Probes for probe cards and their manufacturing methods

Abstract

If the probe (1) is made thinner to correspond to the electrode spacing of the semiconductor device, the mechanical strength becomes insufficient. A design is needed to obtain sufficient mechanical strength with a thin metal plate. Multiple deformable regions (8) of recessed or protruding shapes are provided on the surface of the probe (1) for the probe card; and a skeleton region (9) is provided at the boundary of the adjacent deformable regions (8) to disperse the stress of the deformable regions (8).

Description

Technical Field

[0001] This application relates to probes for probe cards and methods for manufacturing the same. Background Technology

[0002] A probe card is an electrical connection device used to make probes contact the electrode pads of semiconductor devices for power supply, signal input / output, and grounding, in order to perform operational testing of each semiconductor device formed on a wafer. The probe is disposed on the surface of the probe card and configured such that its front end is pressed against the electrode pad of the semiconductor device by a specified pressing pressure.

[0003] To increase the number of semiconductor devices formed on a wafer, the size of the semiconductor devices needs to be reduced. Therefore, the electrode pads of semiconductor devices are designed to be smaller, and the distance (pitch) between the electrode pads is designed to be smaller. The probes need to be made smaller in line with the miniaturization of semiconductor devices. However, if the probes are made smaller, there is a problem that the mechanical strength of the probes will be weakened.

[0004] Therefore, in order to ensure good electrical and mechanical contact between the probe and the electrode pads of the semiconductor device, for example, Patent Document 1 proposes a structure using multilayer metal sheets. Existing technical documents Patent documents

[0005] Patent Document 1: Japanese Patent Publication No. 2018-501490 Summary of the Invention The technical problem that the invention aims to solve

[0006] The probe shown in Patent Document 1 utilizes a high-hardness material to completely cover a multi-layered metal sheet structure with a high-conductivity layer and a high-hardness layer in the core. As shown in Patent Document 1, in order to achieve good electrical and mechanical contact, a structure in which multiple layers of different materials are overlapped is preferred. However, there are limitations in meeting the requirement that the cross-sectional thickness of the probe should be reduced in response, and further breakthroughs are needed.

[0007] In order to enable the probe card to reliably make contact with the electrode pads of the semiconductor device, after the probe makes contact with the electrode pads, the probe card is brought closer to the semiconductor wafer (overdrive), thereby pressing the probe onto the electrode pads of the semiconductor device. Therefore, the probe needs to have the strength to withstand contact pressure exceeding a specified value without breaking. To prevent probe breakage, it is necessary to prevent localized stress concentrations on the probe. Furthermore, to prevent stress concentrations, the surface should be as smooth as possible, making it a non-destructive probe.

[0008] However, there are limitations to making the metal surface smooth, and there is a problem that the thinner the probe cross-section, the easier it is to deform relative to external forces (the stress becomes smaller).

[0009] This application discloses a technology for solving the above-mentioned problems, with the aim of providing a probe that, even when made tiny, contacts the electrodes of a semiconductor device with appropriate needle pressure and has the strength to withstand contact pressure exceeding a specified value without breaking. That is, the purpose of the probe card probe in this application is to provide a structure with high stress (high mechanical strength) by intentionally dispersing stress concentration rather than preventing stress concentration. Technical solutions adopted to solve technical problems

[0010] The probe for the probe card disclosed in this application is characterized by having: a plurality of deformable regions with concave or convex shapes on its surface; and a skeleton region disposed at the boundary of adjacent deformable regions. Invention Effects

[0011] According to the probe card probe disclosed in this application, it is possible to provide a structure that can increase the stress to a specified value even if the plate thickness is reduced. Attached Figure Description

[0012] Figure 1 This is a perspective view showing the schematic structure of the probe according to Embodiment 1. Figure 2 This is a characteristic diagram of the needle pressure of the probe in Implementation Method 1. Figure 3 This is a characteristic diagram of the stress of the probe in Implementation Method 1. Figure 4 This is an explanatory diagram of the probe manufacturing method according to Embodiment 1. Figure 5 This is an explanatory diagram of the probe manufacturing method according to Embodiment 1. Figure 6 This is a three-dimensional view of the surface of the probe in Embodiment 2. Figure 7 This is an explanatory diagram of the probe manufacturing method according to Embodiment 2. Figure 8 This is a diagram showing the area expansion pattern of Embodiment 3. Figure 9 This is a diagram showing a schematic structure of the probe according to embodiment 4. Figure 10 This is a diagram showing a schematic structure of the probe according to embodiment 5. Figure 11 This is a diagram showing a schematic structure of the probe according to embodiment 5. Figure 12This is a diagram showing the pattern of the deformed region on the probe surface of Embodiment 6. Figure 13 This is a diagram showing a schematic structure of the probe according to embodiment 7. Figure 14 This is a diagram showing a schematic structure of the probe according to embodiment 8. Detailed Implementation

[0013] Implementation Method 1 Hereinafter, Embodiment 1 will be described with reference to the accompanying drawings. Furthermore, in the following drawings, the same or equivalent parts are labeled with the same symbols. Figure 1 This is a perspective view showing the structure of the probe used in the probe card of Embodiment 1.

[0014] The probe 1 shown in this embodiment 1 is a so-called vertical probe, which is kept substantially vertical by a first guide plate 2 on the upper side and a second guide plate 3 on the lower side. The second guide plate 3 guides the front end portion 4 of the probe 1 in contact with the electrode pads 5 of the semiconductor device. The first guide plate 2 guides the rear end portion 6 of the probe 1 in connection with an electrode (not shown) connected to the circuit board of the probe card.

[0015] The probe 1 is made of a thin metal plate that serves as a conductive component. Multiple deformation regions 8 and skeleton regions 9 are formed on the surface of the central portion 7 of the probe 1. The deformable region 8 represents the region after the original plane has been deformed. Furthermore, the skeleton region 9 represents the region that joins multiple deformable regions 8. Additionally, the portion corresponding to the edge between the deformable region 8 and the skeleton region 9 is represented as the boundary portion 10.

[0016] In Embodiment 1, an example is shown where a prism-shaped recess is provided on the original plane as the deformable region 8. Furthermore, the portion of the plane between the deformable regions 8 belongs to the skeleton region 9. Here, by comparing a probe without any deformation region 8 with a probe having deformation regions 8 on both the surface and back sides, the following results can be obtained. Specifically, let A be the measurement result of the probe without deformation regions 8 on the surface, and B be the measurement result of the characteristics of the probe 1 with deformation regions 8. After the tip portion 4 of the probe 1 contacts the electrode pad 5, and a further load is applied, pressing the probe 1 against the electrode pad 5 (overdrive state), the relationship between the needle pressure and the overdrive amount is as follows: Figure 2 As shown. Furthermore, the relationship between stress and overdrive is as follows: Figure 3 As shown.

[0017] like Figure 2As shown, the needle pressure at an overdrive of 70 μm is 1.72 gf in the probe without a depression, compared to 1.19 gf in probe 1 with a depression. Furthermore, as... Figure 3 As shown, the maximum stress when the overdrive is 110 μm is 670 MPa in the probe without a depression, compared to 891 MPa in probe 1 with a depression. This confirms that the probe is in a state that meets the mechanical characteristics required for a probe.

[0018] The main factors contributing to the increase in maximum stress were investigated, and the results showed that, as a structural uniqueness, the different surface areas of probe 1 were considered. That is, by setting a deformed region 8 of a square prism recess on the surface of probe 1, the surface area is increased. In the case where the recess is formed by the depression of a square plane (i.e., exhibiting a square prism-shaped recess), the surface area of ​​the top of the square prism does not change since the original surface is simply pressed down. In contrast, the area of ​​the inner wall surface generated by the depression is increased.

[0019] In this embodiment 1, the recesses on the surface and back of the probe are quadrilaterals with one side measuring 20 μm, and the depth of the recesses on the surface side is 3.5 μm, while the depth of the recesses on the back side is 2.5 μm. 429 recesses of the aforementioned dimensions are provided on both the surface and back sides. This increases the depth of the probe on the surface side by 120-120 μm. 2 The area on the back side increased by 85,800 μm. 2 The surface area is increased by the amount of area of ​​the inner wall surface of the depression created by the sinkhole. Here, since large depressions will affect the thickness of probe 1, it is ideal to increase the surface area by setting a large number of small depressions. By designing the size and arrangement of the depression shape, the surface area can be varied arbitrarily.

[0020] Furthermore, the effects obtained through deformation region 8 were analyzed. For probe A (without depressions, with a smooth surface), probe B (with a matrix of prism-shaped depressions), probe C (with staggered prism-shaped depressions), and probe D (with staggered circular depressions), the probe pressure and maximum stress were calculated based on the finite element method (FEM), as shown in Table 1.

[0021] [Table 1] Table 1 FEM results

[0022] As shown in Table 1 above, in the case of probe A, the needle pressure is 1.72 gf when the overdrive is 70 μm, and the maximum stress is 670 MPa when the overdrive is 110 μm. In contrast, under the same conditions, probe B has a needle pressure of 1.19 gf and a maximum stress of 891 MPa, probe C has a needle pressure of 1.18 gf and a maximum stress of 899 MPa, and probe D has a needle pressure of 1.18 gf and a maximum stress of 1164 MPa.

[0023] Furthermore, stress contour plots (plots representing calculated results using contour lines) were created for probes A, B, C, and D. The results showed that probe A exhibited a roughly uniform stress distribution with a maximum stress of 670 MPa. For probe B, the stress was 74 MPa at the planar portion of the bottom surface of deformation region 8, 668 MPa at the skeleton region 9, and a maximum stress of 891 MPa. For probe C, the stress was 74 MPa at the planar portion of the bottom surface of deformation region 8, 674 MPa at the skeleton region 9, and a maximum stress of 899 MPa. For probe D, the stress was 97 MPa at the spherical portion of the bottom surface of deformation region 8, 873 MPa at the skeleton region 9, and a maximum stress of 1164 MPa.

[0024] Based on the above results, it is inferred that when forces are applied to probes A, B, C, and D from the outside, stress concentrates at the boundary 10 between the deformation region 8 and the skeleton region 9. Furthermore, by setting the bottom surface of the deformation region 8 to a planar or spherical shape, stress concentration is achieved at the boundary 10 between the deformation region 8 and the skeleton region 9. This means that when the deformation region 8 is formed by the concavity of the polygonal prism, stress concentration will occur at each vertex of the polygon. Therefore, when an external force is applied, the stress will be distributed to each vertex.

[0025] Therefore, if the deformation region 8 is formed by conical or pyramidal recesses, stress can be dispersed not only at the vertices of the outer periphery but also in a manner that includes the vertices of the cone or pyramid. In this case, the stress concentration generated at the boundary 10 between the deformation region 8 and the skeleton region 9 can be reduced.

[0026] In addition, when the boundary portion is a polygon, although stress concentration will occur at each vertex, the more sides there are, the less stress concentration will be borne by each vertex. Therefore, it can be inferred that when the periphery of the depression is circular, the stress will be dispersed to that periphery. Thus, as explained for probe D, the structure with the spherical depression shape set as deformation region 8 is the structure with the most dispersed stress, forming a probe with a high stress structure.

[0027] Next, regarding the above Figure 1The manufacturing method of the probe 1 shown will be described. There are two methods for fabricating probes. First, the first method involves electroforming, such as... Figure 4 As shown in A, a protruding shape 8a corresponding to the recessed shape caused by the conductive layer 42 is formed on the surface of the substrate 41, and then, as shown in Figure A. Figure 4 As shown in B, a metal layer 43, serving as a probe component, is formed on the surface of the conductive layer 42, thereby creating a deformed region 8 with an expanded area. The metal layer 43 can be formed, for example, by electroforming. Then, the surface is processed to be flat, a mask is provided, and etching is performed to form the probe serving as the target. Then, the probe 1 is removed from the substrate 41 by removing the conductive layer 42.

[0028] like Figure 5 As shown, the second manufacturing method forms a recessed shape on the surface of the metal plate 53 using a first mold 51 and a second mold 52 with recessed surfaces. In this case, compared to forming the metal layer by electroforming, it has the effect of shortening the manufacturing time.

[0029] Furthermore, in Embodiment 1, the structure in which the deformable region 8 is set as a concave shape was described, but the same effect can be obtained by setting the shape as a protruding shape.

[0030] Implementation Method 2 In this second embodiment, the case in embodiment 1 where the concave shape of the deformable region 8 was set as a concave shape based on a quadrangular prism is changed to a concave shape of a triangular pyramid. That is, as follows: Figure 6 The image shown is a three-dimensional view of a portion of the surface of probe 1 cut out, with a recess formed by a triangular pyramid pattern 61. Specifically, the triangular pyramid pattern 61 is formed in the following manner: Figure 7 As shown, the metal plate 73 is clamped and pressure is applied from both sides by a male mold 71 with multiple triangular pyramid shapes arranged together and a female mold 72 with a receiving side shape corresponding to the protruding shape of the triangular pyramid.

[0031] By clamping the metal plate 73 into the male mold 71 and female mold 72, a triangular pyramid pattern 61 with a recessed or protruding shape can be formed on the surface and back of the metal plate 73. Furthermore, by simultaneously stamping the metal plate while forming the triangular pyramid pattern 61, the efficiency of the probe 1 manufacturing process can be improved. In particular, by using stamping to perform surface processing and stamping of the metal plate 73 in a single process, a probe 1 with a triangular pyramid pattern 61 having a recessed or protruding shape on its surface can be manufactured.

[0032] In this embodiment 2, the increase in the surface area of ​​the deformed region 8 is the difference between the surface area of ​​the lateral surface and the area of ​​the base of the triangular pyramid. If for... Figure 1 The pattern of the square prism shown and Figure 6 Comparing the triangular pyramid pattern 61 shown, in the case of the square prism pattern, a concave inner wall surface is required, which limits the approximation of the square prism pattern. In contrast, the triangular pyramid pattern 61 allows for the effect of adjacent triangular pyramids to approach each other infinitely.

[0033] Implementation Method 3 In the probe of this embodiment 3, the pattern of the tetragonal prism of embodiment 1 and the pattern of the triangular pyramid of embodiment 2 are combined and formed on the surface of the probe 1. The probe of this embodiment 3 can increase the surface area in various ways.

[0034] Figure 8 The pattern of the surface of probe 1 is shown. (Example) Figure 8 As shown, this is a planar shape formed by combining a quadrangular prism pattern 81 and a triangular pyramid pattern 61. In this shape, the quadrangular prism pattern 81 and the triangular pyramid pattern 61 are combined and configured such that the edges of the quadrangular prism pattern 81 do not connect, and the quadrangular prism pattern 81 is connected to each other by the triangular pyramid pattern 61.

[0035] In this way, the entire plane can be filled by combining the pattern 81 of the quadrangular prism and the pattern 61 of the triangular pyramid. Furthermore, the area can be expanded even in combinations other than rectangles and triangles. For example, the area can also be increased in the case of a corrugated pattern.

[0036] Implementation Method 4 Probe 1 in Implementation Method 4 is as follows Figure 9 As shown, Figure 9 A represents a pattern on a plane. Figure 9 B shows Figure 9 The cross section at line A9-A9 of point A. For example... Figure 9 As shown in A and B, the surface is configured to have a first deformation region 91 with a spherical concave shape of a first diameter and a second deformation region 92 with a spherical protrusion shape of a second diameter. On the surface of the probe 1, first deformation regions 91 are arranged in an alternating pattern, and second deformation regions 92 are disposed in the space between the first deformation regions 91. It can be inferred that through the arrangement of the first deformation regions 91 and the second deformation regions 92, stress is uniformly distributed, forming a probe with a high stress structure.

[0037] Implementation Method 5 In Embodiments 1 and 2, examples are shown of forming a pattern of a recessed or protruding shape with respect to a vertical probe 1, but it could be, for example... Figure 10As shown, when an area expansion pattern region 101 is provided on the cantilever-shaped probe 1 as a deformation region, a probe with the same needle pressure and stress characteristics as in Embodiment 1 can be obtained. In addition, such as Figure 11 As shown, by setting the area expansion pattern region 101 around the stress concentration region 102 locally generated in the probe 1, the stress in the stress concentration region 102 is dispersed and mitigated, thereby obtaining the required mechanical strength.

[0038] Implementation Method 6 In the case where the pattern in deformation area 8 is a concave or convex shape in the shape of a polygonal prism, as a specific example of a polygon, one can imagine triangles, quadrilaterals, pentagons, hexagons, and more polygonal shapes, etc. In the concave or convex shapes of polygons, stress concentration occurs at the vertices of the polygon. Furthermore, the stress is distributed to each vertex accordingly, based on the number of vertices. That is, in the case of a triangle, the stress relative to the external force is presumed to be 1 / 3 of the stress at each vertex.

[0039] When stress is concentrated at the vertices of a polygon, and the stress is distributed accordingly with the number of vertices, if the number of vertices is increased to form a circle, the stress will be distributed to the entire perimeter of the circle. However, in order to control the distribution of stress to the optimal state, it is ideal to place a predetermined number of vertices at predetermined locations. Here, in this embodiment 6, as Figure 12 As shown, when the skeleton region 9 existing between adjacent first deformation regions 121 includes a plane, a plurality of second deformation regions 122 with concave or convex shapes may be further included in the planar portion of the skeleton region 9.

[0040] When the second deformation region 122 is configured with a concave or convex shape of a polygonal prism in the same manner as the first deformation region 121, it is preferable to set the second deformation region 122 around the periphery of the first deformation region 121 in a seamless manner, such as... Figure 12 As shown, the recess of the prism in the first deformation region 121 is preferably a dodecagonal prism.

[0041] By setting the first deformation region 121 as a concave shape of a dodecagonal prism, its periphery can be filled without gaps by concave or protruding shapes of triangles, quadrilaterals, and hexagons. Therefore, not only can the effect of facilitating stress dispersion be achieved, but also the effect of uniform stress dispersion can be achieved because the same pattern can be repeatedly configured.

[0042] Implementation Method 7 Figure 13The partial cross-sectional shape of probe 1 in embodiment 7 is shown. For example... Figure 13 As shown, Figure 13 A represents a pattern on a plane. Figure 13 B shows Figure 13 The cross section of point A at line A13-A13. For example... Figure 13 As shown in A and B, in this embodiment 7, a covering layer 13 is provided to prevent foreign matter from adhering to the surface of the metal plate of the probe 1 shown in embodiment 4. Furthermore, for example, the surface of the metal plate is smoothly covered in a manner that allows for easy removal even if foreign matter adheres. The above structure is not limited to the probe of embodiment 4; any probe with a deformed area having a concave or convex shape on the surface of the metal plate can similarly solve the problem of foreign matter adhesion by providing a covering layer.

[0043] Ideally, the material of the cover layer 13 is a resin layer that does not hinder the deformation of the metal plate. In particular, in embodiments 1 to 6, multiple deformation regions 8 with recessed or protruding shapes are provided on the surface, which may lead to foreign matter adhesion. Therefore, in order to eliminate the above possibility, the cover layer 13 for smoothing the surface is effective. By having multiple deformation regions 8 with recessed or protruding shapes and skeleton regions 9 on the surface of the conductor, and providing the cover layer 13 on the surface, it is possible to obtain a probe with improved mechanical strength and no foreign matter adhesion.

[0044] Implementation Method 8 When the probe is configured to wrap the low-resistance first metal layer 141 with a second metal layer 142 made of a material harder than the first metal layer 141, such as Figure 14 As shown, by providing a recessed or protruding deformation region 8 on the surface or back of the second metal layer 142 to disperse stress, a probe with high mechanical strength can be provided. Additionally, "concave shape or protruding shape" indicates the case where only "concave shape" is arranged, the case where only "protruding shape" is arranged, and the case where both "concave shape" and "protruding shape" are arranged.

[0045] Figure 14 A is a schematic 3D view of the probe. Figure 14 B shows Figure 14 The cross-section of A at line A14-A14 is shown in the figure. A high-hardness second metal layer 142 covers a low-resistance first metal layer 141. Furthermore, a recessed deformation region 8 is provided on the surface of the second metal layer 142. Even if the deformed area 8 caused by the concave shape becomes a convex shape, the effect of stress dispersion remains unchanged. Furthermore, by providing a covering layer 13 on the surface of the deformed area 8 with a concave or convex shape as in Embodiment 7, it is possible to prevent foreign matter from adhering.

[0046] This application describes various exemplary implementation methods and embodiments, but the various features, methods and functions described in one or more implementation methods are not limited to specific implementation methods, and can be applied to implementation methods alone or in various combinations. Therefore, numerous variations not illustrated are contemplated within the scope of the technology disclosed in this application. These include variations, additions, or omissions of at least one constituent element, as well as the extraction of at least one constituent element and its combination with constituent elements of other embodiments. Symbol Explanation

[0047] 1 Probe; 2 First guide plate; 3 Second guide plate; 4 Front end portion; 5 Electrode pad; 6 Rear end portion; 7 Central portion; 8 Deformation area; 9 Skeleton area; 10 Boundary portion; 13 Cover layer; 41 Substrate; 42 Conductive layer; 43 Metal layer; 51 First mold; 52 Second mold; 53 Metal plate; 61 Triangular pyramid pattern; 71 Positive mold; 72 Negative mold; 73 Metal plate; 81 Quadrangular prism pattern; 91 First deformation area; 92 Second deformation area; 101 Area expansion pattern area; 102 Stress concentration area; 121 First deformation area; 122 Second deformation area; 141 First metal layer; 142 Second metal layer.

Claims

1. A probe for a probe card, characterized in that, The probe card uses a plate-shaped probe with multiple deformable regions on its main surface, including a concave or protruding bottom shape. And a skeleton region, which is located at the boundary of the adjacent deformable region, wherein the recessed shape is a shape that opens in one direction relative to the main surface and is surrounded by an edge. The multiple deformable regions are geometrically configured. The deformation region is formed by deforming the original planar shape of the main surface into a concave or convex shape including a bottom, thereby increasing the surface area of ​​the main surface.

2. The probe for the probe card according to claim 1, characterized in that, The multiple deformable regions are arranged in a matrix.

3. The probe for the probe card according to claim 1, characterized in that, The multiple deformable regions are arranged in an alternating pattern.

4. The probe for the probe card according to claim 1, characterized in that, The deformed area has a polygonal prism-shaped concave or convex shape.

5. The probe for the probe card according to claim 1, characterized in that, The deformed area has a concave or convex polygonal shape.

6. The probe for the probe card according to claim 1, characterized in that, The deformed area has a spherical concave or convex shape.

7. The probe for the probe card according to claim 1, characterized in that, The deformed area is shaped by combining the patterns of a quadrangular prism and a triangular pyramid.

8. The probe for the probe card according to claim 1, characterized in that, The deformed region includes a dodecagonal concave or convex shape.

9. The probe for a probe card according to any one of claims 1 to 8, characterized in that, The deformable region and the skeleton region are covered by a covering layer.

10. The probe for a probe card according to any one of claims 1 to 8, characterized in that, A first metal layer with low resistance is wrapped with a second metal layer made of a hard material, and the deformation area is provided on the surface of the second metal layer.

11. A method for manufacturing a probe for a probe card, characterized in that, A conductive layer is formed on the surface of a substrate. On the main surface of the plate-shaped conductive layer, deformable regions including a recessed or protruding bottom shape and a skeleton region defined at the boundary of the deformable regions are formed. The recessed shape is a shape that opens in one direction relative to the main surface and is surrounded by an edge. Multiple deformable regions are geometrically arranged. The deformation region is formed by deforming the original planar shape of the main surface into a concave or convex shape including a bottom, thereby increasing the surface area of ​​the main surface.

12. A method for manufacturing a probe for a probe card, characterized in that, By using a first mold having a recessed or protruding shape on its surface and a second mold having a protruding or recessed shape on its surface, deformable regions including a recessed or protruding shape at the bottom and a skeleton region defined at the boundary of the deformable regions are formed on the main surface of a sheet-like metal plate. The recessed shape is a shape that opens in one direction relative to the main surface and is surrounded by an edge. A plurality of the deformable regions are geometrically arranged. The deformation region is formed by deforming the original planar shape of the main surface into a concave or convex shape including a bottom, thereby increasing the surface area of ​​the main surface.

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