Probe for probe card

Abstract

This probe (20) for a probe card comprises: a plurality of deformed regions (8), which are provided in two rows in at least one side surface (20S) from among two side surfaces (20S) and which are recessed relative to the side surface (20S), each of the two rows being constituted by a plurality of the deformed regions arranged with intervals therebetween in a lengthwise direction (Z) of the probe (20), the two rows being spaced apart from each other, the two side surfaces (20S) being perpendicular to two planes that are perpendicular to a buckling direction (X) of the probe (20); and a framework region (9) having a zigzag shape between the two rows of the plurality of deformed regions (8). The length of the framework region (9) is greater than the length of the probe (20) in the lengthwise direction (Z).

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] The probe disclosed in Patent Document 1 is a contact probe having at least one multilayer structure including a superposition of a core and a first inner coating layer, and an outer coating layer that completely covers the multilayer structure and is made of a material harder than the core and completely covers the multilayer structure. As shown in Patent Document 1, in order to achieve good electrical contact and mechanical contact, a configuration in which multiple layers made of different materials are superposed is preferable, but there is a limit to 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, the more easily it is deformed by an external force, and the lower its mechanical strength.

[0009] The present application discloses a technology for solving the above-mentioned problems, and aims to provide a probe that, even when miniaturized, can contact the electrode pad of a semiconductor device with an appropriate needle pressure 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 aims to provide a probe for a probe card that can withstand large stresses (having high mechanical strength) 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 is a probe for a probe card, wherein the probe has, on a reference plane of at least one of two side surfaces perpendicular to the two surfaces perpendicular to the buckling direction of the probe, a plurality of deformation regions which are recesses in the side surface and are arranged in two rows with a plurality of spaced apart deformation regions in the longitudinal direction of the probe, and a zigzag-shaped framework region between the two rows of the deformation regions, and the length of the framework region is longer than the length of the probe in the longitudinal direction.

[0012] According to the probe for a probe card disclosed in the present application, even if the plate thickness is thin, the positions where stress concentration occurs can be dispersed, thereby providing a probe for a probe card with high mechanical strength.

[0013] FIG. 3 is a diagram schematically showing a state in which an electronic circuit is tested using a probe card according to embodiment 1. FIG. 4 is a perspective view of a probe according to embodiment 1. FIG. 5 is a cross-sectional view taken along line A-A of FIG. 2, and is a cross-sectional view perpendicular to the longitudinal direction of the probe. FIG. 6 is a diagram showing the positional relationship of deformation regions arranged in two rows according to embodiment 1. FIG. 7 is a cross-sectional view showing a modified example of the probe according to embodiment 1. FIG. 8 is a cross-sectional view perpendicular to the longitudinal direction of the probe according to embodiment 2. FIG. 9 is a cross-sectional view perpendicular to the longitudinal direction of the probe according to embodiment 3. FIG. 10 is a cross-sectional view showing a modified example of the probe according to embodiment 3. FIG. 11 is a diagram showing variations of the deformation region according to embodiment 4. FIG. 12 is a diagram showing variations of the deformation region according to embodiment 4. FIG. 13 is a diagram showing variations of the deformation region according to embodiment 5. FIG. 14 is a diagram showing variations of the deformation region according to embodiment 5. FIG. 15 is a diagram showing variations of the deformation region according to embodiment 5.

[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 an electronic circuit formed on the semiconductor wafer W. 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 establishing electrical continuity between a tester device (not shown) and a tester connection electrode TC on the wiring board 14 of the probe card 100 via 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, and the lower guide 12 provided below the upper guide 11 also 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] FIG. 2 is a perspective view of the probe 20. The left-right direction in FIG. 2 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 an elongated shape. The central portion is curved, and the upper and lower portions extend linearly in the vertical 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 recedes toward the terminal portion 20t, and stress is generated inside the probe 20.

[0021] 3 is a cross-sectional view taken along line AA in FIG. 2, which is a cross-sectional view perpendicular to the longitudinal direction Z of the probe 20. The left-right direction on the paper surface of FIG. 3 is the buckling direction X.

[0022] The probe 20 is conductive and is composed of two types of metals with different resistivities. One is an inner metal (first metal) that constitutes the low-resistance portion L, which is made of a metal with low resistivity such as copper, gold, or silver (Cu, Au, Ag). The low-resistance portion L has high conductivity and functions to improve current resistance. The other is an outer metal (second metal) that constitutes the high-resistance portion H, which has a higher resistivity and lower conductivity than the low-resistance portion L, but has high mechanical strength and springiness, such as a palladium-cobalt (PdCo) alloy. The high-resistance portion H functions to maintain the mechanical strength of the probe 20.

[0023] As shown in Figure 3, a plurality of deformation regions 8 and a framework region 9 are formed on side surfaces 20S perpendicular to two surfaces of the high resistance portion H of the probe 20 perpendicular to the buckling direction X. The deformation region 8 refers to a region where the reference surface 20SB, which is the original flat surface of the probe card, is deformed to form a depression. The framework region 9 refers to a region connecting the plurality of deformation regions 8. The boundary between the deformation region 8 and the framework region 9 is represented by a ridge line 10.

[0024] 2 and 3 show an example in which a plurality of pentagonal prism-shaped depressions are provided in the reference surface 20SB, which is the original flat surface, as the deformation regions 8. The framework region 9 is the flat portion between the deformation regions 8. The plurality of pentagonal prism-shaped deformation regions 8 are provided in two rows along the longitudinal direction Z of the probe 20, and each row is arranged so that the ridge lines 10 of the plurality of deformation regions 8 are aligned in the longitudinal direction at both ends of the side surface 20S in the buckling direction X.

[0025] 4 is a side view of the probe 20, showing the positional relationship of the deformation regions 8 arranged in two rows. The two rows of deformation regions 8 are arranged so that their positions in the longitudinal direction Z of the probe 20 are staggered. In adjacent rows (here, two rows) in the buckling direction X, the pentagonal prism shapes of the deformation regions are inverted in the buckling direction X. In addition, in FIG. 4, the dashed line L1 connecting the right ends of each deformation region 8 in the left row is located to the right of the center line O in the buckling direction X of the side surface 20S, and the dashed line L2 connecting the left ends of each deformation region 8 in the right row is located to the left of the center line O in the buckling direction X of the side surface 20S.

[0026] By arranging the deformation regions 8 in each row in this manner, side beams 20SB1 and 20SB2 extending in the longitudinal direction Z of the probe 20 are formed on each side of the side surface 20S of the high resistance portion H of the probe 20 in the buckling direction X, as shown in Fig. 2. Furthermore, a framework region 91 extending in the longitudinal direction Z in a zigzag shape is formed in the center of the side surface 20S of the probe 20 between the deformation regions 8 arranged in two rows along the longitudinal direction Z. The length P1 of this framework region 91 is longer than the length of the side beams 20SB1 and 20SB2, i.e., the length P2 in the longitudinal direction Z of the portion of the probe 20 where the deformation regions 8 are formed.

[0027] Therefore, when two adjacent deformation regions 8 (each belonging to a different row) in the buckling direction X are viewed in the longitudinal direction Z of the probe 20, parts of each deformation region 8 (protrusions 8T in the buckling direction X) will appear to overlap each other.

[0028] Here, when comparing probe A, which has a structure in which no deformation region 8 is provided, with probe 20, which has a structure in which deformation regions 8 are provided on the front and back sides, the relationship between the needle pressure and the amount of overdrive is smaller for probe 20, which has deformation regions 8.

[0029] Furthermore, an analysis was conducted to determine what effects can be obtained by the deformation region 8. The maximum stress of the probe was calculated using the finite element method (FEM) for probe A, which has no depression (a smooth surface), and probe 20, which has a pentagonal prism-shaped depression. The results showed that when an external force is applied, stress is concentrated on the ridge 10 at the boundary between the deformation region 8 and the framework region 9. It was also found that by making the bottom surface of the deformation region 8 flat, stress is concentrated on the ridge 10 at the boundary between the deformation region 8 and the framework region 9.

[0030] This means that if the deformation region 8 is formed as a depression in a polygonal prism, stress will be concentrated at each vertex of the polygon, and when an external force is applied, the stress will be dispersed to each vertex.

[0031] In this way, by arranging the deformation region 8 as described above in the high resistance portion H that contributes to maintaining the mechanical strength of the probe 20, the length of the framework region 91 can be extended, and the needle pressure of the probe 20 can be reduced while dispersing the areas where stress is concentrated.

[0032] The probe 20 is 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 a three-dimensional structure 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.

[0033] Well-known plating techniques can be used to form each layer. For example, a substrate serving as a cathode and a metal piece serving as an anode are immersed in an electrolyte, and a voltage is applied between the two electrodes, thereby causing metal ions in the electrolyte to adhere to the substrate surface. This type of process is called electroplating, and since 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 an intermediate probe. Furthermore, after this drying process, the portion that will become the lower tip is polished (polishing process) to form the contact portion 20c.

[0034] 5 is a cross-sectional view showing a modified example of the probe 20. As shown in the figure, the thickness of the high resistance portion H on the side surface where the deformation region 8 is not provided may be smaller than that on the side surface 20S where the deformation region 8 is provided. In this case, the electrical resistance of the probe can be reduced.

[0035] According to the probe for probe card of embodiment 1, by arranging the deformation region 8 in the high resistance portion H that contributes to maintaining the mechanical strength of the probe 20, the length of the framework region 91 can be extended, and the needle pressure can be reduced while dispersing the areas where stress is concentrated. Furthermore, for the same needle pressure, the overall length of the probe 20 can be reduced. The number of rows of the deformation region 8 may be three or more. Furthermore, the deformation region 8 may be arranged on only one side surface 20S.

[0036] Embodiment 2. A probe for a probe card according to embodiment 2 will be described below, focusing on the differences from embodiment 1. In this embodiment, a modified example of the deformation region 8 will be described. Figure 6 is a cross-sectional view perpendicular to the longitudinal direction of probe 20 according to embodiment 2. The left-right direction on the paper is the buckling direction X. This embodiment differs from embodiment 1 in that the high resistance portion H, which has spring properties, penetrates to the low resistance portion L, which has low electrical resistance.

[0037] In the first embodiment, the deformation region 8 does not penetrate the high resistance portion H. In the second embodiment, the deformation region 8 penetrates the high resistance portion H, and the low resistance portion L is visible from the side surface 20S of the probe 20. With this configuration, the framework region 91 can exert even more elasticity, and therefore the needle pressure can be further reduced.

[0038] Embodiment 3. A probe card probe according to embodiment 3 will be described below, focusing on the differences from embodiment 2. In this embodiment, a modified example of the deformation region 8 will be described. FIG. 7 is a cross-sectional view perpendicular to the longitudinal direction of the probe according to embodiment 3. In this embodiment 3, as in embodiment 2, the deformation region 8 also penetrates the high resistance portion H. In this embodiment 3, an intermediate layer M (third metal layer) is provided between the high resistance portion H and the low resistance portion L. Note that the deformation region 8 is not provided in the intermediate layer M.

[0039] In the second embodiment, the exposed low resistance portion L must be made of a material that does not melt during sacrificial layer etching, but providing an intermediate layer M that does not melt during sacrificial layer etching to protect the low resistance portion L from melting widens the range of material options for the low resistance portion L. The material for the intermediate layer M can be a material that does not melt during sacrificial layer etching and has a low Young's modulus that is subject to little stress with respect to deformation, such as Pd or Pt, and it is advisable to provide the intermediate layer M according to the required needle pressure and length of the probe 20.

[0040] According to the probe for the probe card of embodiment 2, the range of materials that can be used for the low resistance portion L is increased, thereby making it possible to realize a probe that has even lower resistance than embodiment 2 and that can exhibit even greater elasticity than embodiment 1.

[0041] Fig. 8 is a cross-sectional view showing a modified example of the probe 20. As shown in Fig. 8, the high resistance portion H may be provided only on the side surface 20S where the deformation region 8 is provided. In this case, forming a metal layer in the Y direction by MEMS has the effect of reducing the number of processes.

[0042] Fourth Embodiment A probe for a probe card according to a fourth embodiment will be described below with reference to the drawings. In this embodiment, another example of the deformation region 8 will be described. Figures 9A to 9C are diagrams showing variations of the deformation region 8. As shown in Figure 9A, the triangular prism-shaped deformation regions 8 may be inverted so that they alternately protrude toward the center of the side surface 20S, and arranged in two rows along the longitudinal direction Z of the probe 20.

[0043] Furthermore, as shown in FIG. 9B , when viewed in the buckling direction X, the deformation regions 8 each having a hexagonal prism shape, which has two sides parallel to the buckling direction X of the probe 20 and two sides parallel to the longitudinal direction Z of the probe 20, may be arranged in two rows along the longitudinal direction Z of the probe 20, with the deformation regions 8 alternately inverted in the buckling direction X.

[0044] 9C , when viewed in the buckling direction X, the deformation regions 8, which are semicylindrical triangular prisms, may be inverted so that they alternately protrude toward the center of the side surface 20S and arranged in two rows along the longitudinal direction Z of the probe 20. In either case, as in the first embodiment, the tip of the deformation region protruding in the buckling direction X must be located beyond the center line O of the side surface 20S in the buckling direction. This provides the same effect as the first embodiment.

[0045] Fifth Embodiment. A probe card probe according to a fifth embodiment will now be described with reference to the drawings. In this embodiment, another example of the deformation region 8 will be described. FIGS. 10A, 10B, 10C, and 11 are diagrams showing variations of the deformation region 8. The deformation region 8 may have a triangular truncated pyramid shape as shown in FIG. 10A, a pentagonal truncated pyramid shape as shown in FIG. 10B, or a semi-cylindrical shape as shown in FIG. 10C, the shape of the bottom surface of which is similar to but smaller than the shape of the ridge line 10 of the deformation region 8. That is, the deformation region 8 has a flat central portion 8C, and the peripheral portion surrounding the central portion 8C is an inclined surface SL that slopes toward the side surface 20S. The width of the framework region 91 gradually increases toward the flat surface 8F, thereby increasing the strength of the framework region 91. The probe card probe according to this fifth embodiment also achieves the same effects as those of the first to fourth embodiments.

[0046] 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.

[0047] 100 probe card, 1 frame, 10 ridge line, 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, 20SB1, 20SB2 side beam, 20m center portion, 20S side surface, 20SB reference surface, 20t terminal portion, 8 deformation region, 8T protrusion portion, 9, 91 framework region, C electrode, H high resistance portion, L low resistance portion, M intermediate layer, O center line, TC tester connection electrode, W semiconductor wafer, P1, P2 length, 8C center portion, SL inclined surface, X buckling direction, Y direction perpendicular to buckling direction X, Z longitudinal direction.

Claims

1. A probe for a probe card, the probe having, on at least one of two side surfaces perpendicular to the two surfaces perpendicular to the buckling direction of the probe, a plurality of deformation regions which are recesses in the side surface and arranged in two rows with a plurality of deformation regions spaced apart in the longitudinal direction of the probe, and a zigzag-shaped framework region between the two rows of the deformation regions, the length of the framework region being longer than the length of the probe in the longitudinal direction.

2. A probe for a probe card according to claim 1, wherein when two adjacent deformation regions in the buckling direction are viewed in the longitudinal direction of the probe, portions of the deformation regions appear to overlap each other.

3. The probe for a probe card according to claim 1, wherein the two deformation regions adjacent in the buckling direction have shapes that are inverted in the buckling direction.

4. A probe for a probe card as described in claim 1, wherein the deformation area is either triangular, pentagonal, hexagonal or semi-cylindrical, and in the two adjacent rows, the deformation area in one row has a protruding portion that protrudes toward the other row.

5. A probe for a probe card according to claim 1, wherein the deformation region has a flat bottom surface of the depression and a peripheral portion surrounding the bottom surface that is an inclined surface that widens toward the side surface.

6. A probe for a probe card according to any one of claims 1 to 5, wherein the probe comprises an inner first metal layer having low electrical resistance, and a second metal layer outside the first metal layer that is harder and has spring properties than the first metal layer, and the deformation region is formed in the second metal layer.

7. The probe for a probe card according to claim 6, wherein the deformation region penetrates through the second metal layer.

8. The probe for a probe card according to claim 7, further comprising a third metal layer between the first metal layer and the second metal layer.

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