Metal wire arc height inspection method

Abstract

The invention discloses a metal wire arc height detection method, which comprises the following steps of: shooting above a to-be-measured target metal wire in a to-be-detected semiconductor circuit board by using shooting equipment to obtain a plurality of detection pictures with different definitions; extracting the definition of a target metal wire in each detection picture, recording corresponding shooting parameter information to form a detection picture attribute data set, fitting data in the detection picture attribute data set by taking the shooting parameter information and the definition of the target metal wire as horizontal and vertical coordinates, and constructing a metal wire definition function model; obtaining shooting parameter information corresponding to the clearest point of the target metal wire and shooting parameter information corresponding to the clearest point of the surface of the chip, calculating actual height difference data between the target metal wire and the surface of the chip connected with the target metal wire, and giving out a prompt when the actual height difference of the current measured metal wire does not meet set process requirements. Therefore, automatic measurement of the arc height of the metal wire is realized.

Description

Technical Field

[0001] The invention relates to the technical field of three-dimensional space line detection, and in particular to a method for detecting the height of a metal wire arc. Background Art

[0002] In the semiconductor chip packaging process, metal wires are an important medium for connecting chips with external circuits. The height of the wire arc is one of the key factors affecting the packaging quality and must be controlled within a certain range. If the wire arc height is too high, it may increase the volume of the package, reduce the density of the package, and even affect the performance of the entire integrated circuit. On the contrary, if the wire arc height is too low, it may cause poor contact between the metal wire and the chip or other components, increasing the risk of short circuit. Therefore, measuring the height of the metal wire arc to ensure that the height of the metal wire arc meets the design requirements is a necessary measure to ensure the reliability and stability of semiconductor packaging. However, the current industry generally relies on manual vision and manual operation when measuring the height of the metal wire arc. This method is not only inefficient, but also easily affected by human factors, making it difficult to ensure the accuracy and consistency of the measurement results. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides a method for inspecting the height of a metal wire arc, comprising the following steps:

[0004] S1, obtaining a circuit board from the same batch of semiconductor circuit boards to be inspected, using a photographing device to photograph the target metal line to be measured in the circuit board, obtaining multiple inspection pictures with different sharpness, extracting the sharpness of the target metal line in each inspection picture and recording the corresponding shooting parameter information, to form an inspection picture attribute data set;

[0005] S2, using the shooting parameter information and clarity of the target metal wire as horizontal and vertical coordinates, performing fitting according to the data in the detection image attribute data set, and constructing a metal wire clarity function model, wherein the metal wire clarity function model is configured to reflect the relationship between the shooting parameter information and clarity of the metal wire of the semiconductor circuit board to be detected;

[0006] S3, based on the constructed metal wire clarity function model, obtain the shooting parameter information corresponding to the clearest point of the target metal wire, and obtain the shooting parameter information corresponding to the clearest point on the chip surface, calculate the actual height difference data between the target metal wire and the surface of the connected chip, and issue a prompt when the actual height difference of the current measured metal wire does not meet the set process requirements.

[0007] Preferably, the shooting parameter information is shooting height information, and the step S1 includes: obtaining a circuit board from the same batch of semiconductor circuit boards to be inspected, using a shooting device with a fixed focal length and adjustable height to shoot at multiple preset shooting heights above the target metal wire to be measured in the circuit board, obtaining multiple detection images with different clarity, extracting the clarity of the target metal wire in each detection image and recording the corresponding shooting height information, to form a detection image attribute data set.

[0008] Preferably, the shooting parameter information is the cumulative value information of the object distance and the focal length of the shooting device, and the step S1 includes: obtaining a circuit board from the same batch of semiconductor circuit boards to be inspected, using a shooting device with a variable focal length and a fixed height to shoot at a preset shooting height above the target metal wire to be measured in the circuit board, obtaining multiple detection pictures with different clarity, extracting the clarity of the target metal wire in each detection picture and recording the corresponding shooting parameter information, to form a detection picture attribute data set.

[0009] Preferably, the height information is configured as the height between the camera and a reference plane, or the height between the lens and a reference plane, wherein the reference plane includes but is not limited to a chip surface, a semiconductor substrate surface, a pad, and a bottom of a device.

[0010] Preferably, step S3 includes: the target metal wire to be measured is a first metal wire and a second metal wire that are arranged overlapping each other, adjusting the height of the shooting device to obtain detection images corresponding to the clearest points of the first metal wire and the second metal wire respectively, obtaining height information of each clear point detection image according to the metal wire clarity function model, calculating actual height difference data of the first metal wire and the second metal wire that are arranged overlapping each other, and judging whether the actual height difference data meets the spacing requirement between the two overlapping metal wires required by the set process.

[0011] Preferably, the step S3 further comprises: if the height information corresponding to the clearest point of the target metal wire exceeds a preset maximum height, directly outputting unqualified information.

[0012] The present invention discloses a method for inspecting the arc height of a metal wire. The method uses a photographing device to photograph a target metal wire of a semiconductor circuit board to be inspected, and obtains clarity information and photographing parameter information of the target metal wire for fitting modeling, thereby obtaining the photographing parameter corresponding to the clearest point of the target metal wire, and performing difference calculation between the photographing parameter and the photographing parameter corresponding to the clearest point on the chip surface, thereby realizing automatic measurement of the arc height of the metal wire, avoiding the errors and waste of manpower and material resources caused by traditional manual measurement methods, and improving the efficiency and accuracy of industrial metal wire arc height measurement.

[0013] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0015] Figure 1 The figure is a schematic diagram of the steps of a method for inspecting the height of a metal wire arc disclosed in one embodiment of the present invention.

[0016] Figure 2 A schematic diagram of the steps of a method for inspecting the arc height of a metal wire when the shooting parameter information disclosed in an embodiment of the present invention is shooting height information.

[0017] Figure 3 A schematic diagram of a metal line definition function model disclosed in an embodiment of the present invention.

[0018] Figure 4 The figure shows the actual measured results of the arc height of the metal wire of the product disclosed in one embodiment of the present invention.

[0019] Figure 5 A schematic diagram of the steps of a method for inspecting the arc height of a metal wire when the shooting parameter information disclosed in another embodiment of the present invention is the accumulated value information of the object distance and the focal length of the shooting device. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment 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.

[0021] In the present invention, unless otherwise clearly specified and limited, the technical terms or scientific terms used herein shall have the common meanings understood by persons with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the patent application specification and claims of the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one" or "an" do not indicate a quantity limitation, but indicate the existence of at least one.

[0022] In the semiconductor chip packaging process, metal wires are an important medium for connecting chips with external circuits. The height of the wire arc is one of the key factors affecting the packaging quality and must be controlled within a certain range. If the wire arc height is too high, it may increase the volume of the package, reduce the density of the package, and even affect the performance of the entire integrated circuit. On the contrary, if the wire arc height is too low, it may cause poor contact between the metal wire and the chip or other components, increasing the risk of short circuit. Therefore, measuring the height of the metal wire arc to ensure that the height of the metal wire arc meets the design requirements is a necessary measure to ensure the reliability and stability of semiconductor packaging. However, the current industry generally relies on manual vision and manual operation when measuring the height of the metal wire arc. This method is not only inefficient, but also easily affected by human factors, making it difficult to ensure the accuracy and consistency of the measurement results.

[0023] Therefore, this embodiment discloses a method for inspecting the height of a metal wire arc. Figure 1 As shown, the following steps are included.

[0024] Step S1, obtain a circuit board from the same batch of semiconductor circuit boards to be inspected, use a shooting device to shoot above the target metal line to be measured in the circuit board, obtain multiple inspection pictures with different clarity, extract the clarity of the target metal line in each inspection picture and record the corresponding shooting parameter information, and form a detection picture attribute data set.

[0025] Step S2, using the shooting parameter information and clarity of the target metal wire as the horizontal and vertical coordinates, fitting is performed according to the data in the detection image attribute data set to construct a metal wire clarity function model, and the metal wire clarity function model is configured to reflect the relationship between the shooting parameter information and clarity of the metal wire of the semiconductor circuit board to be detected.

[0026] Step S3, based on the constructed metal wire clarity function model, obtain the shooting parameter information corresponding to the clearest point of the target metal wire, and obtain the shooting parameter information corresponding to the clearest point on the chip surface, calculate the actual height difference data between the target metal wire and the surface of the connected chip, and issue a prompt when the actual height difference of the current measured metal wire does not meet the set process requirements. Specifically, in this embodiment, as shown in the attached Figure 2 As shown, the shooting parameter information is shooting height information. At this time, the metal wire arc height inspection method specifically includes the following steps.

[0027] Step S101, obtain a circuit board from the same batch of semiconductor circuit boards to be inspected, use a shooting device to shoot above the target metal line to be measured in the circuit board, obtain multiple inspection pictures with different clarity, extract the clarity of the target metal line in each inspection picture and record the corresponding shooting parameter information, and form a detection picture attribute data set.

[0028] Specifically, this embodiment is based on the shooting data of the optical shooting device, and finds the clearest point of the target metal wire by constructing a function model to measure the arc height of the metal wire. Specifically, this embodiment measures the height of each metal wire in the semiconductor circuit board based on the metal wire arc height measuring device. The device is equipped with an optical camera with a fixed focal length, which can move up and down above the measuring platform to take pictures of the products placed above the detection platform. During the measurement process, the display board loaded with the product to be measured automatically enters the feed port of the device and is transported to the detection platform along the track via the handling component. The optical detection system controls the camera to move up and down to a preset height to take pictures of the target metal wire to obtain the detection pictures of the target metal wire at different heights. Since the focal length and focus range of the shooting device are fixed, the clarity of the pictures taken at the fixed point at different heights is different, so a fitting model of the clarity of the target metal wire and the corresponding height can be established, and the shooting height of the target metal wire at the same fixed position of the camera can be obtained according to the clarity of the picture corresponding to the fitting model detected. When the clarity of the pictures taken at the two fixed positions is the same, the distance at the two fixed positions can be obtained according to the corresponding height difference. In this embodiment, the distance between the target metal wire and the reference plane can be obtained to measure the arc height of the target metal wire and select the point with the highest clarity as the judgment point to reduce the error, and the detection image includes the detection image whose chip basic surface clarity is greater than the threshold. The clarity of the target metal wire in the detection image is identified by image processing software.

[0029] Further, the shooting height information is configured as the height between the camera and a reference plane, or the height between the lens and a reference plane, and the reference plane includes but is not limited to a chip surface, a semiconductor substrate surface, a pad, and a device bottom. Since the chip surface, the semiconductor substrate surface, the pad, and the device bottom are all at fixed distances, any one of them can be selected as the reference plane.

[0030] At the same time, since the curve equation is determined by three points, the detection image includes using a shooting device with a fixed focal length and adjustable height to shoot at least three preset shooting heights above the target metal wire to be measured in the circuit board to obtain multiple detection images with different clarity to ensure successful model fitting.

[0031] The shooting equipment used in this embodiment is a 65M full-color camera, the lens of which is a 2X telecentric lens, the field of view FOA is 14mm*11mm, the accuracy is 1.6μm per pixel, and the light source uses a four-way RGB light source, which can accurately and clearly show the shape of the metal wire arc to ensure measurement accuracy.

[0032] Step S102, using the shooting parameter information and clarity of the target metal wire as the horizontal and vertical coordinates, fitting is performed according to the data in the detection image attribute data set to construct a metal wire clarity function model, and the metal wire clarity function model is configured to reflect the relationship between the shooting parameter information and clarity of the metal wire of the semiconductor circuit board to be detected.

[0033] Specifically, the fitted metal line definition function model is as shown in the attached figure. Figure 3 As shown. The horizontal coordinate of the model represents the shooting height information of the target metal wire; the vertical coordinate of the model represents the clarity of the picture taken at the corresponding shooting height of the target metal wire; the broken line represents the standard arc height of each metal wire; * represents the measured arc height of each metal wire when there are more pictures in the detection picture data set; + represents the measured arc height of each metal wire when there are fewer pictures in the detection picture data set. It can be clearly observed that when there are more pictures in the detection picture data set, the measured arc height of the metal wire is closer to the standard arc height, that is, taking multiple pictures helps to fit the model more accurately. However, the more pictures are taken, the heavier the burden on the equipment and the longer the data processing time. Therefore, in this embodiment, a function model is constructed by taking 7 pictures for each metal wire, including a picture of the clearest point on the chip surface, a picture of the highest theoretical clarity of the metal wire, and 5 other pictures taken at equal intervals to ensure that the calculation process is accurate and efficient.

[0034] Step S103, based on the constructed metal wire clarity function model, obtain the shooting parameter information corresponding to the clearest point of the target metal wire, and obtain the shooting parameter information corresponding to the clearest point on the chip surface, calculate the actual height difference data between the target metal wire and the surface of the connected chip, and issue a prompt when the actual height difference of the current measured metal wire does not meet the set process requirements.

[0035] Specifically, based on the acquired shooting height information corresponding to the clearest point of the target metal wire and the clearest point on the chip surface, the relative height between the two can be calculated to obtain the arc height of the target metal wire. The calculated actual height difference data is compared with the set process requirements. When the arc height of the metal wire exceeds the set range or threshold, it indicates that it does not meet the standard specification requirements of the metal wire, and a prompt message is issued to remind relevant personnel to take measures or mark it. Through this process, the automatic measurement of the arc height of the target metal wire can be achieved. The actual measurement results are shown in the attached figure. Figure 4 shown.

[0036] Furthermore, the present embodiment can also measure the distance between two metal wires, and the step S3 also includes: the target metal wire to be measured is a first metal wire and a second metal wire that are arranged overlapping each other, adjusting the height of the shooting device to obtain detection images corresponding to the clearest points of the first metal wire and the second metal wire respectively, obtaining the height information of each clear point detection image according to the metal wire clarity function model, calculating the actual height difference data of the first metal wire and the second metal wire that are arranged overlapping each other, and judging whether the actual height difference data meets the spacing requirement between the two metal wires that are arranged overlapping each other as required by the set process.

[0037] Specifically, for two metal wires that overlap each other, the traditional industrial measurement method can usually only measure the lower metal wire when the upper metal wire is not bonded, which has limitations. Once the two metal wires are bonded, due to the obstruction problem, the traditional method cannot accurately measure the arc height of the lower metal wire, nor can it measure the distance between the two metal wires. The method adopted in this embodiment, because the lens size is much larger than the product size, even if the two metal wires completely overlap, the lower metal wire can be observed from a certain tilt angle, and the height of the lower metal wire and the distance between the two metal wires can be accurately calculated and measured. Among them, the existence of the two metal wires, the positions of the two metal wires and the theoretical heights of the metal wires are all prior knowledge.

[0038] In this embodiment, the step S3 further includes: if the height information corresponding to the clearest point of the target metal wire exceeds a preset maximum height, directly outputting unqualified information.

[0039] Specifically, when the height information corresponding to the clearest point of the target metal wire exceeds the preset maximum height, indicating that the arc height of the target metal wire exceeds the theoretical maximum arc height, there is no need to perform subsequent modeling operations, and unqualified information is directly output to reduce the calculation workload of the equipment.

[0040] Furthermore, the step S3 further includes: using an image processing algorithm to decouple the first metal wire and the second metal wire in the detection image, and directly outputting unqualified information if the decoupling fails, which indicates that the distance between the two metal wires is too short and does not meet the set process requirements.

[0041] In another embodiment, as shown in the attached Figure 5 As shown, when the shooting parameter information is the cumulative value information of the object distance and the focal length of the shooting device, the metal wire arc height inspection method specifically includes the following steps.

[0042] Step S201, obtain a circuit board from the same batch of semiconductor circuit boards to be inspected, use a variable focal length and fixed height shooting device to shoot at a preset shooting height above the target metal wire to be measured in the circuit board, obtain multiple inspection pictures with different clarity, extract the clarity of the target metal wire in each inspection picture and record the corresponding shooting parameter information, and form a detection picture attribute data set.

[0043] Specifically, a fixed-position adjustable focal length device such as a liquid lens can be used to take multiple pictures of the target metal wire to be tested at different focal lengths. At this time, since the positions of the target metal wire and the device are fixed, and the focal lengths of the devices are different, the clarity of the target metal wire in the image presented on the device's photosensitive element will be different, and a metal wire clarity function model can be constructed based on this.

[0044] Step S202, using the shooting parameter information and clarity of the target metal wire as the horizontal and vertical coordinates, fitting is performed according to the data in the detection image attribute data set to construct a metal wire clarity function model, and the metal wire clarity function model is configured to reflect the relationship between the shooting parameter information and clarity of the metal wire of the semiconductor circuit board to be detected.

[0045] Specifically, the shooting parameter information at this time can be the accumulated value information of the object distance and the focal length or the focal length, etc. By establishing a function model of the shooting parameter information and clarity of the target metal wire, the focal length corresponding to the highest clarity image can be obtained, and then the focal length difference between the clearest point on the chip surface and the clearest point on the target metal wire can be obtained, thereby calculating the height difference data between the chip surface and the target metal wire.

[0046] Step S203, based on the constructed metal wire clarity function model, obtain the shooting parameter information corresponding to the clearest point of the target metal wire, and obtain the shooting parameter information corresponding to the clearest point on the chip surface, calculate the actual height difference data between the target metal wire and the surface of the connected chip, and issue a prompt when the actual height difference of the current measured metal wire does not meet the set process requirements. Specifically, an object with a known height difference can be used for shooting, and the focal length when the clearest image is obtained at different heights can be recorded, and the functional relationship between the focal length and the height difference can be fitted, and then the arc height of the metal wire can be calculated.

[0047] The present embodiment discloses a method for inspecting the arc height of a metal wire. A shooting device is used to shoot a target metal wire of a semiconductor circuit board to be inspected, and clarity information and shooting parameter information of the target metal wire are obtained for fitting and modeling, thereby obtaining shooting parameters corresponding to the clearest point of the target metal wire, and performing difference calculation between the shooting parameters and the shooting parameters corresponding to the clearest point on the chip surface, thereby realizing automatic measurement of the arc height of the metal wire, avoiding the errors and waste of manpower and material resources caused by traditional manual measurement methods, and improving the efficiency and accuracy of industrial metal wire arc height measurement.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

[0049] In conclusion, the above is only a preferred embodiment of the present invention, and all equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the patent of the present invention.

Claims

1. A method for inspecting the arc height of a metal wire, characterized in that: The steps include: S1, obtaining a circuit board from the same batch of semiconductor circuit boards to be inspected, using a photographing device to photograph the target metal line to be measured in the circuit board, obtaining multiple inspection pictures with different sharpness, extracting the sharpness of the target metal line in each inspection picture and recording the corresponding shooting parameter information, to form an inspection picture attribute data set; S2, using the shooting parameter information and clarity of the target metal wire as horizontal and vertical coordinates, performing fitting according to the data in the detection image attribute data set, and constructing a metal wire clarity function model, wherein the metal wire clarity function model is configured to reflect the relationship between the shooting parameter information and clarity of the metal wire of the semiconductor circuit board to be detected; S3, based on the constructed metal wire clarity function model, obtain the shooting parameter information corresponding to the clearest point of the target metal wire, and obtain the shooting parameter information corresponding to the clearest point on the chip surface, calculate the actual height difference data between the target metal wire and the surface of the connected chip, and issue a prompt when the actual height difference of the current measured metal wire does not meet the set process requirements.

2. The method for inspecting the height of a metal wire arc according to claim 1, characterized in that: The shooting parameter information is shooting height information, and the step S1 comprises: Obtain a circuit board from the same batch of semiconductor circuit boards to be inspected, use a shooting device with a fixed focal length and adjustable height to shoot at multiple preset shooting heights above the target metal wire to be measured in the circuit board, obtain multiple inspection pictures with different clarity, extract the clarity of the target metal wire in each inspection picture and record the corresponding shooting height information, to form a detection picture attribute data set.

3. The method for inspecting the arc height of a metal wire according to claim 1, characterized in that: The shooting parameter information is the cumulative value information of the object distance and the focal length of the shooting device, and the step S1 includes: Obtain a circuit board from the same batch of semiconductor circuit boards to be inspected, use a variable focal length and fixed height shooting device to shoot at a preset shooting height above the target metal wire to be measured in the circuit board, obtain multiple inspection pictures with different clarity, extract the clarity of the target metal wire in each inspection picture and record the corresponding shooting parameter information, to form a detection picture attribute data set.

4. The method for measuring the arc height of a metal wire according to claim 2, characterized in that: The height information is configured as a height between the camera and a reference plane, or a height between the lens and a reference plane, wherein the reference plane includes but is not limited to a chip surface, a semiconductor substrate surface, a pad, and a device bottom.

5. The method for measuring the arc height of a metal wire according to claim 4, characterized in that: The step S3 comprises: The target metal wires to be measured are a first metal wire and a second metal wire that are arranged overlapping each other. The height of the shooting device is adjusted to obtain detection images corresponding to the clearest points of the first metal wire and the second metal wire, respectively. The height information of the detection images of each clear point is obtained according to the metal wire clarity function model, and the actual height difference data of the first metal wire and the second metal wire that are arranged overlapping each other is calculated to determine whether the actual height difference data meets the spacing requirement between the two overlapping metal wires required by the set process.

6. The method for measuring the arc height of a metal wire according to claim 5, characterized in that: The step S3 also includes: if the height information corresponding to the clearest point of the target metal wire exceeds the preset maximum height, directly outputting unqualified information.

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