Probe card horizontal calibration method and apparatus

Abstract

The present disclosure provides a probe card horizontal calibration method, comprising: placing a large cover plate in an initial position, so that the flatness of the large cover plate relative to a working disc is less than a first preset value; loading a probe card on the large cover plate and a wafer to be tested on the working disc; selecting a reference point on the wafer to be tested; collecting three-dimensional position information of the probe corresponding to the reference point and calculating the flatness of the probe card; when the flatness is greater than a second preset value, fitting a plane equation formed by the probes corresponding to the reference point and calculating height adjustment values of the multiple adjustable points, and then performing height adjustment. The method and device provided by the present disclosure can realize rapid and high-precision horizontal calibration of the probe card.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor technology, and more specifically, to a probe card horizontal calibration method and apparatus. Background Technology

[0002] In semiconductor wafer-level testing, the probe station needs to establish electrical contact with the metal pads of the chip on the wafer via a probe card to complete functional testing and parameter detection. To ensure the accuracy and consistency of the test, all probe tips on the probe card should form an ideal plane that approximates the wafer surface. That is, the plane formed by all probes on the probe card needs to be parallel to or within a certain range of the plane of the wafer. Otherwise, some probes will fail to make contact, make excessive contact, or have unstable contact, thus affecting yield and data reliability. Currently, the common method for leveling probe cards mainly relies on manually adjusting the head stage to make the probe surface nearly parallel to the wafer surface. However, manual leveling is inefficient, has limited accuracy, and requires repeated measurements for confirmation, making the operation cumbersome. Especially when the probe station is used with a large-size test head, the test head structure often obstructs the head stage, leaving no space for installing a manual adjustment mechanism, making manual leveling difficult.

[0003] Therefore, there is an urgent need for an effective probe card leveling method and device that can achieve automatic high-precision leveling, thereby ensuring the stability and yield of wafer testing. Summary of the Invention

[0004] The purpose of this disclosure is to provide a probe card horizontal calibration method and apparatus that can automatically detect and adjust the flatness of the probe card, avoid test errors caused by inconsistent contact between the probe and the wafer pad, and improve the test stability and efficiency of the semiconductor probe station.

[0005] In a first aspect, embodiments of this disclosure provide a probe card horizontal calibration method, comprising the following steps:

[0006] The large cover plate is placed in the initial position. At this time, the flatness of the large cover plate relative to the working plate is less than the first preset value. The large cover plate is provided with multiple adjustable positions and at least one fixed reference point.

[0007] A probe card is mounted on the large cover plate, and the wafer to be tested is mounted on the work plate; at least five chip cells are selected on the wafer to be tested, and at least one pad is selected as a reference point in each selected chip cell;

[0008] The probe camera acquires the three-dimensional position information of the probe corresponding to the reference point, and calculates the flatness of the probe card based on the three-dimensional position information of the probe corresponding to the reference point.

[0009] When the flatness is greater than a second preset value, a plane equation formed by the probe corresponding to the reference point is fitted, and the height adjustment value of the plurality of adjustable points is calculated based on the plane equation; and

[0010] The height of the adjustable point is adjusted according to the height adjustment value.

[0011] Optionally, the large cover plate has three adjustable points and one fixed reference point. The large cover plate has a rectangular structure, and the adjustable points and the fixed reference point are respectively located in the areas where the four apex corners of the large cover plate are located.

[0012] Optionally, the plurality of adjustable points are respectively connected to an adjustment motor, which is used to drive the large cover plate to adjust its posture in the vertical direction.

[0013] Optionally, the calibration process ends when the flatness is less than or equal to a second preset value.

[0014] Optionally, in the step of placing the large cover plate in the initial position, where the flatness of the large cover plate relative to the working disc is less than a first preset value, the flatness of the large cover plate relative to the working disc is detected by a mechanical dial indicator.

[0015] Optionally, in the step of selecting at least five chip cells on the wafer under test and selecting at least one pad in each selected chip cell as a reference point, the selected at least five chip cells are distributed in the edge region of the wafer under test.

[0016] Optionally, when the wafer under test has a rectangular layout, the selected at least five chip cells include chip cells located at the four corners of the rectangle;

[0017] When the wafer under test has a circular layout, the selected at least five chip cells include chip cells that are equally spaced on the circumference.

[0018] Optionally, the first preset value is 100 micrometers, and the second preset value is 20 micrometers.

[0019] Optionally, after the step of performing height adjustment of the adjustable point according to the height adjustment value, the method further includes:

[0020] Repeat the step of acquiring the three-dimensional position information of the probe corresponding to the reference point using the probe camera.

[0021] Secondly, embodiments of this disclosure provide a probe card level calibration device, comprising:

[0022] Processor; and

[0023] Memory for storing the executable instructions of the processor;

[0024] The processor is configured to execute the probe card horizontal calibration method by executing the executable instructions.

[0025] Compared with related technologies, the embodiments of this disclosure have at least the following technical effects:

[0026] The probe card horizontal calibration method and apparatus disclosed herein are based on image recognition and three-dimensional space fitting technology. They can automatically acquire probe positions, quickly determine probe card flatness, and achieve rapid leveling through automatic control, thereby improving the consistency of contact between the probe card and the wafer pad and significantly improving testing accuracy and efficiency. Attached Figure Description

[0027] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. In the drawings:

[0028] Figure 1 This is a schematic flowchart illustrating a probe card horizontal calibration method provided in some embodiments of this disclosure;

[0029] Figure 2 This is a schematic diagram of the test apparatus involved in the probe card horizontal calibration method provided in some embodiments of this disclosure;

[0030] Figure 3 This is a schematic diagram of the structure of the large cover plate involved in the probe card horizontal calibration method provided in some embodiments of this disclosure;

[0031] Figure 4 A schematic diagram of the wafer chip unit selected for the probe card horizontal calibration method provided in some embodiments of this disclosure;

[0032] Figure 5 This is a schematic diagram of the structure of a probe card horizontal calibration device provided in some embodiments of this disclosure.

[0033] In the attached diagram: test head 10, large cover plate 20, adjustable positions 21-23, fixed reference point 24, probe card 30, probe 31, wafer under test 40, chip unit 41-45, working disk 50, test machine 60. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this disclosure clearer, the disclosure will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. Based on the embodiments of this disclosure, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this disclosure.

[0035] The terminology used in the embodiments of this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of this disclosure. The singular forms “a,” “the,” and “the” as used in the embodiments of this disclosure and the appended claims are also intended to include the plural forms, and “multiple” generally includes at least two unless the context clearly indicates otherwise.

[0036] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0037] It should be understood that although the terms first, second, third, etc., may be used to describe embodiments of this disclosure, these should not be limited to these terms. These terms are used only to distinguish them. For example, first may also be referred to as second without departing from the scope of embodiments of this disclosure, and similarly, second may also be referred to as first.

[0038] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an article or device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an article or device. Without further limitation, an element defined by the phrase "comprising one" does not exclude the presence of other identical elements in the article or device that includes said element.

[0039] As described in the background section, existing probe card leveling methods suffer from problems such as reliance on manual labor, low efficiency, poor accuracy, and unsuitability for large-size test heads, making it difficult to meet the requirements of modern semiconductor wafer testing.

[0040] To solve or at least alleviate the above-mentioned technical problems, one aspect of this disclosure provides a probe card horizontal calibration method, comprising the following steps:

[0041] S100, the large cover plate is placed in the initial position. At this time, the flatness of the large cover plate relative to the working plate is less than the first preset value. The large cover plate is provided with multiple adjustable positions and at least one fixed reference point.

[0042] S200, a probe card is mounted on the large cover plate, and the wafer to be tested is mounted on the work plate; at least five chip units are selected on the wafer to be tested, and at least one pad is selected as a reference point in each selected chip unit;

[0043] S300: The probe camera acquires the three-dimensional position information of the probe corresponding to the reference point, and calculates the flatness of the probe card based on the three-dimensional position information of the probe corresponding to the reference point.

[0044] S400, when the flatness is greater than a second preset value, fit the plane equation formed by the probe corresponding to the reference point, and calculate the height adjustment value of the plurality of adjustable points based on the plane equation; and

[0045] S500, perform height adjustment of the adjustable point according to the height adjustment value.

[0046] As can be seen, the probe card leveling method provided in this disclosure, based on image recognition and three-dimensional space fitting technology, can automatically obtain the probe position, quickly determine the flatness of the probe card, and achieve rapid leveling through automatic control, thereby improving the consistency of contact between the probe card and the wafer pad and significantly improving the test accuracy and efficiency.

[0047] The optional embodiments of this disclosure are described in detail below with reference to the accompanying drawings.

[0048] This disclosure provides a probe card horizontal calibration method through some embodiments. Figure 2 The diagram shows a portion of the wafer testing structure involved in the aforementioned probe card horizontal calibration process.

[0049] Specifically, such as Figure 2 As shown, the structure involved includes a test head 10, a head stage 20, a probe card 30, a working disk 50, and a tester 60.

[0050] Test head 10 is an electrical signal output / input interface component of test machine 60, used to transmit test signals sent by test machine 60 to probe card 30, and at the same time receive electrical signals returned from the chip on wafer 40 and transmit them back to test machine 60.

[0051] The large cover plate 20 is used to install and position the probe card 30. The large cover plate 20 is provided with multiple adjustable points and at least one fixed reference point. The multiple adjustable points can be used to fine-tune the probe card 30 in the Z direction, thereby realizing the horizontal calibration of the probe card 30.

[0052] The probe card 30 is detachably mounted below the large cover plate 20. Multiple probes 31 are disposed on the lower surface of the probe card 30. The probes 31 are used to contact the chip electrodes on the wafer under test 40 during testing, forming a path for the test signal. The probes 31 can form a corresponding array structure according to the arrangement of the chip electrodes.

[0053] The working tray 50 is positioned directly below the probe card 30 and is used to support the wafer 40 to be tested. The working tray 50 generally has a vacuum adsorption function to fix the wafer position and ensure that the wafer does not shift during testing. The working tray 50 has a lifting function, which can be raised to a predetermined height before testing to bring the wafer 40 to contact the probe 31, and lowered after testing to complete the wafer replacement.

[0054] The wafer under test 40 is typically a semiconductor wafer containing multiple die units, each die unit further including multiple pads for electrical contact, for probe 31 to contact and test.

[0055] The testing machine 60 serves as the main control device for the entire system, controlling the operation of each part of the probe station, sending test signals, and collecting, analyzing, and transmitting data. The testing machine 60 is connected to the test head 10 via a connecting cable to achieve signal transmission.

[0056] refer to Figure 1 In some embodiments, the probe card horizontal calibration method specifically includes the following steps:

[0057] S100, the large cover plate 20 is placed in the initial position, at which time the flatness of the large cover plate 20 relative to the working plate 50 is less than the first preset value.

[0058] In this step, the large cover plate 20 is installed into the probe station structure and adjusted to the initial reference height. The large cover plate 20 is provided with multiple adjustable points and at least one fixed reference point. In some embodiments, such as Figure 3 As shown, the large cover plate 20 has a rectangular structure and is provided with three adjustable points 21, 22, and 23 and a fixed reference point 24. The adjustable points and the fixed reference point are located in the areas where the four apex corners of the large cover plate are located, and are used to support and adjust the spatial attitude of the large cover plate 20.

[0059] The multiple adjustable points are connected to adjustment motors, which drive each adjustable point to move up and down in the vertical direction (Z-axis) to achieve precise attitude adjustment of the large cover plate 20 in space. Before adjustment begins, the positions of the adjustable points and fixed reference points in the machine coordinate system need to be calibrated. The machine coordinate system is a three-dimensional rectangular coordinate system (XYZ coordinate system), with its origin O set at the geometric center of the large cover plate 20.

[0060] The upper surface of the working plate 50 can be considered as a calibration reference plane, typically possessing high flatness and a known calibration height. By measuring the coordinates of the adjustable points and fixed reference points (such as 21, 22, 23, 24) on the large cover plate 20 in the Z-axis direction and comparing them with the reference surface of the working plate 50, the maximum height difference is obtained. This maximum value represents the flatness of the large cover plate 20 relative to the working plate 50. If this maximum height difference is less than a first preset value (e.g., 100 micrometers), it indicates that the current installation state of the large cover plate 20 meets the initial leveling adjustment requirements, and the next calibration step can proceed.

[0061] In practical applications, the flatness can be tested using a mechanical dial indicator. Specifically, a dial indicator or displacement sensor is set at each adjustment point to measure the height change relative to the working plate 50. The flatness is calculated by combining the readings at each point to ensure that the flatness of the large cover plate 20 relative to the working plate 50 in the initial installation state is less than the first preset value.

[0062] S200, a probe card 30 is mounted on the large cover plate 20, and a wafer 40 to be tested is mounted on the working disk 50; at least five chip units (dies) are selected on the wafer 40 to be tested, and at least one pad is selected in each selected chip unit as a reference point.

[0063] In this step, the probe card 30 is installed in the mounting area below the large cover plate 20 and can be fixed by a mechanical clamp. The probe card 30 and the large cover plate 20 cooperate to form a test module, with the probes 31 of the probe card 30 pointing downwards towards the working disk 50 area.

[0064] The wafer under test 40 is loaded onto the working disk 50 via a wafer transfer mechanism and stably fixed on the surface of the working disk 50 by vacuum adsorption. The wafer under test 40 is typically a semiconductor wafer containing multiple chip units (dies), and its surface is arranged with an array of pads for testing.

[0065] In this step, at least five chip cells are selected from the wafer 40 to be tested. Preferably, the selected chip cells are distributed in the edge region of the wafer to improve the coverage of the overall flatness assessment. For a specific example, refer to... Figure 4 When the wafer under test 40 has a circular layout, the selected at least five chip cells may include equally spaced chip cells evenly distributed on the circumference; in addition, when the wafer under test 40 has a rectangular layout, the selected at least five chip cells may include chip cells located in the four corner regions of the rectangle.

[0066] For each selected chip cell, at least one pad within it is further selected as a three-dimensional position reference point. Preferably, pads with the same structural position within the chip cell can be selected (e.g., the first pad in the upper right corner) to ensure consistency of the acquired data. In this step, the coordinates of the selected chip cell and the internal position of the selected pad within the chip cell must be recorded.

[0067] S300: The probe camera acquires the three-dimensional position information of the probe corresponding to the reference point, and calculates the flatness of the probe card based on the three-dimensional position information of the probe corresponding to the reference point.

[0068] In this step, the probe camera in the probe station sequentially detects the probes corresponding to each reference point. Based on the one-to-one correspondence between the pad layout and the probe card design, the placement of the probes corresponding to each reference point on the probe card is predetermined. Therefore, the position of each target probe can be directly located and detected.

[0069] The probe camera can acquire the three-dimensional position information of each target probe in the machine coordinate system, especially its height value in the Z-axis direction. After the probe camera completes the acquisition of the three-dimensional position information of all probes, the flatness of the probe card 30 at the current position is evaluated by analyzing the height difference of each probe in the vertical direction. In some embodiments, the flatness of the probe card 30 can be calculated by measuring the Z-coordinate difference between the highest and lowest points of the measured probes, typically in micrometers.

[0070] After collecting probe height information corresponding to all reference points, plane fitting is performed based on the Z-axis coordinates to calculate the current flatness of the probe card. The flatness can be calculated by fitting a reference plane to all probe Z-coordinate points (e.g., fitting the plane equation using the least squares method), and then using the height difference between the highest and lowest points on that plane as the flatness evaluation value.

[0071] If the calculated flatness is less than or equal to the second preset value (e.g., 20 micrometers), the orientation of the probe card 30 is considered to meet the calibration requirements, and the calibration process can be terminated; otherwise, proceed to step S400 to perform the adjustment operation.

[0072] S400, when the flatness is greater than the second preset value, fit the plane equation formed by the probe corresponding to the reference point, and calculate the height adjustment value of the plurality of adjustable points according to the plane equation.

[0073] In this step, when the calculated flatness of the probe card 30 is greater than the second preset value, the reference plane where the probe tip is located will be fitted based on the previously collected probe three-dimensional position information.

[0074] Specifically, the least squares method can be used to fit the three-dimensional coordinate data of the probes corresponding to all reference points to obtain the plane equation z = Ax + By + C describing the current distribution state of the probe tips, where A and B represent the slopes of the fitted plane in the X and Y directions, respectively, and C is the height offset. The coordinate data comes from the spatial measurement results of the probes corresponding to the aforementioned reference points.

[0075] After fitting, the adjustment amount of each adjustable point on the large cover plate 20 is calculated according to the plane equation. As a specific example, if the large cover plate 20 is provided with three adjustable points 21, 22, and 23 and one fixed reference point 24, the specific calculation method is as follows: Substitute the known coordinates of the fixed reference point 24 and the three adjustable points 21, 22, and 23 in the X and Y directions into the fitted plane equation to obtain the theoretical Z-axis height value corresponding to each point. Using the Z-axis value at the fixed reference point 24 as a reference, it is compared with the Z-values ​​calculated from the three adjustable points to obtain the height difference between each adjustable point and the reference point, which is the required height adjustment value. This height difference is the theoretical target based on which the subsequent adjustment mechanism performs the lifting action.

[0076] S500, perform height adjustment of the adjustable point according to the height adjustment value.

[0077] In this step, the height adjustment values ​​of each adjustable point obtained in step S400 are converted into corresponding control signals to perform height adjustment of the adjustable points.

[0078] In some embodiments, each adjustable point is connected to an independent adjustment motor, which can convert the target height adjustment value into a corresponding pulse equivalent based on the motor's step resolution, thereby controlling the movement of the corresponding motor.

[0079] It is understandable that after adjusting the height of the adjustable site in step S500, the adjustment effect needs to be verified to ensure that the actual posture of the probe card 30 reaches the expected state. Therefore, after executing step S500, the process may further include: re-acquiring the three-dimensional position information of the probe corresponding to the reference point and comparing it with the second preset value.

[0080] If the flatness of the current probe card 30 is less than or equal to the second preset value, it means that the attitude adjustment of the probe card 30 has met the standard and the horizontal calibration process can be terminated; if the flatness of the probe card 30 is greater than the second preset value, steps S400 to S500 can be executed again for further adjustment until the calibration accuracy requirements are met.

[0081] Compared to existing technologies, the probe card horizontal calibration method provided in this disclosure is based on image recognition and three-dimensional space fitting technology. It can automatically obtain the probe position, quickly determine the flatness of the probe card, and achieve rapid leveling through automatic control, thereby improving the consistency of contact between the probe card and the wafer pad and significantly improving the test accuracy and efficiency.

[0082] like Figure 5 As shown, in one aspect of this disclosure, a probe card level calibration apparatus is provided. The apparatus includes: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor, the instructions being executed by the at least one processor to enable the at least one processor to perform the method steps described in the above embodiments.

[0083] This disclosure provides a non-volatile computer storage medium storing computer-executable instructions that can perform the steps described in the above embodiments.

[0084] The transmission device may include a processing device (e.g., a central processing unit) 401, which can perform various appropriate actions and processes according to a program stored in read-only memory (ROM) 402 or a program loaded from storage device 408 into random access memory (RAM) 403. The RAM 403 also stores various programs and data required for the operation of the transmission device. The processing device 401, ROM 402, and RAM 403 are interconnected via bus 404. An input / output (I / O) interface 405 is also connected to bus 404.

[0085] Typically, the following devices can be connected to I / O interface 406: input devices 406 including, for example, touch screen, touchpad, keyboard, mouse, camera, microphone, etc.; output devices 407 including, for example, liquid crystal display (LCD), speaker, etc.; storage devices 408 including, for example, magnetic tape, hard disk, etc.; and communication devices 409.

[0086] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems or apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.

[0087] The above embodiments are only used to illustrate the technical solutions of this disclosure, and are not intended to limit it. Although this disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this disclosure.

Claims

1. A method for horizontal calibration of a probe card, characterized in that, Includes the following steps: Place the large cover plate in the initial position, using the upper surface of the working disk as the calibration reference plane, so that the flatness of the large cover plate relative to the working disk is less than a first preset value. The large cover plate is provided with multiple adjustable points and at least one fixed reference point. A probe card is mounted on the large cover plate, and the wafer to be tested is mounted on the work plate; at least five chip units are selected on the wafer to be tested, and the selected chip units are distributed in the edge area of ​​the wafer to be tested, and at least one pad is selected in each selected chip unit as a reference point; The probe camera acquires the three-dimensional position information of the probe corresponding to the reference point, and calculates the flatness of the probe card based on the three-dimensional position information of the probe corresponding to the reference point. When the flatness is greater than the second preset value, a plane equation formed by the probe corresponding to the reference point is fitted, and the height adjustment value of the plurality of adjustable points is calculated based on the plane equation. as well as The height of the adjustable point is adjusted according to the height adjustment value.

2. The probe card horizontal calibration method according to claim 1, characterized in that, The large cover plate has three adjustable points and one fixed reference point. The large cover plate has a rectangular structure, and the adjustable points and the fixed reference point are respectively located in the four corner areas of the large cover plate.

3. The probe card horizontal calibration method according to claim 1, characterized in that, The plurality of adjustable points are respectively connected to an adjustment motor, which is used to drive the large cover plate to adjust its posture in the vertical direction.

4. The probe card horizontal calibration method according to claim 1, characterized in that, The calibration process ends when the flatness is less than or equal to the second preset value.

5. The probe card horizontal calibration method according to claim 1, characterized in that, In the step of placing the large cover plate in the initial position, where the flatness of the large cover plate relative to the working plate is less than a first preset value, the flatness of the large cover plate relative to the working plate is detected by a mechanical dial indicator.

6. The probe card horizontal calibration method according to claim 5, characterized in that, When the wafer under test has a rectangular layout, the selected at least five chip units include chip units located at the four corners of the rectangle; When the wafer under test has a circular layout, the selected at least five chip cells include chip cells that are equally spaced on the circumference.

7. The probe card horizontal calibration method according to claim 1, characterized in that, The first preset value is 100 micrometers, and the second preset value is 20 micrometers.

8. The probe card horizontal calibration method according to claim 1, characterized in that, After the step of performing height adjustment of the adjustable point according to the height adjustment value, the method further includes: Repeat the step of acquiring the three-dimensional position information of the probe corresponding to the reference point using the probe camera.

9. A probe card horizontal calibration device, characterized in that, include: processor; as well as Memory for storing the executable instructions of the processor; The processor is configured to perform the probe card horizontal calibration method according to any one of claims 1-8 by executing the executable instructions.

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