Wafer chip detection system and method

Abstract

The present application relates to wafer chip detection technical field, especially to a kind of wafer chip detection system and method.The method includes the following steps: using locking mechanism to be fixed in the bearing tray of the wafer chip to be measured, the surface area of wafer chip is scanned under preset illumination angle, and the corresponding reflection light intensity distribution sequence is generated;When continuous fluctuation section appears in reflection light intensity distribution sequence, the boundary curve of the section is extracted, whether the extension length and the curvature change of boundary curve satisfy crack characteristic condition are judged, after crack determination is completed, control probe contacts the electrode pad of wafer chip, constant current is applied and two-end voltage is recorded, and contact resistance value is calculated;Contact resistance value is compared with preset threshold value, if contact resistance exceeds threshold value, then mark as electrode failure risk point;The present application is detected to wafer chip, to realize the joint detection of wafer crack and electrode failure, improve detection accuracy and reliability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wafer chip detection, and in particular to a wafer chip detection system and method. BACKGROUND

[0002] As an important basis for integrated circuit manufacturing, the quality of wafer chips is directly related to the performance and reliability of subsequent devices. During wafer processing and packaging, the wafer surface is easily affected by stress, mechanical force and environmental factors, resulting in cracks. Once the micro cracks expand, it may cause chip functional failure or even whole piece scrap. In addition, the stability of the contact resistance of the electrode pad on the wafer as the key channel for external circuit connection is also an important indicator of chip reliability. In the existing detection technology, optical microscopes or laser interference are usually used to observe the wafer surface to determine whether there are crack defects, but the detection range is limited and it is difficult to quantitatively identify micro cracks, which has the risk of missed detection and misjudgment. There is a lack of fine judgment means for abnormal distribution of electrode pad contact resistance, and it is difficult to realize unified evaluation of structural defects and electrical failure. SUMMARY

[0003] Therefore, it is necessary to provide a wafer chip detection system and method to solve at least one of the above technical problems.

[0004] To achieve the above-mentioned purpose, a wafer chip detection method is applied to a wafer chip, the wafer chip is fixed on a bearing tray, the bearing tray includes a locking mechanism, and the method includes the following steps:

[0005] Step S1: fixing the wafer chip to be tested on the bearing tray by using the locking mechanism, and scanning the surface area of the wafer chip row by row under a preset illumination angle to generate a corresponding reflected light intensity distribution sequence;

[0006] Step S2: when a continuous fluctuation section appears in the reflected light intensity distribution sequence, extracting the boundary curve of the section, determining whether the extension length and curvature change of the boundary curve meet the crack characteristic condition, after the crack determination is completed, controlling the probe to contact the electrode pad of the wafer chip, applying a constant current and recording the voltage across the two ends, and calculating the contact resistance value;

[0007] Step S3: comparing the contact resistance value with a preset threshold value, if the contact resistance exceeds the threshold value, marking it as an electrode failure risk point, obtaining the electrical determination result of the wafer chip, combining the crack determination result and the electrical determination result, and outputting the detection result of the wafer chip.

[0008] The present application also provides a wafer chip detection system applied to a wafer chip, the wafer chip is fixed on a bearing tray, the bearing tray includes a locking mechanism, and is used for executing the wafer chip detection method as described above, and the wafer chip detection system includes:

[0009] The receiving tray is provided with a connecting assembly and a locking mechanism, the connecting assembly is provided with a limiting column and a limiting hole, the limiting column is in sliding fit with the limiting hole, and the locking mechanism is a buckle, a pull buckle or a magnetic attraction buckle;

[0010] The detection module is used for fixing the wafer chip to be detected on the receiving tray by using the locking mechanism, and is used for scanning the surface area of the wafer chip row by row under a preset illumination angle to generate a corresponding reflected light intensity distribution sequence;

[0011] The contact resistance value calculation module is used for extracting a boundary curve of the continuous fluctuation section when the continuous fluctuation section appears in the reflected light intensity distribution sequence, determining whether the extension length and the curvature change of the boundary curve satisfy crack characteristic conditions, controlling the probe to contact the electrode pad of the wafer chip after the crack determination is completed, applying a constant current and recording a two-terminal voltage, and calculating a contact resistance value;

[0012] The wafer chip threshold value determination module is used for comparing the contact resistance value with a preset threshold value, marking as an electrode failure risk point if the contact resistance exceeds the threshold value, obtaining an electrical determination result of the wafer chip, and outputting a detection result of the wafer chip in combination with the crack determination result and the electrical determination result.

[0013] The present application has the following advantages:

[0014] By scanning the surface of the wafer chip row by row under a preset illumination angle, a complete reflected light intensity distribution sequence can be obtained, and the boundary curve is extracted based on the fluctuation section to determine the crack characteristics. Compared with the traditional method of relying on single-point detection or manual microscope observation, this method can realize large-area and automatic scanning and analysis, avoid missing and misjudgment problems, ensure high-precision identification of micro cracks, and significantly improve the comprehensiveness and reliability of wafer structure defect detection.

[0015] By introducing an electrical detection link after the crack determination, the probe contacts the electrode pad of the wafer and applies a constant current, and the two-terminal voltage is collected in real time to calculate the contact resistance, so as to quantitatively determine whether the electrode exists a failure risk. This method not only can identify potential failure points caused by material stress or process defects, but also can complement the structure detection result, effectively avoid the problem of missing electrode contact abnormalities when relying only on optical detection, and realize multi-dimensional quality guarantee of wafer chip.

[0016] By combining the crack determination result with the electrical determination result for output, comprehensive detection of the wafer chip from structural integrity to electrical performance stability can be realized. The dual determination mechanism effectively improves the accuracy and reliability of the detection result, which can not only find hidden cracks in advance, but also can early warn the electrode contact failure risk, and meets the quality control requirements of wafer chip in high reliability application scenarios. BRIEF DESCRIPTION OF DRAWINGS

[0017] Fig. 1 A schematic diagram of a step flow of a wafer chip detection method;

[0018] Fig. 2 A schematic diagram of a module of a wafer chip detection system;

[0019] Fig. 3 A photo of a wafer chip carrying tray;

[0020] Fig. 4 A photo of a wafer chip structure;

[0021] The purposes, functional features and advantages of the present application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0022] The technical method of the present application will be described clearly and completely below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0023] In addition, the accompanying drawings are only schematic illustrations of the present application, and are not necessarily drawn to scale. The same reference numerals in the drawings represent the same or similar parts, and thus repeated descriptions thereof will be omitted. Some of the block diagrams shown in the drawings are functional entities, which do not necessarily correspond to physically or logically independent entities. The functional entities can be implemented in the form of software, or in one or more hardware modules or integrated circuits, or in different network and / or processor methods and / or microcontroller methods.

[0024] It should be understood that although the terms "first", "second" and the like can be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of the exemplary embodiments, a first element can be referred to as a second element, and similarly a second element can be referred to as a first element. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0025] To achieve the above-mentioned purposes, please refer to Figs. 1 to 4 A wafer chip detection method applied to a wafer chip, the wafer chip is fixed on a carrying tray, the carrying tray includes a locking mechanism, and the method includes the following steps:

[0026] Step S1: Fix the wafer chip to be tested onto the carrier tray using the locking mechanism, and scan the surface area of ​​the wafer chip line by line under the preset illumination angle to generate the corresponding reflected light intensity distribution sequence;

[0027] Step S2: When a continuous fluctuation segment appears in the reflected light intensity distribution sequence, extract the boundary curve of the segment, determine whether the extension length and curvature change of the boundary curve meet the crack characteristic conditions, and after the crack determination is completed, control the probe to contact the electrode pad of the wafer chip, apply a constant current and record the voltage at both ends, and calculate the contact resistance value.

[0028] Step S3: Compare the contact resistance value with a preset threshold. If the contact resistance exceeds the threshold, mark it as an electrode failure risk point and obtain the electrical judgment result of the wafer chip. Combine the crack judgment result with the electrical judgment result to output the detection result of the wafer chip.

[0029] In one embodiment, an adsorption locking mechanism in a batch flipping device is used to adjust the diameter... The wafer chips are fixed on the surface of the quartz tray, which has Flatness accuracy. Using wavelength. The laser light source, with the incident angle set as After being expanded by a flat-top lens, a line spot is formed, with a scanning step size of [missing information]. The scanner moves line by line along the X direction. The reflected signal is generated by a linear CCD (4096 pixels, sampling rate...). The system receives light and forms a one-dimensional light intensity sequence, which is then sequentially spliced ​​to obtain the reflected light intensity distribution sequence of the entire wafer surface. The difference between adjacent points in the light intensity distribution sequence is calculated; when the difference remains in the same direction for 15 consecutive sampling points, it is marked as a candidate fluctuation segment. This segment is then subjected to Bessel interpolation and weighted moving average to generate a smoothed boundary curve. The curvature sequence is obtained by calculating the tangent angle difference and the segment length ratio point by point, and compared with a preset crack threshold (curvature). And the extension length The comparison is performed, and if the conditions are met, the crack is confirmed. Then, the XYZ three-axis platform is controlled to move, driving the probe to press against the target electrode pad. Maintain contact under force and apply constant current, sampling frequency Record the voltage across both ends and take the average value, then calculate the contact resistance.

[0030] Query the current electrode's process standard threshold table: when contact resistance Determined to be normal. It was determined to be a warning. The system is identified as having a failure risk. After calculating the resistance, it is automatically categorized, and the pad status is marked in real time on the detection interface. If both a crack detection anomaly and a resistance exceeding the threshold are present, an alarm is immediately triggered on the host computer, and a non-conformance report is generated.

[0031] In another embodiment, a mechanical snap-locking mechanism is used, in conjunction with dual light sources, the first light source being... Ultraviolet LED, the second light source is Infrared laser, respectively with and Alternating incident angles are used to enhance the contrast between shallow cracks and deep defects. The reflected signals are received by a high-sensitivity CMOS camera at a frame rate of... The reflected light intensity distribution sequence is then stitched together in real time using an FPGA. Wavelet packet decomposition filtering is applied to the light intensity sequence to remove high-frequency noise before segment detection. The crack detection threshold is set to the curvature. And the extension length The probe uses a tungsten needle with a tip radius of... Before crimping, the position error is precisely calibrated by optical alignment to be less than [value missing]. Constant current source output current The voltage sampling window is The calculated contact resistance value is stored in the database and bound to the pad number.

[0032] The resistance threshold is dynamically adjusted based on the pad size and location, for example... × Small pad threshold set ,and × Large pad threshold set The test results are visualized in wafer coordinates, with cracked areas marked in red and electrical failure risk points marked in yellow. A test report is then generated and archived for production line quality traceability.

[0033] Of particular importance, step S1 includes:

[0034] The locking mechanism is used to firmly press the wafer chip under test onto the positioning surface of the carrier tray;

[0035] After the wafer chip is fixed, the incident angle of the light source is adjusted to a preset angle range;

[0036] The driving scanning device moves the sampling points along the surface of the wafer chip row by row according to a predetermined path to obtain the reflected light intensity value of each sampling point;

[0037] They are arranged sequentially to form a sequence of reflected light intensity distributions covering the surface area of ​​the wafer chip.

[0038] In an embodiment, the wafer chip to be tested is placed on the center positioning surface of the bearing tray, and the vacuum suction locking mechanism is started to fix the wafer chip. The locking mechanism includes four corner mechanical clamps and a central vacuum suction area. The mechanical clamps gently clamp the edge of the wafer chip at a preset pressure to avoid damaging the surface of the chip. The central vacuum suction generates negative pressure to tightly adhere the wafer chip to the positioning surface of the tray, ensuring that the chip remains stable and does not shift during scanning. After the wafer chip is fixed, the incident angle of the laser light source is adjusted. The angle of the light source is set within a preset range of oblique incidence angles by a precision angle adjustment device. This angle range can effectively highlight the optical characteristics of surface defects. The two-dimensional scanning device is started, and the scanning device moves along the grid path from left to right and from top to bottom along the surface of the wafer chip. The photoelectric sensor carried by the scanning device stays at each sampling point for a short time, collects the reflected light intensity signal at that point, and converts it into a digital quantity. The entire wafer surface is divided into a dense sampling grid, each row containing hundreds of sampling points, and a total of tens of thousands of reflected light intensity data points are obtained. The collected light intensity data is arranged in sequence according to the time sequence of the scanning path to form a one-dimensional reflected light intensity distribution sequence. This sequence completely records the optical reflection characteristics of each region of the wafer chip surface.

[0039] In another embodiment, for large-size wafer chips, a partition locking strategy is adopted, and the locking mechanism is divided into two independent systems: a central region and an edge region. The central region uses a flexible air bag pressure holding method, and the edge region uses a multi-point mechanical clamp to ensure that the flatness of the entire wafer chip surface meets the detection requirements. The light source adjustment uses automatic angle control to automatically optimize the incident angle based on the material properties and surface roughness of the wafer chip, achieving the best defect detection effect. The scanning device is driven by a high-precision linear motor, and the scanning speed and stepping accuracy can be dynamically adjusted according to detection requirements. During scanning, the dwell time of each sampling point is optimized to ensure stable collection of light intensity signals and ensure overall detection efficiency. The photoelectric sensor has a wide dynamic range and can accurately capture weak light intensity changes under different surface conditions. After scanning, the reflected light intensity distribution sequence obtained is subjected to preliminary data processing to remove outliers and noise interference, forming high-quality raw data for subsequent defect recognition analysis.

[0040] Especially important is that the scanning device is driven to move the sampling points along the surface of the wafer chip according to a predetermined path, and the reflected light intensity values of the sampling points are obtained, including:

[0041] The scanning device is driven to move the sampling points along the surface of the wafer chip according to a predetermined path under external control instructions;

[0042] The optical acquisition unit is triggered to obtain the reflected light intensity signal from the surface of the wafer chip at each sampling point during the scanning motion;

[0043] The collected light intensity signals are recorded in sequence as light intensity values of corresponding sampling points according to the scanning order.

[0044] In an embodiment, a scanning start instruction is sent to the motion controller, and the motion controller drives the dual-shaft precision linear motor assembly to start executing a preset grid scanning path immediately after receiving the instruction. The scanning device moves to the starting position at the top left corner of the wafer chip surface, and then moves uniformly from left to right along the first row. When the scanning device moves to a preset sampling point position, the motion controller sends a trigger signal to the optical acquisition unit. The optical acquisition unit starts the photoelectric transducer immediately after receiving the trigger signal, acquires the laser light intensity signal reflected from the wafer chip surface at this moment, and converts the light signal into a voltage signal and then into a digital quantity through an analog-to-digital converter. After the first row scanning is completed, the scanning device automatically moves to the starting position of the next row and continues the scanning and acquisition process from left to right, and the process is repeated row by row until the entire wafer chip surface is covered. During the entire scanning process, the light intensity digital quantity value acquired at each sampling point is transmitted to a data storage buffer in real time and stored in sequence according to the time sequence of the scanning. The data storage automatically assigns a unique sequence number to each light intensity value, ensuring that the spatial position information of each sampling point can be accurately restored during subsequent data processing. After completing the acquisition of the last row, the scanning device automatically returns to the standby position.

[0045] In another embodiment, a closed-loop servo control strategy is used to ensure high-precision positioning of the sampling points for high-density sampling requirements. The dwell time of the scanning device at each sampling point is precisely controlled to ensure sufficient signal integration time for the optical acquisition unit and to avoid affecting the overall scanning efficiency due to excessive dwell time. The optical acquisition unit is equipped with a high-sensitivity photodiode and a low-noise signal amplifier, which can accurately capture the weak changes in the surface reflected light signal. During signal acquisition, the real-time position information and acquisition time stamp of the scanning device are recorded synchronously to establish complete coordinates and time identification for each light intensity value. The acquired light intensity signals are stored in a fixed precision format in a high-speed data storage array after hardware filtering and software noise removal processing. The scanning path adopts a zigzag mode to reduce the idle movement time and improve the scanning efficiency. The entire optical scanning acquisition has real-time monitoring function, which can detect abnormal signals during scanning and adjust the acquisition parameters in time. After scanning is completed, a data integrity report is automatically generated to confirm that all light intensity data of the sampling points have been correctly acquired and stored, providing reliable raw data support for subsequent image reconstruction and defect detection.

[0046] Preferably, step S2 comprises:

[0047] searching for a continuous fluctuation section in the reflected light intensity distribution sequence, and marking the start point and the end point of the section;

[0048] The light intensity curve of the section is extracted with the start point and the end point as boundaries, and a boundary curve is formed after smoothing the curve noise;

[0049] The extension length of the boundary curve is measured, and a combined determination condition of length and curvature is established;

[0050] When the extension length exceeds the preset threshold and the curvature change meets the crack feature condition, it is determined that the section has a crack;

[0051] After the crack determination is completed, the probe pressure contact electrode pad is controlled to apply a constant current and record the voltage across the two ends, and the contact resistance value is calculated.

[0052] In an embodiment, after completing wafer chip fixation and reflected light intensity distribution sequence acquisition, a sliding window search is performed on the reflected light intensity distribution sequence, the window width is set to 20 sampling points, and the step size is 5 sampling points. If the light intensity fluctuation amplitude of more than 15 consecutive sampling points in a window is greater than ±2σ (σ is the global light intensity standard deviation), the starting point of the window is recorded as the starting point of the fluctuation section; When the fluctuation amplitude of consecutive sampling points falls within the range of mean ±σ and remains for more than 10 sampling points, it is recorded as the end point. The start and end positions of a fluctuation section are thus obtained.

[0053] After the section is marked, the light intensity curve corresponding to the section is intercepted, and Savitzky-Golay smoothing filtering is performed on the original curve, the filtering order is set to 3, and the window width is 11 points, to remove random noise and maintain the curve trend. The boundary curve obtained after smoothing is stored for subsequent crack determination.

[0054] After the boundary curve is extracted, the extension length of the boundary curve is calculated using the arc length cumulative algorithm. Specifically, the coordinates of adjacent sampling points and are calculated ;

[0055] The total length of the extension is obtained by summing all the curve sections . At the same time, the discrete curvature of the boundary curve is calculated, the tangent direction is constructed at each sampling point, and the included angle difference between adjacent tangents is calculated , and the ratio of to the corresponding arc length is taken as the local curvature value, and the curvature change sequence is obtained. The and the curvature change sequence are input into the preset combined determination condition, for example: when and the curvature change interval , it is determined that the boundary curve meets the crack feature.

[0056] If the above conditions are met, the section is marked as a crack section, and the start and end position coordinates and the extension length parameter of the crack are recorded. After the crack determination is completed, the probe control module is started to press the precision micro probe to the target electrode pad surface at a pressure of . Then a constant current is applied by a constant current source, and the voltage value across the probe is collected by a high-precision digital multimeter . The electrode contact resistance is calculated , and the value is saved to the detection database to provide support for subsequent electrical determination.

[0057] In another embodiment, assuming that the extension length of a certain fluctuation section is , the curvature change interval is , and the combined condition is determined to be a crack. Then the probe is pressed against the corresponding electrode pad, and the voltage value is measured to be . The contact resistance is calculated to be under a constant current of , which is higher than the preset threshold . The result is marked as "crack + high resistance risk pad" in the detection database.

[0058] Preferably, in the sequence of reflected light intensity distribution, consecutive fluctuation sections are searched, and the start point and end point of the section are marked, including:

[0059] The sequence of reflected light intensity distribution is arranged in a continuous data stream in the order of sampling, and the light intensity difference value of adjacent sampling points is calculated in the continuous data stream;

[0060] When the difference value remains the same in the same direction for consecutive sampling points, it is marked as a fluctuation candidate section;

[0061] The first point where the difference value deviates from the reference threshold at the front end of the fluctuation candidate section is identified as the start point;

[0062] The last point where the difference value falls back to the reference threshold at the end of the fluctuation candidate section is identified as the end point;

[0063] The consecutive fluctuation section is determined with the start point and end point as boundaries.

[0064] ​​In one embodiment, the sequence of reflected light intensity distribution obtained from the wafer surface scanning is processed. The light intensity values obtained from each row scanning are arranged in a continuous data stream according to the sampling sequence, so that each data point can correspond to a specific position on the wafer surface. In the continuous data stream, the light intensity difference between adjacent sampling points is calculated in sequence, and the light intensity trend is determined according to the sign and size of the difference. When the difference of adjacent sampling points continuously remains in the same direction, for example, continuously increases or continuously decreases, it is determined as a fluctuation candidate section. At the front end of the fluctuation candidate section, the first point that deviates from the background noise range is detected as the starting point. The background noise range here can be determined by statistically analyzing the regular fluctuation amplitude of most difference values in the entire light intensity distribution sequence, and generally takes the average fluctuation range plus a safety margin. When the light intensity difference of a certain point exceeds this range, it is considered that an effective fluctuation has occurred, and thus marked as the starting point. At the end of the fluctuation candidate section, the change of the difference value is continuously tracked until the light intensity difference gradually falls back and re-enters the regular fluctuation range. At this time, the point is marked as the end point, indicating the end position of the fluctuation section.

[0065] With the marked starting point and end point as boundaries, the range of the continuous fluctuation section is determined. In subsequent processing, this section will be extracted for generating a boundary curve, as a candidate area for judging whether there is a crack.

[0066] In another embodiment, when scanning a wafer chip with a diameter of 200 mm, the scanning interval is 0.5 mm. In the processing process, it is found that there is a continuous light intensity change from the 300th point to the 340th point in a certain area. The starting point is marked at the 302nd point, and the end point is marked at the 338th point, corresponding to a physical length of about 0.5 mm. This section is then recorded and used as the key detection object in the subsequent crack judgment step.

[0067] Preferably, the light intensity curve of the section is extracted with the starting point and the end point as boundaries, and the boundary curve is formed after smoothing the curve noise, including:

[0068] The light intensity data of the section is intercepted with the starting point and the end point of the continuous fluctuation section as the index range, and the intercepted data is arranged in the sampling sequence to form an original light intensity curve;

[0069] A moving average processing is performed on the original light intensity curve, and a low-pass filtering is added after the moving average processing to suppress local sharp peak disturbance;

[0070] The filtered curve is interpolated and resampled, and the resampling result is taken as the boundary curve and stored.

[0071] In an embodiment, the data processing unit receives the start point and end point information of the determined continuous fluctuation section, and takes the data of the corresponding section from the sequence of reflected light intensity distribution with the start point and end point of the section as the index range. The intercepted data is arranged in the sampling order to form an original light intensity curve of the section. The original curve can fully reflect the change characteristics of the light intensity in the section, but usually contains sharp peak disturbances introduced by optical noise, detector electrical interference and environmental random factors.

[0072] A sliding average processing is performed on the original light intensity curve. In the processing, the processing unit traverses the original curve point by point with a fixed length sliding window, and calculates the mean value of the light intensity of all sampling points in the window to replace the original value of the center point of the window. In this way, the high frequency noise existing in the curve can be effectively weakened and the overall trend of the curve can be maintained.

[0073] After completing the sliding average processing, a low-pass filtering operation is further applied to the smoothed curve. Specifically, the processing unit calls a built-in digital filtering module to perform secondary processing on the sliding average result to suppress residual high frequency peaks and local interference signals. The cutoff frequency of the low-pass filter is preset according to the sampling rate and the characteristic frequency band of the curve, which ensures that the main change trend is preserved while the high frequency disturbance is removed.

[0074] Then, to avoid the problem of segmented discontinuity or excessive sparseness of the curve due to the limited number of sampling points, the data processing unit performs an interpolation resampling operation on the filtered curve. The interpolation method uses piecewise cubic spline interpolation or linear interpolation, which is selected according to the actual smoothness of the curve. The interpolation resampling process generates more interpolation points between the original sampling points, so that the resulting curve is superior to the initial sampling result in both continuity and smoothness.

[0075] The curve obtained by resampling is taken as a boundary curve, and the boundary curve data is stored in a result buffer for subsequent structure feature extraction or defect area boundary fitting. Through this step, stable, smooth and high-resolution expression of the light intensity change of the continuous fluctuation section can be realized.

[0076] In another embodiment, assuming that the detected fluctuation section start point is the 156th point and the end point is the 298th point, 143 light intensity data points are intercepted. The light intensity value range of the original light intensity curve is between 2800 and 3200 digital quantities, and there are about 15-20 local peak disturbances. The sliding average window is set to 5 points, and the fluctuation amplitude of the filtered light intensity curve is reduced from to After processing with a low-pass filter with a cutoff frequency of 12%, local spike disturbances were basically eliminated, and the curve continuity was good. Resampling to 256 points via cubic spline interpolation resulted in boundary curve data occupying approximately 2KB of storage space, with a processing time of approximately 3.5 milliseconds.

[0077] Preferably, measuring the extension length of the boundary curve and establishing a combined judgment condition for length and curvature includes:

[0078] The boundary curve is segmented sequentially along the sampling points, and the distance between adjacent sampling points is calculated for each segment.

[0079] The distances of each segment are summed up, and the extension length of the boundary curve is recorded.

[0080] Establish the tangent direction at each sampling point, calculate the angle difference between adjacent tangents, and use the ratio of the angle difference to the corresponding segment length as the local curvature index.

[0081] The extension length and curvature index are stored to form the criteria for crack combination judgment.

[0082] In one embodiment, boundary curve data containing 256 sampling points is acquired and sequentially labeled as points 1 to 256. Adjacent sampling points are segmented, and the... Point and the The straight-line distance between points is calculated using the formula: Piece distance = This yields 255 segmented distance values. Summing all segmented distances gives a total extension length of 18.6 mm for the boundary curve. Then, a tangent direction is established at each sampling point, and the tangent angle is determined using the slope calculation method based on two points before and after the sampling point. Tangent angle at point = [(No. Point ordinate - the (point y-coordinate) / (the first point) x-coordinate of point - number (x-coordinate of the point). Calculate the angle difference between adjacent tangents and take the absolute value as the curvature index. Divide the angle difference of each segment by the corresponding segment length to obtain the local curvature index, in degrees / mm. Establish the data correspondence, combining the total extension length of 18.6 mm with the average local curvature index of 2.3 degrees / mm to form the geometric characteristic parameters of the boundary curve. According to the preset crack judgment condition: when the extension length is greater than 15 mm and the average curvature index is greater than 2.0 degrees / mm, it is judged as a suspected crack. This boundary curve meets the crack characteristic condition.

[0083] In another embodiment, the boundary curve containing 180 sampling points is processed, and 179 segment distances are calculated, ranging from 0.08 to 0.12 mm, with a total cumulative extension length of 16.8 mm. In the tangent direction calculation, the three-point method is used to calculate the tangent angle, i.e., using the slope of the straight line formed by the current point and one point before and after it. The obtained tangent angle ranges from -15 degrees to +25 degrees, with an average difference of 1.8 degrees between adjacent tangent angles. When calculating the local curvature index, the 179 angle differences are divided by their corresponding segment lengths to obtain a sequence of local curvature indexes, with a maximum value of 8.5 degrees / mm, a minimum value of 0.2 degrees / mm, and an average value of 1.9 degrees / mm. A combined judgment condition is established: an extension length of 16.8 mm combined with an average curvature of 1.9 degrees / mm. Since the average curvature is less than the threshold of 2.0 degrees / mm, the boundary curve is judged to be a surface scratch rather than a crack. The extension length, curvature distribution data, and judgment results are stored together in the detection database.

[0084] Preferably, a tangent direction is established at each sampling point, the angle difference between adjacent tangents is calculated, and the ratio of the angle difference to the corresponding segment length is used as a local curvature index, including:

[0085] At each sampling point on the boundary curve, the direction of the line connecting that point and the adjacent point is taken as the tangent direction and the direction angle is recorded.

[0086] Pair adjacent tangent directions, calculate the angle difference, and form an angle difference sequence;

[0087] In the angle difference sequence, each angle difference is bound to its corresponding sampling point interval, and the start and end positions of the interval are marked;

[0088] For each sampling interval of a marker, the curve length of that interval is measured, and the curve length is used as the denominator parameter to perform a ratio calculation with the corresponding angle difference;

[0089] The result of the ratio calculation is recorded as the local curvature index of the sampling interval, and arranged sequentially according to the sampling point position to form a sequence of local curvature index data.

[0090] In one embodiment, a boundary curve containing 200 sampling points is obtained and labeled as points 0 to 199. A tangent direction is established at each sampling point, using the line connecting that point to its next adjacent point as the tangent direction; that is, the tangent direction at point i is the line connecting the i-th point to the next adjacent point. Time The vector direction. The formula for calculating the tangent direction angle is: Direction angle = (Vertical axis increment, horizontal axis increment) yields 199 directional angle values, ranging from -180 degrees to +180 degrees. Adjacent tangent directions are then paired, i.e., the... The tangent and the first tangent pairs, and 198 tangent direction angles are obtained. The angle difference between each tangent pair is calculated, and sequence data containing 198 angle difference values are formed. Each angle difference is bound to its corresponding sampling point interval, the interval corresponding to the first angle difference is from the first sampling point to the second sampling point, and the start and end positions of the interval are recorded as [x1, x2]. The curve length of each marked interval is measured, that is, the total length of the polyline from the first sampling point to the second sampling point to the third sampling point is calculated: interval length = distance from the first sampling point to the second sampling point + distance from the second sampling point to the third sampling point. The angle difference is taken as the numerator, and the interval length is taken as the denominator to perform a ratio operation, and the local curvature index = angle difference / interval length, with the unit of degree / mm. The sequence containing 198 values of the local curvature index is arranged in the order of the sampling point positions, and is stored in the data buffer area.

[0091] In another embodiment, a boundary curve containing 150 sampling points is processed, and 149 tangent direction angles are established, with the angle distribution range being -165 degrees to +170 degrees. 148 angle difference values are obtained by pairing adjacent tangents, wherein the maximum angle difference is 25.6 degrees, the minimum angle difference is 0.3 degrees, and the average angle difference is 4.2 degrees. In the binding process of the angle difference and the sampling interval, the interval corresponding to the 50th angle difference is [x50, x51], and the curve length of the interval is calculated as: the distance from the 50th point to the 51st point is 0.095 mm, and the distance from the 51st point to the 52nd point is 0.087 mm, and the total interval length is 0.182 mm. The local curvature index of the interval is calculated as: After the calculation of all 148 intervals is completed, the value range of the local curvature index sequence is between 2.1-85.3 degrees / mm, wherein there are 12 intervals with a curvature index exceeding 50 degrees / mm, which are mainly concentrated in the sharp turning parts of the curve. The local curvature index sequence is stored in the order of the positions, and each value occupies a storage space of 4 bytes, and the total sequence data amount is 592 bytes, and the processing time is about 1.2 milliseconds, which provides accurate geometric analysis data for subsequent crack feature judgment.

[0092] Preferably, after the crack judgment is completed, the probe pressure contact electrode pad is controlled to apply a constant current and record the voltage across the two ends, and the contact resistance value is calculated, including:

[0093] After the crack judgment is completed, the probe is driven to move to the target position of the electrode pad, and the probe tip is aligned with the electrode pad; ​​​​​​​​​​​​​

[0094] After alignment is completed, a down-pressing action is performed to make the probe contact the electrode pad surface at a constant speed and maintain a set pressure;

[0095] After contact is stabilized, a constant current source is applied to the probe, with a preset current amplitude of the order of milliamperes, and the current output is kept unchanged;

[0096] During the constant current application, the voltage signal across the probe is collected and recorded in a high-frequency sampling manner to obtain voltage time-series data;

[0097] The average voltage value is calculated from the collected voltage time-series data, and the contact resistance value is calculated by dividing the average voltage value by the applied current.

[0098] In an embodiment, after the crack determination is completed, a precision motor is started to drive the probe assembly to move the probe from the current position to the target electrode pad directly above it according to preset coordinate parameters . A fine adjustment alignment operation is performed by real-time monitoring of the relative position of the probe tip and the electrode pad through microscopic vision to ensure that the deviation between the center axis of the probe and the center point of the pad is controlled within . After alignment is completed, a down-pressing mechanism is started, and the probe is set to descend at a constant speed of per second. When the probe tip contacts the pad surface, a sensor detects the contact signal and stops the descending action. The vertical pressure is continuously applied to the set value of 15 grams, and the pressure sensor is used to monitor and maintain the pressure value in real time. After a waiting period of , a constant current source is started to apply a constant current of to the probe, with a current accuracy controlled within ± , and the continuous output time is . During the current application, the voltage signal across the probe is continuously collected at a high-frequency sampling frequency of every 10,000 times to obtain 10,000 voltage data points. The first 200 and last 200 data points are removed to eliminate transient effects, and the arithmetic mean of the middle 9,600 voltage data is calculated to obtain an average voltage value of . The average voltage value is divided by the applied current to calculate the contact resistance value as .

[0099] In another embodiment, for micro electrode pads, after the probe moves to the target position, precise alignment is performed through a high-magnification optical lens, and the alignment accuracy requirement is within . The down-pressing action is performed at a slower speed, set to per second, and the contact pressure is adjusted to 8 grams to avoid damaging the small pads. The applied constant current is adjusted to , to reduce the impact on sensitive circuits. The sampling frequency is set to 5000 times per second, and the sampling time is 4000 voltage data samples are obtained. After removing the first and last 100 data points, the average voltage value is calculated as The contact resistance value is obtained by division operation The test parameters including current value, voltage value, contact pressure, test time and other information are recorded in the test database together with the resistance calculation results. After the test is completed, the probe is automatically lifted off the pad surface, and the entire test process takes about This resistance value will be compared with the preset threshold value to provide accurate measurement data for subsequent electrical performance determination.

[0100] Preferably, step S3 comprises:

[0101] Query and load the preset threshold level corresponding to the current electrode pad;

[0102] Compare the measured contact resistance value with the threshold level one by one to determine the threshold interval;

[0103] If the contact resistance value is higher than the highest level threshold value, mark the pad as a failure risk point and record the real-time parameters of the pad;

[0104] If the contact resistance value is in the warning interval, mark it for retest, record the retest priority and add the pad to the retest queue;

[0105] According to the preset merging rule, compare the crack determination result and the electrical determination result. If both are out of limits, record as serious unqualified and trigger an upper alarm. If only one is abnormal, record as marginal unqualified and issue a review instruction.

[0106] In an embodiment, according to the number of the current electrode pad being tested, the corresponding preset threshold level parameters are queried and loaded from the threshold configuration database. The pad belongs to a key signal line pad, and the threshold level is set as: excellent interval - , qualified interval - , warning interval - , failure interval greater than . The measured contact resistance value is compared with the upper limit of the excellent interval , and it is found that is greater than , which does not belong to the excellent level. Continue to compare with the upper limit of the qualified interval , and is less than , the contact resistance of the pad is determined to be in the qualified interval. The determination result is recorded as "electrical performance qualified", and the measurement time stamp, resistance value, test condition and other parameters are stored in the pad data record. Since no crack defect is found in the pad, the crack determination result is "physical structure qualified". According to the preset merging rule, when the crack determination and the electrical determination are both qualified, the comprehensive determination result is "pad qualified", and no alarm or retest instruction needs to be triggered. The final test result is written into the wafer chip quality report, and the pad P0156 is marked as a green qualified state.

[0107] In another embodiment, the electrode pad P0089 is detected, which is a power supply pad with strict threshold levels: excellent interval - , qualified interval - , warning interval - , failure interval greater than . The measured contact resistance value is , after comparison, it is found that the value exceeds the failure interval threshold , immediately mark the pad as a failure risk point. Record the real-time parameters of the pad, including: test current , test voltage , contact pressure 8 grams, test temperature 23.5 degrees Celsius, humidity 45%. At the same time, the pad is found to have a suspected crack with a length of , an average curvature of degrees per millimeter in optical detection, and the crack determination result is "physical structure abnormal". According to the preset merging rule, when the crack determination is abnormal and the electrical determination is failed, the comprehensive determination is "serious unqualified". Automatically trigger the upper alarm, and the alarm information includes the pad number, defect type, risk level and other contents, and a red warning window pops up on the operation interface. Mark the pad as unqualified product and display it in red highlight. The entire determination process takes about , which ensures the efficiency requirement of real-time detection.

[0108] Preferably, if the contact resistance value is higher than the highest level threshold, the pad is marked as a failure risk point, and the real-time parameters of the pad are recorded, including:

[0109] determine whether the contact resistance value is above the highest level threshold;

[0110] When the contact resistance is continuously sampled for multiple times and is higher than the highest level threshold, insert the failure risk mark of the pad in the current wafer chip data table;

[0111] read the accurate position parameters and real-time measurement parameters of the pad in the wafer coordinate system, and write them into the determination record;

[0112] The numerical result of the resistance measurement is stored with fixed precision, data validity check is performed, and the stored result is bound with the corresponding pad number.

[0113] In an embodiment, the measured contact resistance value of the electrode pad P0243 is , it is immediately determined whether the value exceeds the highest threshold value of the type of pad . The comparison result shows is greater than , which meets the threshold value exceeding condition. To ensure measurement accuracy, a continuous multiple sampling verification mechanism is started, and 5 consecutive measurements are performed on the pad under the same test conditions, with a measurement interval of . The resistance values obtained by the 5 consecutive measurements are: , , , , , all of which exceed the threshold value . It is confirmed that the pad indeed has a failure risk, and a failure risk marker "RISK_FAIL" is immediately inserted in the 243rd row of the current wafer chip data table. The accurate position parameters of the pad in the wafer coordinate system are read: the X coordinate is , the Y coordinate is , and the rotation angle is 0.25 degrees. At the same time, real-time measurement parameters are recorded, including: ambient temperature 24.2 degrees Celsius, relative humidity 48%, test current 5mA, average test voltage , contact pressure 12 grams, test duration . All parameter information is written into the judgment record file, and the time stamp is accurate to the microsecond level. The resistance measurement result is stored in a fixed precision format with 1 decimal place, data range check is performed to confirm that the value is within a reasonable interval, and it is uniquely bound with the pad number P0243 and stored in the failure risk database.

[0114] In another embodiment, the key power pad P0067 is detected, and the initial measurement obtains a contact resistance value , which is much higher than the highest threshold value of this type of pad . A 3-time continuous verification measurement is started, with a measurement interval of 300ms, and the obtained resistance value sequence is: , , , all of which exceed the threshold value, confirming that it is a failure risk pad. A high risk marker "HIGH_RISK" is inserted in the wafer data table, and the priority level is set to urgent processing. The accurate coordinates of the pad are read as X axis , Y axis , and Z axis height The recorded real-time parameters include: atmospheric pressure 101.2 kPa, test current , peak voltage , steady voltage , voltage fluctuation range , probe contact resistance , total test duration The measured values are stored with fixed 2 decimal precision, no data loss is ensured through data integrity check, and finally a one-to-one binding relationship is established with the pad number P0067.

[0115] The application also provides a wafer chip detection system applied to a wafer chip, the wafer chip is fixed on a bearing tray, the bearing tray comprises a locking mechanism, and the wafer chip detection system is used for executing the wafer chip detection method as described above, and the wafer chip detection system comprises:

[0116] The bearing tray is provided with a connecting assembly and a locking mechanism, the connecting assembly is provided with a limiting column and a limiting hole, the limiting column is in sliding fit with the limiting hole, and the locking mechanism is a buckle, a pull buckle or a magnetic attraction buckle;

[0117] The detection module 101 is used for fixing the wafer chip to be detected on the bearing tray by using the locking mechanism, and the surface area of the wafer chip is scanned row by row under a preset illumination angle to generate a corresponding reflected light intensity distribution sequence;

[0118] The contact resistance value calculation module 102 is used for extracting a boundary curve of a continuous fluctuation section in the reflected light intensity distribution sequence, determining whether the extension length and the curvature change of the boundary curve meet crack characteristic conditions, controlling the probe to contact the electrode pad of the wafer chip after the crack determination is completed, applying a constant current and recording a two-terminal voltage, and calculating a contact resistance value;

[0119] The wafer chip threshold value determination module 103 is used for comparing the contact resistance value with a preset threshold value, marking an electrode failure risk point if the contact resistance exceeds the threshold value, obtaining an electrical determination result of the wafer chip, and outputting a detection result of the wafer chip in combination with the crack determination result and the electrical determination result.

[0120] The above is only a specific embodiment of the application, enabling a person skilled in the art to understand or implement the application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the application. Therefore, the application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for detecting wafer chips, characterized in that, Applied to wafer chips, the wafer chips are fixed to a carrier tray, the carrier tray including a locking mechanism, the method includes the following steps: Step S1: Fix the wafer chip to be tested onto the carrier tray using the locking mechanism, and scan the surface area of ​​the wafer chip line by line under the preset illumination angle to generate the corresponding reflected light intensity distribution sequence; Step S2: When a continuous fluctuation segment appears in the reflected light intensity distribution sequence, the boundary curve of the segment is extracted. The extension length and curvature change of the boundary curve are determined to meet the crack characteristic conditions. After crack determination, the probe is controlled to contact the electrode pads of the wafer chip, a constant current is applied, and the voltage across the two ends is recorded. The contact resistance value is calculated. Step S2 includes: Retrieve continuous fluctuation segments in the reflected light intensity distribution sequence and mark the start and end points of the segments; Using the starting and ending points as boundaries, the light intensity curves of the segments are extracted, and the boundary curves are formed after smoothing out the noise. The extension length of the boundary curve is measured, and a combined judgment condition of length and curvature is established. This includes: The boundary curve is segmented sequentially along the sampling points, and the distance between adjacent sampling points is calculated for each segment. The distances of each segment are summed up, and the extension length of the boundary curve is recorded. Establish the tangent direction at each sampling point, calculate the angle difference between adjacent tangents, and use the ratio of the angle difference to the corresponding segment length as the local curvature index. The extension length and curvature index are stored to form the crack combination judgment conditions; When the extension length exceeds the preset threshold and the curvature change meets the crack characteristic conditions, it is confirmed that there is a crack in the section. After crack detection is completed, control the probe to press the electrode pad, apply a constant current and record the voltage at both ends, and calculate the contact resistance value. Step S3: Compare the contact resistance value with a preset threshold. If the contact resistance exceeds the threshold, mark it as an electrode failure risk point and obtain the electrical judgment result of the wafer chip. Combine the crack judgment result with the electrical judgment result to output the detection result of the wafer chip.

2. The wafer chip testing method according to claim 1, characterized in that, Retrieve continuous fluctuation segments in the reflected light intensity distribution sequence and mark the start and end points of these segments, including: The reflected light intensity distribution sequence is arranged into a continuous data stream according to the sampling order, and the light intensity difference between adjacent sampling points is calculated in the continuous data stream; When the difference maintains the same direction of change across multiple consecutive sampling points, it is marked as a candidate fluctuation segment; Identify the first point at the front end of the fluctuation candidate segment where the difference deviates from the baseline threshold, and set it as the starting point; Identify the point at the end of the fluctuation candidate segment where the last difference falls back to the baseline threshold and set it as the termination point; The continuous fluctuation section is determined by using the starting point and the ending point as boundaries.

3. The wafer chip testing method according to claim 1, characterized in that, Using the starting and ending points as boundaries, the light intensity curves of the segments are extracted, and the boundary curves are smoothed after noise removal, including: The light intensity data of the continuous fluctuation segment is extracted by using the starting and ending points of the segment as the index range, and the extracted data is arranged in the sampling order to form the original light intensity curve. The original light intensity curve is processed by moving average, and a low-pass filter is added after moving average to suppress local spike disturbances. The filtered curve is interpolated and resampled, and the resampled result is used as the boundary curve and stored.

4. The wafer chip testing method according to claim 1, characterized in that, At each sampling point, a tangent direction is established, the angle difference between adjacent tangents is calculated, and the ratio of the angle difference to the corresponding segment length is used as a local curvature index, including: At each sampling point on the boundary curve, the direction of the line connecting the sampling point and the adjacent sampling point is taken as the tangent direction and the direction angle is recorded. Pair adjacent tangent directions, calculate the angle difference, and form an angle difference sequence; In the angle difference sequence, each angle difference is bound to its corresponding sampling point interval, and the start and end positions of the interval are marked; For each sampling interval of a marker, the curve length of that interval is measured, and the curve length is used as the denominator parameter to perform a ratio calculation with the corresponding angle difference; The result of the ratio calculation is recorded as the local curvature index of the sampling interval, and arranged sequentially according to the sampling point position to form a sequence of local curvature index data.

5. The wafer chip testing method according to claim 1, characterized in that, After crack detection is completed, the control probe is pressed against the electrode pad, a constant current is applied and the voltage across the two ends is recorded. The contact resistance value is calculated, including: After the crack detection is completed, the drive probe is moved to the target position of the electrode pad, and the probe tip is aligned with the electrode pad; After alignment, a pressing action is performed to make the probe contact the electrode pad surface at a constant speed and maintain the set pressure; After the contact is stabilized, a constant current source is applied to the probe, with the current amplitude preset to the milliampere level, and the current output is kept constant. During the application of constant current, the voltage signal across the probe is acquired, and the voltage timing data is recorded using a high-frequency sampling method. The average voltage value is calculated from the collected voltage time-series data, and the contact resistance value is calculated by dividing the average voltage value by the applied current.

6. The wafer chip testing method according to claim 1, characterized in that, Step S3 includes: Query and load the preset threshold level corresponding to the current electrode pad; The measured contact resistance values ​​are compared item by item according to the threshold level to determine the threshold range in which they fall. If the contact resistance value is higher than the highest level threshold, mark the pad as a failure risk point and record the real-time parameters of the pad. If the contact resistance value is within the warning range, mark it as needing retesting, record the retesting priority, and add the pad to the retesting queue; The crack judgment result and the electrical judgment result are compared according to the preset merging rules. If both exceed the limit, it is recorded as a serious non-compliance and an alarm is triggered. If only one is abnormal, it is recorded as an edge non-compliance and a review instruction is issued.

7. The wafer chip testing method according to claim 6, characterized in that, If the contact resistance value is higher than the highest level threshold, the pad is marked as a failure risk point, and the real-time parameters of the pad are recorded, including: Determine whether the contact resistance value is above the highest level threshold; When the contact resistance is higher than the highest level threshold in multiple consecutive samples, a failure risk mark for the pad is inserted into the current wafer chip data table. Read the precise position parameters and real-time measurement parameters of the pad in the wafer coordinate system, and write them into the judgment record; The resistance measurement results are stored with fixed precision, data validity is verified, and the stored results are bound to the corresponding pad numbers.

8. A wafer chip inspection system, characterized in that, This system is applied to wafer chips, where the wafer chips are fixed to a carrier tray. The carrier tray includes a locking mechanism for performing the wafer chip inspection method as described in claim 1. The carrier tray is provided with a connecting component and a locking mechanism. The connecting component has a limiting post and a limiting hole, with the limiting post and the limiting hole slidingly engaged. The locking mechanism is a snap-fit, pull-tab, or magnetic snap-fit. The wafer chip inspection system includes: The detection module is used to fix the wafer chip under test to the carrier tray using a locking mechanism, and scan the surface area of ​​the wafer chip line by line under a preset illumination angle to generate the corresponding reflected light intensity distribution sequence. The contact resistance value calculation module is used to extract the boundary curve of a continuous fluctuation segment when a continuous fluctuation segment appears in the reflected light intensity distribution sequence, determine whether the extension length and curvature change of the boundary curve meet the crack characteristic conditions, and after the crack determination is completed, control the probe to contact the electrode pad of the wafer chip, apply a constant current and record the voltage at both ends, and calculate the contact resistance value. The wafer chip threshold determination module compares the contact resistance value with a preset threshold. If the contact resistance exceeds the threshold, it is marked as a risk point for electrode failure, and the electrical determination result of the wafer chip is obtained. Combining the crack determination result and the electrical determination result, the detection result of the wafer chip is output.

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