Probe for probe cards

Abstract

A probe (20) for probe cards, which is to be placed in contact with electrode pads of a semiconductor device and used for supply of power, input / output of signals, and grounding when performing an operation test of individual semiconductor devices formed on a wafer (W), comprises a plurality of three-dimensionally shaped stress-distributing chambers (201K) which are embedded inside the probe (20) and have vertices (10B) and ridges (10) formed by inner wall surfaces.

Description

Probes for probe cards

[0001] The present application relates to a probe for a probe card.

[0002] A probe card is an electrical connection device used to supply power, input / output signals, and ground the semiconductor devices by bringing probes into contact with the electrode pads of the semiconductor devices in order to perform operational tests on the individual semiconductor devices formed on a wafer. The probes are attached to the surface of the probe card, and are configured so that their tips are pressed against the electrode pads of the semiconductor devices with a predetermined pressure.

[0003] In order to increase the number of semiconductor devices formed on a wafer, it is necessary to reduce the size of the semiconductor devices. For this reason, the electrode pads of semiconductor devices are designed to be small, and the distance between the electrode pads (pitch) is also designed to be small. As semiconductor devices become smaller, probes must also be made finer. However, making probes finer reduces the mechanical strength of the probes.

[0004] Therefore, in order to ensure good electrical and mechanical contact with the electrode pads of the semiconductor device, for example, Patent Document 1 proposes a configuration in which a multi-layer metal sheet is used for the probe.

[0005] Special table 2018-501490 publication

[0006] Patent Document 1 discloses a probe having at least one multilayer structure including a core and a first inner coating layer superposed thereon, and an outer coating layer completely covering the multilayer structure and made of a material harder than the core. As shown in Patent Document 1, a structure in which multiple layers made of different materials are superposed is preferable to achieve good electrical and mechanical contact, but there is a limit to how much this can achieve in meeting the demand for a thinner cross-sectional thickness of the probe, and a further breakthrough was needed.

[0007] In an inspection process using a probe card, after the probes have contacted the electrode pads of a semiconductor device, the probe card is moved even closer to the semiconductor wafer (overdrive) to press the probes against the electrode pads of the semiconductor device. Therefore, the probes must be strong enough to withstand a contact pressure greater than a predetermined value. To prevent the probes from being broken, it is necessary to prevent localized stress concentrations on the probes. To prevent this stress concentration, probes with surfaces as smooth and free of scratches as possible are required.

[0008] However, there is a limit to how smooth a metal surface can be made, and there is a problem in that the thinner the cross-section of the probe is, the more easily it is deformed by an external force (the mechanical strength is reduced).

[0009] The present application discloses a technology for solving the above-mentioned problems, and aims to provide a probe for a probe card that can contact the electrode pad of a semiconductor device with an appropriate needle pressure even when the probe is made fine, and is strong enough not to be broken even when a contact pressure greater than a predetermined value is applied.

[0010] In other words, the probe for a probe card of the present application is a probe for a probe card with high mechanical strength that can withstand large stresses by having a structure that intentionally disperses the locations where stress concentration occurs, rather than preventing stress concentration from occurring.

[0011] The probe for a probe card disclosed in the present application comprises a plurality of three-dimensional stress dispersion chambers embedded inside the probe and having ridges and vertices defined by inner wall surfaces.

[0012] According to the probe for a probe card disclosed in the present application, even if the plate thickness is thin, it is possible to provide a probe for a probe card having high mechanical strength by dispersing the positions where stress concentration occurs.

[0013] 11 is a diagram schematically illustrating a state in which an electronic circuit is tested using a probe card according to embodiment 1. FIG. 12 is a perspective view of a probe according to embodiment 1. FIG. 13 is a plan view showing the shapes of three metal layers constituting the probe according to embodiment 1. FIG. 14 is a cross-sectional view taken along A-A in FIG. 2, and is a cross-sectional view cut perpendicular to the longitudinal direction Z of the probe. FIG. 15 is a perspective view of a probe according to embodiment 2. FIG. 16 is a plan view showing the shapes of three metal layers constituting the probe according to embodiment 2. FIG. 17 is a cross-sectional view taken along B-B in FIG. 5. FIG. 18 is a cross-sectional view cut perpendicular to the longitudinal direction Z of the probe according to embodiment 3. FIG. 19 is a perspective view of a probe according to embodiment 4. FIG. 19 is a plan view showing the shapes of three metal layers constituting the probe according to embodiment 4. FIG. 19 is a perspective view of a probe according to embodiment 5. FIG. 19 is a cross-sectional view taken along C-C in FIG. 11.

[0014] Embodiment 1. A probe for a probe card according to embodiment 1 will be described below with reference to the drawings. FIG. 1 is a diagram schematically illustrating the state of testing an electronic circuit using a probe card 100. In this specification, the upper side of the paper in FIG. 1 will be referred to as "top" and the lower side of the paper will be referred to as "bottom." That is, the side to be tested as viewed from the probe card 100 will be referred to as "bottom." The left-right direction of the paper in FIG. 1 will be referred to as the buckling direction X, and the direction from the front to the back of the paper and the opposite direction will be referred to as the direction Y perpendicular to the buckling direction X. The longitudinal direction of the probe 20 (the vertical direction of the paper in FIG. 1) will be referred to as the longitudinal direction Z.

[0015] The probe card 100 is a device used to test the electrical characteristics of electronic circuits formed on a semiconductor wafer W. The probe card 100 is equipped with a large number of probes 20, each of which is brought into contact with an electrode C on the electronic circuit. The characteristic test of the electronic circuit is performed by bringing the semiconductor wafer W close to the probe card 100, bringing the tips of the probes 20 into contact with the electrodes C on the electronic circuit, and conducting the electrodes C to a tester device (not shown) via the tester connection electrodes TC on the wiring substrate 14 of the probe card 100 and the probes 20.

[0016] The probe card 100 includes a hollow frame 1, an upper guide 11 attached to the upper end of the frame 1, a lower guide 12 attached to the lower end of the frame 1, a fixing plate 13 for fixing the upper guide 11, and a wiring board 14. An intermediate guide may be further provided between the upper guide 11 and the lower guide 12.

[0017] The upper guide 11 has a plurality of guide holes 11H penetrating in the vertical direction. The lower guide 12 provided below the upper guide 11 has a plurality of guide holes 12H penetrating in the vertical direction. Above the group of the plurality of guide holes 11H provided in the upper guide 11 is an opening 13H provided in the fixing plate 13. A wiring board 14 is disposed on the upper surface of the fixing plate 13. The wiring board 14 has a plurality of probe connection pads 14P on its lower surface that come into contact with the terminal portions 20t at the upper ends of the probes 20.

[0018] A plurality of probes 20 are inserted and guided through the guide holes 12H and 11H, respectively. The probes 20 are vertical probes that are arranged perpendicular to the test object (electronic circuits formed on the semiconductor wafer W).

[0019] 1 is the buckling direction X of the probe 20, i.e., the direction in which the probe 20 elastically deforms when the probe card 100 is overdriven. The probe 20 has a long, thin rectangular prism shape. The probe 20 extends linearly in the up-down direction. The probe 20 has a contact portion 20c at its lower end (one end). A terminal portion 20t is formed at its upper end (the other end).

[0020] When the probe 20 is overdriven, a compressive force is applied in the longitudinal direction Z, and the probe 20 easily undergoes buckling deformation in the buckling direction X in response to a reaction force from the test object. The contact portion 20c retracts toward the terminal portion 20t, and at this time, stress is generated inside the probe 20.

[0021] FIG. 2 is a perspective view of the probe 20. FIG. 3 is a plan view showing the shapes of the three metal layers that make up the probe 20. The probe 20 is made of a conductive metal. The first to third metal layers 20L1 to 20L3 of the probe 20 are each thin layers of the same metal. The first metal layer 20L1 and the third metal layer 20L3 are formed in a flat plate shape. The second metal layer 20L2, which is sandwiched between the first metal layer 20L1 and the third metal layer 20L3, has a plurality of hexagonal column-shaped holes 20H spaced apart in the longitudinal direction Z of the probe 20 and aligned in the stacking direction R of the metal layers of the probe 20. The first metal layer 20L1, the second metal layer 20L2, and the third metal layer 20L3 are stacked in order and integrated by welding each metal layer together.

[0022] In FIG. 2, the buckling direction X is the same as the stacking direction R of the three metal layers, but the buckling direction may be the direction Y perpendicular to the stacking direction R of the metal layers.

[0023] 4 is a cross-sectional view taken along line A-A in FIG. 2, and is a cross-sectional view taken perpendicular to the longitudinal direction Z of the probe 20. The left-right direction of the paper in FIG. 4 is the buckling direction X. A cross-section perpendicular to the longitudinal direction Z of the probe 20 is as shown in FIG. 4 at the portion where the hole 20H is disposed in the second metal layer 20L2, and the hole 20H forms a cavity 20K1 (stress dispersion chamber) that is surrounded by its inner wall, the first metal layer 20L1, and the third metal layer 20L3. In this way, the cavity 20K1 is formed inside the probe 20.

[0024] Here, when comparing probe A, which does not have a cavity 20K1, with probe 20, which has a cavity 20K1, the needle pressure relative to the amount of overdrive is smaller for probe 20, which has a cavity 20K1.

[0025] Furthermore, an analysis was conducted to determine what effects can be obtained by the cavity 20K1. The maximum stress of the probes A, which does not have the cavity 20K1, and the probe 20, which has the hexagonal prism-shaped cavity 20K1, was calculated using the finite element method (FEM). The results showed that when an external force is applied, the stress is concentrated at each vertex 10B of the cavity 20K1 shown in FIG. 2 and at the ridge 10 formed by the two adjacent faces that make up the cavity 20K1.

[0026] Therefore, by embedding hexagonal column-shaped cavities 20K1 as stress dispersion chambers at predetermined intervals in the longitudinal direction Z of the probe 20, stress can be uniformly dispersed to each vertex 10B and each ridge 10.

[0027] The first metal layer 20L1 to the third metal layer 20L3 of the probe 20 are fabricated using so-called MEMS (Micro Electro Mechanical Systems) technology (probe intermediate formation process). MEMS technology is a technology for creating fine three-dimensional structures using photolithography and sacrificial layer etching. Photolithography is a technology for processing fine patterns using photoresist, which is used in semiconductor manufacturing processes, etc. Sacrificial layer etching is a technology for creating three-dimensional structures by forming a lower layer called a sacrificial layer, forming layers that constitute the structure on top of it, and then removing only the sacrificial layer by etching.

[0028] Well-known plating techniques can be used to form the first metal layer 20L1 to the third metal layer 20L3. For example, by immersing a substrate as a cathode and a metal piece as an anode in an electrolyte and applying a voltage between the two electrodes, metal ions in the electrolyte can be attached to the substrate surface. This type of process is called electroplating, and because it is a wet process in which the substrate is immersed in an electrolyte, a drying process is performed after the plating process to obtain the first metal layer 20L1 to the third metal layer 20L3. After this drying process, the first metal layer 20L1 to the third metal layer 20L3 are stacked and welded together. The portion that will become the lower tip is polished (polishing process) to form the contact portion 20c.

[0029] According to the probe for probe card of embodiment 1, the stress generated inside the probe 20 during testing can be distributed to each vertex 10B and each ridge 10 of the cavity portion 20K1, thereby achieving both maintenance of mechanical strength and reduction of needle pressure.

[0030] Second Embodiment. A probe card probe according to a second embodiment will be described below, focusing on differences from the first embodiment. FIG. 5 is a perspective view of the probe 20. FIG. 6 is a plan view showing the shapes of the three metal layers constituting the probe 20. FIG. 7 is a cross-sectional view taken along the line B-B of FIG. 5. In the first embodiment, the probe 20 was described, in which a plurality of independent hexagonal column-shaped cavities 20K1 are embedded in a metal column made of three metal layers and aligned in the longitudinal direction Z. In the second embodiment, the plurality of cavities 20K1 of the probe 20 are interconnected by narrow cavities 20K2. The cavities 20K2 communicate with the outside of the probe 20 at several points.

[0031] The cavities 20K1 and 20K2 are initially formed as sacrificial layers in the process of manufacturing the probe 20, and are then removed by etching. That is, in the first embodiment, in order to form the cavity 20K1, it was necessary to manufacture the first metal layer 20L1 to the third metal layer 20L3 individually and then weld them together. In the second embodiment, all of the holes 20H in the second metal layer 20L2 are connected by the grooves 20M1. Furthermore, by forming at least two grooves 20M2 that communicate with several of the holes 20H and open to the outside of the probe 20, there is an advantage that the probe 20 can be manufactured in a single process.

[0032] The manufacturing process of the probe 20 is generally as follows: First, the first metal layer 20L1 is formed. Next, the second metal layer 20L2 is formed in a portion other than the portion that will become the hole 20H and the grooves 20M1 and 20M2. Next, a sacrificial layer is formed in the hole 20H and the grooves 20M1 and 20M2. Next, the third metal layer 20L3 is formed. Finally, the sacrificial layer is melted to form a plurality of cavities 20K1 and 20K2 inside the probe 20.

[0033] According to the probe for the probe card of the second embodiment, all steps can be completed as a series of steps using MEMS, and therefore, in addition to the effects of the first embodiment, it is possible to provide a probe 20 with even higher mechanical strength.

[0034] Third Embodiment. A probe card probe according to a third embodiment will be described below, focusing on differences from the first embodiment. FIG. 8 is a cross-sectional view of the probe 20 taken perpendicular to the longitudinal direction Z. In this embodiment, an example will be described in which the cavity 20K1 is sealed with a material different from the probe 20 body. As shown in FIG. 4, the cavity 20K1 described in the first embodiment is filled with a material softer than the surrounding probe 20 body. Examples of the material to be filled include a metal such as Au, a resin, and the like. When filling the cavity 20K1 with Au or the like, a layer of Au is formed in the cavity 20K1 after forming the second metal layer 20L2 described in the second embodiment, and then a third metal layer 20L3 is formed to seal the cavity 20K1. The same applies to the case of a resin.

[0035] According to the probe for a probe card according to the third embodiment, all steps can be completed as a series of steps using MEMS, as in the second embodiment. Therefore, in addition to the effects of the first embodiment, it is possible to provide a probe 20 with even higher mechanical strength.

[0036] Furthermore, when Au or the like is used as the metal to be housed in the hole 20H, the conductivity of the probe is improved and the same effects as those of the first embodiment are achieved. When a resin is housed, the flexibility of the probe 20 during buckling deformation can be increased.

[0037] Embodiment 4 A probe for a probe card according to embodiment 4 will be described below, focusing on the differences from embodiment 1. Fig. 9 is a perspective view of probe 20. Fig. 10 is a plan view showing the shapes of the three metal layers that make up probe 20.

[0038] The probe 20 is formed of three metal layers, just like in the first embodiment. The probe 20 according to this embodiment differs from the probe 20 according to the first embodiment in the configuration of the second metal layer 20L2. Notches 20CT recessed toward the inside of the probe 20 are alternately provided in the longitudinal direction Z of the probe 20 on both surfaces of the second metal layer 20L2 in the direction Y perpendicular to the buckling direction X.

[0039] The manufacturing process of the probe 20 is generally as follows: First, a first metal layer 20L1 is formed. Next, a portion of the second metal layer 20L2 other than the portion that will become the cutout portion 20CT is formed on the first metal layer 20L1. Next, a sacrificial layer is formed in the cutout portion 20CT. Next, a third metal layer 20L3 is formed on the second metal layer 20L2. Finally, the sacrificial layer is melted to form multiple cavities 20K3 inside the probe 20. These cavities 20K3 are open to the outside of the probe 20.

[0040] As in the third embodiment, the cavity 20K3 may be sealed by filling it with resin or a metal that is softer and has lower electrical resistance than the main body of the probe 20. In this case, the same effects as in the third embodiment can be achieved.

[0041] Fifth Embodiment. A probe card probe according to a fifth embodiment will be described below, focusing on differences from the first embodiment. FIG. 11 is a perspective view of the probe 20. FIG. 12A is a cross-sectional view taken along the line CC of FIG. 11. FIG. 12B is a cross-sectional view showing a modified example of the probe 20. As shown in FIG. 11, the probe 20 is composed of two types of metals with different electrical resistivities. One is an inner metal constituting a low-resistivity portion L made of a metal with low resistivity, such as copper, gold, or silver (Cu, Au, Ag). The low-resistivity portion L has high conductivity and functions to improve current-withstand performance. The other is an outer metal constituting a high-resistivity portion H, such as a palladium-cobalt (PdCo) alloy, which has higher resistivity and lower conductivity than the low-resistivity portion L, but has high mechanical strength and springiness. The high-resistivity portion H functions to maintain the mechanical strength of the probe 20.

[0042] 12A and 12B, the high resistance portion H of the probe 20 surrounds the low resistance portion L. Focusing only on the high resistance portion H, a plurality of rectangular prism-shaped recesses 20R are formed on the inner walls on both sides of the high resistance portion H in the buckling direction X. The recesses 20R (stress dispersion chambers) are formed at equal intervals along the longitudinal direction Z of the probe 20.

[0043] As shown in FIG. 12B , multiple rows of small depressions 20R may be arranged along the longitudinal direction Z of the probe 20. The insides of the depressions 20R are low-resistance portions L. Therefore, focusing only on the low-resistance portions L, the low-resistance portions L have multiple protrusions LT that protrude in the buckling direction X from both sides in the buckling direction X. As described above, stress acting inside the probe 20 is concentrated at each vertex 10B and each ridge 10 formed in the probe 20. Therefore, by evenly providing multiple depressions 20R inside the high-resistance portions H, which have high mechanical strength and springiness, it is possible to evenly distribute the stress acting inside the probe 20 when the probe 20 buckles.

[0044] Although various exemplary embodiments and examples are described in this application, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless modifications not illustrated are contemplated within the scope of the technology disclosed in this application. For example, this includes cases where at least one component is modified, added, or omitted, or where at least one component is extracted and combined with components of another embodiment.

[0045] 100 probe card, 1 frame, 10 ridge line, 10B vertex, 11 upper guide, 11H guide hole, 12 lower guide, 12H guide hole, 13 fixing plate, 13H opening, 14 wiring board, 14P probe connection pad, 20 probe, 20c contact portion, 20H hole, 20K1, 20K2, 20K3 cavity portion, 20M1, 20M2 groove, 20R recess, 20t terminal portion, C electrode, H high resistance portion, 20CT notch portion, L low resistance portion, H high resistance portion, 20L1 first metal layer, 20L2 second metal layer, 20L3 third metal layer, LT protrusion portion, R stacking direction, TC tester connection electrode, W semiconductor wafer, X buckling direction, Y direction perpendicular to buckling direction X, Z longitudinal direction.

Claims

1. A probe for a probe card, The probe is a probe for a probe card, and includes a plurality of closed stress dispersion chambers embedded inside the probe, each of which has a three-dimensional shape with ridges and apexes defined by inner wall surfaces.

2. A probe for a probe card, comprising: The probe includes a plurality of stress dispersion chambers embedded inside the probe, each of which has a three-dimensional shape having a ridge line and a vertex defined by an inner wall surface, The stress dispersion chamber is hollow, A probe for a probe card, wherein all of the stress dispersion chambers communicate with the outside of the probe.

3. A probe for a probe card, comprising: The probe includes a plurality of stress dispersion chambers embedded inside the probe, each of which has a three-dimensional shape having a ridge line and a vertex defined by an inner wall surface, The probe includes a low resistance portion made of a metal layer having an electrical low resistance, a high resistance portion having a higher electrical resistance than the low resistance portion and having a spring property is provided outside the low resistance portion, The stress dispersion chamber is formed in the high resistance portion.

4. The probe for a probe card according to claim 3 , wherein the stress dispersion chamber is open to an outer surface of the probe.

5. 4. The probe for a probe card according to claim 3, wherein the stress dispersion chamber contains a metal having a lower electrical resistance than surrounding metals.

6. 4. The probe for a probe card according to claim 3, wherein the stress dispersion chamber contains a resin.

7. 4. The probe for a probe card according to claim 3, wherein the stress dispersion chamber contains the same metal as the low resistance portion.