Cantilever-type 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

Cantilever probe for probe card

[0001] The present application relates to a cantilever-type 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. 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.

[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 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 come into contact with 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 there is a problem in that the thinner the cross-section of the probe is, the more easily it is deformed by an external force (the mechanical strength is reduced).

[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.

[0013] The cantilever-type probe for a probe card disclosed in the present application comprises a base portion, a needle tip portion, and a beam portion located between the base portion and the needle tip portion, and the beam portion comprises a plurality of stress dispersion portions in the longitudinal direction where stress is concentrated more than in other portions of the beam portion.

[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.

[0015] 1. A perspective view of a cantilever-type probe for a probe card according to embodiment 1. A plan view of the portion surrounded by the dashed line in FIG. 1. A cross-sectional view taken along A-A in FIG. 2A. A cross-sectional view showing the state in which a sacrificial layer is disposed to manufacture the portion surrounded by the dashed line in FIG. 1. A diagram showing the manufacturing of the cross-sectional view taken along B-B in FIG. 3A. A cross-sectional view of a modified example of a probe according to embodiment 2. A plan view of a modified example of a probe according to embodiment 2. A cross-sectional view taken along C-C in FIG. 5A. A plan view of a modified example of a probe according to embodiment 2. A cross-sectional view taken along D-D in FIG. 6A. A plan view of a modified example of a probe according to embodiment 2. A cross-sectional view taken along E-E in FIG. 7A. A cross-sectional view of a modified example of a probe according to embodiment 3. A cross-sectional view taken along F-F in FIG. 8A. A plan view of a modified example of a probe according to embodiment 4. A cross-sectional view taken along G-G in FIG. 9A.

[0016] Embodiment 1. A cantilever probe for a probe card according to embodiment 1 will now be described with reference to the drawings. FIG. 1 is a perspective view of a cantilever probe for a probe card 20 (hereinafter simply referred to as probe 20). 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." The direction in which probe 20 buckles (elastically deforms) when overdriven is referred to as buckling direction X, and the direction perpendicular to buckling direction X, i.e., the thickness direction of probe 20, is referred to as plate thickness direction Y. The longitudinal direction of beam portion 21B of probe 20 is referred to as 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 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 with respect to the test object (electronic circuits 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 tip 22 that protrudes upward from the top end of the main body 21. 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 tip 22 on the test object side and the base 21D.

[0020] The elastically deforming portion 21U is formed with two elongated holes 21UH that extend in the longitudinal direction Z and penetrate in the plate thickness direction Y, and the elongated holes 21UH divide the elastically deforming portion 21U into two beam portions 21B.

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

[0022] Fig. 2A is a plan view of the portion 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 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.

[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, the effects obtained by the recess 21R were analyzed. The maximum stress of the probe was calculated using the finite element method (FEM) for the probe A without the recess 21R and the probe 20 with the rectangular prism-shaped recess 21R. The results showed that when an external force is applied, the stress is concentrated at each vertex 10B of the recess 21R shown in FIG. 2B and at the ridge 10 formed by the two adjacent faces that make up the recess 21R.

[0026] Therefore, by arranging the rectangular prism-shaped depressions 21R as stress dispersion portions evenly in the longitudinal direction Z of the beam portion 21B of the probe 20, the stress acting inside during overdrive can be evenly dispersed to each vertex 10B and each ridge 10 of the depression 21R. Note that, although Fig. 2B shows an example in which the depression 21R does not penetrate the high resistance portion H (in other words, the high resistance portion H is present between the depression 21R and the low resistance portion L), the depression 21R may be provided so as to penetrate the high resistance portion H and reach the low resistance portion L (in other words, the low resistance portion L is exposed from the depression 21R), and by making the ridge 10 of the depression 21R longer, stress concentration in the depression 21R can be further increased compared to when the depression 21R does not penetrate the high resistance portion H.

[0027] Figure 3A is a cross-sectional view showing the state in which a sacrificial layer G is disposed to manufacture the portion surrounded by the dashed line in Figure 1. Arrow R indicates the stacking direction during manufacturing. Figure 3B is a diagram showing the manufacturing of the B-B cross-sectional portion of Figure 3A. However, Figure 3A shows the state in which the high resistance portion has been further plated from the state in Figure 3B. For convenience of explanation, Figures 3A and 3B are not scaled the same.

[0028] The probe 20 is fabricated using so-called MEMS (Micro Electro Mechanical Systems) technology. 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 F, 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 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 an electrolyte, a drying process is performed after the plating process. 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 the sacrificial layers G. Next, the low resistance portion L is formed on top of that, and then the 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, the probe 20 is obtained, in which the recess 21R is formed on the 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 described, they may also be manufactured using a single type of metal. Also, although an example in which the elastically deforming 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. A cantilever-type probe for a probe card according to embodiment 2 will be described below, focusing on the differences from embodiment 1. Fig. 4 is a cross-sectional view of a modified example of probe 20. In embodiment 1, an example was described in which recess 21R is provided only on one surface (upper surface) of surface 21BS perpendicular to buckling direction X of beam portion 21B of probe 20, but recess 21R may be provided only on the other surface 21BS (lower surface) perpendicular to buckling direction X of 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. 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. 6B is a cross-sectional view taken along D-D in FIG. 6A. Furthermore, as shown in FIGS. 5A and 5B, the recesses 21R may have a truncated pyramid shape, or as shown in FIGS. 6A and 6B, they may have a truncated cone shape. FIG. 7A is a plan view of a modified example of the probe 20. FIG. 7B is a cross-sectional view taken along E-E in FIG. 7A. Furthermore, as shown in FIGS. 7A and 7B, the recesses 21R may have a shape obtained by cutting a cylinder in the axial direction. Arranging many recesses narrows the spacing between adjacent recesses 21R, reducing the strength of the partition walls 9 between the recesses 21R. Therefore, the side surfaces of the recesses 21R are inclined to ensure the strength of the partition walls 9 between adjacent recesses 21R.

[0034] According to the cantilever type 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. A cantilever-type probe for a probe card according to embodiment 3 will be described below, focusing on the differences from embodiment 1. Fig. 8A is a cross-sectional view of a modified example of probe 20. Fig. 8B is a cross-sectional view taken along the line F-F in Fig. 8A. In embodiments 1 and 2, examples have been described in which recess 21R is provided on surface 21BS perpendicular to buckling direction X of beam portion 21B of probe 20, but through-hole 21Bh may be provided that penetrates beam portion 21B in thickness direction Y.

[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 A cantilever-type probe for a probe card according to embodiment 4 will be described below, focusing on the differences from embodiment 1. Figure 9A is a plan view of a modified example of probe 20. Figure 9B is a cross-sectional view taken along line G-G of Figure 9A.

[0038] 9A and 9B , a configuration may be adopted in which the recess 21R penetrates the high resistance portion H and the low resistance portion L is exposed from the recess 21R. In this case, there is an advantage that the manufacturing process can be omitted compared to the first to third embodiments.

[0039] 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.

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

Claims

1. A cantilever-type probe for a probe card, comprising: The probe has a base portion, a tip portion, and a beam portion between the base portion and the tip portion, The beam portion is a cantilever-type probe for a probe card, the beam portion having a plurality of stress dispersion portions on at least one surface perpendicular to the buckling direction of the beam portion, where stress concentration occurs more than in other portions of the beam portion.

2. 2. The cantilever-type probe for a probe card according to claim 1, wherein the stress dispersion portion is a recess provided on at least one surface perpendicular to the buckling direction of the beam portion.

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

4. The beam portion includes a low resistance portion made of a metal layer having an electrical low resistance, a high resistance portion having a higher electrical resistance than the low resistance portion and made of a metal layer having spring properties; 4. 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 which are stacked, 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.