Cantilever probe for probe card

Abstract

This cantilever-type probe (20) for a probe card comprises a seat part (21D), a needle point part (22), and a beam part (21B) between the seat part (21D) and the needle point part (22). The beam part (21B) comprises, in the longitudinal direction (Z) thereof, a plurality of stress distribution sections (21R, 21Bh) where greater stress concentration occurs than in other portions of the beam part (21B).

Description

[Technical Field]

[0001] The present application relates to a cantilever-type probe for a probe card. [Background technology]

[0002] A probe card is an electrical connection device used to supply power, input / output signals, and ground the semiconductor devices by contacting probes 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 provided on the surface of the probe card, and are configured so that their tips are pressed against the electrode pads of the semiconductor device 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. To this end, 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. Therefore, as semiconductor devices become smaller, probes must also be made finer. However, making probes finer reduces the mechanical strength of the probes, which is a problem.

[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 multilayer metal sheet is used for the probe. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2018-501490 Summary of the Invention [Problem to be solved by the invention]

[0006] The probe shown in Patent Document 1 discloses 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 that is harder than the core and completely covers the multilayer structure.

[0007] As shown in Patent Document 1, a structure in which multiple layers made of different materials are stacked 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.

[0008] In the semiconductor device inspection process using the above-mentioned probe card, in order to ensure contact with the electrode pads of the semiconductor device, after the probes have contacted the electrode pads, the probe card is brought even closer to the semiconductor wafer (overdrive) to press the probes against the electrode pads of the semiconductor device.

[0009] For this reason, the probe must be strong enough to withstand a contact pressure greater than a predetermined value without being mechanically destroyed. To prevent the probe from being destroyed, it is necessary to prevent localized stress concentration on the probe. To prevent this stress concentration, a probe with a surface as smooth and free of scratches as possible is required.

[0010] However, there is a limit to how smooth a metal surface can be made, and the thinner the cross-section of the probe, the more easily it is deformed by an external force (the lower the mechanical strength).

[0011] The present application discloses a technology for solving the above-mentioned problems, and aims to provide a cantilever-type 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.

[0012] In other words, the cantilever-type probe for a probe card of the present application is a cantilever-type 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. [Means for solving the problem]

[0013] The cantilever probe for a probe card disclosed in the present application comprises: Plate-shaped A base portion, a needle tip portion, The aforementioned Base and The aforementioned a beam portion between the needle tip portion and the beam portion; the buckling direction of the beam portion is a direction perpendicular to the plate thickness direction of the probe, The beam portion has a stress dispersion portion where stress is concentrated more than other portions of the beam portion. The aforementioned At least one plane perpendicular to the buckling direction Inside all the outer circumferences of It is provided with multiple units. [Effects of the Invention]

[0014] According to the cantilever type 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 cantilever type probe for a probe card with high mechanical strength. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a perspective view of a cantilever probe for a probe card according to a first embodiment. FIG. [Figure 2A] FIG. 2 is a plan view of the portion surrounded by the dashed line in FIG. [Figure 2B] 2B is a cross-sectional view taken along the line AA in FIG. 2A. [Figure 3A] 2 is a plan view showing a state in which a sacrificial layer is disposed to manufacture the portion surrounded by the dashed line in FIG. 1. FIG. [Figure 3B] 3B is a diagram showing a state in which the portion of line BB in FIG. 3A is manufactured. FIG. [Figure 4] FIG. 10 is a cross-sectional view of a modified example of the probe according to the second embodiment. [Figure 5A] FIG. 10 is a plan view of a modified example of the probe according to the second embodiment. [Figure 5B] 5B is a cross-sectional view taken along CC in FIG. 5A. [Figure 6A] FIG. 10 is a plan view of a modified example of the probe according to the second embodiment. [Figure 6B] FIG. 6B is a cross-sectional view taken along the line DD in FIG. 6A. [Figure 7A] FIG. 10 is a plan view of a modified example of the probe according to the second embodiment. [Figure 7B] 7B is a cross-sectional view of FIG. 7A taken along the line E-E. [Figure 8A] FIG. 11 is a cross-sectional view of a modified example of the probe according to the third embodiment. [Figure 8B] FIG. 8B is a cross-sectional view of FIG. 8A shown in FIG. 8A. [Figure 9A] FIG. 10 is a plan view of a modified example of the probe according to the fourth embodiment. [Figure 9B] GG cross-sectional view of FIG. 9A. DETAILED DESCRIPTION OF THE INVENTION

[0016] Embodiment 1 The cantilever probe for a probe card according to the first embodiment will be described below with reference to the drawings. FIG. 1 is a perspective view of a cantilever-type probe 20 for a probe card (hereinafter simply referred to as the probe 20). 1 will be referred to as "top" and "bottom." The direction in which the probe 20 buckles (elastically deforms) when overdriven is referred to as the buckling direction X, and the thickness direction of the probe 20, which is perpendicular to the buckling direction X, is referred to as the plate thickness direction Y. The longitudinal direction of the beam portion 21B of the probe 20 is referred to as the longitudinal direction Z.

[0017] The probes 20 are components used in a probe card (not shown). The probe card is a device used to test the electrical characteristics of electronic circuits formed on a semiconductor wafer. The characteristic test of the electronic circuit is performed by bringing the semiconductor wafer close to the probe card, bringing the needle tips 22 of the probes 20 into contact with electrodes on the electronic circuit, and establishing electrical continuity between a tester device and the tester connection electrodes on the wiring board of the probe card via the probes 20.

[0018] The probe 20 is a cantilever-type probe that is arranged so that the beam portion 21B is substantially horizontal to the test object (an electronic circuit formed on a semiconductor wafer). Although the probe 20 is shown in Fig. 1 as an example having two beam portions 21B, the number of beam portions 21B may be one, or three or more.

[0019] The probe 20 has a thin plate-shaped main body 21 and a probe tip 22 that protrudes upward from the upper end of the main body. The main body 21 includes a terminal 21T that is connected to a wiring land of a wiring board (not shown), a base 21D that rises upward from the terminal 21T, and an elastic deformation portion 21U that is located between the probe tip 22 on the test object side and the base 21D.

[0020] Two elongated holes 21UH are formed in the elastic deformation portion 21U, extending in the longitudinal direction Z and penetrating in the plate thickness direction Y, and the elongated holes 21UH divide the elastic deformation portion 21U into two beam portions 21B.

[0021] When probe 20 is overdriven, compressive force is applied in the vertical direction in FIG. 1, and the probe 20 easily undergoes buckling deformation in buckling direction X in response to a reaction force from the test object. At this time, stress is generated inside probe 20. Probe 20 has a plurality of recesses 21R as stress dispersion portions on a surface 21BS of beam portion 21B perpendicular to the buckling direction X, which distributes the stress generated inside probe 20 during overdrive. The plurality of recesses 21R are arranged in a line in the longitudinal direction Z of beam portion 21B.

[0022] Fig. 2A is a plan view of the part surrounded by the dashed line in Fig. 1. It is a view of the beam portion 21B as seen in the buckling direction X. FIG. 2B is a cross-sectional view taken along line AA in FIG. 2A.

[0023] The probe 20 is conductive and composed of two types of metals with different resistivities. One is an inner metal (first metal) that constitutes the low-resistance portion L, 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, made of a palladium-cobalt (PdCo) alloy or the like, which has higher resistivity and lower conductivity than the low-resistance portion L, but has high mechanical strength and springiness. The high-resistance portion H functions to maintain the mechanical strength of the probe 20.

[0024] 2A, a plurality of rectangular pillar-shaped recesses 21R are arranged at intervals in the longitudinal direction Z on a surface 21BS (top surface) perpendicular to the buckling direction X of the beam portion 21B. The recesses 21R are formed in the high resistance portion H. When the probe A without the recesses 21R is compared with the probe 20 with the recesses 21R, the probe 20 with the recesses 21R has a smaller needle pressure in terms of the relationship between the needle pressure and the amount of overdrive.

[0025] Furthermore, we analyzed what effects can be obtained by the depression 21R. The maximum stress of the probe was calculated using the finite element method (FEM) for probe A, which does not have depression 21R, and probe 20, which has depression 21R in the shape of a rectangular pillar. The results showed that when an external force is applied, stress is concentrated at each vertex 10B of depression 21R shown in Figure 2B and at the ridge 10 formed by the two adjacent faces that make up depression 21R.

[0026] Therefore, by arranging rectangular prism-shaped depressions 21R as stress dispersion sections evenly in the longitudinal direction Z of the beam section 21B of the probe 20, the stress acting inside during overdrive can be evenly distributed to each vertex 10B and each ridge 10 of the depressions 21R. In addition, Figure 2B shows an example in which the recess 21R does not penetrate the high resistance portion H (in other words, the high resistance portion H is present between the recess 21R and the low resistance portion L), but the recess 21R may be arranged so that it penetrates the high resistance portion H and reaches the low resistance portion L (in other words, the low resistance portion L is exposed from the recess 21R), and by making the ridge 10 of the recess 21R longer than when the recess 21R does not penetrate the high resistance portion H, the stress concentration in the recess 21R can be further increased.

[0027] FIG. 3A shows a state in which a sacrificial layer G is disposed to fabricate the portion enclosed by the dashed line in FIG. 1. flat In plan view can be, Lamination direction View from R . In FIG. 3A, the photoresist F is not shown. Figure 3B shows the BB of Figure 3A. line Manufacture the part Show status Figure The arrow R indicates the stacking direction during manufacturing. For ease of explanation, the scales of FIGS. 3A and 3B are different.

[0028] The probe 20 is fabricated using so-called MEMS (Micro Electro Mechanical Systems) technology. MEMS technology is a technology that uses photolithography technology and sacrificial layer etching technology to create fine three-dimensional structures. Photolithography technology is a technology for processing fine patterns using photoresist F that is used in semiconductor manufacturing processes, etc. Sacrificial layer etching technology is a technology that creates a three-dimensional structure by forming a lower layer called a sacrificial layer G, forming layers that constitute the structure on top of it, and then removing only the sacrificial layer G by etching.

[0029] Well-known plating techniques can be used to form the high resistance portion H and the low resistance portion L. 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 surface of the substrate. This type of process is called electroplating, and since it is a wet process in which the substrate is immersed in the electrolyte, a drying process is performed after the plating process. Then, after the drying process, the needle tip portion 22 is polished by a polishing process.

[0030] Specifically, as shown in FIG. 3B, first, the bottom layer of the high resistance portion H is formed between sacrificial layers G. Next, a low resistance portion L is formed on top of that, and then a sacrificial layer G is formed in the portion that will become the recess 21R. Furthermore, after the remaining portion of the high resistance portion H is formed, the photoresist F and the sacrificial layer G are removed. Through the above steps, a probe 20 is obtained in which a recess 21R is formed on a surface 21BS perpendicular to the buckling direction X of the beam portion 21B. Note that, although an example in which two types of metal are used for the high resistance portion H and the low resistance portion L has been shown, it may also be manufactured using a single type of metal. Also, although an example in which the elastic deformation portion 21U is divided into multiple beam portions 21B has been described, it is not necessary for it to be divided.

[0031] According to the cantilever-type probe for a probe card of embodiment 1, the stress generated inside the probe 20 during testing can be evenly distributed to each vertex 10B and each ridge 10 of the recess 21R, thereby achieving both maintenance of mechanical strength and reduction of needle pressure.

[0032] Embodiment 2 The cantilever-type probe for a probe card according to the second embodiment will be described below, focusing on the differences from the first embodiment. FIG. 4 is a cross-sectional view of a modified example of the probe 20. As shown in FIG. In the first embodiment, an example has been described in which the recess 21R is provided only on one surface (upper surface) of the surface 21BS of the beam portion 21B of the probe 20 that is perpendicular to the buckling direction X. However, the recess 21R may be provided only on the other surface 21BS (lower surface) that is perpendicular to the buckling direction X of the beam portion 21B, or may be provided on both surfaces as shown in FIG. 4.

[0033] FIG. 5A is a plan view of a modified example of the probe 20. FIG. FIG. 5B is a cross-sectional view taken along CC in FIG. 5A. FIG. 6A is a plan view of a modified example of the probe 20. FIG. FIG. 6B is a cross-sectional view taken along line DD of FIG. 6A. Furthermore, the recess 21R may have a truncated quadrangular pyramid shape as shown in FIGS. 5A and 5B, or may have a truncated cone shape as shown in FIGS. 6A and 6B. FIG. 7A is a plan view of a modified example of the probe 20. FIG. FIG. 7B is a cross-sectional view taken along the line EE of FIG. 7A. 7A and 7B, the recesses 21R may have a shape obtained by cutting a cylinder in the axial direction. If many recesses are arranged, the distance between adjacent recesses 21R becomes narrow, which reduces the strength of the partition walls 9 between the recesses 21R. Therefore, the side surfaces of the recesses 21R are sloped to ensure the strength of the partition walls 9 between adjacent recesses 21R.

[0034] According to the cantilever probe for a probe card according to the second embodiment, even if a large number of recesses 21R are provided, the strength between adjacent recesses 21R can be ensured.

[0035] Embodiment 3 The cantilever-type probe for a probe card according to the third embodiment will be described below, focusing on the differences from the first embodiment. FIG. 8A is a cross-sectional view of a variation of the probe 20. As shown in FIG. FIG. 8B is a cross-sectional view taken along the line F-F of FIG. 8A. In the first and second embodiments, the recess 21R is provided on the surface 21BS perpendicular to the buckling direction X of the beam portion 21B of the probe 20, but a through hole 21Bh penetrating in the thickness direction Y of the beam portion 21B may be provided.

[0036] The cantilever probe for a probe card according to the third embodiment provides the same effects as those of the first embodiment.

[0037] Embodiment 4 The cantilever-type probe for a probe card according to the fourth embodiment will be described below, focusing on the differences from the first embodiment. FIG. 9A is a plan view of a modified example of the probe 20. FIG. FIG. 9B is a cross-sectional view taken along line GG in FIG. 9A.

[0038] 9A and 9B, the recess 21R may penetrate the high resistance portion H, and the low resistance portion L may be exposed from the recess 21R. This has the advantage that the manufacturing process can be omitted compared to the first to third embodiments.

[0039] Although the present application describes various exemplary embodiments and examples, the various features, aspects, and functions described in one or more embodiments are not limited to application to a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are conceivable within the scope of the technology disclosed in this application, including, for example, cases where at least one component is modified, added, or omitted, and cases where at least one component is extracted and combined with a component of another embodiment. [Explanation of symbols]

[0040] 20 probe, 21 main body, 22 needle tip, 21B beam, 21Bh through hole, 21BS surface, 21D base, 21U elastic deformation part, 9 partition, 21R recess, 21UH oblong hole, 21T terminal part, 10 ridge, 10B vertex, F photoresist, G sacrificial layer, H high resistance part, L low resistance part, X buckling direction, Y plate thickness direction, Z longitudinal direction.

Claims

1. A cantilever-type probe for a plate-shaped probe card, comprising: a base portion, a tip portion, and a beam portion located between the base portion and the tip portion; the buckling direction of the beam portion is a direction perpendicular to the plate thickness direction of the probe, The beam portion is a cantilever-type probe for a probe card, and has a plurality of stress distribution portions inward from all outer peripheries of at least one surface of the beam portion perpendicular to the buckling direction, where stress concentration occurs more than in other portions of the beam portion.

2. 2. The cantilever probe for a probe card according to claim 1, wherein the stress dispersion portion is a recess provided on the one surface of the beam portion.

3. 2. The cantilever probe for a probe card according to claim 1, wherein the stress dispersion portion is a through hole that penetrates the beam portion in the buckling direction.

4. The beam portion includes a low resistance portion made of a metal layer having low electrical resistance; a high resistance portion having a higher electrical resistance than the low resistance portion and made of a metal layer having spring properties; 3. The cantilever-type probe for a probe card according to claim 1, wherein the stress dispersion portion is formed in the high resistance portion.

5. the beam portion includes the low resistance portion and the high resistance portion stacked together, 5. The cantilever-type probe for a probe card according to claim 4, wherein the stress dispersion portion is a recess provided in the high resistance portion, and the low resistance portion is exposed from the recess.

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