Probe for chip testing, method for manufacturing probe, and testing head

Abstract

The application discloses a kind of probes for chip testing, its manufacturing method and test head, belong to semiconductor testing technical field.The probe includes longitudinally extending probe main body and composite needle tip structure at its needle tip end.The composite needle tip structure is jointly constituted by conductive material filled in the recess of probe main body needle tip end and the metal sheet part at needle tip end, and the hardness of conductive material is greater than the hardness of metal sheet.During manufacturing, first, recess is formed by photoetching on the metal sheet corresponding to needle tip end, then high-hardness conductive material is filled, and finally, independent probe is formed by cutting.The composite structure of high-hardness conductive material and metal sheet significantly improves the wear resistance and deformation resistance of probe needle tip, prolongs the service life;And good process compatibility, easy to mass production.

Description

Technical Field

[0001] This invention relates to the field of semiconductor chip testing technology, specifically to a probe for a test head used in chip testing, a method for manufacturing the probe, and the test head itself. Background Technology

[0002] In semiconductor manufacturing processes, wafer-level testing is a critical step in ensuring chip functionality and yield. As the electrical connection interface between the testing equipment and the chip under test, the performance of the core component of the probe card—the contact probe—directly determines the accuracy and reliability of the test.

[0003] Probe cards typically consist of multiple contact probes, each with a tip and a tail. The tip is used to make contact with the contact pads or bumps on the chip on the wafer. During testing, the probes need to withstand thousands or even millions of contact cycles while maintaining stable electrical contact performance and low contact resistance.

[0004] Existing contact probes are typically made of a single alloy material (such as copper alloys, nickel-cobalt alloys, etc.), which presents the following technical problems:

[0005] (1) Tip wear and oxidation. During repeated contact testing, friction between the probe tip and the pad leads to tip wear and a gradual increase in contact resistance. At the same time, some alloy materials are prone to oxidation in the air, forming an oxide film, which further increases the contact resistance and affects the test accuracy. Especially in high-frequency testing and high-density packaging scenarios, the problems of tip wear and oxidation are more prominent.

[0006] (2) Insufficient probe tip contact performance. The hardness of a single alloy material is limited, making it difficult to effectively penetrate the oxide layer on the surface of the pad. Although it is known that using high-hardness precious metals such as rhodium can improve contact performance, rhodium is brittle and difficult to use directly as the probe body. How to locally integrate high-hardness precious metals at the probe tip while ensuring structural integrity is a technical challenge facing the industry.

[0007] (3) The fabrication process of composite probes is complex. To address the above issues, the industry has attempted to locally add precious metals to the probe tip, but existing fabrication methods suffer from complex processes, low yield, and difficulty in mass production. In particular, for probes with micron-sized dimensions, how to accurately integrate different metals at the tip while maintaining the consistency and mechanical properties of the probe body remains a significant technical challenge. Summary of the Invention

[0008] To address the shortcomings of existing technologies, this invention provides a probe for chip testing and its fabrication method. The probe has a composite tip structure with high hardness and long lifespan, and the fabrication method is highly precise and cost-controllable.

[0009] To address the aforementioned technical problems, in a first aspect, the present invention provides a method for fabricating a probe for chip testing, comprising the following steps:

[0010] Provide a metal sheet;

[0011] Grooves are formed on the metal sheet at the tips of the probe bodies to be formed;

[0012] The groove is filled with a conductive material; wherein the hardness of the conductive material is greater than the hardness of the metal sheet; and

[0013] The metal sheet filled with the conductive material is cut to form a plurality of independent probe bodies; wherein the cutting satisfies the condition that the conductive material filled in the groove is retained at the tip of each probe body, so as to form a composite tip structure at the tip of the probe body composed of the conductive material retained at the tip of the probe body and the metal sheet portion at the tip of the probe body.

[0014] As a further improvement to the above manufacturing method, the groove formation includes: covering the surface of the metal sheet with a mask, and etching the groove on the metal sheet corresponding to the tip of the probe. Preferably, the etching method includes one or more of ion beam etching, laser etching, or reactive ion etching. This method employs a process route of first forming grooves on the metal sheet, then filling them with conductive material, and finally cutting them into shape. This method combines the high precision of semiconductor photolithography / etching processes with the convenience of metal processing, enabling precise control of the probe tip's shape, size, and position. It is highly suitable for manufacturing high-density probe cards with pitches at the tens of micrometer level, meeting the testing requirements of advanced chips.

[0015] As a further improvement to the above manufacturing method, the method further includes the step of removing the mask after etching the groove and before cutting the metal sheet; the removal method includes plasma ashing or wet etching.

[0016] As a further improvement to the above manufacturing method, the method of filling the conductive material includes one or more of sputtering deposition, vapor deposition, electroplating deposition, or electroless plating deposition.

[0017] As a further improvement to the above manufacturing method, the method further includes the step of forming an insulating layer on at least a portion of the outer surface of the probe body, excluding the tip and tail ends, after obtaining the composite tip structure. By providing an insulating layer on the surface of the probe body portion, short circuits between adjacent probes in a high-density arrangement can be effectively prevented. As a further improvement to the manufacturing method, the material of the insulating layer is selected from polyimide, pyrene, silicon dioxide, alumina, or silicon nitride.

[0018] As a further improvement to the above manufacturing method, the step of creating the groove specifically includes: forming a window for defining the probe tip and an etched area for forming the groove on the surface of the metal sheet by photolithography and etching processes.

[0019] Furthermore, the step of creating the groove includes: fixing the metal sheet to a rigid substrate; sequentially forming a first photoresist layer, a barrier layer, and a second photoresist layer on the surface of the metal sheet; exposing and developing the second photoresist layer to form a first etching window corresponding to the tip of each probe body; selectively etching the barrier layer using the first etching window to expose the first photoresist layer at that location; removing the remaining second photoresist layer, and then exposing and developing the first photoresist layer again to form a second etching window corresponding to each probe tip to expose the surface of the metal sheet; etching the metal sheet using the second etching window to form the groove; and removing the remaining first photoresist layer and barrier layer. Based on standard photolithography, etching, deposition, and laser cutting technologies, this method is highly compatible with existing MEMS (Micro-Electro-Mechanical Systems) probe manufacturing processes, requiring no complex special equipment, and facilitating large-scale, low-cost production.

[0020] As a further improvement to the above manufacturing method, the metal sheet is fixed to the rigid substrate by an adhesive layer, a vacuum suction cup, or a mechanical clamp. Furthermore, after etching the metal sheet and before cutting it, the metal sheet is released from the rigid substrate.

[0021] As a further improvement to the above manufacturing method, the rigid substrate is a silicon wafer, a ceramic wafer, a glass wafer, or a sapphire wafer.

[0022] As a further improvement to the above manufacturing method, the method also includes the step of: grinding the tip of the probe body after cutting so that the test contact area on the composite tip structure that is in electrical contact with the chip under test is formed into a curved contact area.

[0023] As a further improvement to the above manufacturing method, the thickness of the metal sheet is 30 micrometers to 200 micrometers.

[0024] As a further improvement to the above manufacturing method, the cutting is performed using a femtosecond laser or a picosecond laser.

[0025] Secondly, the present invention also provides a probe for chip testing, which is manufactured using any of the above-described manufacturing methods.

[0026] Specifically, the probe includes a probe body extending longitudinally and a composite tip structure located at the tip of the probe body. The composite tip structure has a test contact area for electrical contact with the chip under test; the test contact area is independently defined by the conductive material retained at the tip of the probe body, or jointly defined by the conductive material retained at the tip of the probe body and the metal sheet portion of the tip of the probe body.

[0027] As a further technical solution for the probe product: when the test contact area is a planar structure, the test contact area is jointly defined by the conductive material and the metal sheet portion. When the test contact area is a sharp protruding structure, the test contact area is independently defined by the conductive material.

[0028] As a further improvement to the probe product, the metal sheet is made of any alloy material selected from nickel-tungsten alloy, nickel-cobalt alloy, nickel-manganese alloy, palladium alloy, rhenium-tungsten alloy, or copper alloy.

[0029] As a further improvement to the probe product, the conductive material is selected from any one or more elements of rhodium, platinum, iridium, nickel, and ruthenium, or from an alloy with any of these metallic elements as the base.

[0030] As a further improvement to the probe product, in the composite tip structure, the conductive material retained at the tip of the probe body has a length measured in the longitudinal direction of 10 micrometers to 1000 micrometers. Furthermore, the maximum dimension of the conductive material retained at the tip of the probe body in the direction perpendicular to the longitudinal direction is 20% to 100% of the maximum dimension of the probe body in the corresponding direction.

[0031] As a further improvement to the probe product, the cross-section of the probe body is rectangular, circular, or elliptical.

[0032] As a further improvement to the probe product, the composite tip structure also includes a coating covering its outer surface, the coating material being selected from one or more of nickel alloys, pure rhodium, pure palladium, rhodium alloys, and palladium alloys. Preferably, the thickness of the coating is from 0.5 micrometers to 10 micrometers.

[0033] As a further improvement to the probe product, the composite tip structure further includes an adhesive film layer located between the conductive material and the inner wall of the groove formed by the metal sheet; the material of the adhesive film layer is selected from any one or more elements selected from nickel, gold, silver, platinum, and palladium, or from an alloy with any of these metal elements as the matrix. Preferably, the thickness of the adhesive film layer is 0.01 micrometers to 3 micrometers.

[0034] By selecting highly conductive metal sheets and conductive materials, as well as optional adhesive films and surface coatings, the overall resistance and signal transmission performance of the probe were further optimized.

[0035] Thirdly, the present invention also provides a test head for chip testing, the test head including an upper guide, a plurality of probes as described above, and a lower guide; wherein the upper guide and the lower guide are spaced apart from each other to define an air gap, and are provided with corresponding guide holes for the probes to slide therein.

[0036] Compared with the prior art, the technical solution provided by the present invention has the following significant advantages: The present invention forms a composite tip structure by opening a groove at the tip of the metal sheet and filling it with a high-hardness conductive material (hardness greater than that of the metal sheet). When the composite tip structure contacts the chip under test, the high-hardness material bears the main wear and contact stress, which significantly improves the wear resistance and deformation resistance of the probe, thereby greatly extending the overall service life of the probe and ensuring the stability of the contact resistance during long-term testing. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the overall structure of a probe provided in this application of the present invention;

[0038] Figure 2 This is an exploded view of a composite needle tip structure provided in this application of the present invention;

[0039] Figure 3 This is a cross-sectional schematic diagram of a composite needle tail structure provided in this application of the present invention;

[0040] Figure 4A This is the first composite needle tip configuration provided in this application of the present invention;

[0041] Figure 4B This is a second composite needle tip configuration provided in this application of the present invention;

[0042] Figure 4C This is a third composite needle tip configuration provided in this application of the present invention;

[0043] Figure 5 A process flow diagram of the first probe fabrication method (mask etching and grooving method) provided in this application of the present invention;

[0044] Figure 6 A process flow diagram of the second probe fabrication method (photolithography electroplating method) provided in this application of the present invention;

[0045] Figures 7A-7D A schematic diagram illustrating the steps of a method for fabricating a first probe according to the present invention application;

[0046] Figure 8A - 8G is a schematic diagram of the various steps of the method for manufacturing a second probe according to the present invention application;

[0047] Figure 9A This is a detailed cross-sectional schematic diagram of a composite needle tip structure provided in this application of the present invention;

[0048] Figure 9B A detailed cross-sectional schematic diagram of another composite needle tip structure provided in this application of the present invention;

[0049] Figure 10 This is a detailed layered schematic diagram of a composite needle tail structure provided in this application of the present invention;

[0050] Figure 11A for Figure 4B A schematic diagram of the configuration of the composite needle tail structure;

[0051] Figure 11B for Figure 11A A schematic diagram of the composite needle tail structure after it has been tapered;

[0052] Figures 12A-12C for Figure 3 The composite needle tail structure is used to form different conductive contact areas. Detailed Implementation

[0053] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0054] (a) Probe

[0055] like Figure 1 As shown, the probe 10 of the present invention extends along the longitudinal direction Y and includes a probe body 10C. The probe body 10C has a composite needle tip structure 10A located at a first end (needle tip) and a composite needle tail structure 10B located at a second end (needle tail).

[0056] The probe body 10C is made of an alloy material. The alloy material of the probe body 10C is selected from any one of nickel-tungsten (Ni-W) alloy, nickel-cobalt (Ni-Co) alloy, nickel-manganese (Ni-Mn) alloy, rhenium-tungsten alloy, palladium alloy, or copper alloy. Preferably, the material of the probe body 10C is a nickel-tungsten alloy, which has good elastic modulus, fatigue life, and electrical conductivity. The cross-sectional shape of the probe body 10C can be rectangular, circular, or elliptical, preferably rectangular, to facilitate guidance and positioning.

[0057] The composite tip structure 10A is located at the first end of the probe body 10C and includes one or more first bonding portions 20 made of a first conductive material. The hardness of the first conductive material is greater than the hardness of the alloy material of the probe body 10C. The first conductive material is selected from any one or more elements of rhodium (Rh), platinum (Pt), iridium (Ir), nickel (Ni), and ruthenium (Ru), or alloys with any of these metallic elements as the matrix; preferably, it is rhodium. Rhodium has a Vickers hardness of approximately HV 600-1500, making it an ideal high-hardness contact material with excellent chemical inertness and oxidation resistance.

[0058] like Figure 2 , Figures 4A-4C As shown, a first support portion 21 is provided at the first end of the probe body 10C, and the first connecting portion 20 is supported by the first support portion 21. The first support portion 21 is formed to have a shape complementary to the first connecting portion 20. The first support portion 21 has a first mating surface 21A and a second mating surface 21B, which face and mat with the first mating surface 20A and the second mating surface 20B of the first connecting portion 20, respectively. In the actual finished product, the first connecting portion 20 and the first support portion 21 are formed as one piece, and the mating surfaces between them form an inseparable bonding interface.

[0059] The length of the first joint 20 measured along the longitudinal direction Y is 10 micrometers to 1000 micrometers, and its thickness along the orthogonal direction Z perpendicular to the longitudinal direction is 20% to 100% of the maximum thickness of the probe body 10C in the corresponding direction. When the thickness of the first joint 20 is equal to the thickness of the probe body 10C, the first joint 20 extends through the entire end; when the thickness of the first joint 20 is less than the thickness of the probe body 10C, the first joint 20 occupies only a portion of the end thickness.

[0060] The first connecting portion 20 and the first supporting portion 21 each have their own free end faces 22A and 22B. A test contact area 22 for the probe 10 is formed in the composite tip structure 10A; this test contact area 22 is the region where the probe 10 makes electrical contact with the chip under test (typically a chip pad). In this example, the free end face 22A of the first connecting portion 20 can either protrude from or be flush with the free end face 22B of the first supporting portion 21. When the free end face 22A protrudes from the free end face 22B, the test contact area 22 is formed solely by the free end face 22A; when they are flush, the test contact area 22 is formed jointly by the free end faces 22A and 22B. Specifically, when the test contact area 22 is designed as a planar structure, it is formed jointly by the free end faces 22A and 22B; when the test contact area 22 is designed as a sharp protrusion structure, it is formed solely by the free end face 22A of the first connecting portion 20.

[0061] like Figure 3 , Figure 10 As shown, the composite needle tail structure 10B is located at the second end of the probe body 10C and includes one or more second bonding portions 30. A second support portion 31 is provided at the second end of the probe body 10C, and the second bonding portion 30 is supported by the second support portion 31. The second bonding portion 30 is made of a second conductive material, which is selected from any one or more elements of nickel (Ni), titanium (Ti), chromium (Cr), gold (Au), silver (Ag), platinum (Pt), palladium (Pd), and rhodium (Rh), or an alloy with any one of these metal elements as the base. In this example, the second bonding portion 30 has a layered structure and includes at least two different metal layers (the material of these metal layers is the second conductive material). Specifically, the second bonding portion 30 includes an adhesion layer 32 and a contact layer 33 covering the adhesion layer 32. The material of the adhesion layer 32 is selected from any one or more elements of nickel, titanium, and chromium, or an alloy with any one of these metal elements as the base. The material of the contact layer 33 is selected from any one or more elements selected from gold (Au), silver (Ag), platinum (Pt), palladium (Pd), and rhodium (Rh), or an alloy selected from any of these metallic elements as the base. The free end face of the second bonding portion 30 can independently form the conductive contact area where the probe tail end of the probe 10 abuts against the MLO substrate pad, or the conductive contact area can be formed jointly by part or all of the free end face of the second bonding portion 30 and the free end face of the second support portion 31. Specifically, as... Figure 12A The conductive contact area may be defined solely by the free end face of the second support portion 31; or it may be as follows: Figure 12B As shown, it is defined by the contact layer 33 on the second joint 30; it can also be as follows Figure 12CAs shown, the second support portion 31 and the second bonding portion 30 are simultaneously defined by the adhesion layer 32 and the contact layer 33. The specific form can be adjusted according to the actual situation or requirements. When one of the layers on the free end face of the second bonding portion 30 and / or the second support portion 31 is made of gold or gold alloy, the free end face constitutes a gold-gold contact layer, which can form a gold-gold contact with the gold surface of the MLO substrate pad, and has the advantages of low contact resistance and stability in high temperature environment.

[0062] In a preferred embodiment, the second bonding portion 30 further includes an innermost substrate layer (not shown in the figure), the material of which is the same as that of the probe body 10C, for example, a nickel-tungsten alloy; the adhesion layer 32 covers the substrate layer.

[0063] In a preferred embodiment, the middle portion of the probe body 10C (i.e., at least a portion of the area between the probe tip and the probe tail, excluding the portion at the probe tip and the probe tail) is also covered with an insulating layer 40. The insulating layer 40 is made of a material selected from polyimide (PI), parylene, silicon dioxide (SiO2), aluminum oxide (Al2O3), or silicon nitride (Si3N4). The insulating layer 40 has a thickness of 1 micrometer to 20 micrometers and is used to prevent electrical short circuits between adjacent probes, especially in scenarios where the spacing between adjacent probes in a high-density probe card is less than 50 micrometers.

[0064] like Figure 4A As shown, in the first configuration of the composite tip structure 10A, there is one first connecting portion 20 located at a corner of the first end of the probe body 10C, with at least two adjacent side surfaces exposed, excluding the free end face 22A that forms the contact area 22. This configuration securely anchors the first connecting portion 20 to the first support portion 21, preventing it from easily falling off.

[0065] like Figure 4B and Figure 11A As shown, in the second configuration of the composite tip structure 10A, the first joint 20 has a thickness reduction portion ("thickness reduction portion" refers to not "filling" the groove after slotting) to reduce the area of ​​the contact region 22. The reduction portion 25 reduces the thickness of the test contact region 22 to 20% to 80% of the thickness H of the probe body 10C, preferably 50%. A smaller contact area is beneficial for subsequent fabrication of a tapered tip structure, such as... Figure 11B As shown, it is a composite needle tip structure after "conicalization".

[0066] like Figure 4CAs shown, in the third configuration of the composite tip structure, the first end 10A has two first joint portions 20' and 20" arranged at intervals between each other. The first joint portions 20' and 20" are symmetrically distributed on both sides of the first support portion 21 with respect to the longitudinal axis of the probe body 10c. This configuration, with first joint portions on both sides, further increases the high-hardness contact area and extends the probe's service life.

[0067] like Figure 9A , 9B As shown, in various configurations of the composite needle tip structure 10A, an adhesive film layer 24 may be provided between the mating surfaces of the first bonding portion 20 and the first support portion 21. The material of the adhesive film layer 24 is selected from any one or more elements selected from nickel, gold, silver, platinum, and palladium, or from an alloy with any of these metal elements as the matrix, preferably gold. The thickness of the adhesive film layer 24 is 0.01 micrometers to 3 micrometers, and it is used to enhance the interfacial bonding force between the first bonding portion 20 and the first support portion 21. For example, an adhesive film layer 24 is provided between the first mating surface 21A of the first support portion 21 and the first mating surface 20A of the first bonding portion 20. The adhesive film layer 24 is used to enhance the adhesion between the two before the bonding interface is formed, or to further strengthen the bond between the two after the bonding interface is formed.

[0068] Furthermore, the composite tip structure 10A may also include a coating 23 covering the side surfaces of the non-test contact surfaces of the first support portion 21 and the first joint portion 20. The coating 23 is made of a conductive alloy with low internal stress (such as a nickel alloy) or a conductive alloy with high wear resistance (such as rhodium or its alloys). Specifically, the material of the coating 23 is selected from one or more of the following groups: nickel alloy, pure rhodium, pure palladium, rhodium alloy, palladium alloy. The thickness of the coating 23 is from 0.5 micrometers to 10 micrometers, serving both as a protective sleeve for the composite tip structure 10A and improving the overall wear resistance of the tip.

[0069] (II) Probe fabrication method

[0070] like Figure 5 and Figures 7A-7D As shown, the present invention provides a method for fabricating a first probe, comprising the following steps:

[0071] S101: Provide a metal sheet. Specifically: Provide a metal sheet 100 made of an alloy material (such as a nickel-tungsten alloy). The thickness of the sheet 100 is 30 micrometers to 200 micrometers, preferably 60 micrometers to 90 micrometers. The planar dimensions of the sheet 100 are determined according to mass production requirements, such as 100mm × 100mm.

[0072] S102: Covering the surface of a metal sheet with a mask. For example... Figure 7AAs shown, a mask 200 is coated onto the surface of a metal sheet 100. The material of the mask 200 is selected from polyimide, pyrene, silica, alumina, or silicon nitride. Coating methods include spin coating (suitable for polyimide), chemical vapor deposition (CVD, suitable for pyrene, silica, and silicon nitride), or physical vapor deposition (PVD, suitable for alumina). The thickness of the mask 200 is from 1 micrometer to 20 micrometers. After coating, a curing process is performed. A mask fixture 201 is provided above the mask 200, with windows opened at positions corresponding to the tip and tail of the probe to be formed.

[0073] S103: Etching and grooving. For example... Figure 7B As shown, on the metal sheet 100, at the positions corresponding to the future probe tip and tail end, an etching and grooving process is performed to form a pair of grooves 202 (i.e., tip groove and tail end groove, the number of grooves can be determined according to the number of the first joint and the second joint).

[0074] Etching and grooving methods include one or more of the following:

[0075] Ion beam etching (IBE) is a technique that uses a focused ion beam (FIB) or a wide-beam ion beam to selectively etch an insulating layer. Argon ions (Ar⁺) can be used as the ion source. Ion beam etching offers advantages such as high precision and good anisotropy, making it suitable for fabricating micron-level fine windows.

[0076] Laser ablation: Utilizing femtosecond or picosecond lasers for selective ablation. Laser wavelengths can be selected from 355nm (ultraviolet) or 532nm (green light), with pulse widths ranging from 10 fs to 10 ps. Laser ablation offers high efficiency and is suitable for high-volume grooving. Patterning is achieved through a galvanometer scanning system.

[0077] Reactive ion etching (RIE): For silicon dioxide or silicon nitride insulating layers, reactive ion etching can be performed using CF4 / CHF3 plasma. The etching pattern must first be defined using photolithography before RIE etching is performed.

[0078] Inductively Coupled Plasma Etching (ICP-RIE): It can etch various metals and alloys, photoresists, organic polymer materials, and silicon nitride.

[0079] After slotting, the dimensions of the pair of grooves 202 are determined according to the design dimensions of the probe tip and tail. For the tip groove at the tip position, the window length is 10-1000 micrometers, and the width is equal to or less than the sheet thickness; for the tail groove at the tail position, the window length is 20-500 micrometers. The depth of the groove 202 is 5-50 micrometers.

[0080] S104: Metal filler. For example... Figure 7C As shown, a pair of grooves 202 are filled with the required first conductive material 20 and second conductive material 30, respectively, to form a composite needle tip structure and a composite needle tail structure. If the conductive material is designed to be multi-layered, it is filled layer by layer sequentially.

[0081] Filling methods include:

[0082] Sputtering: The desired first conductive material (such as rhodium or a rhodium alloy) is sputtered into a groove at the tip of the nozzle. The sputtering thickness is controlled according to design requirements. For deeper grooves, multiple sputtering operations or electroplating can be combined to thicken the groove.

[0083] Evaporation: This method uses electron beam evaporation or resistive evaporation to deposit metal in grooves. Evaporation offers good density and uniformity, making it suitable for thin-layer deposition.

[0084] Electroplating: For deeper grooves, electroplating is the preferred filling method. A seed layer (e.g., sputtered thin layer of gold or nickel) is first formed on the sheet surface, and then rhodium (needle tip) is electroplated into the groove. Rhodium plating electrolytes can be rhodium sulfate-based or rhodium sulfamate-based solutions. For gold plating, sulfite-based cyanide-free gold plating solutions can be used.

[0085] Electroless plating deposition: For applications where an external current is not required, electroless nickel or gold plating can be used. Electroless plating offers good uniformity and is suitable for filling complex-shaped grooves.

[0086] After filling, remove mask fixture 201 and remove mask 200. Removal methods include plasma ashing or wet etching.

[0087] S105: Laser cutting. For example... Figure 7D As shown, the filled metal sheet is cut into individual probes using laser cutting. The laser cutting employs femtosecond, picosecond, or nanosecond lasers, with wavelengths selectable at 355nm, 532nm, or 1064nm. The kerf width is 5-20 micrometers, with a cutting accuracy of ±2 micrometers. The cutting path is determined according to the probe's design profile, ensuring that each probe's tip and tail contain the first and second conductive material structures, respectively.

[0088] S106: Fabricate an insulating layer. As required by the design, fabricate an insulating layer in the middle portion of the probe body (here, the middle portion refers to at least the portion located between the tip and the tail of the probe).

[0089] In addition, the cut probes can be ground to form a curved contact area between the composite tip structure and the composite tail structure, thereby optimizing the contact performance.

[0090] like Figure 6 and Figures 8A-8D As shown, the present invention provides a second probe fabrication method, comprising the following steps:

[0091] S201: Fixing a metal sheet to a rigid substrate. For example... Figure 8A As shown, a metal sheet 100 made of an alloy material is provided and fixed to a rigid substrate 300. The rigid substrate 300 is a silicon wafer, a ceramic wafer (such as alumina ceramic), a glass wafer, or a sapphire wafer, preferably a silicon wafer. The metal sheet 100 is fixed to the rigid substrate 300 by an adhesive layer 301 (such as heat-releasing adhesive, light-releasing adhesive, or temporary bonding adhesive), a vacuum chuck, or a mechanical clamp. After fixing, there should be no relative displacement between the sheet 100 and the substrate 300.

[0092] S202: Apply the first photoresist. (Example: ...) Figure 8A As shown, photoresist 400 is coated on the surface of metal sheet 100. Photoresist 400 can be positive or negative, and the coating method includes spin coating, spray coating, or slot coating. The thickness of photoresist 400 is 5-50 micrometers.

[0093] S203: Deposit a barrier layer 401 on the surface of the first photoresist. For example... Figure 8B As shown, the barrier layer 401 can be selected from polyimide, silicon dioxide, or silicon nitride. The thickness of the barrier layer 401 is from 10 micrometers to 40 micrometers.

[0094] S204: A second photoresist 402 is coated on the surface of the barrier layer 401. For example... Figure 8B As shown, photoresist 402 can be either positive or negative, and the coating methods include spin coating, spray coating, or slot coating. The thickness of photoresist 402 is 5-20 micrometers.

[0095] S205: Define the etching barrier window. The etching barrier window 403 is defined at the corresponding positions of the probe tip and tail using photolithography. For example... Figure 8C As shown, a photomask is used to expose the photoresist 402 to ultraviolet light (wavelength 365nm / 405nm / 436nm). After exposure, development is performed to remove the photoresist (positive photoresist) at the window position or retain the photoresist (negative photoresist) at the window position.

[0096] The size and position of window 403 are consistent with the design of the probe's tip and tail. For the tip position, the window length is 10-1000 micrometers; for the tail position, the window length is 20-500 micrometers. The window width is equal to or less than the sheet thickness.

[0097] S206: Etching barrier layer. For example... Figure 8DAs shown, based on the properties of the barrier layer, a suitable etching method is selected to etch the barrier layer 401 to form window 403'.

[0098] S207: Define the fill window. For example... Figure 8E As shown, photolithography is used to process the photoresist 400 to define etching and filling windows 403 at the corresponding needle tip and needle tail positions.

[0099] S208: Etching grooves. For example... Figure 8F As shown, grooves 20 and 30 are etched on the surface of the metal sheet 100 (etching includes one or more of ion beam etching, laser etching or ion etching).

[0100] S209: Metal filler. For example... Figure 8G As shown, the required first conductive material and second conductive material are filled into the grooves 20 and 30 to form a composite needle tip structure and a composite needle tail structure, respectively. The filling method is the same as in S104.

[0101] S210: Photoresist Removal and Release. Remove the photoresist and barrier layer, and release the metal sheet from the rigid substrate. Photoresist removal methods include: oxygen plasma ashing (O2 plasma, power 100-500W, time 5-30 minutes) or a dedicated photoresist stripping solution (such as NMP-based stripping solution, temperature 60-80°C). The release method from the substrate depends on the fixation method: if thermally release adhesive is used, it is released by heating to the release temperature; if light-release adhesive is used, it is released after ultraviolet light irradiation; if temporary bonding adhesive is used, it is released by solvent dissolution.

[0102] S211: Cut the metal sheet into individual probes using laser cutting. Laser cutting. Cut the released metal sheet into individual probes using laser cutting. The laser parameters are the same as in step S105 of route one, using a femtosecond laser or picosecond laser. The cutting path ensures that the tip and tail of each probe contain electroplated first and second conductive material structures, respectively.

[0103] Similarly, after cutting, the probe can be ground to create a curved contact area between the tip and tail of the composite needle.

[0104] (III) Examples of specific process parameters

[0105] The following two sets of specific process parameters are provided to illustrate the feasibility of the present invention, but do not constitute a limitation on the scope of protection.

[0106] The first set of probe fabrication steps and specific parameters are as follows: S101: Nickel-tungsten alloy sheet, 70μm thick, planar dimensions 100mm×100mm. S102: PECVD fabrication of silicon dioxide mask 200, deposition temperature 80-250℃. Then, a titanium alloy mask 201 is applied. Thickness 50μm, tip window 70μm×150μm, tail window 50μm×70μm. S103: Etching and grooving: First, reactive ion etching removes mask 200, then ICP-RIE dry etching is used to form grooves in the alloy. S104: Filling the metal tip: Rhodium sputtering, 30μm thick; Tail: First, copper plating 5μm, then rhodium plating, then gold sputtering 3μm. S105: Laser cutting with picosecond laser (wavelength 355nm, pulse width 10ps, frequency 200kHz), kerf width 10μm. The second set of probe fabrication steps and specific parameters are as follows: S201: 70μm nickel-tungsten alloy sheet, fixed to a 4-inch silicon wafer using thermal release adhesive. S202: Coating with positive photoresist AZ4620, spin-coating thickness 15μm, pre-baking at 100°C / 3min. S203: PECVD deposition of a SiO2 barrier layer, gas source: silane + N2O, deposition temperature 80-250°C, 10μm thickness. S204: Coating with positive photoresist AZ4620, spin-coating thickness 10μm, pre-baking at 100°C / 3min. S205: Photolithography with UV exposure at 365nm, dose 200mJ / cm², developer AZ400K diluted 1:4, development 60s. S206: Etching of the barrier layer using a 6:1 BOE solution at a constant temperature of 35°C. S207: Photolithography UV exposure at 365nm, dose 200mJ / cm², developer AZ400K diluted 1:4, development 60s. S208: ICP-RIE etching of alloy sheet using a cavity pressure of 1.2 Pa, ICP source power 600 W, bias power 100 W, stage temperature 22℃. S209: Tip rhodium plating: rhodium sulfate plating solution, 50°C, 2A / dm², 30μm; tip first plated with 5μm nickel (nickel sulfamate, 2A / dm²), then with 5μm gold (gold sulfite, 0.5A / dm²). S210: Resin removal using O2 plasma ashing; heating to 120°C to release thermally released resist. BOE removal of residual blocking layer. S211: Picosecond laser cutting (wavelength 355nm, pulse width 10ps), kerf width 10μm. (iv) Test head containing probes

[0107] The present invention also relates to a test head (probe head) for testing chips (or similar electronic devices), comprising an upper guide, a plurality of probes 10 as described above, and a lower guide. The upper and lower guides are spaced apart from each other to define an air gap and are provided with corresponding guide holes for the probes 10 to slide therein. The composite tip structure 10A of the probes 10 faces the device under test, and the composite tail structure 10B faces the space transducer or MLO substrate.

[0108] During testing, the tip of probe 10 contacts the pad of the chip under test. At this time, the first contact portion 20 effectively penetrates the oxide layer on the pad surface, thereby obtaining a reliable electrical connection with low contact resistance. Simultaneously, the tail end of probe 10 contacts the gold surface of the MLO substrate pad. Due to the presence of the second contact portion 30, the contact resistance remains stable even under high-temperature testing environments up to 150°C. Furthermore, the probe body 10C, made of nickel-tungsten alloy, possesses excellent elasticity and fatigue strength, ensuring that probe 10 continues to function normally after millions of contact cycles.

[0109] If electrical isolation is required between adjacent probes, the insulation layer 40 in the middle part of the probe body can be retained to effectively prevent short circuits when adjacent probes bend and deform in the air gap.

[0110] In practical applications, the industry typically employs a "tip cleaning" process to improve probe contact performance. However, this operation continuously wears down the tip, causing it to gradually shorten. By adopting a composite tip structure, under the same three-dimensional dimensions, the tip's wear resistance is significantly improved, with wear amounting to only 50% of that of traditional tips. This effectively reduces the number of tip cleaning cycles and extends the probe's lifespan.

[0111] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. It will be apparent to those skilled in the art that various modifications or variations can be made to the probes used for chip testing according to actual application requirements. Such modifications or variations do not depart from the essence of the present invention and should all be included within the scope of protection of the present invention.

Claims

1. A method for fabricating a probe for chip testing, characterized in that, The method includes: Provide metal sheets; Grooves are formed on the metal sheet at the tips of the probe bodies to be formed; The groove is filled with a conductive material; wherein the hardness of the conductive material is greater than the hardness of the metal sheet; and The metal sheet filled with the conductive material is cut to form a plurality of independent probe bodies; wherein the cutting satisfies the condition that the conductive material filled in the groove is retained at the tip of each probe body, so as to form a composite tip structure at the tip of the probe body composed of the conductive material retained at the tip of the probe body and the metal sheet portion at the tip of the probe body.

2. The manufacturing method according to claim 1, characterized in that, The process of creating the groove includes: covering the surface of the metal sheet with a mask, and etching the groove on the metal sheet corresponding to the tip of the needle.

3. The manufacturing method according to claim 2, characterized in that, The etching method includes one or more of ion beam etching, laser etching, or reactive ion etching.

4. The manufacturing method according to claim 2, characterized in that, Also includes: After etching the grooves and before cutting the metal sheet, remove the mask; The removal methods include plasma ashing or wet etching.

5. The manufacturing method according to claim 1, characterized in that, The method of filling the conductive material includes one or more of sputtering deposition, vapor deposition, electroplating deposition, or electroless plating deposition.

6. The manufacturing method according to claim 1, characterized in that, Also includes: After obtaining the composite needle tip structure, an insulating layer is formed on at least a portion of the outer surface of the probe body, excluding the needle tip and the needle tail.

7. The manufacturing method according to claim 6, characterized in that, The insulating layer is made of a material selected from polyimide, pyrene, silicon dioxide, aluminum oxide, or silicon nitride.

8. The manufacturing method according to claim 1, characterized in that, The groove includes: On the surface of the metal sheet, a window for defining the probe tip and an etched area for forming the groove are sequentially formed by photolithography and etching processes.

9. The manufacturing method according to claim 8, characterized in that, The groove includes: The metal sheet is fixed to a rigid substrate; A first photoresist layer, a barrier layer, and a second photoresist layer are sequentially formed on the surface of the metal sheet. The second photoresist layer is exposed and developed to form the first etching window corresponding to the tip of each probe body; Using the first etching window, the barrier layer is selectively etched to expose the first photoresist layer at that location; Remove the remaining second photoresist layer, then expose and develop the first photoresist layer to form a second etching window corresponding to each needle tip, so as to expose the surface of the metal sheet; The groove is formed by etching the metal sheet using the second etching window; Remove the remaining first photoresist layer and barrier layer.

10. The manufacturing method according to claim 9, characterized in that, The metal sheet is fixed to the rigid substrate by an adhesive layer, a vacuum suction cup, or a mechanical clamp.

11. The manufacturing method according to claim 10, characterized in that, Also includes: After etching the metal sheet is completed and before cutting the metal sheet, the metal sheet is released from the rigid substrate.

12. The manufacturing method according to claim 9, characterized in that, The rigid substrate is a silicon wafer, ceramic wafer, glass wafer, or sapphire wafer.

13. The manufacturing method according to claim 1, characterized in that, Also includes: The tip of the probe body after cutting is ground to form a curved contact area on the composite tip structure that makes electrical contact with the chip under test.

14. The manufacturing method according to claim 1, characterized in that, The thickness of the metal sheet is 30 micrometers to 200 micrometers.

15. The manufacturing method according to claim 1, characterized in that, The cutting is performed using a femtosecond laser or a picosecond laser.

16. A probe for chip testing, characterized in that, The invention includes a probe body extending longitudinally and a composite tip structure located at the tip of the probe body, the composite tip structure being manufactured by the manufacturing method of any one of claims 1-15.

17. The probe according to claim 16, characterized in that, The composite tip structure has a test contact area for electrical contact with the chip under test; wherein the test contact area is independently defined by the conductive material retained on the tip of the probe body, or is jointly defined by the conductive material retained on the tip of the probe body and the metal sheet portion of the tip of the probe body.

18. The probe according to claim 17, characterized in that, When the test contact area is a planar structure, the test contact area is defined by the conductive material and the metal sheet portion.

19. The probe according to claim 17, characterized in that, When the test contact area is a sharp protrusion structure, the test contact area is independently defined by the conductive material.

20. The probe according to claim 16, characterized in that, The metal sheet is made of any alloy material selected from nickel-tungsten alloy, nickel-cobalt alloy, nickel-manganese alloy, palladium alloy, rhenium-tungsten alloy, or copper alloy.

21. The probe according to claim 16, characterized in that, The conductive material is selected from any one or more elements of rhodium, platinum, iridium, nickel, and ruthenium, or from an alloy with any of these metallic elements as the base.

22. The probe according to claim 16, characterized in that, In the composite tip structure, the conductive material retained at the tip of the probe body has a longitudinal length of 10 micrometers to 1000 micrometers.

23. The probe according to claim 22, characterized in that, The maximum dimension of the conductive material retained at the tip of the probe body in the direction perpendicular to the longitudinal direction is 20% to 100% of the maximum dimension of the probe body in the corresponding direction.

24. The probe according to claim 16, characterized in that, The cross-section of the probe body is rectangular, circular, or elliptical.

25. The probe according to claim 16, characterized in that, The composite needle tip structure also includes a coating covering its outer surface, the material of which is selected from one or more of nickel alloy, pure rhodium, pure palladium, rhodium alloy, and palladium alloy.

26. The probe according to claim 25, characterized in that, The coating has a thickness of 0.5 micrometers to 10 micrometers.

27. The probe according to claim 16, characterized in that, The composite needle tip structure further includes an adhesive film layer located between the conductive material and the inner wall of the groove formed by the metal sheet; wherein the material of the adhesive film layer is selected from any one or more elements selected from nickel, gold, silver, platinum, and palladium, or selected from an alloy with any of these metal elements as the base.

28. The probe according to claim 27, characterized in that, The thickness of the adhesive film layer is from 0.01 micrometers to 3 micrometers.

29. A test head for chip testing, comprising an upper guide, a plurality of probes as described in any one of claims 16-28, and a lower guide; wherein, The upper guide and the lower guide are spaced apart from each other to define an air gap, and are provided with corresponding guide holes for the probe to slide therein.

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