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

Technical Field

[0001] This application relates to a probe for a probe card.

Background Art

[0002] A probe card is an electrical connection device used to perform an operation test on individual semiconductor devices formed on a wafer by bringing probes into contact with electrode pads of the semiconductor devices to supply power, input / output signals, and ground. The probes are provided on the surface of the probe card and are configured such that the tips are pressed against the electrode pads of the semiconductor devices with a predetermined pressing force.

[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 the semiconductor devices are designed to be small, and the distance (pitch) between the electrode pads is designed to be small. In response to the miniaturization of semiconductor devices, it is necessary to make the probes finer. However, when the probes are made finer, there is a problem that the mechanical strength of the probes becomes weak.

[0004] For this reason, in order to ensure good electrical and mechanical contact with the electrode pads of the semiconductor devices, for example, in Patent Document 1, a configuration using a multilayer metal sheet for the probes has been proposed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Patent Document 1 discloses a contact probe having at least one multilayer structure including the superposition of a core and a first inner coating layer, and an outer coating layer made of a material harder than the core that completely covers the multilayer structure. As shown in Patent Document 1, a configuration consisting of multiple layers of different materials stacked together is preferable to achieve good electrical and mechanical contact. However, there are limitations to meeting the requirement of reducing the thickness of the probe's cross-section, and further breakthroughs were needed.

[0007] In the testing process using probe cards, to ensure contact with the electrode pads of the semiconductor device, the probe is pressed further against the electrode pads of the semiconductor device by moving the probe card closer to the semiconductor wafer (overdrive) after the probe has made contact with the electrode pads. Therefore, the probe needs to have sufficient strength to withstand contact pressure exceeding a predetermined value without mechanical failure. To prevent the probe from failing, it is necessary to avoid localized stress concentration on the probe. And to prevent this stress concentration, the probe needed to have as smooth and scratch-free a surface as possible.

[0008] However, there are limits to how smooth the metal surface can be, and there was a problem that the thinner the thickness of the probe's cross-section, the lower its mechanical strength became, making it more susceptible to deformation under external forces.

[0009] This application discloses a technology that solves the above-mentioned problems, and aims to provide a probe that, even when miniaturized, can contact the electrode pads of a semiconductor device with appropriate needle pressure and possesses strength that prevents damage even when a contact pressure exceeding a predetermined value is applied.

[0010] In other words, the purpose of the probe for probe cards of this invention is not to prevent stress concentration from occurring, but rather to provide a probe for probe cards that can withstand large stresses (high mechanical strength) by having a structure that intentionally disperses the locations where stress concentration occurs. [Means for solving the problem]

[0011] The probe for probe cards disclosed herein is A probe for a probe card, The probe has a reference plane on at least one of the two sides perpendicular to each of the two faces perpendicular to the buckling direction of the probe, Multiple deformation regions, which are recesses on the side surface, are provided in two rows, spaced apart, along the longitudinal direction of the probe, It comprises a zigzag-shaped frame region between the two rows of deformation regions, The length of the frame region is longer than the longitudinal length of the probe. [Effects of the Invention]

[0012] The probe for a probe card disclosed herein makes it possible to provide a probe for a probe card with high mechanical strength by dispersing the locations where stress concentration occurs, even when the plate thickness is reduced. [Brief explanation of the drawing]

[0013] [Figure 1] This diagram schematically shows the state of inspecting an electronic circuit using a probe card according to Embodiment 1. [Figure 2] This is a perspective view of the probe according to Embodiment 1. [Figure 3] Figure 2 shows a cross-sectional view AA, which is a cross-sectional view perpendicular to the longitudinal direction of the probe. [Figure 4] This figure shows the positional relationship of the two rows of deformation regions according to Embodiment 1. [Figure 5]It is a cross-sectional view showing a modification example of the probe according to Embodiment 1. [Figure 6] It is a cross-sectional view perpendicular to the longitudinal direction of the probe according to Embodiment 2. [Figure 7] It is a cross-sectional view perpendicular to the longitudinal direction of the probe according to Embodiment 3. [Figure 8] It is a cross-sectional view showing a modification example of the probe according to Embodiment 3. [Figure 9A] It is a diagram showing variations of the deformation region according to Embodiment 4. [Figure 9B] It is a diagram showing variations of the deformation region according to Embodiment 4. [Figure 9C] It is a diagram showing variations of the deformation region according to Embodiment 4. [Figure 10A] It is a diagram showing variations of the deformation region according to Embodiment 5. [Figure 10B] It is a diagram showing variations of the deformation region according to Embodiment 5. [Figure 10C] It is a diagram showing variations of the deformation region according to Embodiment 5. [Figure 11] It is a diagram showing variations of the deformation region according to Embodiment 5.

Mode for Carrying Out the Invention

[0014] Embodiment 1. Hereinafter, the probe for a probe card according to Embodiment 1 will be described with reference to the drawings. FIG. 1 is a diagram schematically showing an inspection state of an electronic circuit by a probe card 100. In this specification, the upper side of the paper surface of FIG. 1 is referred to as "upper" and the lower side as "lower" for explanation. That is, when viewed from the probe card 100, the inspection object side is "lower". Also, the left - right direction of the paper surface of FIG. 1 is taken as the buckling direction X, and the direction from the front to the back of the paper surface and the opposite direction are taken as the direction Y perpendicular to the buckling direction X. Further, the longitudinal direction of the probe 20 (the up - down direction of the paper surface of FIG. 1) is taken 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 number of probes 20, each of which is made to contact electrodes C on the electronic circuits formed on the semiconductor wafer W. The characteristic testing of the electronic circuits is performed by bringing the semiconductor wafer W close to the probe card 100, making contact with the electrodes C on the electronic circuits with the tips of the probes 20, and connecting the tester connection electrodes TC on the wiring board 14 of the probe card 100 to a tester device (not shown) via the probes 20.

[0016] The probe card 100 comprises 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 securing the upper guide 11, and a wiring board 14. An intermediate guide may be provided between the upper guide 11 and the lower guide 12.

[0017] The upper guide 11 has a plurality of guide holes 11H that penetrate in the vertical direction, and the lower guide 12, located below the upper guide 11, also has a plurality of guide holes 12H that penetrate in the vertical direction. Above the plurality of guide holes 11H in the upper guide 11 is an opening 13H in the fixing plate 13. A wiring board 14 is placed 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 contact the terminal portion 20t at the upper end of the probe 20.

[0018] Then, multiple probes 20 are inserted and guided so as to pass through guide holes 12H and 11H, respectively. The probes 20 are vertical probes positioned perpendicular to the object to be inspected (electronic circuits formed on the semiconductor wafer W).

[0019] Figure 2 is a perspective view of the probe 20. The left-right direction in Figure 2 is the buckling direction X of the probe 20, that is, 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 part is curved, and the upper and lower parts extend linearly in the vertical direction. The lower end (one end) of the probe 20 is provided with a contact portion 20c. The upper end (the other end) has a terminal portion 20t formed therein.

[0020] During overdrive, the probe 20 is subjected to a compressive force in its longitudinal direction Z, causing it to easily buckle in the buckling direction X in response to the reaction force from the object being inspected. The contact portion 20c retracts toward the terminal portion 20t, and stress is generated inside the probe 20.

[0021] Figure 3 is a cross-sectional view AA of Figure 2, which is a cross-sectional view perpendicular to the longitudinal direction Z of the probe 20. The left-right direction in Figure 3 is the buckling direction X.

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

[0023] As shown in Figure 3, multiple deformation regions 8 and frame regions 9 are formed on the side surfaces 20S perpendicular to the two surfaces perpendicular to the buckling direction X of the high-resistance portion H of the probe 20. A deformation region 8 refers to a region where the reference plane 20SB, which is the original plane of the probe card, is deformed and a depression is formed. A frame region 9 refers to a region that connects the multiple deformation regions 8. The boundary between the deformation regions 8 and the frame regions 9 is represented as a ridge line 10.

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

[0025] Figure 4 is a side view of the probe 20, showing the positional relationship of the two rows of deformation regions 8. The two rows of deformation regions 8 are arranged so that the positions of the probe 20 in the longitudinal direction Z are staggered. In adjacent rows (two rows in this case) in the buckling direction X, the pentagonal prism shape of the deformation region is inverted in the buckling direction X. Also, in Figure 4, the dashed line L1 connecting the right ends of each deformation region 8 in the left row is 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 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 the side surface 20S of the high-resistance portion H of the probe 20, on each side in the buckling direction X, as shown in Figure 2. In addition, a framework region 91 is formed in the center of the side surface 20S of the probe 20, extending in the longitudinal direction Z in a zigzag shape 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, that is, the length P2 in the longitudinal direction Z of the portion of the probe 20 where the deformation regions 8 are formed.

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

[0028] Here, the prototype of the structure without deformation region 8 Bu and When comparing a probe 20 with a structure that has deformation regions 8 on both the front and back sides, the relationship between the amount of overdrive and the tracking force is smaller for the probe 20 with deformation regions 8.

[0029] Furthermore, we analyzed what effects could be obtained from deformation region 8. (The following sentence appears to be a fragment of a text snippet:) Bu, For a probe 20 with a pentagonal prism-shaped recess, the maximum stress of the probe was determined using the finite element method (FEM). The results showed that when an external force is applied, the stress concentrates on the ridge line 10 at the boundary between the deformation region 8 and the frame region 9. Furthermore, it was found that by making the bottom surface of the deformation region 8 planar, the stress concentrates on the ridge line 10 at the boundary between the deformation region 8 and the frame region 9.

[0030] This indicates that if the deformation region 8 is formed by a depression in a polygonal prism, stress concentration will occur at each vertex of the polygon, and therefore, when an external force is applied, the stress can be distributed to each vertex.

[0031] In this way, by placing the deformation region 8 in the high-resistance section H, which contributes to maintaining the mechanical strength of the probe 20, as described above, the length of the framework region 91 can be extended, dispersing the stress concentration points while reducing the needle pressure of the probe 20.

[0032] Probe 20 is fabricated using so-called MEMS (Micro Electro Mechanical Systems) technology (probe intermediate formation process). MEMS technology is a technique that uses photolithography and sacrificial layer etching to create fine three-dimensional structures. Photolithography is a technique for processing fine patterns using photoresist, which is used in semiconductor manufacturing processes. Sacrificial layer etching is a technique that creates a three-dimensional structure by forming a lower layer called a sacrificial layer, forming layers that make up the structure on top of it, and then removing only the sacrificial layer by etching.

[0033] Well-known plating techniques can be used for forming each layer. For example, by immersing a substrate as the cathode and a metal piece as the anode in an electrolyte and applying a voltage between the two electrodes, metal ions in the electrolyte can be deposited onto 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 a probe intermediate. After this drying process, the lower tip portion is polished (polishing process) to form the contact portion 20c.

[0034] Figure 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 without the deformation region 8 may be smaller than that of the side 20S on which 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 cards of Embodiment 1, by placing the deformation region 8 in the high-resistance section H that contributes to maintaining the mechanical strength of the probe 20, the length of the frame region 91 can be extended, dispersing the stress concentration points and reducing the tracking force. Furthermore, the overall length of the probe 20 can be reduced for the same tracking force. Note that there may be three or more rows of deformation regions 8. Also, the deformation region 8 may be placed only on one side 20S.

[0036] Embodiment 2. The probe for the probe card according to Embodiment 2 will be described below, focusing on the differences from Embodiment 1. This embodiment describes a modified example of the deformation region 8. Figure 6 is a cross-sectional view of the probe 20 according to Embodiment 2, perpendicular to the longitudinal direction. The left-right direction of the paper is the buckling direction X. This differs from Embodiment 1 in that the springy, high-resistance section H extends all the way to the low-resistance section L with low electrical resistance.

[0037] In Embodiment 1, the deformation region 8 did not penetrate the high-resistance section H. In Embodiment 2, the deformation region 8 penetrates the high-resistance section H, and the low-resistance section L is visible from the side surface 20S of the probe 20. With this configuration, the framework region 91 can exhibit even greater elasticity, thereby further reducing the tracking force.

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

[0039] In Embodiment 2, the exposed low-resistance portion L must be made of a material that does not melt during sacrificial layer etching. By providing an intermediate layer M that does not melt during sacrificial layer etching to protect the low-resistance portion L from melting, the range of materials that can be selected for the low-resistance portion L is broadened. The material of the intermediate layer M can be a material with a low Young's modulus that does not melt during sacrificial layer etching and has low stress on deformation, such as Pd or Pt. The intermediate layer M should be provided 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, making it possible to realize a probe that is even lower in resistance than Embodiment 2 and exhibits even greater elasticity than Embodiment 1.

[0041] Figure 8 is a cross-sectional view showing a modified example of the probe 20. As shown in Figure 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 process steps.

[0042] Embodiment 4. The probe for the probe card according to Embodiment 4 will be described below with reference to the figures. This embodiment describes another example of the deformation region 8. Figures 9A to 9C show variations of deformation region 8. As shown in Figure 9A, the deformed regions 8 of the triangular prism may be inverted so that they alternately protrude towards the center of the side surface 20S, and arranged in two rows along the longitudinal direction Z of the probe 20.

[0043] Alternatively, as shown in Figure 9B, when viewed in the buckling direction X, the hexagonal prism-shaped deformation regions 8, each having two sides parallel to the buckling direction X and two sides parallel to the longitudinal direction Z of the probe 20, may be alternately reversed in the buckling direction X and arranged in two rows along the longitudinal direction Z of the probe 20.

[0044] As shown in Figure 9C, when viewed in the buckling direction X, the semi-cylindrical (half-bodied) triangular prism deformation regions 8 may be reversed so that they alternately protrude towards 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 Embodiment 1, the tip of the deformation region protruding in the buckling direction X must be located beyond the center line O in the buckling direction of the side surface 20S. This produces the same effect as in Embodiment 1.

[0045] Embodiment 5. The probe for the probe card according to Embodiment 5 will be described below with reference to the figures. This embodiment describes another example of the deformation region 8. Figures 10A, 10B, 10C, and 11 show variations of the deformation region 8. The deformation region 8 may be a truncated triangular pyramid shape as shown in Figure 10A, a truncated pentagonal pyramid shape as shown in Figure 10B, or a semi-circular shape as shown in Figure 10C, where the shape of the base is similar to the edge 10 of the deformation region 8 and smaller than the shape of the edge 10. In other words, the deformation region 8 has a central part 8C that is a plane, and the surrounding part that encloses the central part 8C is an inclined surface SL that slopes outward toward the side surface 20S. The width of the framework region 91 is , central part 8C The strength of the framework region 91 is increased by making it gradually larger towards the end. The probe for the probe card according to this embodiment 5 also produces the same effects as in embodiments 1 to 4.

[0046] Although this application describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but can be applied individually or in various combinations to the embodiments. Accordingly, countless variations not illustrated are conceivable within the scope of the art disclosed herein. These include, for example, modifying, adding or omitting at least one component, or even extracting at least one component and combining it with components of other embodiments. [Explanation of Symbols]

[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 part, 20SB1, 20SB2 Side beam, 20m Central part, 20S Side, 20SB Reference plane, 20t Terminal part, 8 Deformation area, 8T Protrusion, 9, 91 Framework area, C Electrode, H High resistance part, L Low resistance part, M Intermediate layer, O Center line, TC Tester connection electrode, W Semiconductor wafer, P1, P2 Length, 8C Central part, 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 has at least one of two sides perpendicular to each of the two faces perpendicular to the buckling direction of the probe, Multiple deformation regions, which are recesses on the side surface, are provided in two rows, spaced apart, along the longitudinal direction of the probe, It comprises a zigzag-shaped frame region between the two rows of deformation regions, A probe for a probe card in which the length of the frame region is longer than the length of the probe in the longitudinal direction.

2. The probe for a probe card according to claim 1, wherein, assuming that two adjacent deformation regions in the buckling direction are viewed in the longitudinal direction of the probe, a portion of each deformation region appears to overlap with one another.

3. The probe for a probe card according to claim 1, wherein the two deformed regions adjacent to each other in the buckling direction have a shape that is inverted in the buckling direction.

4. The probe for a probe card according to claim 1, wherein the deformation region is one of a triangle, a pentagon, a hexagon, or a semi-circular shape, and in two adjacent rows, the deformation region of one row has a projection that protrudes toward the other row.

5. The probe for a probe card according to claim 1, wherein the deformation region is an inclined surface in which the bottom surface of the depression is flat and the surrounding portion surrounding the bottom surface is inclined to widen toward the side surface.

6. The probe has an inner first metal layer that has low electrical resistance, The first metal layer is provided with a second metal layer that is harder and more springy than the first metal layer on its outer surface. The probe for a probe card according to any one of claims 1 to 5, wherein the deformation region is formed in the second metal layer.

7. The probe for a probe card according to claim 6, wherein the deformed region penetrates 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.

Images