Test methods, devices under test, probe cards, and probe systems for microbump testing

Abstract

A testing method for microbump testing includes a device under test (DUT) comprising a first bump unit configured to transmit power or ground signals and a second bump unit configured to transmit test signals. Both the first and second bump units have a plurality of clustered microbumps, or one of them may have only a single, larger bump. The second bump unit's plurality of microbumps includes selected microbumps and simulated microbumps. A testing device comprising a stage and a probe card is provided, wherein the probes of the probe card have substantially the same probe body dimensions. The DUT is placed on the stage, and the probes of the probe card are used to test the DUT. This invention reduces the manufacturing difficulty and cost of the probe card, as well as the difficulty of on-machine testing; avoids overly complex DUT designs; and avoids problems with probe flatness caused by varying probe wear.

Description

Test method, device under test, probe card and probe system for microbump testing The present invention relates to a micro-bump testing technology, and in particular to a testing method, a tested device, a probe card and a probe system for micro-bump testing. As system-in-package (SIP) technology becomes increasingly important, 2.5D / 3D stacking package technology is gaining increasing attention in the electronics market. Chiplets or interposers utilize microbumps for 2.5D / 3D stacking, leading to an increasing demand for microbump testing. Because each device under test has a large number of microbumps, each with a very small size (approximately 10-30µm in diameter) and a center-to-center spacing (approximately 25-60µm), directly contacting the microbumps with probe cards for testing is difficult and expensive to manufacture, and also poses practical challenges for on-device testing. Therefore, the current testing method primarily uses sacrificial pads (also known as schemed pads), which design additional contact pads (with a larger center-to-center spacing, such as 80-180µm) to allow the probes to make electrical contact. However, this testing method not only wastes available chip area but also negatively impacts high-frequency / high-speed testing. Currently, the industry is attempting to design additional sacrificial bumps (also known as schemed bumps) to allow for electrical contact between the probes. This approach reduces the difficulty of probe card production and on-chip testing by increasing bump size and center-to-center spacing. However, this approach also wastes available chip real estate and is limited by the available trace space and number. The industry is also experimenting with a different testing method called selected bump testing, which tests only certain microbumps rather than all of them. While this method allows for a wider center-to-center spacing between probes on the probe card, it still presents challenges testing very small bumps. Furthermore, this method complicates the design of the device under test, making it difficult to adopt universally. Since the majority of the microbumps on each device under test are power microbumps that transmit power signals and ground microbumps that transmit ground signals, a testing method in which a single probe contacts multiple power microbumps and / or ground microbumps can be used. This significantly reduces the number of probes on the probe card, thereby reducing the cost of the probe card. However, in addition to the power microbumps and / or ground microbumps, each device under test also has a smaller number of test microbumps for inputting and outputting test signals. If a single probe is still used to contact a single test microbump, a hybrid probe method is required. This means that two or more probe types are used on the same probe card, so that the probe contacting multiple power microbumps and / or ground microbumps generates a greater contact force, while the probe contacting a single test microbump generates a smaller contact force. However, when using at least two different probe types on the same probe card, due to the different wear rates of the probes of different probe types, the probe card is prone to poor probe planarity after a period of use, meaning that the probe tips are not located on the same horizontal plane. In view of the above-mentioned deficiencies, the main purpose of the present invention is to provide a test method, a device under test, a probe card and a probe system for micro-bump testing, which can reduce the difficulty and cost of manufacturing the probe card and the difficulty of on-machine testing, and avoid the design of the device under test being too complicated, and avoid the use of mixed needles, thereby avoiding the problem of poor probe flatness caused by different wear amounts of probes of different needle types. To achieve the above-mentioned object, the present invention provides a test method for microbump testing, which uses a probe card in a probe system to test a device under test having a plurality of microbumps. The steps of the test method include: providing a device under test, the device under test including a first bump unit for transmitting a first signal, and a second bump unit for transmitting a second signal, the first signal being one of a power signal and a ground signal, and the second signal being a test signal different from the power signal and the ground signal, and the device under test having one of the following three configurations: the device under test is configured such that the first bump unit includes a plurality of first microbumps clustered together, and the second bump unit includes a plurality of second microbumps clustered together, the number of first microbumps of the first bump unit is the same as the number of second microbumps of the second bump unit, the first microbumps are all configured to transmit the first signal, and the second microbumps include at least one selected microbump configured to transmit the second signal. The device under test is configured such that the first bump unit includes a plurality of first micro-bumps clustered together, and the second bump unit includes only a single second bump, the area of ​​the second bump is larger than the area of ​​the single first micro-bump, the first micro-bumps are all configured to transmit the first signal, and the second bumps are configured to transmit the second signal; and the device under test is configured such that the first bump unit includes only a single first bump, and the second bump unit includes a plurality of second micro-bumps clustered together, the area of ​​the first bump is larger than the area of ​​the single second micro-bump, the first bumps are configured to transmit the first signal, the second micro-bumps include at least one selected micro-bump configured to transmit the second signal, and at least one dummy micro-bump that is unable to transmit the second signal outside the second bump unit; A testing device is provided, which includes a carrier and the probe card, the probe card includes a plurality of probes, each probe includes a needle head located at one end thereof and used to touch the device under test, a needle tail located at the other end of the probe, and a needle body located between the needle head and the needle tail, and the needle body portions of the plurality of probes have substantially the same size; and the device under test is placed on the carrier of the testing device, and the device under test is tested by contacting the probe of the probe card with the device under test. During the test, the first bump unit is only contacted by one of the plurality of probes, and the second bump unit is only contacted by another one of the plurality of probes. The device under test for micro-bump testing provided by the present invention is the device under test provided in the aforementioned testing method. In this way, the power micro-bumps for transmitting power signals and the ground micro-bumps for transmitting ground signals on the device under test can be configured according to the aforementioned first bump unit. That is, a plurality of power micro-bumps or ground micro-bumps (i.e., first micro-bumps) are grouped together to form a first bump unit, so that the same probe can be used to simultaneously contact the plurality of first micro-bumps of the same first bump unit to provide power signals or ground signals to the circuits respectively corresponding to them; or the plurality of first micro-bumps can be replaced with a larger first bump, so that a probe can be used to contact the first bump to provide power signals or ground signals to the circuits respectively corresponding to the original plurality of first micro-bumps. As for the test microbumps on the device under test used to transmit test signals, since their number is relatively small, they can be configured according to the aforementioned second bump unit configuration. That is, additional microbumps (i.e., dummy microbumps) are added near the test microbumps (i.e., selected microbumps) actually used to transmit test signals to form a second bump unit. The same probe can be used to simultaneously contact multiple second microbumps (including selected microbumps and dummy microbumps) of the same second bump unit to provide test signals to the circuit corresponding to the selected microbump. In this way, the dummy microbumps can withstand part of the probe contact force, thereby allowing the needle pressure exerted on the selected microbump to be the same as the needle pressure exerted on the first microbump or first bump. Alternatively, the dummy microbump can be omitted and the selected microbump can be replaced with a larger second bump, so that the needle pressure exerted on the second bump can be the same as the needle pressure exerted on the first microbump. In this way, the probe card can be equipped with a smaller number of probes, and the probes can have a larger center-to-center spacing, and each probe is used to contact multiple microbumps or a single larger bump. Therefore, the difficulty of manufacturing the probe card, the cost and the difficulty of on-machine testing will be lower, and the design of the device under test will not be too complicated. In addition, the needle body dimensions of the probes of the probe card are substantially the same, which means that the needle body dimensions of the probes are substantially the same in structure and / or length, width and thickness, and / or cross-sectional area. For example, the needle body dimensions of the probes can be substantially the same in structure, length, width, thickness, cross-sectional area, etc., so that the probes can generate substantially the same probe contact force and wear. Of course, in addition to the same needle body, the needle head and / or needle tail dimensions of the probes can also be substantially the same, but the influence of these two parts on the probe contact force is relatively small. In other words, the present invention can avoid the use of mixed needles, thereby avoiding the problem of poor probe flatness that may be caused by different wear amounts of probes of different needle types. Among them, avoiding the use of mixed needles means that all identical probes are used, or at least all probes with substantially identical needle body dimensions are used. The identical probes include a needle head, a needle tail, and a needle body that are substantially identical in structure and / or substantially identical in length, width, thickness, and / or substantially identical in cross-sectional area. For example, the structure, length, width, thickness, cross-sectional area, etc. are substantially identical.Although the above description uses the concept of “the probe pressures on the microbumps are the same”, a person skilled in the art may also understand this as “the contact forces applied by the probes to the microbumps are the same”. Preferably, the probe tips of the plurality of probes have the same cross-sectional area. This allows the probe tips to exert the same contact force on the first and second bump units on the device under test and to experience the same degree of wear, thereby preventing the probe card from experiencing poor probe flatness after a period of use. Preferably, each probe is either a straight needle or a curved needle. Thus, the present invention is applicable to vertical probes, which extend generally vertically but have a curved shaft that allows for slight elastic deformation when contacting the device under test. The vertical probes can be straight needles that are manufactured, with the bending of the shaft occurring due to misalignment of the probe base's guide plate during installation. Alternatively, the vertical probes can be curved needles (commonly known as cobras) that are manufactured to be curved. The present invention can employ either straight or curved needles depending on the intended use. Preferably, the device under test is configured so that when the first bump unit and the second bump unit are contacted by the probe tip, the first bump unit and the second bump unit are subjected to the same probe pressure. For example, when the first bump unit includes a plurality of first microbumps and the second bump unit includes a plurality of second microbumps, the number of first microbumps and the number of second microbumps are the same, so that the first bump unit and the second bump unit are subjected to the same probe contact force applied by the probe with equal areas, thereby causing the first bump unit and the second bump unit to be subjected to the same probe pressure. Alternatively, when one of the first and second bump units includes a plurality of microbumps and the other includes a larger single bump, the number, spacing, and / or area of ​​the microbumps can be designed to match the area of ​​the larger single bump so that the first bump unit and the second bump unit are subjected to the same probe pressure. In this way, the probe card can produce consistent probe test performance and avoid the problem of poor probe flatness caused by different probe wear. Preferably, the first bump unit has a first top surface for contact with the probes of the probe card, and the second bump unit has a second top surface for contact with the probes of the probe card, with the first and second top surfaces being located substantially on the same horizontal plane. Thus, regardless of whether the first and second bump units each include multiple microbumps or only a single, larger bump, their top surfaces are substantially located on the same horizontal plane. This allows the probe tips to simultaneously contact the desired bumps and / or microbumps, thereby achieving consistent probe testing performance and avoiding issues with poor probe flatness due to varying probe wear. Preferably, the dummy microbumps of the second bump unit are substantially the same size as the selected microbumps. Thus, since most microbumps on the device under test are substantially the same size, when additional microbumps (i.e., dummy microbumps) are added near the test microbump (i.e., the selected microbump), the dummy microbumps are made substantially the same size as the selected microbumps. This maintains the consistency of microbump sizes on the device under test, resulting in a simpler design and easier microbump placement. Furthermore, the probe contact force is more evenly distributed, facilitating consistent probe testing performance. Preferably, there is no electrical connection between the dummy micro-bumps and the selected micro-bumps of the second bump unit. In other words, the dummy micro-bumps are only configured to share the probe contact force with the selected micro-bumps and do not have any signal transmission function. This can reduce the number of circuits in the device under test and make it easier to design and manufacture. However, the dummy micro-bumps and the selected micro-bumps can also be electrically connected to each other, so that the dummy micro-bumps can also receive the test signal transmitted by the probe. Although it cannot be transmitted outside the second bump unit to which it belongs, it can be transmitted to the selected micro-bumps of the second bump unit to which it belongs. This can improve the stability of the second bump unit in transmitting the test signal. Preferably, the probes of the probe card are configured so that when contacting the device under test to test the device under test, the multiple probes provide the same probe contact force, so that the bumps and microbumps on the device under test are subjected to the same probe pressure, and the problem of poor probe flatness caused by different probe wear can be avoided. Preferably, the probe tips of the plurality of probes have substantially the same cross-sectional shape, thereby generating consistent probe testing performance. More preferably, the cross-sectional shape of the needle heads of the plurality of probes is one of circular and rectangular, so as to facilitate contact with bumps and / or micro-bumps on the device under test. Preferably, the needle body of the probe includes at least one slit, which penetrates the needle body along a first transverse axis, so that the needle body is defined by the at least one slit into at least two arms, and the at least two arms are separated from each other along a second transverse axis, and the needle body is bent along the second transverse axis. The slit thus weakens the rigidity of the probe shaft, reducing the contact force applied by the probe to the device under test, thereby preventing damage to the bumps and / or microbumps of the device under test due to excessive probe contact force. For high-frequency and high-speed testing, shorter probes are often used to achieve good electrical transmission characteristics. Shorter probes have higher rigidity and contact force, and in this case, the slit can be used to reduce the probe contact force. Furthermore, the slit enhances the elasticity of the probe shaft, ensuring the elastic deformation of the probe shaft along the second transverse axis. Preferably, the plurality of probes include a first probe and a second probe, the cross-sectional area of ​​the needle head of the second probe is smaller than the cross-sectional area of ​​the needle head of the first probe. During the test, the needle head of the first probe contacts the plurality of first microbumps simultaneously, and the needle head of the second probe contacts only a single second microbump. Thus, even if the needle head of the second probe is sized to contact only a single second micro-bump, the first and second probes still meet the aforementioned condition of substantially identical needle body dimensions. This allows the first and second probes to generate substantially identical probe contact forces, resulting in substantially identical probe wear, thereby avoiding the problem of poor probe flatness. More preferably, the projection range of the needle body of the second probe covers the plurality of second micro-bumps. Thus, even if the tips of the first and second probes contact different numbers of microbumps, the projections of the body portions of the first and second probes still correspond to the same number of microbumps. Therefore, the arrangement of the second microbumps can be the same as that of the first microbumps. This allows the microbumps of the device under test to maintain a neat arrangement, such as a matrix arrangement, resulting in a simple and consistent microbump design for the device under test. Preferably, in the configuration of the device under test, the plurality of first micro-bumps are four first micro-bumps arranged in a 2×2 array; and the plurality of second micro-bumps are four second micro-bumps arranged in a 2×2 array. Thus, when the probe tip contacts the four first microbumps of the first bump unit and the four second microbumps of the second bump unit, each of the first and second microbumps corresponds to a corner of the probe tip (hereinafter referred to as a corner microbump), rather than the first and second microbumps corresponding to the center of the probe tip. In a 2x2 array, the corner microbumps are more clearly positioned and easier to locate. The probe design can be fine-tuned and optimized for corner locations, improving probe-microbump docking accuracy, particularly when only corner microbumps need to be tested. Furthermore, within the same area, the distance between microbumps in a 2x2 array is relatively large (compared to arrangements with a larger number of microbumps, such as a 3x3 array). This reduces the risk of signal interference between adjacent microbumps. For precision testing, this configuration helps improve measurement accuracy, especially when the test signal is sensitive to interference between adjacent microbumps. The probe card for microbump testing provided by the present invention is used in a probe system and is used to test a device under test having a plurality of microbumps. The probe card includes a main circuit board, a space converter, and a probe head, wherein the probe head and the main circuit board are arranged on two opposite sides of the space converter. The probe head includes at least one guide plate unit and a plurality of probes, wherein the guide plate unit is provided with a plurality of guide holes, and the probes are slidably inserted into the guide holes. Each probe includes a needle head located at one end thereof and used to touch the device under test, a needle tail located at the other end, and a needle body located between the needle head and the needle tail. The needle body portions of the plurality of probes are substantially the same in size, and the needle tail portions of the probes are electrically connected to the space converter. The device under test is the device under test as described above. When the probe card tests the device under test, the device under test is placed on a carrier of the probe system, the first bump unit is contacted by only one of the plurality of probes, and the second bump unit is contacted by only another one of the plurality of probes. Thus, the probe card can be used in the aforementioned test method and can achieve the aforementioned effect. Such a probe card can reduce the difficulty, cost and difficulty of on-machine testing, avoid the design of the device under test being too complicated, and avoid the use of mixed needles, thereby avoiding the problem of poor probe flatness caused by different wear amounts of probes of different needle types. The probe system for microbump testing provided by the present invention is configured to test a device under test having a plurality of microbumps. The probe system includes a carrier configured to carry the device under test, a probe card as described above, a visual device, and a signal generating and analyzing device. The visual device is configured to capture an optical image of at least a portion of the probe system, and the signal generating and analyzing device is configured to provide a test signal to the device under test and / or receive a result signal from the device under test. In this way, the optical image captured by the visual device can be used to selectively change the relative position of the probe tips of the probe card and the carrier, so that the probe tips contact the bumps and / or micro-bumps of the device under test. The signal generation and analysis device then provides test signals to the device under test and / or receives result signals from the device under test through the probe card. Such a probe system can be used to execute the aforementioned test method, thereby testing the device under test and achieving the aforementioned effect. The detailed structure, features, assembly, and use of the test method, device under test, probe card, and probe system for microbump testing provided by the present invention will be described in the detailed description of the embodiments that follow. However, those skilled in the art will appreciate that the detailed description and the specific embodiments listed for implementing the present invention are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. The applicant first explains that in the embodiments and drawings to be introduced below, the same reference numbers represent the same or similar elements or their structural features. It should be noted that the elements and structures in the drawings are for illustrative purposes only and are not drawn according to actual proportions and quantities. Moreover, if practically possible, the features of different embodiments can be applied interchangeably. Secondly, when it is mentioned that an element is disposed on another element, it means that the aforementioned element is directly disposed on the other element, or the aforementioned element is indirectly disposed on the other element, that is, one or more other elements are disposed between the two elements. When it is mentioned that an element is "directly" disposed on another element, it means that no other elements are disposed between the two elements. Referring first to FIG1 , a probe system 10 for microbump testing according to a first preferred embodiment of the present invention includes a test apparatus 20, a visual device 12, and a signal generating and analyzing device 16. The test apparatus 20 includes a carrier 21 and a probe card 22. A wafer 30 is placed on the carrier 21, and a plurality of devices under test 31 are formed on the wafer 30. The probe card 22 includes a main circuit board 221, a space transformer 222, and a probe head 40. The main circuit board 221 and the probe head 40 are disposed on opposite sides of the space transformer 222. The probe head 40 includes an upper guide plate unit 41, a lower guide plate unit 42, and a plurality of probes 43 extending through the upper and lower guide plate units 41 and 42. Referring to Figures 2 and 3, the upper guide plate unit 41 includes a plurality of upper guide holes 411, and the lower guide plate unit 42 includes a plurality of lower guide holes 421. The probes 43 are slidably disposed through the upper and lower guide holes 411 and 421. To simplify the diagrams and facilitate illustration, Figures 2 and 3 only show one upper guide hole 411, one lower guide hole 421, and one probe 43. Figures 2 and 3 respectively illustrate two probes with different structural types, which can be selected based on different usage requirements. Both probes are not intended to be provided simultaneously in the same probe card 22. The probe 43 includes a probe head 431 at one end, a probe tail 432 at the other end, and a probe body 433 located between the probe head 431 and the probe tail 432. The probe head 431 is inserted through the lower guide hole 421 to contact the device under test 31. The probe tail 432 is inserted through the upper guide hole 411 to abut against the contact pad on the lower surface of the space transformer 222, thereby electrically connecting to the space transformer 222. This allows the probe 43 to be electrically connected to the signal generating and analyzing device 16 through the space transformer 222 and the main circuit board 221. Specifically, by capturing an optical image of at least a portion of the probe system 10 using the visual device 12, the relative position of the probe head 431 of the probe 43 of the probe card 22 and the carrier 21 can be determined. This relative position can then be selectively changed so that the probe head 431 of the probe 43 contacts the bumps and / or microbumps (described in detail below) of the device under test 31. The signal generation and analysis device 16 then provides a test signal to the device under test 31 and / or receives a result signal from the device under test 31 via the probe card 22, thereby testing the device under test 31. The probe body 433 is located between the upper and lower guide plate units 41 and 42 and is typically designed to deform slightly elastically when the probe 43 contacts the device under test 31, as described in detail below. According to certain embodiments of the present invention, such as those shown in FIG. 2 and FIG. 3 , each probe 43 included in the probe head 40 may be a "buckling beam" probe, which is what is known in the art. That is, the shaft portion 433 of the probe 43 may have a constant transverse cross-section (e.g., substantially rectangular, preferably square or rectangular) along its entire length, wherein the shaft portion 433 is adapted to bend and / or flex at a substantially central position, thereby deforming during testing of the device under test 31. However, in certain other embodiments, the shaft portion 433 of each probe 43 does not necessarily have a constant transverse cross-section along its entire length. The term "substantially rectangular" as used herein refers to a rectangle and other possible results that may be produced to produce a rectangular transverse cross-section of the probe shaft, such as a trapezoid. More specifically, a person skilled in the art of the present invention should understand that even if the equipment used to manufacture the probe 43 is designed to produce a probe having a rectangular transverse cross-section, the transverse cross-section of the probe 43 actually produced may still have certain tolerances or manufacturing errors, resulting in the transverse cross-section of the probe shaft 433 of the probe 43 not being a geometrically perfect rectangle in some embodiments. The probe 43 applicable to the present invention may include at least a straight probe (as shown in FIG2 ) or a bent probe (or pre-bent probe) (as shown in FIG3 ). A straight probe refers to a probe 43 that is straight upon manufacture, and the curvature of its needle body 433 is produced by the lateral misalignment of the upper and lower guide plate units 41 and 42 when the probe is installed on the upper and lower guide plate units 41 and 42. A bent probe refers to a probe 43 that is curved upon manufacture, that is, its needle body 433 is originally curved and does not require the lateral misalignment of the upper and lower guide plate units 41 and 42. More specifically, a straight probe may be, for example, a forming wire (FW) or a microelectromechanical probe (MEMS wire, MW). A pre-bent probe may be, for example, a cobra probe or a microelectromechanical probe with a pre-bent needle body. As shown in FIG4 , the needle head 431 of each probe 43 (only the needle heads 431 of six probes 43 are schematically shown in FIG4 ) is configured to abut against a bump (described in detail below) of a device under test 31 integrated in the semiconductor wafer 30 . When a load is applied to each probe 43 (for example, the bottom end of each probe 43 contacts the corresponding bump and is subjected to force during testing of the device under test 31 ), the needle body 433 of each probe 43 can deflect and deform in an arc shape along its longitudinal development axis. It should be noted that when probe 43 is used to test device 31, probe head 431 of probe 43 contacts the bump of device 31 and then moves closer to each other by a test stroke (overdrive, OD) or overtravel, OT). This causes the probe shaft 433 of probe 43 to be compressed and deformed. Furthermore, probe head 431 of probe 43 presses against the bump of device 31. During this period, the force applied by probe 43 to the bump of device 31 is defined as the probe contact force in the present invention. The greater the probe contact force, the lower the contact resistance between probe 43 and the bump of device 31. The probe contact force is measured by applying OD / OT to probe 43, causing the probe shaft 433 to bend and deform. The force applied by probe 43 to a force sensor is then measured. Specifically, the probe contact force includes probe deformation force and probe friction force. The probe deformation force refers to the force required to elastically deform the probe 43 during the aforementioned test stroke. The probe deformation force depends on many factors, such as the material properties of the probe 43 (e.g., Young's modulus, elastic modulus), the final geometry and dimensions of the probe 43 (e.g., length, thickness, width, etc.). The probe friction force refers to the frictional force exerted on the probe 43 by the walls of the upper guide via 411 and / or the lower guide via 421. The probe contact force steadily pushes the tail 432 of the probe 43 against the contact pad of the space transformer (ST) 222, thereby buckling the shaft 433 of the probe 43. This creates an electrical connection between the probe 43 and the bump of the device under test 31, thereby establishing an electrical connection from the bump of the device under test 31 to the tester through the probe 43. The following describes the testing method provided by the present invention and further describes the bump configuration of the device under test 31. Referring to Figures 4 to 6, the testing method includes the following steps a) to c). a) A device under test 31 is provided. The device under test 31 has a chip connection surface and a microbump array composed of a plurality of microbumps on the chip connection surface. The microbump array includes a first bump unit 33 for transmitting a first signal and a second bump unit 35 for transmitting a second signal. The first signal is one of a power signal (e.g., a chip package power bus PWR) and a ground signal (e.g., a chip package ground bus GND). The second signal is a test signal (e.g., a chip package data signal bus I / O) that is different from the power signal and the ground signal. Furthermore, the device under test 31 in this embodiment is configured such that the first bump unit 33 includes four first microbumps 331 clustered together, i.e., formed in a 2×2 array, and the second bump unit 35 includes four second microbumps 351 clustered together, i.e., formed in a 2×2 array. The number of first microbumps 331 in the first bump unit 33 is the same as the number of second microbumps 351 in the second bump unit 35, and the number can be plural, such as two, three, four, or more. The first microbumps 331 are all configured to transmit a first signal, i.e., the four first microbumps 331 collectively transmit a power signal or a ground signal. The second microbumps 351 include at least one selected microbump 351A configured to transmit a second signal, and at least one dummy microbump 351B that is unable to transmit the second signal outside the second bump unit 35. In this embodiment, the four second micro-bumps 351 include only one selected micro-bump 351A, and the remaining three are dummy micro-bumps 351B. As shown in FIG1 , a device under test 31 is formed on a wafer 30. To simplify the diagram and facilitate explanation, FIG1 schematically illustrates only the device under test 31, without showing the first and second microbumps 331 and 351 on the device under test 31. FIG4 also schematically illustrates only one device under test 31 on the wafer 30. In reality, the device under test 31 has a significant number of bump units. FIG4 and FIG5 schematically illustrate only six bump units, two of which are the first and second bump units 33 and 35 described above. The remaining bump units can be similar to the first bump unit 33, used to transmit power or ground signals, or can be similar to the second bump unit 35, used to transmit test signals. It should be noted that the first and second microbumps 331, 351 and / or the first and second bumps 333, 353 (described in detail below) on the device under test 31 of the present invention may have been formed on the wafer 30 when the wafer 30 is manufactured. Alternatively, a redistribution layer may be formed on the surface of the wafer 30 after the wafer 30 is manufactured, and the first and second microbumps 331, 351 and / or the first and second bumps 333, 353 may be arranged on the redistribution layer. b) Provide a test device 20, as shown in FIG1 . The probe card 22 in the test apparatus 20 provided by the present invention, in principle, does not use mixed probes. This avoids the problem of different probe types causing different wear due to different contact forces, which could lead to poor probe flatness. Because the shaft portion 433 accounts for a large proportion of the probe 43's length and has a significant impact on the probe contact force, the present invention only defines the shaft portions 433 of the probes 43 in the probe card 22 as having substantially identical dimensions. This means that the shaft portions 433 of the probes 43 have substantially identical structure, length, width, thickness, and / or cross-sectional area. For example, in this embodiment, at least the shaft portions 433 of the probes 43 are substantially identical in structure, length, width, thickness, and cross-sectional area. This allows the probes 43 to generate substantially identical probe contact forces and wear. In another embodiment, the probe card 22 may utilize all identical probes 43, for example, all probes 43 have substantially identical structure, length, width, thickness, and cross-sectional area. In the embodiment shown in FIG. 4 , the needle heads 431 of the probes 43 are identical, having the same cross-sectional area and the same cross-sectional shape (which may be circular or rectangular). c) The device under test 31 is placed on the carrier 21 of the test equipment 20, and the device under test 31 is tested by contacting the probes 43 of the probe card 22. During the test, the first bump unit 33 is contacted by only one of the probes 43, and the second bump unit 35 is contacted by only another one of the probes 43. In other words, the bump units configured on the device under test 31 are designed to allow all microbumps within the same bump unit to be contacted by the same probe 43, with each probe 43 contacting only one bump unit. Since the actual device under test 31 is typically equipped with a larger number of power microbumps and ground microbumps, and a smaller number of test microbumps, the power microbumps or ground microbumps are configured as the aforementioned first bump units 33, allowing the same probe 43 to simultaneously contact multiple first microbumps 331, thereby providing power or ground signals to their corresponding circuits. Since the test microbumps need to transmit different test signals respectively, the same probe 43 cannot contact multiple test microbumps at the same time. In order to make the needle pressure on the test microbump the same as that on the first microbump 331, the configuration of the second bump unit 35 is to add other microbumps (i.e., simulated microbump 351B) near the test microbump actually used to transmit the test signal (i.e., selected microbump 351A), so that the same probe 43 can contact the selected microbump 351A and the simulated microbump 351B at the same time, and then provide a test signal to the circuit corresponding to the selected microbump 351A. In this way, the simulated microbump 351B can bear part of the probe contact force, so that the needle pressure on the selected microbump 351A can be the same as that on the first microbump 331. As can be seen, the primary function of dummy microbump 351B is to share the probe contact force with the selected microbump 351A. Therefore, dummy microbump 351B and the selected microbump 351A do not need to be electrically connected. This eliminates the need for dummy microbump 351B to connect to any wiring, reducing the number of circuits in the device under test 31 and making it easier to design and manufacture. Dummy microbump 351B can be substantially the same size as the selected microbump 351A, ensuring consistent microbump size across the device under test 31. This results in a simpler design and facilitates microbump placement. It also distributes the probe contact force more evenly, facilitating consistent probe testing performance. Secondly, in another embodiment, the second bump unit 35 is configured so that the simulated microbump 351B and the selected microbump 351A are electrically connected to each other, for example, through wiring electrical connection, so that the simulated microbump 351B can not only bear part of the probe contact force but also receive the test signal transmitted by the probe 34. However, the simulated microbump 351B is configured so that it cannot transmit the test signal outside the second bump unit 35 to which it belongs, but can only transmit it to the selected microbump 351A of the second bump unit 35 to which it belongs, and then transmit the test signal to the outside of the second bump unit 35 to which it belongs through the selected microbump 351A. In this way, the stability of the second bump unit 35 in transmitting the test signal can be improved. 7 and 8 , a second preferred embodiment of the present invention provides another configuration of bumps of the device under test 31 . In this embodiment, the device under test 31 is configured such that the first bump unit 33 includes four clustered first micro-bumps 331, and the second bump unit 35 includes only a single second bump 353. The area of ​​the second bump 353 is larger than that of the single first micro-bump 331. The first micro-bumps 331 are configured to transmit a first signal, that is, to transmit a power signal or a ground signal. The second bump 353 is configured to transmit a second signal, that is, to transmit a test signal. In other words, the device under test 31 in this embodiment is similar to the device under test 31 in the first preferred embodiment, except that the second bump unit 35 in this embodiment does not share the probe contact force by additionally providing other microbumps near the test microbump, but instead replaces the test microbump with a larger second bump 353, so that the needle pressure exerted on the second bump 353 can be the same as the needle pressure exerted on the first microbump 331. 9 and 10 , a third preferred embodiment of the present invention provides another configuration of bumps of a device under test 31 . In this embodiment, the device under test 31 is configured such that the first bump unit 33 includes only a single first bump 333, and the second bump unit 35 includes four clustered second micro-bumps 351. The area of ​​the first bump 333 is larger than the area of ​​a single second micro-bump 351. The first bump 333 is configured to transmit a first signal, i.e., a power signal or a ground signal. The second micro-bumps 351 include at least one selected micro-bump 351A configured to transmit a second signal, and at least one dummy micro-bump 351B that is unable to transmit the second signal outside the second bump unit 35. In other words, the device under test 31 in this embodiment is similar to the device under test 31 in the first preferred embodiment, except that this embodiment replaces the multiple first micro-bumps 331 in the first preferred embodiment with a larger first bump 333. That is, the circuits corresponding to the original multiple first micro-bumps 331 are all connected to the first bump 333. As long as a probe 43 is used to contact the first bump 333, a power signal or a ground signal can be provided to these circuits. In this way, the needle pressure received by the second micro-bump 351 can be the same as the needle pressure received by the first bump 333. As shown in Figures 9 and 10, the first bump unit 33 has a first upper surface 335 for contact with the probe 43, that is, the top area of ​​the arc surface of the first bump 333; the second bump unit 35 has a second upper surface 355 for contact with the probe 43, that is, the top area of ​​the arc surface of each second micro-bump 351; the first upper surface 335 and the second upper surface 355 are substantially located on the same horizontal plane P, so that the needle head 431 of the probe 43 can simultaneously contact the bumps and / or micro-bumps it needs to touch, thereby producing consistent probe testing performance and avoiding the problem of poor probe flatness caused by different probe wear. Similarly, in the embodiments shown in Figures 8 and 6, the first upper surface 335 of the first bump unit 33 and the second upper surface 355 of the second bump unit 35 are also substantially located on the same horizontal plane P, which can also achieve the aforementioned effect. 11 to 13 , a fourth preferred embodiment of the present invention provides another probe configuration. The device under test 31 in this embodiment is the same as that shown in FIG. 5 . The plurality of probes in this embodiment have the same needle tail portion 432 and needle body portion 433 , but differ in the size of the needle head portion 431 . Specifically, the probes in this embodiment include a first probe 43A for contacting the first bump unit 33 and a second probe 43B for contacting the second bump unit 35. The cross-sectional area of ​​the shaft 433 and the head 431 of the first probe 43A is the same, equivalent to the area of ​​the projection range A1 of the head 431. The cross-sectional area of ​​the second probe 43B is gradually reduced by a tapered portion 436 between the shaft 433 and the head 431, resulting in a larger cross-sectional area of ​​the shaft 433 of the second probe 43B (equivalent to the area of ​​its projection range A2) than the cross-sectional area of ​​the head 431 (equivalent to the area of ​​its projection range A3). As can be seen from Figures 11 to 13 , the cross-sectional areas of the shafts 433 of the first and second probes 43A and 43B, as well as the head 431 of the first probe 43A, are identical, with their projections A1 and A2 covering four microbumps, respectively. However, the cross-sectional area of ​​the head 431 of the second probe 43B is smaller, with its projection A3 covering only one microbump. During the test, the head 431 of the first probe 43A simultaneously contacts all first microbumps 331 of the first bump unit 33, while the head 431 of the second probe 43B contacts only a single second microbump, specifically, microbump 351A. In other words, the probes of the present invention can have different sizes of their heads 431 while maintaining substantially the same size of their shafts 433. This allows the first and second probes 43A, 43B to generate substantially the same probe contact force, resulting in substantially the same amount of probe wear, thereby avoiding the problem of poor probe flatness. Furthermore, even if the heads 431 of the first and second probes 43A, 43B contact different numbers of microbumps, the second bump unit 35 can still be configured such that all of its second microbumps 351 are within the projection area A2 of the shaft 433 of the second probe 43B. This ensures that the projection areas A1 and A2 of the shaft 433 of the first and second probes 43A, 43B still correspond to the same number of microbumps. Therefore, the arrangement of the second microbumps 351 can be the same as that of the first microbumps 331. This allows the microbumps of the device under test 31 to maintain a neat arrangement, such as a matrix arrangement, resulting in a simple and consistent microbump design for the device under test 31. As shown in Figure 11 , the probe's shaft 433 in this embodiment includes two slits 434. Slits 434 extend along the longitudinal direction of the probe's shaft 433. That is, when the probe's shaft 433 is not yet bent or deformed, the slits 434 extend along a longitudinal axis (the Z axis). Furthermore, the slits 434 extend through the probe's shaft 433 along a first transverse axis (the Y axis). The two slits 434 define three thin, sheet-like arms 435 on the probe's shaft 433. These arms 435 are separated from each other along a second transverse axis (the X axis). These slits 434 weaken the rigidity of the probe's shaft 433, thereby reducing the probe's contact force and thereby preventing damage to the microbumps of the device under test 31 caused by excessive probe contact force. In addition, the needle body 433 originally extends linearly along the Z-axis. When the upper and lower guide plate units 41 and 42 are misaligned with each other along the X-axis, the needle body 433 bends along the X-axis into the state shown in Figure 11. When the needle head 431 contacts the test device 31 and is subjected to force, the needle body 433 can be further elastically bent along the X-axis. The aforementioned slit 434 can enhance the elasticity of the needle body 433 bending along the X-axis, ensuring the elastic deformation effect of the needle body 433 bending along the X-axis. In summary, the present invention provides a testing method, probe system 10, and device under test 31 for microbump testing, wherein the bumps and / or microbumps on the device under test 31 are configured so that each probe 43 of the probe card 22 contacts a plurality of microbumps or a single larger bump. This allows the probe card 22 to be equipped with a smaller number of probes 43 with a larger center-to-center spacing between the probes 43. This reduces the manufacturing difficulty, cost, and testing complexity of the probe card 22, and also reduces the complexity of the device under test 31 design. Furthermore, the probe card 22 can utilize substantially identical probes 43 throughout, thus avoiding the use of mixed probes. This avoids the problem of poor probe flatness that may result from varying wear on probes of different needle types. Finally, it must be reiterated that the constituent elements disclosed in the aforementioned embodiments of the present invention are merely illustrative and are not intended to limit the scope of the present invention. Replacements or modifications of other equivalent elements should also be covered by the scope of the patent application of this case. 10: Probe system 12: Vision device 16: Signal generation and analysis device 20: Test equipment 21: Carrier 22: Probe card 221: Main circuit board 222: Space transformer 30: Wafer 31: Device under test 33: First bump unit 331: First microbump 333: First bump 335: First top surface 35: Second bump unit 351: Second microbump 351A: Selected microbump 351B: Simulated microbump 353: Second bump 355: Second top surface 40: Probe head 41: Upper guide plate unit 411: Upper guide hole 42: Lower guide plate unit 421: Lower guide hole 43: Probe 43A: First probe 43B: Second probe 431: Head portion 432: Tail portion 433: Body portion 434: Slit 435: Arm portion 436: Tapered portion A1, A2, A3: Projection range P: Horizontal plane FIG1 is a schematic diagram of a probe system and a wafer for microbump testing provided by a first preferred embodiment of the present invention. FIG2 and FIG3 are schematic cross-sectional views of a probe head of a probe card of the probe system, respectively illustrating the use of straight and curved probes. FIG4 is a schematic perspective view of a device under test on the wafer and its corresponding probe. FIG5 is a schematic top view of the device under test. FIG6 is a schematic front view of the device under test and its corresponding probe. FIG7 is a schematic top view of the device under test for microbump testing provided by a second preferred embodiment of the present invention. FIG8 is a schematic front view of the device under test and its corresponding probe. FIG9 is a schematic top view of the device under test for microbump testing provided by a third preferred embodiment of the present invention. FIG10 is a schematic front view of the device under test and its corresponding probe. FIG11 is a schematic cross-sectional view of a probe head of a probe card for microbump testing provided by a fourth preferred embodiment of the present invention. FIG12 is a schematic front view of the device under test and its corresponding probe provided by the fourth preferred embodiment of the present invention. FIG13 is a schematic top view of the device under test, and schematically shows the projection ranges of the needle bodies and needle heads of the corresponding first and second probes. 30: Wafer 31: Device under test 33: first bump unit 331: first micro bump 35: Second bump unit 351: second micro bump 351A: Selected microbumps 351B: Simulated micro bumps 43: Probe 431: Needle head

Claims

1. A test method for microbump testing, comprising testing a device under test (DUT) having a plurality of microbumps using a probe card in a probe system, the test method comprising the steps of: providing the DUT, the DUT including a first bump unit for transmitting a first signal and a second bump unit for transmitting a second signal, the first signal being one of a power signal and a ground signal, the second signal being a test signal different from the power signal and the ground signal, the DUT having one of the following three configurations: The device under test is configured such that the first bump unit includes a plurality of first microbumps clustered together, and the second bump unit includes a plurality of second microbumps clustered together. The number of first microbumps in the first bump unit is the same as the number of second microbumps in the second bump unit. The first microbumps are all configured to transmit the first signal. The second microbumps include at least one selected microbump configured to transmit the second signal, and at least one simulated microbump that cannot transmit the second signal outside the second bump unit. The device under test is configured such that the first bump unit includes a plurality of first microbumps clustered together, and the second bump unit includes only a single second bump, the area of ​​which is larger than the area of ​​the single first microbump, the first microbumps being configured to transmit the first signal, and the second bump being configured to transmit the second signal; and the device under test is configured such that the first bump unit includes only a single first bump, and the second bump unit includes a plurality of second microbumps clustered together, the area of ​​which is larger than the area of ​​the single second microbump, the first bump being configured to transmit the first signal, and the second microbumps including at least one selected microbump configured to transmit the second signal, and at least one simulated microbump that cannot transmit the second signal outside the second bump unit; A testing apparatus is provided, comprising a platform and a probe card, the probe card comprising a plurality of probes, each probe comprising a head at one end for contacting the device under test, a tail at the other end, and a body between the head and the tail, the body portions of the probes being substantially the same size; and the device under test is placed on the platform of the testing apparatus, and the device under test is tested by contacting the device under test using the probes of the probe card, wherein during the test, a first bump unit is contacted only by one of the probes, and a second bump unit is contacted only by the other of the probes.

2. The test method for microbump testing as described in claim 1, wherein the probes have the same cross-sectional area at their tips.

3. The test method for microbump testing as described in claim 1, wherein each probe is one of a straight needle and a bent needle.

4. The test method for microbump testing as described in claim 1, wherein the device under test is configured such that when the first bump unit and the second bump unit are in contact with the tip of the probe, the first bump unit and the second bump unit are subjected to the same needle pressure.

5. The test method for microbump testing as described in claim 1, wherein the first bump unit has a first upper surface for contact with a probe of the probe card, the second bump unit has a second upper surface for contact with a probe of the probe card, and the first upper surface and the second upper surface are substantially on the same horizontal plane.

6. The test method for microbump testing as described in claim 1, wherein the simulated microbump of the second bump unit is substantially the same size as the selected microbump.

7. The test method for microbump testing as described in claim 1, wherein there is no electrical connection between the simulated microbump of the second bump unit and the selected microbump.

8. The test method for microbump testing as described in claim 1, wherein the probes of the probe card are configured to provide the same probe contact force when testing the device under test by contacting the device under test.

9. The test method for microbump testing as described in claim 1, wherein the probes have substantially the same cross-sectional shape at their tips.

10. The test method for microbump testing as described in claim 9, wherein the cross-sectional shape of the probe tip is either circular or rectangular.

11. The test method for microbump testing as described in claim 1, wherein the probe body includes at least one slit extending through the probe body along a first transverse axis, such that the probe body is defined by the at least one slit into at least two arms, the at least two arms being separated from each other along a second transverse axis, and the probe body being bent along the second transverse axis.

12. The test method for microbump testing as described in claim 1, wherein the probes include a first probe and a second probe, the cross-sectional area of ​​the tip of the second probe being smaller than the cross-sectional area of ​​the tip of the first probe, and during the test, the tip of the first probe simultaneously contacts the plurality of first microbumps, while the tip of the second probe contacts only a single second microbump.

13. The test method for testing microbumps as described in claim 12, wherein the projection range of the probe body of the second probe covers the plurality of second microbumps.

14. A device under test (DUT) for microbump testing, comprising a first bump unit for transmitting a first signal and a second bump unit for transmitting a second signal, the first signal being one of a power signal and a ground signal, the second signal being a test signal different from the power signal and the ground signal, the DUT having one of the following three configurations: the DUT is configured such that the first bump unit includes a plurality of first microbumps clustered together, and the second bump unit includes a plurality of second microbumps clustered together, the number of first microbumps in the first bump unit being the same as the number of second microbumps in the second bump unit, the first microbumps being configured to transmit the first signal, and the second microbumps including at least one selected microbump configured to transmit the second signal, and at least one simulated microbump that cannot transmit the second signal outside the second bump unit; The device under test is configured such that the first bump unit includes a plurality of first microbumps clustered together, and the second bump unit includes only a single second bump, the area of ​​which is larger than the area of ​​the single first microbump, the first microbumps being configured to transmit the first signal, and the second bump being configured to transmit the second signal; and the device under test is configured such that the first bump unit includes only a single first bump, and the second bump unit includes a plurality of second microbumps clustered together, the area of ​​which is larger than the area of ​​the single second microbump, the first bump being configured to transmit the first signal, and the second microbumps including at least one selected microbump configured to transmit the second signal, and at least one simulated microbump that cannot transmit the second signal outside the second bump unit; The first bump unit has a first upper surface for contact with one of the probes of the probe card, and the second bump unit has a second upper surface for contact with another probe of the probe card. The first upper surface and the second upper surface are substantially located on the same horizontal plane.

15. The apparatus for testing microbumps as described in claim 14, wherein the plurality of first microbumps are four of the first microbumps arranged in a 2x2 array; and the plurality of second microbumps are four of the second microbumps arranged in a 2x2 array.

16. The apparatus for testing microbumps as described in claim 14, wherein the simulated microbumps of the second bump unit are substantially the same size as the selected microbumps.

17. The apparatus for testing microbumps as described in claim 14, wherein there is no electrical connection between the simulated microbumps of the second bump unit and the selected microbumps.

18. The device under test for microbump testing as described in claim 14, wherein the device under test is used to perform testing by contact with the probe card, the probe card including a plurality of probes, each probe including a needle head at one end for contacting the device under test, a needle tail at the other end, and a needle body between the needle head and the needle tail, the needle bodies of the probes being substantially the same size, and the device under test being configured such that when the first bump unit and the second bump unit are contacted by the needle heads of the probes, the first bump unit and the second bump unit experience the same needle pressure.

19. A probe card for testing microbumps, used in a probe system and for testing a device under test having a plurality of microbumps, the probe card comprising: a main circuit board; a space converter; and a probe head disposed on opposite sides of the main circuit board on the space converter, the probe head comprising at least one guide plate unit and a plurality of probes, the guide plate unit having a plurality of vias through which the probes are slidably disposed, each probe comprising a head at one end for contacting the device under test, a tail at the other end, and a body between the head and the tail, the body portions of the probes being substantially the same size, and the tail portions of the probes being electrically connected to the space converter; wherein, The device under test is as described in any one of claims 14 to 17, and when the probe card tests the device under test, the device under test is placed on a support platform of the probe system, the first bump unit is contacted only by one of the probes, and the second bump unit is contacted only by the other of the probes.

20. A probe system for testing microbumps, configured to test a device under test having a plurality of microbumps, the probe system comprising: a stage configured to support the device under test; a probe card as described in claim 19; a vision device configured to capture an optical image of at least a portion of the probe system; and a signal generation and analysis device configured to perform at least one of providing a test signal to the device under test and receiving a result signal from the device under test.

21. The probe system for microbump testing as described in claim 20, wherein the probe tips have the same cross-sectional area.

22. The probe system for microbump testing as described in claim 20, wherein each probe is one of a straight needle and a bent needle.

23. The probe system for microbump testing as described in claim 20, wherein the device under test is configured such that when the first bump unit and the second bump unit are in contact with the tip of the probe, the first bump unit and the second bump unit experience the same needle pressure.

24. The probe system for microbump testing as described in claim 20, wherein the probes of the probe card are configured to provide the same contact force when testing the device under test by contacting it.

25. The probe system for microbump testing as described in claim 20, wherein the probe tips have substantially the same cross-sectional shape.

26. The probe system for microbump testing as described in claim 20, wherein the cross-sectional shape of the probe tip is either circular or rectangular.

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