection image of the through-hole structure 510 of the substrate 500. A digital microscope system 200 is configured to acquire a 2D interference image of the through-hole structure 510 of the substrate 500. A computing unit 300 is electrically connected to the projection optics system 100 and the digital microscope system 200. The computing unit 300 is configured to analyze the oblique projection image from the projection optics system 100 to obtain multiple parameters of the substrate 500 and to analyze the 2D interference image from the digital microscope system 200 to obtain stereoscopic image information of the substrate 500.

[0116] FIG. 1B This is a schematic diagram of a projection optical system 100 according to an embodiment of the present invention. The projection optical system 100 includes a light source 110, a projection lens 120, and an image sensor 130. The light source 110 is configured to illuminate the back surface 502 of a substrate 500. The projection lens 120 is located on the front surface 504 of the substrate 500. The projection lens 120 is configured to acquire an obliquely projected image of the through-hole structure 510 of the substrate 500. The image sensor 130 is configured to record the image captured by the projection lens 120.

[0117] The projection lens 120 of the projection optical system 100 is a telecentric lens. In this embodiment, there is an angle between the first optical axis AX1 of the projection lens 120 and the second optical axis AX2 of the parallel diverging light emitted from the light source 110. For example, this angle is in the range of 40 to 50 degrees. In this embodiment, this angle is 45 degrees. In some other embodiments, the optical axis of the projection lens 120 and the optical axis of the parallel diverging light emitted from the light source 110 are parallel to each other (e.g., FIG. 1A (Example). That is, the illumination method can be dark field illumination or bright field illumination. Furthermore, the shape of the beam emitted by the light source 110 is not limited.

[0118] FIG. 1CThis is a schematic diagram of a digital microscope system 200 according to an embodiment of the present invention. The digital microscope system 200 includes a laser source 210 and an image sensor 230. The laser source 210 is a point source and is configured to emit incident light 212. The image sensor 230 is configured to record a 2D interference image formed after the incident light 212 passes through the through-hole structure 510 of the substrate 500. In some embodiments, the distance between the stage 400 and the image sensor 230 is adjustable to improve resolution. The digital microscope system 200 is a lens-free system, such as digital lensless holographic microscopy or digital axis holographic microscopy, but the present invention is not limited thereto.

[0119] In some embodiments, the projection optics system 100 and the digital microscope system 200 can be used independently. The optical inspection device 10 is a non-contact and non-destructive inspection method, thereby providing feedback in real time.

[0120] FIG. 2 Image acquired by projection optical system 100. (Refer to...) FIG. 1B and FIG. 2 The projection optics system 100 scans the substrate 500 to acquire multiple oblique projection images IM1, IM2, and IM3. In this embodiment, the computing unit 300 is configured to execute a depth-of-focus algorithm to obtain a processed image IM4. The depth-of-focus algorithm is used to enhance the depth of the oblique projection images IM1, IM2, and IM3. As a result, the contour of the via structure 510 in the processed image IM4 can be more accurate than the contour of the via structure 510 in the oblique projection images IM1, IM2, and IM3.

[0121] FIGS. 3A-3D Image of the laser-modified substrate acquired by the projection optical system 100. (Refer to...) FIG. 1B and FIGS. 3A-3D The image of the laser-modified region 510 is processed to increase its resolution, for example, using a depth-of-field extension algorithm. These images are then analyzed by the computing unit 300 to obtain multiple parameters of the laser-modified region 510.

[0122] For example, the parameters of the laser-modified region 510 include depth, angle, spacing, density, linewidth, and internal cracks, but this invention is not limited thereto. These parameters will be combined with... FIGS. 3A-3D Detailed explanation.

[0123] FIG. 3AThis is an image of the laser-modified region 510, marked with coordinates. In this way, the spacing between the laser-modified regions 510 can be calculated. FIG. 3B An image showing the internal crack IC that occurs around region 510 after laser modification. FIG. 3C The image is used to mark the dense portion P1 and the sparse portion P2 of the region 510 after laser modification. FIG. 3D This image shows the depth DP, linewidth LW, and angle AN of the laser-modified region 510. Angle AN represents the angle between the length direction of the laser-modified region 510 and the lateral direction of the laser-modified substrate 500.

[0124] Based on the parameters detected by the projection optics system 100, the quality of laser refining can be confirmed and reported to improve the laser refining process.

[0125] FIG. 4 Image of the etched holes obtained by the projection optical system 100. (Refer to...) FIG. 1B and FIG. 4 In this embodiment, the image is an obliquely projected image processed by a full depth-of-field algorithm. In some other embodiments, other algorithms that can enhance or extend the depth of field of the telecentric lens can be used in conjunction with the projection optics system 100.

[0126] FIG. 5 Image of the etched holes obtained by the projection optical system 100. (Refer to...) FIG. 1B and FIG. 5 The image of the etched hole 510 is processed and analyzed by the computing unit 300 to obtain multiple parameters of the etched hole 510. The parameters of the oblique projection image are analyzed and corrected to obtain the corresponding parameters of the vertical image of the etched hole 510. In this way, the left and right wall information of the etched hole 510 can be obtained.

[0127] For example, the parameters of the etched hole 510 include the upper critical dimension, middle critical dimension, lower critical dimension, spacing, diameter, shape, roughness, height, and central axis, but the present invention is not limited thereto. These parameters will be... FIGS. 6-8 Detailed explanation.

[0128] FIG. 6 2D contour analysis of the image acquired by the projection optical system 100. (Refer to...) FIG. 1B and FIG. 6 . FIG. 6 The 2D outline of the etched hole shown illustrates the left profile LP, the right profile RP, the left waviness LW, the right waviness RW, and the central axis CL.

[0129] FIG. 7A schematic diagram of analysis parameters for the image acquired by the projection optical system 100. (Refer to...) FIG. 1B and FIG. 7 The schematic diagram of the etched hole is hourglass-shaped in cross-sectional view. The schematic diagram shows the upper critical dimension TCD, middle critical dimension MCD, lower critical dimension BCD, shape, heights H1 and H2, and central tilt angle CTA. The middle critical dimension MCD is half-height. The narrowest critical dimension NCD is the dimension at the narrowest point of the etched hole. In this embodiment, the narrowest critical dimension NCD and the middle critical dimension MCD are located at the same position. In different embodiments, the position of the narrowest critical dimension NCD may be higher or lower than the position of the middle critical dimension MCD. The diameter of the etched hole 510 is substantially equal to the upper critical dimension TCD, or the average of the upper critical dimension TCD, the middle critical dimension MCD, and the lower critical dimension BCD, but the invention is not limited thereto.

[0130] The shape parameters include sidewall cone angles, such as the upper left cone angle LTA, upper right cone angle RTA, lower left cone angle LBA, and lower right cone angle RBA. The height includes a first height H1 and a second height H2. The first height H1 represents the distance from the top of the etched hole 510 to its narrowest point. The second height H2 represents the distance from the narrowest point of the etched hole 510 to its bottom. The height ratio of the first height H1 to the second height H2 can be determined. The thickness of the substrate 500 is substantially equal to the sum of the first height H1 and the second height H2.

[0131] FIG. 8 A schematic diagram illustrating the roughness profile analysis of the image acquired by the projection optical system 100. (Refer to...) FIG. 1B and FIG. 8 The roughness profile shows the roughness LR on the left and the roughness RR on the right of the etched hole 510.

[0132] By scanning the substrate 500 using the projection optics system 100 and processing and analyzing the oblique projection image, the outline of the etched hole 510 from top to bottom can be detected. Specifically, in conventional methods, only the top or bottom of the etched hole 510 can be clearly detected in the vertical image. Therefore, any damage or obstruction of the etched hole 510 that cannot be seen in the vertical image can be clearly seen in the oblique projection image using the projection optics system 100. In addition, multiple via structures can be detected simultaneously, which can shorten the scanning time of the substrate 500. The sidewall taper angle of the via structure can be detected, allowing the metal plating process to be performed to form vias (metal conductors) with small critical dimensions (e.g., a critical dimension of less than 5 micrometers and a sidewall taper angle of less than 8 degrees).

[0133] FIG. 9This is a schematic diagram of generating a 2D interferometric image according to an embodiment of the present invention. FIG. 10 for FIG. 9 2D interferometric image IM5 acquired by a digital microscope system 200. (Refer to...) FIG. 1C , FIG. 9 and FIG. 10 The incident light 212 is a plane wave that travels toward the front surface 504 of the substrate 500. A portion of the incident light 212 that is not interfered with by the via structure 510 forms uninterrupted light 214. Another portion of the incident light 212 that is interfered with by the via structure 510 forms interfering light 216. The uninterrupted light 214 and the interfering light 216 interfere with each other to form a 2D interference image IM5.

[0134] FIG. 11 for FIG. 9 3D images stacked IM6 were obtained from a digital microscope system 200. (See reference...) FIG. 1C , FIG. 10 and FIG. 11 The computing unit 300 is configured to execute the back-propagation reconstruction algorithm on the 2D interferometric image IM5 to obtain a 3D image stack IM6 of the etched holes 510. The back-propagation reconstruction algorithm is used to calculate the gradient information of the 2D interferometric image IM5 to reconstruct the 3D structural details. FIG. 12 for FIG. 11 The stereoscopic image IM7 is reconstructed from the stacked 3D images IM6. In some other embodiments, the aforementioned depth-of-field extension algorithm or other algorithms can be applied to 2D interferometric images.

[0135] FIG. 13 An image of a laser-modified substrate is obtained by a digital microscope system 200 according to an embodiment of the present invention. (See reference...) FIG. 1C and FIG. 13 The 3D image stack of the laser-modified substrate 500 is processed using a pseudo-image elimination algorithm and / or a super-resolution algorithm to improve resolution, and analyzed to obtain stereoscopic image information of the laser-modified region 510 of the substrate 500. For example, the stereoscopic image information of the laser-modified region 510 includes the laser modification accuracy and map scan. FIG. 13 As shown, missed emissions or double emissions (DS) during laser refining operations can be revealed through 3D imagery. Therefore, the accuracy of laser refining and map scanning can be confirmed and improved.

[0136] FIGS. 14A-14E An image of the etched hole 510 is obtained by a digital microscope system 200 according to an embodiment of the present invention. (See reference...) FIG. 1C as well as FIGS. 14A-14EThe images of these etched holes 510 are processed by the computing unit 300 to increase resolution and analyze to obtain stereoscopic image information of the etched holes 510. For example, the stereoscopic image information of the etched holes 510 includes upper critical dimensions, middle critical dimensions, lower critical dimensions, upper curvature, lower curvature, spacing, diameter, height, axis, surface roughness, cross-sectional view, and map scan, but the present invention is not limited thereto. In addition, multiple via structures can be detected simultaneously, which can shorten the scanning time of the substrate 500. The sidewall taper angle of the via structure can be detected, allowing the metal electroplating process to be performed to form vias (metal conductors) with smaller critical dimensions.

[0137] FIG. 14A This is an image of the surface of substrate 500, revealing the surface roughness produced on substrate 500 during the etching process. The surface roughness needs to be within a suitable range so that subsequent metal plating processes can be performed well.

[0138] FIG. 14B It is a 3D image of substrate 500. FIG. 14C It is along FIG. 14B Cross-sectional view along the axial direction. FIG. 14D It is along FIG. 14B Cross-sectional view along the coronal direction. FIG. 14D It is along FIG. 14B Cross-sectional view in the sagittal direction.

[0139] FIG. 15 This is a schematic diagram of the 3D point cloud data for reconstructing the through-hole structure. Multiple images at different heights in the stack of 3D images of the etched hole are processed and analyzed to obtain point cloud data (PCD). In this way, the point cloud data can be reconstructed to display the 3D outline of the etched hole 510.

[0140] By inspecting the substrate 500 using a digital microscope system 200 and processing and analyzing 2D interferometric images, the 3D contour of the etched hole 510 can be determined. In some embodiments, when the via structure 510 is elliptical and therefore unclear in oblique projection images, it can be clearly examined using stereoscopic image information or 3D point cloud data.

[0141] FIG. 16A This is a schematic diagram of the detection angle according to an embodiment of the present invention. The substrate 500a is detected via a detection angle α, such that the shape of the test wall (see...) FIG. 7 ), diameter (see FIG. 7 ), outline (see FIG. 6 and FIG. 8 (or defects can be detected.) FIG. 16B For having FIG. 16AA schematic diagram of the detection image obtained from the detection angle. In this embodiment, the through-hole structures 510a do not overlap. In some embodiments, the detection angle α is in the range of 15 degrees to 65 degrees. In some preferred embodiments, the detection angle α is in the range of 40 degrees to 45 degrees, but the present invention is not limited thereto.

[0142] FIG. 17A and FIG. 17B This is a schematic diagram of the detection image of overlapping through-hole structures. Compared to FIG. 16B , FIG. 17A The density of the through-hole structures 510b is relatively high (in other words, the spacing p between the through-hole structures 510b is relatively small), and FIG. 17A The diameter of the through-hole structure 510c is relatively large. As a result, the adjacent through-hole structures 510b and 510c overlap and the through-hole structure cannot be completely detected.

[0143] FIG. 18 This is a schematic diagram of the rotation angle according to an embodiment of the present invention. FIG. 17A The substrate 500b is detected by a detection angle α and a rotation angle ψ to solve the problem. FIG. 17A and FIG. 17B The problem described herein. In some embodiments, the rotation angle ψ is in the range of 0 to 50 degrees. In some preferred embodiments, the rotation angle ψ is in the range of 15 to 45 degrees, but the invention is not limited thereto.

[0144] For example, the first spacing is the minimum spacing. When the detection angle α is 45 degrees and the rotation angle ψ is 15 degrees, the relationship between the minimum spacing p, the substrate thickness t, and the diameter can be described by the minimum spacing equation: p(t,d)=At^2+Btd+Cd^2+Dt+Ed+F. FIG. 19 This is a chart with minimum spacing obtained according to the minimum spacing formula.

[0145] For example, coefficient A is in the range of -0.000415484 to -0.000375915, coefficient B is in the range of 0.00224595 to 0.00203205, coefficient C is in the range of -0.00077763 to -0.00070357, coefficient D is in the range of 0.526785 to 0.476615, coefficient E is in the range of 1.677795 to 1.518005, and coefficient F is in the range of -15.46797 to -13.99483. Coefficients A to F are not limited to the above ranges.

[0146] According to the minimum spacing equation, the user of the optical inspection device 10 can calculate the optimal spacing of the via structures in the substrate to avoid overlap. For example, when the thickness t is 1000 micrometers and the diameter d is 100 micrometers, the spacing can be approximately 434 to 480 micrometers.

[0147] FIG. 20 This is a schematic diagram of an inspection image of a laser-modified substrate 500 according to an embodiment of the present invention. A minimum spacing equation can be applied before laser modification of the substrate. In the minimum spacing equation, the diameter d represents the linewidth LW of the laser-modified region 510d. Therefore, the user of the optical inspection device 10 can calculate a better spacing for the laser-modified regions 510d in the substrate to avoid overlap.

[0148] FIG. 21 This is a flowchart of the operation method 600 for the optical inspection equipment. The operation method 600 begins in step S1, where the calculation unit calculates the minimum spacing based on the default linewidth of the laser-modified area and the substrate thickness (see...). FIG. 1A ).like FIG. 20 As shown, the preset linewidth LW and the thickness t of the laser-modified substrate 500d can determine the optimal spacing p of the laser-modified region 510d before laser modification. The operation method 600 of the optical inspection equipment continues to step S2, performing laser modification on the substrate to form multiple laser-modified regions.

[0149] Reference FIG. 1A and FIG. 21 The operation method 600 of the optical inspection equipment continues to step S3, whereby the oblique projection image of the laser-modified region 510 is obtained through the projection optical system 100. The operation method 600 of the optical inspection equipment continues to step S4, whereby the 2D interference image of the laser-modified region 510 is obtained through the digital microscope system 200. In some embodiments, the order of steps S3 and S4 can be reversed.

[0150] The operation method 600 of the optical inspection equipment continues to step S5, where the calculation unit 300 analyzes the oblique projection image to obtain multiple parameters of the laser-modified region 510 and analyzes the 2D interference image to obtain the stereoscopic image information of the laser-modified region 510 (e.g., ...). FIGS. 3A-3D as well as FIG. 13 (As shown).

[0151] The operation method 600 of the optical inspection equipment continues to step S6, where the calculation unit 300 calculates the minimum spacing based on the preset diameter of the etched holes and the thickness of the substrate. For example... FIG. 18 As shown, the preset diameter d and the thickness t of the substrate 500b can determine the optimal spacing p of the etched holes 510b before the etching process.

[0152] The operation method 600 of the optical inspection equipment continues to step S7, forming a plurality of etched holes 510 in the substrate 500. The operation method 600 of the optical inspection equipment continues to step S8, acquiring obliquely projected images of the etched holes 510 through the projection optical system 100. The operation method 600 of the optical inspection equipment continues to step S9, acquiring 2D interference images of the etched holes 510 through the digital microscope system 200. In some embodiments, the order of steps S8 and S9 can be reversed.

[0153] The operation method 600 of the optical inspection equipment continues to step S10, where the calculation unit 300 analyzes the oblique projection image to obtain multiple parameters of the etched hole 510 and analyzes the 2D interference image to obtain the stereoscopic image information of the etched hole 510. (e.g.) FIGS. 4-5 , FIGS. 11-12 , FIGS. 14A-14E ,as well as FIG. 15 (As shown).

[0154] In summary, optical inspection equipment provides non-contact and non-destructive testing methods, offering real-time feedback. The shape and contour of the entire via structure can be obtained through oblique projection images from a projection optics system and 2D interferometric images from a digital microscope system. Furthermore, multiple via structures can be inspected simultaneously, reducing substrate scanning time. The sidewall cone angles of the via structure can be detected, enabling metal plating processes to form vias (metal conductors) with smaller critical dimensions. Before performing laser modification or etching processes, the optimal spacing of the via structures can be calculated using a minimum spacing equation to avoid overlap.

[0155] Although the present invention has been disclosed above by way of embodiments, it is not intended to limit the present invention. Any person skilled in the art can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. An optical detection device, characterized by A projection optical system configured to obtain oblique projection images of a plurality of via structures in a substrate; A digital microscope system configured to obtain 2D interference images; and A computing unit electrically connected to the projection optical system and the digital microscope system, wherein the computing unit is configured to analyze the 2D interference images to obtain stereoscopic image information and analyze the oblique projection images to obtain a plurality of parameters of the plurality of via structures. The projection optical system further comprises:

2. The optical detection device of claim 1, wherein, A light source configured to illuminate a back surface of the substrate; A projection lens located at a front surface of the substrate, wherein the projection lens is configured to obtain the oblique projection images of the plurality of via structures of the substrate; and An image sensor configured to record images from the projection lens. The projection lens of the projection optical system is telecentric.

3. The optical detection device of claim 2, wherein, The computing unit is configured to perform a depth of field extension algorithm or a full depth of field algorithm to obtain the plurality of parameters of the plurality of via structures.

4. The optical detection device of claim 1, wherein, The plurality of via structures are etched holes, and the plurality of parameters include upper critical dimension, middle critical dimension, lower critical dimension, sidewall angle, pitch, diameter, roughness, height, and central axis.

5. The optical detection device of claim 1, wherein, The plurality of via structures are laser-modified regions, and the plurality of parameters include depth, angle, pitch, density, line width, and internal crack.

6. The optical detection device of claim 1, wherein, The digital microscope system further comprises:

7. The optical detection device of claim 1, wherein, A laser light source configured to emit incident light toward the substrate; and An image sensor configured to record the 2D interference images formed after the incident light passes through the plurality of via structures. Further comprising:

8. The optical detection device of claim 7, wherein, A carrier stage, wherein the substrate is disposed on the carrier stage, and a distance between the carrier stage and the image sensor is adjustable. The computing unit is configured to perform a back propagation reconstruction algorithm on the 2D interference images to obtain a 3D image stack of the plurality of via structures.

9. The optical detection device of claim 1, wherein, The computing unit is configured to perform an artifact removal algorithm on the 3D image stack.

10. The optical detection device of claim 9, wherein, The computing unit is configured to perform a super-resolution algorithm on the 3D image stack.

11. The optical detection device of claim 9, wherein, The plurality of via structures are etched holes, and the stereoscopic image information includes upper critical dimension, middle critical dimension, lower critical dimension, sidewall angle, upper circularity, lower circularity, pitch, diameter, height, axis, surface roughness, cross-sectional view, and map scan.

12. The optical detection device of claim 1, wherein, The plurality of via structures are laser-modified regions, and the stereoscopic image information includes laser modification accuracy and map scan.

13. The optical detection device of claim 1, wherein, A method comprising:

14. A method of operating an optical detection apparatus, characterized by, forming a plurality of etched holes in a substrate; obtaining first oblique projection images of the plurality of etched holes by a projection system; obtaining first 2D interference images of the plurality of etched holes by a digital microscope system; and analyzing the first oblique projection images by a computing unit to obtain a plurality of parameters and analyzing the first 2D interference images to obtain stereoscopic image information. Further comprising: calculating a first pitch by the computing unit according to a pre-determined diameter of the plurality of etched holes and a thickness of the substrate before forming the plurality of etched holes in the substrate.

15. The method of operating an optical detection apparatus according to claim 14, wherein, ​ ​ 16. The method of operating an optical detection apparatus according to claim 14, wherein, The method for obtaining the first oblique projection image of the plurality of etched holes through the projection system further comprises: irradiating a back surface of the substrate by a light source; obtaining the first oblique projection image of the plurality of etched holes of the substrate through a projection lens; and recording an image of the projection lens through an image sensor.

17. The method of operating an optical detection apparatus according to claim 14, wherein, The method for obtaining the first 2D interference image of the plurality of etched holes through the digital microscope system further comprises: emitting incident light to irradiate the substrate by a laser light source; and recording an image of the incident light after passing through the plurality of etched holes through an image sensor.

18. The method of operating an optical detection apparatus according to claim 14, wherein, Before forming the plurality of etched holes in the substrate, performing laser modification on the substrate to form a plurality of laser-modified regions.

19. The method of operating an optical detection apparatus according to claim 18, wherein, The method further comprises: Before performing laser modification on the substrate to form the plurality of laser-modified regions, calculating a first interval by the calculation unit according to a default line width of the plurality of laser-modified regions and a thickness of the substrate.

20. The method of operating an optical detection apparatus according to claim 19, wherein, The method further comprises: obtaining a second oblique projection image of the plurality of laser-modified regions through the projection system; and obtaining a second 2D interference image of the plurality of laser-modified regions through the digital microscope system.

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