An interconnection line defect detection system and method based on phase-locked synchronous image processing

Abstract

The invention relates to the field of infrared thermal imaging detection technology, and proposes an interconnection line defect detection system and method based on phase-locked synchronous image processing, comprising: a controller, used for sending a control signal to an excitation control module; an excitation power supply module, used for generating a corresponding excitation current according to the excitation signal, the excitation power supply module being electrically connected to a power pin or a function pin of an object to be detected; an image acquisition module, used for acquiring a thermal infrared image of the object to be detected that generates periodic heat waves under current excitation; a processing module, used for analyzing and processing the acquired thermal infrared image to obtain a temperature signal of the object to be detected, performing phase-locked correlation processing on the temperature signal with the temperature signal of a defect-free area as a reference, and generating amplitude, phase and depth information of each pixel point in the thermal infrared image; and an imaging module, used for performing three-dimensional feature imaging according to the amplitude, phase and depth information of each pixel point in the thermal infrared image and displaying the specific position and size of the interconnection line defect.

Description

Technical Field

[0001] The present invention relates to the field of infrared thermal imaging detection technology, and more specifically, to an interconnection line defect detection system and method based on phase-locked synchronous image processing. Background Art

[0002] As the complexity of integrated circuits (ICs) continues to increase, failure analysis on ICs faces increasingly stringent challenges. The purpose of failure analysis is to locate the failure points of abnormal chips (signal detection errors). Many of these failure points are related to local heat dissipation, such as interconnect defects, oxide or node cracks, high solder resistance, etc. Among the several technologies for IC failure analysis, non-destructive testing technology is one of the important means.

[0003] Infrared thermal imaging detection technology is mainly based on the principle of infrared radiation. It observes and records the temperature change information on the surface of the inspected object, and analyzes the changing temperature through thermal wave theory and signal processing methods, so as to analyze the surface and internal defects or structures of the inspected workpiece. At present, active infrared thermal imaging detection is mostly used for failure analysis of ICs, that is, artificial active excitation is used to stimulate the inspected object to produce a changing temperature field. The excitation method of active infrared thermal imaging detection can be divided into several categories according to the physical characteristics of the excitation source, such as optical excitation, thermal excitation, vibration excitation, and electromagnetic excitation. When electromagnetic excitation is used, the amplitude of the IC to be tested is modulated by input current excitation, and image acquisition is performed with an infrared imager, and image analysis of the acquired infrared image is further performed to achieve defect detection.

[0004] However, the detection depth of defects measured by electromagnetic excitation thermal imaging technology is related to the skin depth and heat diffusion depth. If the object to be tested is an IC with a multi-layer metal structure, it cannot well excite the IC defects with a three-dimensional structure to emit thermal waves, making it difficult to give the precise spatial position of the defect. Summary of the invention

[0005] In order to overcome the defect in the prior art that it is difficult to give an accurate defect spatial position when performing defect detection on an IC with a multi-layer metal structure, the present invention provides an interconnection line defect detection system and method based on phase-locked synchronous image processing.

[0006] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0007] An interconnection line defect detection system based on phase-locked synchronous image processing includes a controller, an excitation control module, an excitation power module, an image acquisition module, a processing module and an imaging module, wherein:

[0008] The controller is used to send a control signal to the excitation control module; the excitation power supply module is used to generate a corresponding excitation current according to the excitation signal output by the excitation control module, and the output end of the excitation power supply module is electrically connected to the power pin or function pin of the object to be tested placed on the platform; the image acquisition module is arranged above the platform, and is used to collect thermal infrared images of the object to be tested that generates periodic thermal waves under current excitation; the processing module is used to analyze and process the thermal infrared images collected by the image acquisition module to obtain the temperature signal of the object to be tested, divide the defect-free area image according to the degree of change of the temperature signal of each pixel point, perform phase-locked correlation processing on the temperature signal, and generate the amplitude, phase and depth information of each pixel point in the thermal infrared image; the imaging module is used to perform three-dimensional feature imaging and display according to the amplitude, phase and depth information of each pixel point in the thermal infrared image, and obtain the specific position and size of the interconnection line defect in the object to be tested according to the three-dimensional image displayed by the imaging module.

[0009] During use, the chip or circuit module to be tested is placed on the platform as the object to be tested. After adjusting the position and parameters, the controller is used to control the excitation control module and the excitation power supply module to generate an excitation current, and the power pins or function pins of the chip or circuit module to be tested are excited by current, so as to periodically heat the relevant interconnection lines of the object to be tested and generate heat waves. The interconnection line defects in the object to be tested will produce abnormal heat waves with changed amplitude or phase under periodic heating. The thermal infrared image collected by the image acquisition module is further analyzed and phase-locked correlation is calculated by the processing module to obtain the amplitude, phase and depth information of each pixel in the thermal infrared image, which is used to construct a three-dimensional image, and the specific position and size of the interconnection line defects in the object to be tested are obtained according to the display of the three-dimensional image.

[0010] As a preferred embodiment, the excitation control module includes: a phase-locked signal generating unit, which is used to generate a periodic phase-locked signal according to the control signal output by the controller; the phase-locked signal includes a sine wave signal or a pulse wave signal; a high-frequency signal generating unit, which is used to generate a continuous high-frequency AC signal according to the control signal output by the controller; and an amplitude modulation unit, which is used to perform amplitude modulation according to the phase-locked signal and the high-frequency AC signal output by the phase-locked signal generating unit and the high-frequency signal generating unit respectively, to generate an excitation signal.

[0011] As a preferred solution, the processing module includes: an image processing unit, which is used to analyze and process the thermal infrared image acquired by the image acquisition module to obtain the temperature signal of the object to be measured; a reference signal generating unit, which is used to generate a reference signal using the temperature signal of the defect-free area in the thermal infrared image as a reference, or to output a sine wave with a frequency of the phase-locked frequency as a reference signal; a phase-locked correlation calculation unit, which is used to perform phase-locked correlation processing based on the temperature signal of the object to be measured and the reference signal, extract the amplitude and phase of each pixel point in the thermal infrared image at a specific frequency as a characteristic value for output, and extract the depth information of each pixel point in the thermal infrared image for output.

[0012] As a preferred solution, the image acquisition module includes a binocular thermal imager.

[0013] As a preferred solution, the image acquisition module adopts a solid immersion lens (SIL).

[0014] Furthermore, the present invention also proposes a method for detecting interconnection line defects based on phase-locked synchronous image processing, comprising the following steps:

[0015] S1, generating an excitation signal with a periodic phase-locked signal;

[0016] S2, generating an excitation current according to an excitation signal with a periodic phase-locked signal, and performing current excitation on a circuit pin or a function pin of the object to be tested whose function is known, so that the interconnection wires in the object to be tested are periodically heated under the action of the current excitation and generate heat waves;

[0017] S3, using an image acquisition module to acquire thermal infrared images of the object to be measured from two angles to obtain a thermal infrared image including a temperature signal of a periodic thermal wave;

[0018] S4, analyzing and processing the thermal infrared image to obtain a temperature signal of each pixel point, and dividing the defect-free area image according to the degree of change of the temperature signal of each pixel point;

[0019] S5, generating a reference signal, and performing phase-locked correlation processing based on the reference signal and the temperature signal of each pixel in the thermal infrared image to obtain a characteristic value and depth information of each pixel in the thermal infrared image;

[0020] S6. Perform three-dimensional feature imaging and display according to the feature value and depth information of each pixel point in the thermal infrared image, and obtain the specific position and size of the interconnection line defect according to the display result.

[0021] As a preferred solution, in the step S1, the step of generating an excitation signal with a periodic phase-locked signal includes: amplitude modulating a continuous high-frequency AC signal and a periodic phase-locked signal to generate an excitation signal; the phase-locked signal includes a sine wave signal or a pulse wave signal.

[0022] As a preferred solution, when the phase-locked signal and the high-frequency AC signal are sinusoidal signals, the continuous high-frequency AC signal and the periodic phase-locked signal are amplitude modulated, and the expression of the generated excitation signal i is as follows:

[0023] i=I A ·sin(2πf lock-in t)·sin(2πf carry t)

[0024] In the formula, I A represents the maximum amplitude of the excitation signal i, f lock-in Indicates the phase-locked signal frequency, f carry represents the frequency of high-frequency AC signal, and t represents time.

[0025] As a preferred solution, the characteristic value includes the amplitude and phase of each pixel point in the thermal infrared image at a specific frequency.

[0026] As a preferred solution, in step S5, the step of performing phase-locked correlation processing based on the reference signal and the temperature signal of each pixel in the thermal infrared image includes:

[0027] S5.1. Generate a reference signal according to the temperature signal of each pixel in the defect-free area image, or set a sine wave with a frequency of a phase-locked frequency as the reference signal;

[0028] S5.2. Using the reference signal as an in-phase reference signal, and performing a Hilbert transform on the reference signal to obtain an orthogonal reference signal;

[0029] S5.3, multiplying the temperature signal and the in-phase reference signal and performing fast Fourier transformation to obtain a real signal, and multiplying the temperature signal and the orthogonal reference signal and performing fast Fourier transformation to obtain an imaginary signal;

[0030] S5.4, calculating the amplitude and phase of the real signal and the imaginary signal to obtain the amplitude and phase of each pixel in the thermal infrared image, and outputting the amplitude and phase of a specific frequency as a characteristic value;

[0031] S5.5. Extract the depth information of each pixel in the thermal infrared image and output it.

[0032] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0033] The present invention performs current excitation with a phase-locked signal on the power pin or the function pin of the object to be tested, and the excitation current achieves periodic heating and generates heat waves after passing through the interconnection line, and then collects and analyzes the thermal infrared image through the image acquisition module and the processing module, obtains a three-dimensional heat distribution map according to the amplitude, phase and depth information of each pixel point, and performs imaging processing, so that the specific position and size of the interconnection line defect can be intuitively obtained, effectively overcoming the deficiency of the infrared thermal imaging nondestructive testing technology in losing three-dimensional geometric information when detecting defects in complex circuit modules;

[0034] The present invention utilizes phase-locked thermal imaging and binocular vision computing, and has the advantages of high signal-to-noise ratio, high precision, and the ability to detect three-dimensional features of interconnect line defects of the inspected object, and can be applied to fields such as interconnect line defect detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is an architectural diagram of an interconnect defect detection system based on phase-locked synchronous image processing according to Example 1.

[0036] Figure 2 This is an architectural diagram of an interconnect defect detection system based on phase-locked synchronous image processing according to Example 2.

[0037] Figure 3 This is a flow chart of the interconnection line defect detection method based on phase-locked synchronous image processing of Example 3.

[0038] Figure 4 This is a flow chart of phase-locked correlation processing in Example 4. DETAILED DESCRIPTION

[0039] The drawings are for illustrative purposes only and should not be construed as limiting the present patent;

[0040] In order to better illustrate the present embodiment, some parts in the drawings may be omitted, enlarged or reduced, and do not represent the size of the actual product;

[0041] It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0042] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0043] Example 1

[0044] This embodiment proposes an interconnection line defect detection system based on phase-locked synchronous image processing, such as Figure 1 , which is a schematic diagram of the interconnection line defect detection system based on phase-locked synchronous image processing according to the present embodiment.

[0045] The interconnection line defect detection system based on phase-locked synchronous image processing proposed in this embodiment includes a controller 1, an excitation control module 2, an excitation power supply module 3, an image acquisition module 4, a processing module 5 and an imaging module 6.

[0046] The output end of the controller 1 is connected to the control end of the excitation control module 2 and the processing module 5 respectively, so as to control the excitation control module 2 and the processing module 5 to start working, and to obtain and store the temperature signal analyzed and processed by the processing module 5 in real time.

[0047] The excitation control module 2 in this embodiment is used to generate an excitation signal with a periodic phase-locked signal according to the control signal output by the controller 1 .

[0048] The excitation power supply module 3 is used to generate a corresponding excitation current according to the excitation signal output by the excitation control module 2, and the output end of the excitation power supply module 3 is electrically connected to the power pin or function pin of the object to be tested placed on the platform.

[0049] Image acquisition module 4 The image acquisition module 4 is arranged above the platform, and is used to acquire thermal infrared images of periodic heat waves generated by the object to be measured under the condition of current excitation.

[0050] The processing module 5 is used to analyze and process the thermal infrared image collected by the image acquisition module 4 to obtain the temperature signal of the object to be measured, divide the defect-free area image according to the degree of change of the temperature signal of each pixel point, perform phase-locked correlation processing on the temperature signal, and generate the amplitude, phase and depth information of each pixel point in the thermal infrared image.

[0051] Among them, according to the thermal wave time map generated by each pixel point, the temperature change gradient of each area of ​​the object to be tested in space can be obtained. In this embodiment, the area without obvious temperature change is divided into a defect-free area. Then, the average temperature change of any pixel point or several pixels in the defect-free area is used as a reference to perform phase-locked correlation processing.

[0052] The imaging module 6 is used to perform three-dimensional feature imaging and display according to the amplitude, phase and depth information of each pixel point in the thermal infrared image, and obtain the specific position and size of the interconnection line defect in the object to be tested according to the three-dimensional image displayed by the imaging module 6.

[0053] In the specific implementation process, the chip or circuit module to be tested is first placed on the platform as the object to be tested. After adjusting the position and parameters of the image acquisition module 4, the controller 1 is used to send a control signal to the excitation control module 2. The excitation control module 2 generates an excitation signal with a periodic phase-locked signal according to the control signal output by the controller 1. The excitation power supply module 3 generates a corresponding excitation current according to the excitation signal output by the excitation control module 2, and transmits the current to the power pin or function pin of the object to be tested through an electrical connection line for current excitation, so as to periodically heat the relevant interconnection lines of the object to be tested and generate heat waves. The interconnection line defects in the object to be tested will generate abnormal heat waves with changed amplitude or phase under periodic heating.

[0054] The image acquisition module 4 acquires thermal infrared images of the object to be measured, and transmits the acquired thermal infrared images to the processing module 5 for analysis and processing. In this embodiment, the image acquisition module 4 adopts a binocular thermal imager.

[0055] The processing module 5 analyzes the collected thermal infrared image and performs phase-locked correlation calculation, extracts the amplitude and phase of each pixel in the thermal infrared image at a specific frequency as a characteristic value for output, and extracts the depth information of each pixel in the thermal infrared image for output, so as to construct a three-dimensional image. When extracting the depth information of each pixel in the thermal infrared image, the distance can be inferred by calculating the time taken by the thermal imager at different angles to obtain each pixel in the image, thereby obtaining the depth information.

[0056] Finally, the imaging module 6 performs three-dimensional feature imaging and displays it according to the amplitude, phase and depth information of each pixel point in the thermal infrared image. The user can obtain the specific position and size of the interconnection line defect in the object to be tested according to the display of the three-dimensional image.

[0057] In this embodiment, current is excited on the power pin or function pin of the object to be tested, and the exciting current is periodically heated and generates heat waves after passing through the interconnection line. The temperature signal generated by the heat wave is captured by the image acquisition module 4, and phase-locked correlation is performed. A three-dimensional heat distribution map is obtained based on the amplitude, phase and depth information of each pixel point in the thermal infrared image, thereby realizing the detection and positioning of interconnection line defects and obtaining the specific position and size of the interconnection line defects.

[0058] Example 2

[0059] This embodiment makes improvements on the interconnection line defect detection system based on phase-locked synchronous image processing proposed in Embodiment 1.

[0060] The interconnection line defect detection system based on phase-locked synchronous image processing proposed in this embodiment includes a controller 1, an excitation control module 2, an excitation power supply module 3, an image acquisition module 4, a processing module 5 and an imaging module 6.

[0061] The output end of the controller 1 is connected to the control end of the excitation control module 2 and the processing module 5 respectively, the output end of the excitation control module 2 is connected to the input end of the excitation power module 3, and the output end of the excitation power module 3 is connected to the power pin or function pin of the object to be measured. The image acquisition module 4 is arranged above the object to be measured, the output end of the image acquisition module 4 is connected to the input end of the processing module 5, and the output end of the processing module 5 is connected to the input end of the imaging module 6.

[0062] In this embodiment, the excitation control module 2 includes a phase-locked signal generating unit 21 , a high-frequency signal generating unit 22 and an amplitude modulation unit 23 .

[0063] Among them, the phase-locked signal generating unit 21 is used to generate a periodic phase-locked signal according to the control signal output by the controller 1, the high-frequency signal generating unit 22 is used to generate a continuous high-frequency AC signal according to the control signal output by the controller 1, and the amplitude modulation unit 23 is used to perform amplitude modulation according to the phase-locked signal and the high-frequency AC signal output by the phase-locked signal generating unit 21 and the high-frequency signal generating unit 22 respectively to generate an excitation signal.

[0064] In this embodiment, the phase-locked signal includes a sine wave signal or a pulse wave signal. When the phase-locked signal is a sine wave, the phase-locked frequency is twice the frequency of the sine wave.

[0065] Furthermore, the processing module 5 in this embodiment includes an image processing unit 51 , a reference signal generating unit 52 , and a phase-locked correlation calculating unit 53 .

[0066] Among them, the image processing unit 51 is used to analyze and process the thermal infrared image collected by the image acquisition module 4 to obtain the temperature signal of the object to be measured; the reference signal generating unit 52 is used to generate a reference signal with the temperature signal of the defect-free area in the thermal infrared image as a reference, or to output a sine wave with a frequency as the phase-locked frequency as a reference signal; the phase-locked correlation calculation unit 53 is used to perform phase-locked correlation processing according to the temperature signal and the reference signal of the object to be measured, extract the amplitude and phase of each pixel point in the thermal infrared image at a specific frequency as a characteristic value for output, and extract the depth information of each pixel point in the thermal infrared image for output.

[0067] Furthermore, in this embodiment, a binocular thermal imager is used as the image acquisition module 4, and a solid immersion lens (SIL) is used to further improve the resolution limit.

[0068] According to Sparrow's criterion, optical resolution is limited to:

[0069]

[0070] Where θ is the half angle of the light cone and the objective, n is the refractive index of the medium surrounding the sample, and the product n*sin(θ) represents the numerical aperture NA. For a given objective magnification factor, the brightness of the image (and therefore the measured signal-to-noise ratio) increases as the square of sin(θ), because the number of photons reaching the detector increases with the solid angle used by the objective. Even for high-brightness microscope objectives, θ is rarely larger than 30° to 45° for technical reasons, so sin(θ) is at most between 0.5 and 0.7. Therefore, in air (n=1), the optical resolution can only be slightly better than the wavelength λ used for imaging.

[0071] Therefore, the image acquisition module 4 in this embodiment uses a medium-wave thermal imager operating in the range of 3-5 μm, which can obtain a higher resolution.

[0072] In a specific implementation process, a chip or circuit module to be tested with known functions is placed as an object to be tested on a platform suitable for infrared thermal imaging, the positions of a binocular thermal imager and the object to be tested are adjusted, and the parameters of the binocular thermal imager are set so that the binocular thermal imager can accurately obtain the temperature signal of the object to be tested in the tested area.

[0073] The controller 1 is used to start the phase-locked signal generating unit 21, the high-frequency signal generating unit 22, and the processing module 5 to work. The processing module 5 controls the binocular thermal imager to start working, and acquires and stores the thermal infrared image returned by the binocular thermal imager in real time.

[0074] The high-frequency signal generating unit 22 outputs a continuous high-frequency AC signal and transmits the high-frequency AC signal to the amplitude modulation unit 23. At the same time, the phase-locked signal generating unit 21 outputs a periodic phase-locked signal and transmits the phase-locked signal to the amplitude modulation unit 23. The amplitude modulation unit 23 generates an excitation signal after amplitude modulation according to the phase-locked signal and the high-frequency AC signal output by the phase-locked signal generating unit 21 and the high-frequency signal generating unit 22 respectively.

[0075] The excitation signal is obtained by multiplying the phase-locked signal and the high-frequency AC signal. When the phase-locked signal and the high-frequency AC signal are both expressed in the form of sine waves, the expression of the excitation signal is as follows:

[0076] i=I A ·sin(2πf lock-in t)·sin(2πf carry t)

[0077] In the formula, I A represents the maximum amplitude of the excitation signal i, f lock-in Indicates the phase-locked signal frequency, f carry represents the frequency of high-frequency AC signal, and t represents time. lock-in and f carryDifferent settings are made according to the properties of the object to be measured. lock-in Usually in the range of 0.01Hz to tens of Hz, f carry Usually in the range of tens of kHz to hundreds of kHz.

[0078] The excitation power supply module 3 generates a corresponding excitation current according to the excitation signal. The excitation current is input into the power pin of the object to be tested for current excitation. The power-related interconnection lines in the object to be tested are periodically heated under the action of the current excitation and generate heat waves. At this time, the power-related interconnection line defects in the object to be tested will produce abnormal heat waves with changed amplitude or phase under periodic heating.

[0079] A binocular thermal imager is used to collect temperature signal images of periodic heat waves generated by the object to be measured from two angles respectively, and the two-way images are transmitted to the image processing unit 51 in the processing module 5.

[0080] The image processing unit 51 stores and analyzes the collected thermal infrared image to obtain the temperature signal of the object to be measured, and then transmits it to the reference signal generating unit 52. At the same time, the image processing unit 51 calculates the distance of each pixel in the image by calculating the time obtained by the thermal imager at different angles, and obtains the depth information of each pixel. The reference signal generating unit 52 generates a reference signal with the temperature signal of the defect-free area as a reference, or outputs a sine wave with a frequency of the phase-locked frequency as a reference signal, and transmits the reference signal and the original temperature signal to the phase-locked correlation calculation unit 53. The phase-locked correlation calculation unit 53 performs phase-locked correlation processing based on the temperature signal of the object to be measured and the reference signal, extracts the amplitude and phase of each pixel in the thermal infrared image at a specific frequency such as the phase-locked frequency as a characteristic value for output, and extracts the depth information of each pixel in the thermal infrared image for output.

[0081] Specifically, in the phase-locked correlation processing process, the reference signal is used as the in-phase reference signal, and the reference signal is Hilbert transformed to obtain an orthogonal reference signal. Then, the temperature signal and the in-phase reference signal are multiplied and fast Fourier transformed to obtain the real signal, and the temperature signal and the orthogonal reference signal are multiplied and fast Fourier transformed to obtain the imaginary signal. Then, after calculating the amplitude and phase of the real signal and the imaginary signal, the amplitude and phase signals are obtained, and the amplitude and phase of a specific frequency (such as the phase-locked frequency) are used as characteristic values.

[0082] The processing module 5 transmits the amplitude, phase and depth information of each pixel point in the thermal infrared image to the imaging module 6, and the imaging module 6 performs three-dimensional feature imaging and displays it according to the amplitude, phase and depth information of each pixel point in the thermal infrared image. The user can obtain the specific position and size of the interconnection line defect of the power pin in the object to be tested based on the three-dimensional feature imaging result.

[0083] The excitation power supply module 3 then performs current excitation on the functional pins of the object to be tested and other pins of different unit modules respectively, and repeats the above steps to determine the specific position and size of the interconnection line defects related to the function in the object to be tested.

[0084] In this embodiment, accurate detection of interconnect defects in a chip or circuit module with known functions can be achieved, and geometric feature information of complex interconnect defects can be provided. Compared with flash-excited infrared thermal imaging and electromagnetic-excited phase-locked thermal imaging, the depth detection can be better achieved. Combining infrared thermal imaging with binocular vision technology can effectively overcome the deficiency of infrared thermal imaging nondestructive testing technology in losing three-dimensional geometric information when detecting complex circuit module defects.

[0085] Example 3

[0086] This embodiment proposes an interconnection line defect detection method based on phase-locked synchronous image processing, which can be optionally applied to the interconnection line defect detection system based on phase-locked synchronous image processing proposed in Embodiment 1 or 2.

[0087] like Figure 3 FIG. 1 is a flow chart of the interconnection line defect detection method based on phase-locked synchronous image processing according to the present embodiment.

[0088] The interconnection line defect detection method based on phase-locked synchronous image processing proposed in this embodiment includes the following steps:

[0089] S1. Generate an excitation signal with a periodic phase-locked signal.

[0090] S2. Generate an excitation current according to an excitation signal with a periodic phase-locked signal, and perform current excitation on the circuit pins or functional pins of the object to be tested whose functions are known. The interconnection wires in the object to be tested are periodically heated under the action of the current excitation and generate heat waves.

[0091] S3, using the image acquisition module 4 to acquire thermal infrared images of the object to be measured from two angles, to obtain a thermal infrared image including a temperature signal of a periodic thermal wave.

[0092] S4, analyzing and processing the thermal infrared image to obtain the temperature signal of each pixel point, and dividing the defect-free area image according to the degree of change of the temperature signal of each pixel point;.

[0093] S5. Generate a reference signal, and perform phase-locked correlation processing based on the reference signal and the temperature signal of each pixel in the thermal infrared image to obtain the characteristic value and depth information of each pixel in the thermal infrared image.

[0094] S6. Perform three-dimensional feature imaging and display according to the feature value and depth information of each pixel point in the thermal infrared image, and obtain the specific position and size of the interconnection line defect according to the display result.

[0095] In this embodiment, the phase-locked signal includes a sine wave signal or a pulse wave signal.

[0096] In the specific implementation process, the chip or circuit module to be tested is first placed on the platform as the object to be tested, and the excitation current with a periodic phase-locked signal generated in steps S1 and S2 is used to current excite the circuit pins or functional pins of the object to be tested whose functions are known. The power-related interconnection lines in the object to be tested are periodically heated under the action of the current excitation and generate heat waves. At this time, the power-related interconnection line defects in the object to be tested will generate abnormal heat waves with changed amplitude or phase under periodic heating.

[0097] Therefore, through steps S3 to S6, a thermal infrared image of the object to be tested that generates thermal waves is collected, and the temperature signal of each pixel is further analyzed and processed. The reference signal and the temperature signal are combined to perform phase-locked correlation calculation to obtain the characteristic value and depth information of each pixel in the thermal infrared image, which is used for three-dimensional imaging, so as to facilitate intuitive observation of the specific position and size of the interconnection line defects.

[0098] In this embodiment, phase-locked thermal imaging and binocular vision computing are used, which have the advantages of high signal-to-noise ratio, high precision, and the ability to detect three-dimensional features of interconnection line defects of the inspected object, and can be applied to fields such as interconnection line defect detection.

[0099] Example 4

[0100] This embodiment makes improvements on the interconnection line defect detection method based on phase-locked synchronous image processing proposed in Embodiment 3.

[0101] The interconnection line defect detection method based on phase-locked synchronous image processing proposed in this embodiment includes the following steps:

[0102] S1. Generate an excitation signal with a periodic phase-locked signal.

[0103] In this step, the continuous high-frequency AC signal and the periodic phase-locked signal are amplitude modulated to generate an excitation signal.

[0104] The phase-locked signal in this embodiment includes a sine wave signal or a pulse wave signal.

[0105] When the phase-locked signal and the high-frequency AC signal are sinusoidal signals, the continuous high-frequency AC signal and the periodic phase-locked signal are amplitude modulated, and the expression of the generated excitation signal i is as follows:

[0106] i=I A ·sin(2πf lock-in t)·sin(2πf carry t)

[0107] In the formula, I A represents the maximum amplitude of the excitation signal i, f lock-in Indicates the phase-locked signal frequency, f carry represents the frequency of high-frequency AC signal, and t represents time.

[0108] S2. Generate an excitation current according to an excitation signal with a periodic phase-locked signal, and perform current excitation on the circuit pins or functional pins of the object to be tested whose functions are known. The interconnection wires in the object to be tested are periodically heated under the action of the current excitation and generate heat waves.

[0109] S3, using the image acquisition module 4 to acquire thermal infrared images of the object to be measured from two angles, to obtain a thermal infrared image including a temperature signal of a periodic thermal wave.

[0110] In one embodiment, a binocular thermal imager is used as the image acquisition module 4 , and a solid immersion lens technology is used to improve the resolution limit of the image acquisition module 4 .

[0111] S4, analyzing and processing the thermal infrared image to obtain the temperature signal of each pixel point, and performing image segmentation on the thermal infrared image to obtain a non-defective area image and a defective area image.

[0112] S5. Generate a reference signal according to the temperature signal of each pixel in the defect-free area image, and perform phase-locked correlation processing according to the reference signal and the temperature signal of each pixel in the thermal infrared image to obtain the characteristic value and depth information of each pixel in the thermal infrared image.

[0113] Furthermore, in this embodiment, the step of performing phase-locked correlation processing based on the reference signal and the temperature signal of each pixel in the thermal infrared image includes:

[0114] S5.1. Generate a reference signal according to the temperature signal of each pixel in the defect-free area image, or set a sine wave with a frequency of the phase-locked frequency as the reference signal.

[0115] S5.2. Use the reference signal as an in-phase reference signal and perform Hilbert transform on the reference signal to obtain an orthogonal reference signal.

[0116] S5.3. The temperature signal and the in-phase reference signal are multiplied and fast Fourier transformed to obtain a real signal, and the temperature signal and the orthogonal reference signal are multiplied and fast Fourier transformed to obtain an imaginary signal.

[0117] S5.4. Calculate the amplitude and phase of the real signal and the imaginary signal to obtain the amplitude and phase of each pixel in the thermal infrared image, and output the amplitude and phase of a specific frequency as a characteristic value.

[0118] S5.5. Extract the depth information of each pixel in the thermal infrared image and output it.

[0119] like Figure 4 As shown, it is a flow chart of phase-locked correlation processing in this embodiment.

[0120] In this embodiment, the characteristic value includes the amplitude and phase of each pixel in the thermal infrared image at a specific frequency, for example, the amplitude and phase of each pixel at a phase-locked frequency.

[0121] S6. Perform three-dimensional feature imaging and display according to the feature value and depth information of each pixel point in the thermal infrared image, and obtain the specific position and size of the interconnection line defect according to the display result.

[0122] In the specific implementation process, the chip or circuit module to be tested is placed on the platform as the object to be tested, and the excitation current with a periodic phase-locked signal generated in steps S1 and S2 is used to excite the circuit pins or functional pins of the object to be tested whose functions are known. The power-related interconnection wires in the object to be tested are periodically heated and generate heat waves under the action of the current excitation. At this time, the power-related interconnection wire defects in the object to be tested will generate abnormal heat waves with changed amplitude or phase under periodic heating. After image acquisition and image analysis processing in steps S3 to S6, a three-dimensional imaging result is obtained, and the specific position and size of the interconnection wire defects can be intuitively observed.

[0123] The same or similar reference numerals correspond to the same or similar components;

[0124] The terms used in the drawings to describe positional relationships are only used for illustrative purposes and should not be construed as limiting this patent;

[0125] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. An interconnection line defect detection system based on phase-locked synchronous image processing, characterized in that: include: Controller (1); An excitation control module (2) is used to generate an excitation signal with a periodic phase-locked signal according to a control signal output by the controller (1); These include: A phase-locked signal generating unit (21) is used to generate a periodic phase-locked signal according to a control signal output by the controller (1); the phase-locked signal comprises a sine wave signal or a pulse wave signal; A high-frequency signal generating unit (22), used for generating a continuous high-frequency AC signal according to a control signal output by the controller (1); and an amplitude modulation unit (23) for performing amplitude modulation according to the phase-locked signal and the high-frequency AC signal respectively output by the phase-locked signal generating unit (21) and the high-frequency signal generating unit (22), so as to generate an excitation signal; An excitation power supply module (3) is used to generate a corresponding excitation current according to an excitation signal output by the excitation control module (2), wherein an output end of the excitation power supply module (3) is electrically connected to a power pin or a function pin of an object to be tested placed on the platform; An image acquisition module (4), the image acquisition module (4) being arranged above the platform and used for acquiring a thermal infrared image of a periodic thermal wave generated by the object to be measured under the condition of electric current excitation; The processing module (5) is used to analyze and process the thermal infrared image collected by the image collection module (4) to obtain the temperature signal of the object to be measured, divide the defect-free area image according to the degree of change of the temperature signal of each pixel point, perform phase-locked correlation processing on the temperature signal, and generate the amplitude, phase and depth information of each pixel point in the thermal infrared image; it includes: An image processing unit (51) is used to analyze and process the thermal infrared image acquired by the image acquisition module (4) to obtain a temperature signal of the object to be measured; A reference signal generating unit (52) is used to generate a reference signal using a temperature signal of a defect-free area in a thermal infrared image as a reference, or to output a sine wave having a frequency equal to a phase-locked frequency as a reference signal; and, a phase-locked correlation calculation unit (53), configured to perform phase-locked correlation processing according to the temperature signal of the object to be measured and the reference signal, extract the amplitude and phase of each pixel point in the thermal infrared image at a specific frequency as a characteristic value for output, and extract the depth information of each pixel point in the thermal infrared image for output; The imaging module (6) is used to perform three-dimensional feature imaging and display according to the amplitude, phase and depth information of each pixel point in the thermal infrared image; and obtain the specific position and size of the interconnection line defect in the object to be tested according to the three-dimensional image displayed by the imaging module (6).

2. The interconnection line defect detection system based on phase-locked synchronous image processing according to claim 1 is characterized in that: The image acquisition module (4) comprises a binocular thermal imager.

3. The interconnection line defect detection system based on phase-locked synchronous image processing according to claim 2 is characterized in that: The image acquisition module (4) adopts a solid immersion lens.

4. A method for detecting interconnection line defects based on phase-locked synchronous image processing, applied to the interconnection line defect detection system based on phase-locked synchronous image processing according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1, generating an excitation signal with a periodic phase-locked signal; the phase-locked signal includes a sine wave signal or a pulse wave signal; S2, generating an excitation current according to an excitation signal with a periodic phase-locked signal, and performing current excitation on a circuit pin or a function pin of the object to be tested whose function is known, so that the interconnection wires in the object to be tested are periodically heated under the action of the current excitation and generate heat waves; S3, using an image acquisition module to acquire thermal infrared images of the object to be measured from two angles to obtain a thermal infrared image including a temperature signal of a periodic thermal wave; S4, analyzing and processing the thermal infrared image to obtain a temperature signal of each pixel point, and dividing the defect-free area image according to the degree of change of the temperature signal of each pixel point; S5, generating a reference signal, and performing phase-locked correlation processing based on the reference signal and the temperature signal of each pixel in the thermal infrared image to obtain a characteristic value and depth information of each pixel in the thermal infrared image; the characteristic value includes the amplitude and phase of each pixel in the thermal infrared image at a specific frequency; S6. Perform three-dimensional feature imaging and display according to the feature value and depth information of each pixel point in the thermal infrared image, and obtain the specific position and size of the interconnection line defect according to the display result.

5. The interconnection line defect detection method based on phase-locked synchronous image processing according to claim 4 is characterized in that: In the step S1, the step of generating an excitation signal with a periodic phase-locked signal includes: performing amplitude modulation on a continuous high-frequency AC signal and a periodic phase-locked signal to generate an excitation signal.

6. The interconnection line defect detection method based on phase-locked synchronous image processing according to claim 5 is characterized in that: When the phase-locked signal and the high-frequency AC signal are sinusoidal signals, the continuous high-frequency AC signal and the periodic phase-locked signal are amplitude modulated to generate an excitation signal i The expression is as follows: In the formula, I A Indicates the stimulus signal i The maximum amplitude of f lock-in Indicates the phase-locked signal frequency, f carry Represents the frequency of high-frequency AC signal, t For time.

7. The interconnection line defect detection method based on phase-locked synchronous image processing according to claim 6 is characterized in that: In step S5, the step of performing phase-locked correlation processing based on the reference signal and the temperature signal of each pixel in the thermal infrared image includes: S5.

1. Generate a reference signal according to the temperature signal of each pixel in the defect-free area image, or set a sine wave with a frequency of a phase-locked frequency as the reference signal; S5.

2. Using the reference signal as an in-phase reference signal, and performing a Hilbert transform on the reference signal to obtain an orthogonal reference signal; S5.3, multiplying the temperature signal and the in-phase reference signal and performing fast Fourier transformation to obtain a real signal, and multiplying the temperature signal and the orthogonal reference signal and performing fast Fourier transformation to obtain an imaginary signal; S5.4, calculating the amplitude and phase of the real signal and the imaginary signal to obtain the amplitude and phase of each pixel in the thermal infrared image, and outputting the amplitude and phase of a specific frequency as a characteristic value; S5.

5. Extract the depth information of each pixel in the thermal infrared image and output it.

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