Coaxial probe, probe card and test system

Abstract

The invention relates to the technical field of wafer testing, and discloses a coaxial probe, a probe card and a testing system. The coaxial probe comprises a probe tip main body and an electrical interconnection structure. The needle point main body comprises at least one central conductor and an outer side base body; the central conductor is inserted into the outer base body; a test needle tip is formed at one end of the central conductor, is positioned on the outer side of the outer-side base body and is used for abutting against a to-be-tested device; one side of the electrical interconnection structure is connected with the other end, away from the test needle tip, of the center conductor, and the other side of the electrical interconnection structure is used for being connected with a test instrument. By forming the test needle tip at one end of the central conductor and arranging the electrical interconnection structure, the problem that the precision requirement of the needle tip and coaxial section integration process of the existing coaxial probe is increased greatly along with the rise of the working frequency band is solved. The problems that the integration process of the tip and the coaxial cross section of the existing coaxial probe is influenced by the coaxial cross section and tip manufacturing technology, the batch production cannot be realized, and the cost is high are solved.

Description

Technical Field

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

[0002] An integrated circuit (IC) is a miniaturized circuit manufactured using semiconductor technology that integrates circuit components to perform specific functions. As IC integration increases, IC testing faces technical challenges such as long test cycles, high test complexity, and high test costs. In the RF field, radio frequency integrated circuits (RFICs) are wireless communication system components dedicated to signal processing, including transceivers, mixers, and amplifiers.

[0003] With the widespread adoption of 5G, the terahertz (THz) frequency band has attracted widespread attention as a potential application band for 6G communications. With frequencies ranging from 0.1 THz to 10 THz and wavelengths ranging from 3 mm to 30 microns, THz offers the advantages of ultra-large bandwidth and ultra-high communication speeds in the communications field, supporting massive device connectivity and ultra-high user data rates reaching terabit / s. As the core component of 6G THz communication systems, the precise measurement of chip RF performance is a current research hotspot and a key technical bottleneck.

[0004] Currently, 6G chip testing is primarily based on the coaxial packaging test method of a vector network analyzer (VNA). This method requires the packaged chip to be fixed on a circuit board and connected to the vector network analyzer via an RF coaxial connector and coaxial cable to measure the chip's signal. However, this method cannot avoid errors introduced by fixtures, packaging, leads, etc., and cannot achieve automated measurement. In the terahertz frequency band, with the miniaturization of chips, electrical probe testing technology has gradually become mainstream. The probe can avoid errors caused by coaxial packaging and achieve automated measurement of chips on the wafer. The test data is closer to the performance of the chip itself, with the advantages of accurate testing, low error, and automation.

[0005] Terahertz-band electrical probes can be categorized by packaging type into coaxial and waveguide types. The former integrates the test tip into the coaxial end, with the other end serving as the signal input. This allows for an operating frequency range from direct current (DC) to 0.5 THz, offering low transmission loss and low design costs. However, as the operating frequency increases, the precision requirements for integrating the test tip with the coaxial cable increase dramatically. Currently, coaxial probes cannot exceed the 0.5 THz frequency limit, limiting their application and functional versatility. Furthermore, the integration process, hampered by the coaxial cross-section and test tip manufacturing techniques, cannot be mass-produced, resulting in a still-uncomfortable overall cost. Waveguide probes can utilize the micro-electro-mechanical system (MEMS) mass manufacturing process to integrate the probe tip with other functions (probe, filtering, bias, etc.), with a maximum operating frequency of up to 1.1 THz. However, since a waveguide is used as the interface between the probe and the instrument, the operating frequency band of each probe is limited by the waveguide size, with common bands such as 75 GHz to 110 GHz, 325 GHz to 500 GHz, and 750 GHz to 1100 GHz. This requires constant replacement of probes and calibration of the test system for ultra-wideband 6G chip testing, which cannot solve the problems of long test cycles and high test complexity. Summary of the Invention

[0006] The present invention provides a coaxial probe, a probe card and a test system, which are used to solve at least one of the above-mentioned defects of existing coaxial probes and waveguide probes.

[0007] A first aspect of the present invention provides a coaxial probe, comprising: 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.

[0008] According to the present invention, a coaxial probe is provided, wherein the material of the outer substrate is selected from at least one of silicon, silicon dioxide, silicon nitride, gallium nitride, gallium arsenide or silicon carbide.

[0009] According to the present invention, a coaxial probe is provided, wherein the electrical interconnection structure includes an interposer or a first circuit board.

[0010] According to the present invention, a coaxial probe is provided, further comprising: The radio frequency function module is integrated on the other side of the electrical interconnection structure and is used to connect to the test instrument.

[0011] According to the present invention, the coaxial probe is provided, wherein the height of the central conductor is 80 micrometers to 500 micrometers.

[0012] According to the present invention, a coaxial probe is provided, wherein the height of the test needle tip is 3 micrometers to 5 micrometers.

[0013] According to the present invention, a coaxial probe is provided, wherein the cross section of the test needle tip is circular or polygonal.

[0014] According to the present invention, a coaxial probe is provided, wherein the tip body includes at least two center conductors.

[0015] A second aspect of the present invention provides a probe card, comprising a unit group; the unit group comprises any one of the coaxial probes described above.

[0016] A third aspect of the present invention provides a testing system, comprising the coaxial probe described in any one of the above items, or comprising the probe card described in any one of the above items.

[0017] The coaxial probe provided by the present invention forms a test needle tip at one end of the central conductor. Compared with the coaxial probe in the prior art, it eliminates the need for the existing needle tip to be aligned and integrated with the coaxial cross section, thereby solving the problem that the precision requirements of the needle tip and coaxial cross section integration process of the existing coaxial probe increase with the increase of the working frequency band. In addition, it also overcomes the problem that the integration process of the needle tip and coaxial cross section of the existing coaxial probe cannot be achieved in batches due to the influence of the coaxial cross section and needle tip manufacturing technology, and the high cost. By setting up an electrical interconnection structure, the coaxial probe of the present invention can be integrated with other radio frequency functional modules (such as signal transmission sources, detectors, antennas, filters, etc.) through existing advanced packaging processes, such as silicon through-holes, rewiring and other processes, so that the size of the coaxial probe of the present invention can be at the micron level, which is obviously much smaller than the size of existing coaxial probes and waveguide probes, thus providing possibilities for the design of probe cards.

[0018] The probe card and the testing system provided by the present invention have at least the above advantages because they include the above coaxial probes. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] 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.

[0020] Figure 1 This is one of the structural schematic diagrams of the coaxial probe provided by the present invention.

[0021] Figure 2 This is the second structural schematic diagram of the coaxial probe provided by the present invention.

[0022] 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.

[0023] Figure 4 yes Figure 3 Schematic cross-section of the tip body of the coaxial probe.

[0024] 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.

[0025] Figure 6 yes Figure 5 Schematic diagram of the top view structure of the tip body of the coaxial probe.

[0026] Figure 7 It is a schematic diagram of the chip arrangement structure on the wafer under test.

[0027] Figure 8 yes Figure 7 Schematic diagram of the arrangement of adjacent chips on the wafer under test.

[0028] Figure 9 It is a schematic diagram of the structure of a chip on the wafer under test.

[0029] Figure 10 It is a schematic structural diagram of the probe card provided by the present invention.

[0030] Figure 11 yes Figure 10 Schematic diagram of the structure of a unit group of the probe card.

[0031] Figure 12 This is one of the structural diagrams of the test system provided by the present invention.

[0032] Figure 13 This is the second structural diagram of the test system provided by the present invention.

[0033] Figure 14 This is the third structural diagram of the test system provided by the present invention.

[0034] Figure 15 This is the fourth structural diagram of the test system provided by the present invention.

[0035] 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

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] like Figures 1 to 6 As 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.

[0041] 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.

[0042] 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.

[0043] Optionally, the outer substrate 112 is made of silicon.

[0044] 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.

[0045] Preferably, the outer substrate 112 is a cylindrical structure.

[0046] 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.

[0047] 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.

[0048] 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 .

[0049] Optionally, the material of the wear-resistant metal layer is selected from at least one of nickel, cobalt or ruthenium.

[0050] Optionally, the test needle tip 113 and the center conductor 111 may be made of the same material or different materials.

[0051] 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.

[0052] 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 .

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] In one embodiment of the present invention, the cross section of the test needle tip 113 is circular or polygonal.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] like Figure 2As 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).

[0065] 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 .

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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 .

[0072] 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.).

[0073] 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.

[0074] Optionally, the material of the interposer is preferably silicon, but glass, organic substrate, ceramic substrate, etc. may also be selected.

[0075] 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.

[0076] Optionally, the metal of the redistribution layer is preferably the same as the metal of the center conductor 111 .

[0077] Optionally, the first circuit board may be a PCB circuit board.

[0078] 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.

[0079] 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.

[0080] like Figure 4 for Figure 3Schematic 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 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).

[0081] Maximum operating frequency : Formula (1).

[0082] Maximum power capacity : Formula (2).

[0083] in, Take 3.14159.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] like Figure 11 As 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] Optionally, m is a positive integer greater than 1.

[0096] Optionally, n is a positive integer greater than 1.

[0097] Optionally, m is a positive integer greater than 1, and n is a positive integer greater than 1.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] 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.

[0102] 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.

[0103] 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.

[0104] 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.

[0105] 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.

[0106] like Figures 12 to 15As 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.

[0107] 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.

[0108] 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 side of the first circuit board of the coaxial probe away from the test needle tip 113 is connected to the second circuit board 220. In other words, the unit groups 210 are arranged in a periodic array on the second circuit board 220.

[0109] 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.

[0110] Optionally, the test instrument includes but is not limited to a vector network analyzer.

[0111] 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.

[0112] 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.

[0113] 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.

[0114] Illustratively, the first driving component includes but is not limited to a linear motor.

[0115] Exemplarily, the second driving component includes but is not limited to a linear motor.

[0116] 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.

[0117] 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.

[0118] 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.

[0119] 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 .

[0120] 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.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] 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.

[0128] 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.

[0129] 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 coaxial probe, characterized in that: include: A needle tip body (110) comprises at least one central conductor (111) and an outer substrate (112); the central conductor (111) is disposed in 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.

2. The coaxial probe according to claim 1, characterized in that 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.

3. The coaxial probe according to claim 1, characterized in that The electrical interconnection structure (120) includes an intermediate board or a first circuit board.

4. The coaxial probe according to claim 1, characterized in that Also includes: A radio frequency function module (130) is integrated on the other side of the electrical interconnection structure (120) and is used to connect to the test instrument.

5. The coaxial probe according to claim 1, characterized in that The height of the central conductor (111) is 80 microns to 500 microns.

6. The coaxial probe according to claim 1, characterized in that The height of the test needle tip (113) is 3 micrometers to 5 micrometers.

7. The coaxial probe according to claim 1, characterized in that The cross section of the test needle tip (113) is circular or polygonal.

8. The coaxial probe according to any one of claims 1 to 7, characterized in that: The needle tip body (110) includes at least two center conductors (111).

9. A probe card, characterized in that: Comprising a unit group (210); the unit group (210) comprises the coaxial probe according to any one of claims 1 to 8.

10. A testing system, characterized in that: The coaxial probe according to any one of claims 1 to 8, or the probe card according to claim 9.

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