Cantilever probe for probe card

Abstract

A cantilever probe (20) for a probe card includes a base portion (21D), a tip portion (22), and a beam portion (21B) located between the base portion (21D) and the tip portion (22), the beam portion (21B) includes a plurality of stress dispersion portions (21R, 21Bh), and the stress dispersion portions (21R, 21Bh) generate more stress concentration than other portions of the beam portion (21B).

Description

Technical Field

[0001] The present application relates to a cantilever probe for a probe card. Background Art

[0002] The probe card is an electrical connection device used to contact the electrode pads of the semiconductor device with probes to supply power, input and output signals, and connect ground to perform an operation test of each semiconductor device formed on a wafer. The probes are provided on the surface of the probe card, and are configured so that the tips thereof are pressed against the electrode pads of the semiconductor device 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. Therefore, the electrode pads of the semiconductor devices are designed to be smaller, and the distance (pitch) between the electrode pads is designed to be smaller. Therefore, corresponding to the miniaturization of the semiconductor devices, it is necessary to make the probe finer. However, when the probe is made finer, there is a problem that the mechanical strength of the probe is weakened.

[0004] Therefore, in order to ensure good electrical and mechanical contact with the electrode pad of the semiconductor device, for example, Patent Document 1 proposes a structure using a multilayer metal sheet in a probe. Prior art literature Patent Literature

[0005] Patent Document 1: Japanese Patent Application No. 2018-501490 Summary of the invention Technical 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 and an outer coating, wherein the multilayer structure includes a core and a first inner coating overlapping, and the outer coating completely covers the multilayer structure, is made of a material with a higher hardness than the core, and completely covers the multilayer structure.

[0007] 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 stacked is preferred. However, this structure has limitations in satisfying the requirement of reducing the cross-sectional thickness of the probe, and further breakthroughs are needed.

[0008] In the inspection process of the semiconductor device using the probe card, in order to ensure contact with the electrode pad of the semiconductor device, after the probe contacts the electrode pad, the probe card is brought closer to the semiconductor wafer (overdrive) to press the probe to the electrode pad of the semiconductor device.

[0009] Therefore, the probe needs to have a strength that will not be mechanically damaged even if a contact pressure exceeding a specified value is applied. In order to prevent the probe from being damaged, it is necessary not to generate local stress concentration on the probe. In addition, in order to avoid this stress concentration, the probe is required to have a smooth surface and no damage as much as possible.

[0010] However, there are limitations in smoothing the metal surface, and there is a problem that the thinner the cross-section of the probe is, the easier it is to deform in response to external forces (the mechanical strength decreases).

[0011] The present application discloses a technology for solving the above-mentioned technical problems, and its purpose is to provide a cantilever probe for a probe card, which can contact the electrode pad of a semiconductor device with an appropriate needle pressure even if the probe is made fine, and has a strength that will not be destroyed even if a contact pressure exceeding a specified value is applied.

[0012] That is, the purpose of the cantilever probe for a probe card of the present application is to provide a cantilever probe for a probe card with high mechanical strength that can withstand large stress by having a structure in which the locations where stress concentration occurs are intentionally dispersed, rather than not causing stress concentration. Technical solutions adopted to solve technical problems

[0013] The cantilever probe for the 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, The beam portion includes a plurality of stress dispersion portions in a length direction, and stress concentration is higher in the stress dispersion portions than in other portions of the beam portion. Effects of the Invention

[0014] According to the cantilever probe for a probe card disclosed in the present application, it is possible to provide a cantilever probe for a probe card which can disperse the locations where stress concentration occurs and has high mechanical strength even if the plate thickness is set to be thin. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a perspective view of a cantilever probe for a probe card according to the first embodiment. Figure 2A yes Figure 1 A top view of the portion surrounded by the dotted line. Figure 2B yes Figure 2A AA section view. Figure 3A is shown to configure the sacrificial layer to be manufactured by Figure 1 A cross-sectional view of a state of a portion surrounded by a dotted line. Figure 3B Is manufacturing Figure 3A Figure 1. A cross-sectional view of the BB section. Figure 4 It is a cross-sectional view of a modified example of the probe of the second embodiment. Figure 5A It is a top view of a modified example of the probe of the second embodiment. Figure 5B yes Figure 5A CC cross-sectional view. Fig. 6A It is a top view of a modified example of the probe of the second embodiment. Figure 6B yes Fig. 6A DD cross-sectional view. Fig. 7A It is a top view of a modified example of the probe of the second embodiment. Figure 7B yes Fig. 7A EE cross-sectional view. Fig. 8A It is a cross-sectional view of a modified example of the probe of the third embodiment. Figure 8B yes Fig. 8A FF cross-sectional view. Fig.9A It is a top view of a modified example of the probe of the fourth embodiment. Fig. 9B yes Fig.9A GG cross-sectional view. DETAILED DESCRIPTION

[0016] Implementation method 1. Hereinafter, the cantilever probe for the probe card according to the first embodiment will be described with reference to the drawings. Figure 1 1 is a perspective view of a cantilever probe 20 for a probe (hereinafter simply referred to as a probe 20 ). In this manual, Figure 1 The above of the paper is referred to as "upper" and the below of the paper is referred to as "lower". The direction in which the probe 20 is buckled (elastically deformed) during overdrive is referred to as the buckling direction X, and the thickness direction of the probe 20, which is a direction orthogonal to the buckling direction, is referred to as the plate thickness direction Y. In addition, the length direction of the beam portion 21B of the probe 20 is referred to as the length direction Z.

[0017] The probe 20 is a component used in a probe card (not shown). The probe card is a device used to inspect the electrical characteristics of an electronic circuit formed on a semiconductor wafer. The characteristics inspection of the electronic circuit is performed as follows: the probe card is brought close to the semiconductor wafer, the needle tip 22 of the probe 20 is brought into contact with an electrode on the electronic circuit, and the test device is connected to the test connection electrode of the wiring substrate of the probe card via the probe 20.

[0018] The probe 20 is a cantilever probe arranged so that the beam portion 21B is substantially horizontal to the inspection object (electronic circuit formed on the semiconductor wafer). Figure 1 Although an example including two beam portions 21B is shown in the figure, 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 needle tip 22 protruding upward from the upper end of the main body. The main body 21 includes: a terminal 21T connected to a wiring pad of a wiring substrate (not shown); a base 21D rising upward from the terminal 21T; and an elastic deformation portion 21U between the needle tip 22 and the base 21D located on the inspection object side.

[0020] The elastic deformation portion 21U has two long holes 21UH extending in the longitudinal direction Z and penetrating in the plate thickness direction Y. The elastic deformation portion 21U is divided into two beam portions 21B by the long holes 21UH.

[0021] When the probe 20 is overdriven, Figure 1 The probe 20 is easily buckled and deformed in the buckling direction X by the reaction force from the inspection object due to the compressive force in the up-down direction. At this time, stress is generated inside the probe 20. The probe 20 includes a plurality of recesses 21R as stress dispersing portions on a surface 21BS of the beam 21B perpendicular to the buckling direction X to disperse the stress generated inside during overdrive. The plurality of recesses 21R are arranged in a row along the longitudinal direction Z of the beam 21B.

[0022] Figure 2A yes Figure 1 21B is a top view of the portion surrounded by the dotted line. Figure 2B yes Figure 2A AA section view.

[0023] The probe 20 is composed of two metals with electrical conductivity and different resistivity. One of them is the inner metal (first metal) constituting the low resistance portion L, and the low resistance portion L is made of metals with low resistivity such as copper, gold, silver (Cu, Au, Ag). The low resistance portion L has the effect of making the electrical conductivity higher and improving the current resistance performance. The other is the outer metal (second metal) constituting the high resistance portion H, and the high resistance portion H is made of metals with resistivity higher than the low resistance portion L such as palladium cobalt (PdCo) alloy, and the high resistance portion H has low electrical conductivity but high mechanical strength and elasticity. The high resistance portion H works to maintain the mechanical strength of the probe 20.

[0024] like Figure 2AAs shown, on the surface 21BS (upper surface) of the beam portion 21B perpendicular to the buckling direction X, a plurality of quadrangular prism-shaped recesses 21R are arranged at intervals in the length direction Z. The recesses 21R are formed in the high resistance portion H. Here, if the probe A without the recesses 21R and the probe 20 with the recesses 21R are compared, in terms of the relationship between the needle pressure and the overdrive amount, the needle pressure of the probe 20 with the recesses 21R is smaller.

[0025] In addition, the effects obtained by the recess 21R were analyzed. The maximum stress of the probe was calculated based on the finite element method (FEM) for the probe A without the recess 21R and the probe 20 with the recess 21R in the shape of a quadrangular prism. It was found that when a force is applied from the outside, the stress is concentrated on Figure 2B Each vertex 10B of the recess 21R and an edge line 10 formed by two adjacent surfaces constituting the recess 21R are shown.

[0026] Therefore, by arranging the quadrangular prism-shaped depressions 21R as stress dispersion parts uniformly along the longitudinal direction Z of the beam portion 21B of the probe 20 , the stress acting inside during overdrive can be uniformly dispersed to the vertices 10B and ridges 10 of the depressions 21R. In addition, Figure 2B , an example is shown in which the recess 21R does not penetrate the high resistance portion H (in other words, the high resistance portion H exists between the recess 21R and the low resistance portion L), but the recess 21R can also be arranged 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 recess 21R). Compared with the case where the recess 21R does not penetrate the high resistance portion H, the ridge line 10 of the recess 21R can be increased, thereby further improving the stress concentration on the recess 21R.

[0027] Figure 3A is a diagram showing the configuration of the sacrificial layer to produce Figure 1 The arrow R shows the stacking direction during manufacturing. Figure 3B Is manufacturing Figure 3A However, from Figure 3B The state after further plating the high resistance part becomes Figure 3A In addition, for the sake of illustration, Figure 3A and Figure 3B The scales are different.

[0028] The probe 20 is manufactured using the so-called MEMS (Micro Electro Mechanical Systems) technology. MEMS technology is a technology for manufacturing fine three-dimensional structures using photolithography technology and sacrificial layer etching technology. Photolithography technology is a processing technology for fine patterns using photoresist F used in semiconductor manufacturing processes, etc. In addition, the sacrificial layer etching technology is a technology in which a lower layer called a sacrificial layer G is formed, and after a layer constituting a structure is formed on it, only the sacrificial layer G is removed by etching to manufacture a three-dimensional structure.

[0029] In the formation process of the high resistance portion H and the low resistance portion L, a known plating technique can be used. For example, the substrate as the cathode and the metal sheet as the anode are immersed in an electrolyte, and a voltage is applied between the two electrodes, so that the metal ions in the electrolyte can be attached to the surface of the substrate. Such a process is called electroplating, which is a wet process in which the substrate is immersed in an electrolyte. Therefore, a drying process is performed after the plating process. After the drying process, the needle tip 22 is ground by a grinding process.

[0030] Specifically, if Figure 3B As shown, 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 thereon, and then the sacrificial layer G is formed on the portion that becomes the recess 21R. And, 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 in which the recess 21R is formed on the surface 21BS of the beam portion 21B perpendicular to the buckling direction X is obtained. In addition, in this embodiment, an example of a high resistance portion H and a low resistance portion L using two metals is shown, but it can also be manufactured using a single metal. In addition, an example in which the elastic deformation portion 21U is divided into a plurality of beam portions 21B is described, but it is not necessary to divide it.

[0031] According to the cantilever probe for the probe card of the first embodiment, the stress generated inside during inspection can be uniformly dispersed to each vertex 10B and each ridge line 10 of the recess 21R, so that both the maintenance of mechanical strength and the reduction of the needle pressure can be achieved.

[0032] Implementation method 2. Hereinafter, the cantilever probe for the probe card according to the second embodiment will be described focusing on the parts different from the first embodiment. Figure 4 It is a cross-sectional view of a modified example of the probe 20 . In the first embodiment, the example of providing the recess 21R only on one surface (upper surface) of the surface 21BS of the beam portion 21B of the probe 20 perpendicular to the buckling direction X is described, but the recess 21R may be provided only on the other surface 21BS (lower surface) of the beam portion 21B perpendicular to the buckling direction X, or may be provided as follows. Figure 4 Set up in both as shown.

[0033] Figure 5A It is a cross-sectional view of a modified example of the probe 20 . Figure 5B yes Figure 5A CC cross-sectional view. Fig. 6A It is a cross-sectional view of a modified example of the probe 20 . Figure 6B yes Fig. 6A DD cross-sectional view. In addition, if Figure 5A , Figure 5B As shown, the recess 21R may also be in the shape of a quadrangular pyramid, or may be in the shape of Fig. 6A , Figure 6B As shown, it is in the shape of a truncated cone. Fig. 7A It is a cross-sectional view of a modified example of the probe 20 . Figure 7B yes Fig. 7A EE cross-sectional view. In addition, if Fig. 7A , Figure 7B As shown, the recess 21R may also be a shape obtained by cutting a cylinder in the axial direction. If there are many recesses, the intervals between adjacent recesses 21R will become narrower, thereby reducing the strength of the partition wall 9 between the recesses 21R. For this reason, the side surfaces of the recesses 21R are inclined to ensure the strength of the partition wall 9 between adjacent recesses 21R.

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

[0035] Implementation method three. Hereinafter, the cantilever probe for the probe card of the third embodiment will be described focusing on the parts different from the first embodiment. FIG. 8 is a cross-sectional view of a modified example of the probe 20 . Figure 8B yes Fig. 8A FF cross-sectional view. In the first and second embodiments, the example in which the recess 21R is provided on the surface 21BS of the beam portion 21B of the probe 20 perpendicular to the buckling direction X is described, but a through hole 21Bh penetrating in the plate thickness direction Y of the beam portion 21B may be provided.

[0036] According to the cantilever probe for the probe card of the third embodiment, the same effects as those of the first embodiment are achieved.

[0037] Implementation method four. Hereinafter, the cantilever probe for the probe card according to the fourth embodiment will be described focusing on the parts different from the first embodiment. Fig.9A It is a top view of a modified example of the probe 20 . Fig. 9B yes Fig.9A GG cross-sectional view.

[0038] like Fig.9A , Fig. 9B As shown, the recess 21R may penetrate the high resistance portion H, and the low resistance portion L may be exposed from the recess 21R. In this case, there is an advantage that the manufacturing process can be omitted compared with the first to third embodiments.

[0039] The present application describes various exemplary embodiments and examples, but various features, methods, and functions described in one or more embodiments are not limited to application to specific embodiments and can be applied to the embodiments alone or in various combinations. Therefore, numerous modifications not shown are contemplated within the technical scope disclosed in this application, including, for example, modifications, additions, or omissions of at least one component, and also including extraction of at least one component and combination with components of other embodiments. Explanation of symbols

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

Claims

1. A cantilever probe for a probe card, characterized in that: include: Base part; Needle tip; and a beam portion between the base portion and the needle tip portion, The beam portion includes a plurality of stress dispersion portions in a length direction, and stress concentration is higher in the stress dispersion portions than in other portions of the beam portion.

2. The cantilever probe for a probe card according to claim 1, characterized in that: The stress dispersion portion is a depression provided on at least one surface of the beam portion that is perpendicular to the longitudinal direction.

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

4. The cantilever probe for a probe card according to any one of claims 1 to 3, characterized in that: The beam portion includes: a low resistance portion formed of a low resistance metal layer; and a high resistance portion composed of a metal layer having a higher resistance than the low resistance portion and having elasticity, The stress dispersion portion is formed in the high resistance portion.

5. The cantilever probe for a probe card according to claim 4, characterized in that: The beam portion includes the low resistance portion and the high resistance portion stacked together. The stress dispersion portion is a depression provided in the high resistance portion, and the low resistance portion is exposed from the depression.

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