Probe card and test system

Abstract

The invention relates to the technical field of wafer testing, and discloses a probe card and a testing system. The probe card comprises a plurality of unit groups which are periodically arranged; the unit group comprises at least two coaxial probes; wherein at least one coaxial probe is used for abutting against the input end of a to-be-tested device, and at least one coaxial probe is used for abutting against the output end of the to-be-tested device. According to the invention, through the plurality of unit groups arranged in the periodic array, a plurality of devices can be tested at a time when wafer testing is carried out, so that the wafer testing speed is improved, the wafer testing time is shortened, and the problems of low testing speed and long testing time existing in wafer testing in the prior art are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of wafer testing, and in particular to a probe card and a testing system. Background Art

[0002] Probe cards are a critical tool in wafer testing. As semiconductor manufacturing advances to the 5nm process node, the number of transistors integrated into a single chip has reached hundreds of billions, dramatically increasing the probability of defects in manufacturing. If chips with manufacturing defects are directly packaged, production costs will increase significantly. Therefore, the importance of wafer-level testing cannot be underestimated and has become a core step in ensuring chip yield.

[0003] Probe cards primarily consist of probe heads, printed circuit boards, and interface modules. During wafer-level testing, probe cards provide the physical and electrical connections between the testbed and the wafer under test. They require excellent signal transmission efficiency and reliable mechanical contact. Excellent transmission performance ensures signal stability and fidelity during testing, ensuring complete signal transmission for optimal test results. Mechanical contact requires low-damage, good contact between the micro-nano probe tip and the pad, requiring precise control of contact force.

[0004] Currently, probe cards primarily include cantilever probe cards, vertical probe cards, and MEMS probe cards. Cantilever probe cards utilize a single-ended fixed cantilever spring probe structure, achieving vertical contact through the elastic deformation of the cantilever beam. Cantilever probe cards are easy to replace, have low maintenance costs, and offer strong compatibility, but they suffer from poor transmission and physical contact performance. High parasitic capacitance between probes leads to high signal loss. Furthermore, the cantilever structure's control over contact force exhibits significant deviations, which can easily lead to pad damage and increase costs. Consequently, cantilever probe cards exhibit low test accuracy and are only suitable for mature process testing. They are gradually being replaced by other probe card structures for advanced process testing.

[0005] Vertical probe cards are equipped with vertically arranged spring probes that are guided by a probe barrel to achieve precise vertical movement, creating a stable contact force and thus a longer service life. However, vertical probe cards are expensive to manufacture, and if damaged, individual probes cannot be replaced; once damaged, the entire probe array must be replaced, resulting in high maintenance costs. Using vertical probe cards for wafer-level testing also increases testing costs.

[0006] MEMS probe cards demonstrate unique advantages in wide-bandgap power semiconductor testing. Their multi-layer structure design can effectively improve the tensile strength and ductility of the probes, meeting the needs of high-current testing. The development of flip-chip bonding technology, new metal needle tips and other technologies has further promoted the application of MEMS probe cards in high-end testing fields.

[0007] MEMS probe cards have significant advantages over cantilever probe cards and vertical probe cards, mainly in terms of high precision, high density, low contact force, and excellent mechanical and electrical properties.

[0008] MEMS probe cards use micromachining technology to achieve miniaturization and high-precision manufacturing of probes, and can accommodate smaller pad spacing and higher test frequencies. The application of MEMS technology in probe cards is mainly reflected in its advantages of high precision, miniaturization, and mass production. Through MEMS technology, probe cards can achieve smaller needle tip spacing and higher test density to meet the needs of modern semiconductor testing. They can achieve precise control at the micron level, are suitable for testing high-density integrated circuits, and can achieve high-density array layouts. In addition, MEMS probe cards also have the characteristics of low contact force, which can reduce damage to the wafer being tested.

[0009] Although MEMS probe cards have demonstrated significant advantages in wafer-level testing, they still face challenges that need to be addressed. Current MEMS probe card research has explored a variety of tip designs, including "hoe-shaped" metal tip structures and multi-layer plating schemes. However, mechanical strength still needs to be optimized. Multiple studies have shown that the metal tips used in current MEMS probe cards wear out after repeated contact tests, altering their electrical properties and increasing contact resistance, which in turn impacts test stability and reliability. Tips manufactured using novel plating processes, such as titanium-nickel shape memory alloys, can provide greater contact force and minimize wear, but their electrical properties, such as contact impedance, are high and cannot meet the demands of practical applications. Furthermore, MEMS probe cards still have shortcomings in signal integrity. Traditional probe cards suffer from high insertion loss and poor signal integrity. The complex structure of the metal tip is complex and expensive to manufacture, significantly increasing production costs. Currently, there is still room for improvement in MEMS probe card tip structures regarding durability, contact resistance, manufacturing costs, and fine-pitch testing.

[0010] In addition, with the continuous evolution of semiconductor process nodes, the number of integrated circuit devices on the wafer has increased significantly, which has put forward higher requirements for the efficiency and accuracy of the wafer testing process. The current mainstream wafer testing method usually uses the existing probe card to test only a single chip on the wafer under test before testing the next chip. 4 As a result, the cost of test time becomes the primary factor affecting the entire test cycle. In addition, the need to repeatedly calibrate the test system when changing chips for testing also leads to a longer overall test cycle, especially in large-scale wafer production.

[0011] Therefore, how to improve the test speed of the wafer under test and reduce the test time is an urgent problem that the industry needs to solve. Summary of the Invention

[0012] The present invention provides a probe card and a testing system for solving the problems of low testing speed and long testing time in wafer testing in the prior art.

[0013] A first aspect of the present invention provides a probe card comprising a plurality of periodically arranged unit groups; the unit groups comprise at least two coaxial probes; wherein at least one of the coaxial probes is used to abut against the input end of a device under test, and at least one of the coaxial probes is used to abut against the output end of the device under test.

[0014] According to the probe card provided by the present invention, the plurality of unit groups are arranged in m rows and n columns, wherein at least one of m and n is a positive integer greater than 1.

[0015] The probe card provided by the present invention further includes: A second circuit board, one side of the second circuit board is connected to the unit group, and the other side is used to connect to the testing instrument.

[0016] According to the probe card provided by the present invention, a through hole is provided on the second circuit board.

[0017] According to the probe card provided by the present invention, the coaxial probe comprises: The needle tip body includes at least one central conductor and an outer substrate; the central conductor is inserted into the outer substrate; one end of the central conductor forms a test needle tip, the test needle tip is located outside the outer substrate, and the test needle tip is used to abut against the device under test; An electrical interconnection structure, one side of which is connected to the other end of the central conductor away from the test needle tip, and the other side of which is used to connect to a test instrument.

[0018] The present invention also provides a testing system comprising the probe card described in any one of the above items and a testing instrument; the testing instrument is electrically connected to an end of the coaxial probe of the probe card away from the device under test.

[0019] The test system provided according to the present invention further includes: a driving module connected to the probe card and configured to drive the probe card to move closer to or away from the wafer under test; A test needle tip monitoring module is used to detect the contact status between the test needle tip and the wafer under test; wherein the contact status includes contact and non-contact; The control module is connected to the driving module and the test probe tip monitoring module. When there is no contact, the control module controls the driving module to drive the probe card close to the wafer under test. When there is contact, the control module controls the driving module to stop driving the probe card.

[0020] According to the test system provided by the present invention, the driving module includes: a first driving component connected to the probe card, and configured to drive the probe card to approach or move away from the wafer under test; The second driving component is connected to the wafer under test and is used to drive the wafer under test to move closer to or away from the probe card.

[0021] According to the test system provided by the present invention, the test needle tip monitoring module includes: a second light source, disposed on one side of the test needle tip, for emitting a second light beam; The receiver is arranged on the other side of the test needle tip and is used to receive the second light beam.

[0022] The test system provided according to the present invention further includes: A force feedback module is connected to the control module and is used to detect the contact force between the test needle tip and the wafer under test; based on the relationship between the contact force and the contact force threshold, the control module controls the action of the driving module.

[0023] The probe card provided by the present invention can test multiple devices at a time during wafer testing through multiple unit groups arranged in a periodic array, thereby improving the speed of wafer testing and shortening the time of wafer testing, solving the problems of low test speed and long test time in wafer testing in the prior art.

[0024] The test system provided by the present invention has at least the above advantages because it includes the above probe card. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 This is one of the structural schematic diagrams of the coaxial probe provided by the present invention.

[0027] Figure 2 This is the second structural schematic diagram of the coaxial probe provided by the present invention.

[0028] Figure 3 This is one of the three-dimensional structural schematic diagrams of the needle tip body of the coaxial probe provided by the present invention.

[0029] Figure 4 yes Figure 3 Schematic cross-section of the tip body of the coaxial probe.

[0030] Figure 5 This is the second schematic diagram of the three-dimensional structure of the needle tip body of the coaxial probe provided by the present invention.

[0031] Figure 6 yes Figure 5 Schematic diagram of the top view structure of the tip body of the coaxial probe.

[0032] Figure 7 It is a schematic diagram of the chip arrangement structure on the wafer under test.

[0033] Figure 8 yes Figure 7 Schematic diagram of the arrangement of adjacent chips on the wafer under test.

[0034] Figure 9 It is a schematic diagram of the structure of a chip on the wafer under test.

[0035] Figure 10 It is a schematic structural diagram of the probe card provided by the present invention.

[0036] Figure 11 yes Figure 10 Schematic diagram of the structure of a unit group of the probe card.

[0037] Figure 12 This is one of the structural diagrams of the test system provided by the present invention.

[0038] Figure 13 This is the second structural diagram of the test system provided by the present invention.

[0039] Figure 14 This is the third structural diagram of the test system provided by the present invention.

[0040] Figure 15 This is the fourth structural diagram of the test system provided by the present invention.

[0041] Reference numerals: 110, needle tip body; 111, center conductor; 112, outer substrate; 113, test needle tip; 120. Electrical interconnection structure; 130. RF function module; 131. Signal generator; 132. Signal receiver; 133. Function chip; 210, unit group; 220, second circuit board; 221, through hole; 300. Wafer under test; 400. Stage; 500. Force feedback module. DETAILED DESCRIPTION

[0042] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0043] In the description of the embodiments of the present invention, it should be noted that, unless otherwise specified or limited, the terms "connected" and "connection" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections, electrical connections; and direct connections or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of the present invention based on the specific circumstances.

[0044] In the embodiments of the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, a first feature being "above," "above," or "above" a second feature may mean that the first feature is directly above or diagonally above the second feature, or simply means that the first feature is at a higher level than the second feature. A first feature being "below," "below," or "below" a second feature may mean that the first feature is directly below or diagonally below the second feature, or simply means that the first feature is at a lower level than the second feature.

[0045] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0046] like Figures 1 to 6As shown, a specific embodiment of the first aspect of the present invention provides a coaxial probe. The coaxial probe includes a needle tip body 110 and an electrical interconnection structure 120. The needle tip body 110 includes at least one center conductor 111 and an outer substrate 112; the center conductor 111 is disposed within the outer substrate 112; one end of the center conductor 111 forms a test needle tip 113, which is located outside the outer substrate 112 and is used to abut the device under test. One side of the electrical interconnection structure 120 is connected to the other end of the center conductor 111 away from the test needle tip 113, and the other side of the electrical interconnection structure 120 is used to connect to a test instrument.

[0047] In the present invention, by forming a test tip 113 at one end of the center conductor 111, the existing step of aligning and integrating the tip with the coaxial cross section is eliminated compared to coaxial probes in the prior art. This solves the problem of the existing coaxial probes requiring increased precision in the tip and coaxial cross section integration process as the operating frequency band increases. Furthermore, the problem of the existing coaxial probe tip and coaxial cross section integration process being limited by the coaxial cross section and tip manufacturing technology, which hinders mass production and leads to high costs, is overcome. By providing an electrical interconnect structure 120, the coaxial probe of the present invention can be integrated with other RF functional modules 130 (e.g., signal transmitters, detectors, antennas, filters, etc.) on the same chip through existing advanced packaging processes, such as through-silicon vias and rewiring. This allows the coaxial probe of the present invention to be sized at the micron level, which is significantly smaller than the sizes of existing coaxial and waveguide probes, thus providing possibilities for probe card design.

[0048] In one embodiment of the present invention, the material of the outer substrate 112 is selected from at least one of silicon, silicon dioxide, silicon nitride, gallium nitride, gallium arsenide, or silicon carbide. In other words, the outer substrate 112 of the present invention is a silicon-based material, which can improve the anti-interference performance of the signal during internal transmission and reduce signal loss.

[0049] Optionally, the outer substrate 112 is made of silicon.

[0050] Optionally, the cross section of the outer base 112 may be polygonal, elliptical, or circular. Polygonal shapes include triangles, quadrilaterals, pentagons, etc. The shape of the outer base 112 is not limited in the present invention.

[0051] Preferably, the outer substrate 112 is a cylindrical structure.

[0052] In one embodiment of the present invention, the center conductor 111 forms a test needle tip 113 by micro-bumps or metal micro-nano additives.

[0053] In one embodiment of the present invention, the test tip 113 can be manufactured using through-silicon via (TSV) technology and a micro-pumping process. For example, a through-hole is machined in the center of the outer substrate 112 using TSV technology and then filled with metal to form a central conductor 111 with the test tip 113 at one end.

[0054] Optionally, the outer side surface of the test needle tip 113 is electroplated with a wear-resistant metal layer to enhance the wear resistance of the test needle tip 113 .

[0055] Optionally, the material of the wear-resistant metal layer is selected from at least one of nickel, cobalt or ruthenium.

[0056] Optionally, the test needle tip 113 and the center conductor 111 may be made of the same material or different materials.

[0057] Optionally, the material of the central conductor 111 can be selected from metals with good electrical conductivity such as gold, silver or platinum, or aluminum or copper can be used according to the height of the outer substrate 112 and the working frequency band of the coaxial probe.

[0058] Optionally, the lower end surface of the test needle tip 113 contacts the upper end surface of the outer substrate 112 and is connected to one end of the central conductor 111 wrapped by the outer substrate 112 .

[0059] Optionally, the material of the test needle tip 113 is selected from metals with excellent electrical conductivity such as gold, silver or platinum. It can also be formed into an alloy by coating the metal surface with a high hardness metal such as nickel, cobalt, ruthenium, etc. according to the test pad requirements of the device under test to enhance the wear resistance of the test needle tip 113.

[0060] Exemplarily, the outer substrate 112 wraps the center conductor 111, the upper end of the center conductor 111 forms a test needle tip 113, and the lower end surface of the test needle tip 113 abuts the upper end surface of the outer substrate 112; the lower end of the center conductor 111 is exposed to facilitate welding and fixing with the electrical interconnection structure 120 to form a reliable connection.

[0061] In one embodiment of the present invention, the axial dimension of the center conductor 111 is greater than the radial dimension; the height of the center conductor 111, that is, the axial dimension of the center conductor 111 is generally less than 1000 microns.

[0062] Optionally, the height of the central conductor 111 is 80 micrometers to 500 micrometers, which also shows that the size of the coaxial probe of the present invention is at the micrometer level.

[0063] Optionally, the overall height of the needle tip body 110 may be 200 microns to 500 microns, which is convenient for processing and maintains low resistance.

[0064] In one embodiment of the present invention, the height of the test needle tip 113, that is, the axial dimension of the test needle tip 113 is less than 10 micrometers, so as to form a reliable contact with the pad of the device under test.

[0065] Optionally, the height of the test needle tip 113 is 3 microns to 5 microns, and a miniaturized design using a coaxial probe is possible.

[0066] In one embodiment of the present invention, the cross section of the test needle tip 113 is circular or polygonal.

[0067] like Figure 2 、 Figure 5 and Figure 6 As shown, the test needle tip 113 can optionally be a sphere. The side of the test needle tip 113 facing the center conductor 111 is flat, and the side facing the device under test is spherical. This ensures both a reliable connection with the center conductor 111 and a reliable contact with the device under test.

[0068] like Figure 3 As shown, the test tip 113 can optionally be wedge-shaped. The area of ​​the lower end surface of the test tip 113 is much larger than the area of ​​the upper end surface of the test tip 113. For example, the upper end surface of the test tip 113 can be equivalent to a line, that is, the test tip 113 forms a line contact with the pad of the device under test.

[0069] Optionally, the test tip 113 is conical. The lower end surface of the test tip 113 is circular, and the area of ​​the upper end surface is much smaller than that of the lower end surface. For example, the upper end surface of the test tip 113 can be equivalent to a point, that is, the test tip 113 forms a point contact with the pad of the device under test.

[0070] like Figure 2 As shown, in one embodiment of the present invention, a coaxial probe includes a probe tip body 110. Probe tip body 110 comprises a central conductor 111 and an outer base 112. Central conductor 111 is disposed within outer base 112. One end of central conductor 111 forms a test tip 113. This coaxial probe has a wider range of applications, not only for testing RF circuits but also for testing processing chips and CPUs (central processing units).

[0071] like Figure 1 As shown, in one embodiment of the present invention, the coaxial probe further includes a radio frequency (RF) functional module 130 ; RF functional module 130 is integrated on the other side of the electrical interconnect structure 120 and is used to connect to a test instrument. In other words, the electrical interconnect structure 120 can be connected to the test instrument via the RF functional module 130 .

[0072] Optionally, the radio frequency function module 130 includes a signal generator 131 and / or a signal receiver 132. Specifically, the signal generator 131 and / or the signal receiver 132 are integrated on the other side of the interposer away from the needle tip body 110 and can be connected to a test instrument.

[0073] Optionally, the radio frequency function module 130 further includes a function chip 133. Specifically, the function chip 133 includes a DC polarization chip and / or a DC reading chip.

[0074] like Figure 1 As shown, in another embodiment of the present invention, a coaxial probe includes a probe tip body 110. Probe tip body 110 comprises at least two center conductors 111 and an outer base 112. Center conductors 111 are disposed within outer base 112. One end of center conductor 111 forms a test probe tip 113. This coaxial probe structure is typically used in radio frequency circuit testing and has a relatively narrow scope of application.

[0075] Optionally, the electrical interconnection structure 120 has a ground wire and a signal wire; the ground wire is connected to at least one center conductor 111 of the needle tip body 110, one end of the signal wire is connected to other center conductors 111 in the needle tip body 110, and the other end is used to connect to the RF function module 130.

[0076] Optionally, the needle tip body 110 includes three center conductors 111, forming a common ground-signal-ground needle tip shape, that is, a GSG needle tip. In addition, the needle tip shape can also be GS, SG, GSSG, GSGSG and other shapes according to test needs. Preferably, the height of the test needle tip 113 may be 3 micrometers to 5 micrometers, and the diameter of the maximum cross section may be at least one of 20 micrometers, 25 micrometers, 50 micrometers, 75 micrometers, or 100 micrometers.

[0077] Preferably, the height of the central conductor 111 may be 80 micrometers to 500 micrometers, and the diameter of the cross section of the central conductor 111 is the same as the diameter of the maximum cross section of the test needle tip 113 .

[0078] In one embodiment of the present invention, the electrical interconnect structure 120 comprises an interposer or a first circuit board. This design allows for rerouting of signal and ground lines to separate pads, thereby achieving electrical connection between the functional module and the tip body 110. This rerouting process allows the tip body 110 to be integrated on the same chip with the RF functional module 130 (e.g., signal generator, detector, filter, polarization circuit, etc.).

[0079] It's important to note that circuit boards provide mechanical support and electrical connections for electronic components (such as chips, resistors, and capacitors), enabling signal transmission and power distribution through copper traces. Interposers typically serve as an intermediate transfer layer, connecting components of different sizes, processes, or spacing (such as chips and PCBs), addressing interconnect density mismatches.

[0080] Optionally, the material of the interposer is preferably silicon, but glass, organic substrate, ceramic substrate, etc. may also be selected.

[0081] Optionally, the number of redistribution layers is generally 2, but 3 or more layers can be implemented depending on the number of integrated functions and needs.

[0082] Optionally, the metal of the redistribution layer is preferably the same as the metal of the center conductor 111 .

[0083] Optionally, the first circuit board may be a PCB circuit board.

[0084] It is understandable that when using a coaxial probe to test the same device under test, two coaxial probes are usually required. The functions of these two coaxial probes are different. One coaxial probe is used to input signals to the device under test (such as the chip under test), so it can be called a signal input probe; the other coaxial probe is used to output the signal output by the device under test, so it can be called a signal output probe.

[0085] The RF functional module 130 of the signal input probe includes a DC polarization and signal generator 131. The RF functional module 130 of the signal output probe includes a DC readout and signal detector.

[0086] like Figure 4 for Figure 3 Schematic diagram of a cross-sectional view of the tip body of the coaxial probe in FIG. wherein a is the radius of the center conductor 111 connected to the signal line in the electrical interconnect structure 120, and b is the radius of the outer substrate 112, which is coaxially arranged with the center conductor 111. The outer substrate 112 of the present invention is a silicon substrate. The theoretical performance of the coaxial probe of the present invention in terms of operating frequency band and power capacity far exceeds that of existing polymer-based coaxial probes. The theoretical calculation process is as follows: Assuming a is 50 microns and b is 100 microns, the center conductor 111 is covered by the outer substrate 112 of high-resistance silicon. The dielectric constant of the high-resistance silicon material characteristic is The dielectric electric field breakdown strength is 11.9. The maximum operating frequency is 0.64 THz according to formula (1); the maximum power capacity is 45 kW according to formula (1).

[0087] Maximum operating frequency : Formula (1).

[0088] Maximum power capacity : Formula (2).

[0089] in, Take 3.14159.

[0090] The existing polymer-based coaxial probe has a diameter of 50 microns and a diameter of 100 microns. The center conductor of the existing coaxial probe is coated with a polyethylene outer matrix. The dielectric constant of polyethylene is The dielectric breakdown voltage is 11.9. The maximum operating frequency of the existing polymer-based coaxial probe is 0.42 THz, and the maximum power capacity is about 19 kW.

[0091] In summary, the operating frequency band of the coaxial probe proposed in the present invention covers DC to terahertz and higher frequencies, wherein the coaxial material is made of silicon-based material coated with metal, and the test needle tip is formed by micro-bumps or metal micro-nano additives. The probe can be integrated with other RF functional modules (emitter, detector, antenna, filter, etc.) on the same chip through advanced packaging processes such as through-silicon vias and rewiring. Compared with the two mainstream technologies of waveguide probes and coaxial probes, the coaxial probe proposed in the present invention breaks through the common technical bottleneck of the limited operating frequency band of the two, and avoids the decline in test accuracy and production yield caused by assembly. The probe proposed in the present invention can make the probe manufacturing technology compatible with the integrated circuit process (IC process), and can realize the miniaturization and arraying of the probe. By combining with advanced packaging, it is expected to realize the diversification of probe functions and on-chip vector network systems.

[0092] like Figure 10 and Figure 11 As shown, a specific embodiment of the second aspect of the present invention provides a probe card. The probe card is prepared based on the coaxial probe of any of the above embodiments. The probe card includes a unit group 210; the unit group 210 includes the coaxial probe of any of the above embodiments.

[0093] In the present invention, since the size of the coaxial probe of any of the above embodiments is at the micron level, a probe card can be prepared using the coaxial probe, and the device to be tested can be tested using the probe card.

[0094] Optionally, the device to be tested may be a wafer to be tested, or may be a device placed on a wafer, the device including a chip. In other words, the probe card of this embodiment may be used to test the chip on the wafer to be tested.

[0095] like Figure 11As shown, in one embodiment of the present invention, the probe card includes a unit assembly 210; the unit assembly 210 includes at least two coaxial probes according to any of the above-described embodiments; at least one coaxial probe is used to abut the input terminal of the device under test, and at least one coaxial probe is used to abut the output terminal of the device under test. One unit assembly 210 can be used to test a single chip on a wafer under test.

[0096] like Figure 10 As shown, in another embodiment of the present invention, the probe card includes multiple periodically arranged unit groups 210; each unit group 210 includes at least two coaxial probes according to any of the above-described embodiments; at least one coaxial probe is configured to abut the input terminal of the device under test, and at least one coaxial probe is configured to abut the output terminal of the device under test. By providing multiple periodically arranged unit groups 210, multiple devices under test on a wafer can be tested simultaneously, thereby increasing wafer testing speed and reducing testing costs.

[0097] Existing wafers are usually tested using coaxial probes, which can only complete the test of a single device on the wafer at a time before the next device is tested. 4 The cost of test time becomes the primary factor affecting the entire test cycle. Obviously, the probe card of the present invention can realize the simultaneous acquisition of chip signals of the entire wafer, which can greatly save test costs. At the same time, the probe card design is still compatible with mature silicon-based manufacturing processes. Compared with the current all-metal needle tip cantilever structure probe card, its process stability and mechanical reliability are greatly improved.

[0098] It should be noted that, in the unit set 210 , the coaxial probe that contacts the input terminal of the device under test can be referred to as a signal input probe, and the coaxial probe that contacts the input terminal of the device under test can be referred to as a signal output probe.

[0099] It can be understood that the periodic array form of the unit group 210 on the probe card is determined by the device arrangement on the wafer under test. In other words, the arrangement of the unit group 210 can be consistent with the device arrangement on the wafer under test, so as to facilitate the simultaneous acquisition of signals of the devices on the wafer under test in a single time.

[0100] In one embodiment of the present invention, the plurality of unit groups 210 are arranged in m rows and n columns, wherein at least one of m and n is a positive integer greater than 1.

[0101] Optionally, m is a positive integer greater than 1.

[0102] Optionally, n is a positive integer greater than 1.

[0103] Optionally, m is a positive integer greater than 1, and n is a positive integer greater than 1.

[0104] like Figure 13 、 Figure 14 and Figure 15 As shown, in one embodiment of the present invention, the probe card further includes a second circuit board 220. One side of the second circuit board 220 is connected to the unit assembly 210, and the other side is used to connect to the test instrument. The design of the second circuit board 220 provides a mounting base for the unit assembly 210, making the probe card more portable.

[0105] Optionally, a plurality of unit groups 210 are periodically arrayed on one side of the second circuit board 220, each unit group 210 including two coaxial probes, which have different functions during a specific test process. The other side of the second circuit board 220 is used to connect to a test instrument.

[0106] Figure 7 This is a schematic diagram of the chip arrangement structure on the wafer under test. There are more than 10 devices placed on the wafer under test. 4 When the wafer is fixed, 10 4 The arrangement of the components is the same. Figure 8 As shown, the lateral distance between the signal test pads of two adjacent devices (also called chips, i.e., devices under test) is W, and the longitudinal distance between the signal test pads of two adjacent devices is L; the distance between the input test pad and the output test pad of the same device is D.

[0107] It should be noted that the signal test pads include signal input test pads and signal output test pads. The signal input pads are the input terminals of the device under test, and the signal output test pads are the output terminals of the device under test. During the test process, the coaxial probe that abuts the signal input test pads can be referred to as the signal input probe, which has a signal input function. The coaxial probe that abuts the signal output test pads can be referred to as the signal output probe, which has a signal output function.

[0108] Based on the arrangement of the above devices, a probe card can be designed. Figure 10 As shown, the distance between two coaxial probes in the same unit group 210 in the probe card is D, the lateral distance between coaxial probes with the same function in two adjacent unit groups 210 is W, and the longitudinal distance between coaxial probes with the same function in two adjacent unit groups 210 is L. This design allows the probe card to complete the test of all devices on the wafer at one time, shortening the test time and reducing the test cost.

[0109] Figure 9 This is a schematic diagram of the structure of a chip on the wafer under test. The arrangement of the coaxial probes of the unit group 210 can be designed based on the distribution of the pads on a chip. The coaxial probes in the unit group 210 correspond one-to-one with the pads of the corresponding chip.

[0110] Figures 13 to 15 As shown, in one embodiment of the present invention, a through hole 221 is formed on the second circuit board 220; through hole 221 is used to allow a light beam to pass through the second circuit board 220 and illuminate the device under test. With this design, when using the probe card to test chips on the wafer under test, the position of each probe card can be determined by the light beam passing through through hole 221, providing accurate data for the movement of the probe card and ensuring that the test needle tip 113 of the probe card can abut the corresponding pad.

[0111] Optionally, the central axis of the through hole 221 coincides with the central axis of the second circuit board 220. This design facilitates the establishment of a coordinate system to determine the position of each chip on the wafer being measured.

[0112] like Figures 12 to 15 As shown, the third aspect of the present invention provides a test system, which includes the coaxial probe according to any of the above embodiments, or includes the probe card according to any of the above embodiments.

[0113] In this embodiment, because the test system includes the coaxial probe or probe card of any of the above embodiments, it has at least the above advantages, which will not be described in detail here.

[0114] Optionally, the test system includes a probe card of any of the above-mentioned embodiments. The probe card includes a plurality of periodically arranged unit groups 210; the unit group 210 includes at least two coaxial probes. The test needle tip 113 of at least one coaxial probe is used to abut against the signal input pad of the device under test, and the test needle tip 113 of at least another coaxial probe is used to abut against the signal output pad of the device under test. The first circuit board 120 of the coaxial probe is connected to the second circuit board 220 on one side away from the test needle tip 113. In other words, the unit groups 210 are arranged in a periodic array on the second circuit board 220.

[0115] In one embodiment of the present invention, the test system further comprises a test instrument, which is electrically connected to an end of the coaxial probe away from the device under test. The test instrument can be used to test the chip under test on the wafer under test.

[0116] Optionally, the test instrument includes but is not limited to a vector network analyzer.

[0117] like Figure 12As shown, the test system specifically includes a probe card, which includes a unit assembly 210. Unit assembly 210 includes two coaxial probes; one coaxial probe serves as a signal input probe, and the other coaxial probe serves as a signal output probe. The signal output terminal of the vector network analyzer (i.e., the test instrument) is electrically connected to the signal input probe, and the signal receiving terminal of the vector network analyzer is electrically connected to the signal output probe. The test needle tip 113 of the signal input probe abuts the signal input pad of the device under test, and the test needle tip 113 of the signal output probe abuts the signal output pad of the device under test. Starting the vector network analyzer can test the device under test. The signal source parameters are controlled by a vector network analyzer. The input signal is fed into the device under test (DUT) via the redistribution layer of the signal input probe's interposer (i.e., electrical interconnect structure 120) and then the signal test tip (test tip 113 connected to the signal line of the redistribution layer) is used. After being processed by the DUT, the signal is extracted by the signal test tip of the signal output probe. The signal is collected by a signal detector via the redistribution layer of the signal output probe's interposer (i.e., electrical interconnect structure 120). The vector network analyzer then processes the signal to determine the performance of the DUT. Compared to traditional coaxial probes, the coaxial probes described in the present invention are at least 100 times smaller in overall size. Furthermore, both the signal generation and acquisition modules can be integrated on-chip within the test tip, reducing signal path loss and noise generation, thereby improving the signal-to-noise ratio. Furthermore, the vector network analyzer retains only the signal control and processing functions, reducing instrument complexity and optimizing costs.

[0118] In one embodiment of the invention, the test system further includes a drive module, a test probe tip monitoring module, and a control module; the control module is connected to the drive module and the test probe tip monitoring module; the drive module is connected to the probe card and is used to drive the probe card toward or away from the wafer under test; the test probe tip monitoring module is used to detect the contact between the test probe tip and the wafer under test, where the contact conditions include contact and non-contact; when non-contact occurs, the control module controls the drive module to drive the probe card toward the wafer under test; when contact occurs, the control module controls the drive module to stop driving the probe card. This design ensures that the test probe tip contacts the pads of the device on the wafer under test, avoiding the phenomenon of performing tests without contact.

[0119] Optionally, the drive module includes a first drive component and a second drive component; the first drive component is connected to the probe card and is used to drive the probe card toward or away from the wafer under test; the second drive component is connected to the wafer under test and is used to drive the wafer under test toward or away from the probe card; and the control module is connected to both the first drive component and the second drive component. The first drive component is controlled to drive the probe card toward the pad of the device on the wafer under test until the distance between the test probe tip and the pad meets a distance threshold; then, the second drive component drives the carrier 400 (with the wafer under test 300 placed thereon) toward the test probe tip 113, causing the pad to actively approach the test probe tip 113 until it contacts the test probe tip 113. Compared to directly driving the test probe tip 113 to actively approach the pad, this embodiment, in which the second drive component drives the wafer under test 300 to actively approach the pad, can reduce the probability of damage to the test probe tip 113 and, to a certain extent, increase the service life of the test probe tip 113.

[0120] Illustratively, the first driving component includes but is not limited to a linear motor.

[0121] Exemplarily, the second driving component includes but is not limited to a linear motor.

[0122] Optionally, the test needle tip monitoring module includes a second light source and a receiver; the second light source is arranged on one side of the test needle tip 113, for emitting a second light beam; the optical axis of the second light beam intersects with the moving direction of the test needle tip 113. The receiver is arranged on the other side of the test needle tip, for receiving the second light beam. The test needle tip 113 can allow the second light beam to pass through or be used to block the second light beam. When the test needle tip 113 is located in the optical path of the second light beam, the test needle tip 113 blocks the second light beam, and the receiver cannot receive the second light beam, indicating that the test needle tip 113 is in contact with the pad. When the test needle tip 113 leaves the second light beam, the second light beam can pass through the test needle tip 113, and the receiver can receive the second light beam, indicating that the test needle tip is not in contact with the pad.

[0123] like Figure 14 and Figure 15 As shown, in one embodiment of the present invention, the test system further includes a force feedback module 500; the force feedback module 500 is connected to the control module; the force feedback module 500 is used to detect the contact force between the test needle tip 113 and the wafer under test 300; the control module controls the drive module based on the relationship between the contact force and the contact force threshold. This not only ensures good contact between the test needle tip and the wafer under test, but also reduces the wear rate of the test needle tip 113, thereby increasing the service life of the test needle tip 113.

[0124] It should be noted that the contact force threshold can be a point value, for example, the contact force threshold is 2 mN. The contact force threshold can also be a range value, that is, the minimum value of the contact force threshold is 2 mN and the maximum value is 6 mN.

[0125] Optionally, the force feedback module 500 is disposed on the lower side of the carrier 400 , and the wafer 300 to be measured is placed on the upper side of the carrier 400 .

[0126] Optionally, when the contact force threshold is a point value, if the contact force is less than the contact force threshold, the control module controls the driving module to drive the test needle tip 113 to continue to approach the pad of the wafer under test 300. If the contact force is not less than the contact force threshold, the control module controls the driving module to stop moving, indicating that the test needle tip is in good contact with the pad.

[0127] Optionally, when the contact force threshold is within a range, when the contact force is less than the minimum value of the contact force threshold, the control module controls the driving module to drive the test needle tip 113 to continue to approach the pad of the wafer under test. When the contact force is within the range of the contact force threshold, the control module controls the driving module to stop moving, indicating that the test needle tip is in good contact with the pad at this time. When the contact force is greater than the maximum value of the contact force threshold, the control module controls the driving module to drive the test needle tip 113 to move in a direction away from the pad. The control module controls the action of the driving module according to the size of the contact force, so that the contact force is within the range of the contact force threshold. This not only ensures good contact between the test needle tip 113 and the wafer under test 300, but also reduces the wear rate of the test needle tip 113 and improves the service life of the test needle tip 113.

[0128] Specifically, the minimum contact force threshold can be 2 millinewtons (mN), and the maximum contact force threshold can be 6 millinewtons (mN). That is, when the contact force F satisfies the following conditions: 2 mN ≤ F ≤ 6 mN, the control module controls the drive module to stop moving. When the contact force F satisfies the following conditions: F < 2 mN, the control module controls the drive module to drive the probe card closer to the wafer under test until the contact force F falls within the contact force threshold range. When the contact force F satisfies the following conditions: F > 6 mN, the control module controls the drive module to drive the probe card away from the wafer under test until the contact force F falls within the contact force threshold range.

[0129] In one embodiment of the present invention, the test system further includes a first optical detection module connected to a control module. The first optical detection module emits a first light beam, which passes through a through hole 221 and irradiates the wafer 300 under test, and coincides with a marking symbol on the wafer 300 under test. The control module establishes a three-dimensional coordinate system with the marking symbol as the center O and the plane on which the wafer 300 under test is located as the XOY plane. This design can determine the distance between the test needle tip 113 and the pad, and the spatial position of each pad can be determined, ensuring that the test needle tip 113 can accurately contact the corresponding pad, thereby facilitating control of the movement distance of the test needle tip 113 or the wafer 300 under test.

[0130] Optionally, the first optical detection module includes a first light source configured to emit a first light beam, the optical axis of which is parallel to the direction of movement of the probe card, and a height detection assembly connected to the control module to detect the actual height h between the probe card and the wafer.

[0131] Optionally, the height detection component can determine the actual height h between the probe card and the wafer under test by obtaining the distance between the probe card and its virtual image (the wafer under test can perform mirror imaging on the probe card to form a virtual image of the probe card) in real time.

[0132] In one embodiment of the present invention, the use process of the test system includes: When using a probe card for testing, the wafer 300 to be tested is first placed on the carrier 400, and the marking symbol on the edge of the wafer to be tested is determined by the first light source. With the marking symbol as the center of the circle and the plane where the wafer to be tested is located as the XOY plane, an XYZ three-dimensional coordinate system is established to facilitate subsequent automated system testing. The control module then controls the first drive component to drive the probe card to move in the negative direction of the Z axis until the actual height h of the test needle tip of the probe card from the wafer is no greater than the height threshold (for example, 20 microns). Next, the control module controls the second drive component to drive the wafer to be tested to move in the positive direction of the Z axis, and records the contact between the test needle tip 113 and the wafer to be tested through the second light source and the receiver. At the same time, the force feedback module measures the contact force F generated during contact. The control module controls the second drive component to drive the wafer to be tested to move in the Z axis direction until the contact force F is within the contact force threshold range, so that not only good contact can be formed. After completing the above calibration, the device on the wafer 300 to be tested can be measured.

[0133] After completing the test of the multiple chips under test in the aforementioned area of ​​wafer 300, the control module controls the second drive assembly to drive stage 400 along the X and Y axes, moving the multiple chips under test in the next area to the bottom of the probe card. The Z-axis calibration steps are then repeated until all the chips under test in all areas of wafer 300 are tested. This testing process eliminates the need for multiple calibrations of the probe card and the chips under test, saving testing time and reducing the time cost of the chips under test.

[0134] In summary, the coaxial probe provided by the present invention has a wider operating frequency band than the waveguide probe. The operating frequency band of the waveguide probe is limited by the operating frequency band of the waveguide, while the operating frequency band of the coaxial probe covers from the DC band to the high frequency band. At the same time, the coaxial probe has advantages in size, volume, weight, and cost, but the current coaxial probe is difficult to break through 0.5 THz due to process limitations. While having the above advantages, the coaxial probe of the present invention adopts a new matrix material to improve power capacity and can adapt to extreme environments such as high temperature and high pressure. The probe card wafer-level testing solution can provide higher design freedom for radio frequency integrated circuits, while improving the efficiency of batch wafer-level testing and reducing testing costs.

[0135] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A probe card, characterized in that: The invention comprises a plurality of periodically arranged unit groups (210); the unit group (210) comprises at least two coaxial probes; wherein at least one of the coaxial probes is used to abut against the input end of the device under test, and at least one of the coaxial probes is used to abut against the output end of the device under test.

2. The probe card according to claim 1, wherein The plurality of unit groups (210) are arranged in m rows and n columns, wherein at least one of m and n is a positive integer greater than 1.

3. The probe card according to claim 2, wherein: Also includes: A second circuit board (220), one side of the second circuit board (220) is connected to the unit group (210), and the other side is used to connect to a testing instrument.

4. The probe card according to claim 3, wherein: A through hole (221) is provided on the second circuit board (220).

5. The probe card according to any one of claims 1 to 4, wherein: The coaxial probe comprises: A needle tip body (110) comprises at least one central conductor (111) and an outer substrate (112); the central conductor (111) is inserted into the outer substrate (112); one end of the central conductor (111) forms a test needle tip (113), the test needle tip (113) is located outside the outer substrate (112), and the test needle tip (113) is used to abut against a device to be tested; An electrical interconnection structure (120), one side of the electrical interconnection structure (120) is connected to the other end of the central conductor (111) away from the test needle tip (113), and the other side of the electrical interconnection structure (120) is used to connect to a test instrument.

6. A testing system, characterized in that: The invention comprises the probe card according to any one of claims 1 to 5, and a testing instrument; the testing instrument is electrically connected to an end of the coaxial probe of the probe card away from the device under test.

7. The test system according to claim 6, characterized in that: Also includes: a driving module connected to the probe card and configured to drive the probe card to move closer to or away from the wafer under test; A test needle tip monitoring module is used to detect the contact status between the test needle tip and the wafer under test; wherein the contact status includes contact and non-contact; The control module is connected to the driving module and the test probe tip monitoring module. When there is no contact, the control module controls the driving module to drive the probe card close to the wafer under test. When there is contact, the control module controls the driving module to stop driving the probe card.

8. The test system according to claim 7, characterized in that: The driving module includes: a first driving component connected to the probe card, and configured to drive the probe card to approach or move away from the wafer under test; The second driving component is used to connect with the wafer under test and drive the wafer under test to move closer to or away from the probe card.

9. The test system according to claim 7, characterized in that: The test needle tip monitoring module includes: a second light source, disposed on one side of the test needle tip, for emitting a second light beam; The receiver is arranged on the other side of the test needle tip and is used to receive the second light beam.

10. The test system according to any one of claims 7 to 9, characterized in that: Also includes: a force feedback module, connected to the control module, and configured to detect the contact force between the test needle tip and the wafer under test; The control module controls the action of the driving module based on the relationship between the contact force and the contact force threshold.

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