probe card

Abstract

The purpose of this invention is to provide a probe card that is less prone to poor contact. Furthermore, the purpose of this invention is to provide a probe card with good high-frequency characteristics, good current resistance, and good conductivity. The present invention comprises: a wiring substrate 10 having one or more probe electrodes 102; an upper guide plate 13 separated from the wiring substrate 10 and disposed opposite to the wiring substrate 10, having one or more upper guide holes 131; a lower guide plate 14 separated from the upper guide plate 13 and disposed opposite to the upper guide plate 13, having one or more lower guide holes 141; and a probe group 15G comprising two or more probes 15 inserted into the same upper guide holes 131 and the same lower guide holes 141, and connected to the same probe electrodes 102 and the same electrode pads 201 of the object being inspected; each probe 15 constituting the probe group 15G can be independently bent and deformed between the upper guide plate 13 and the lower guide plate 14, and its lower end can move independently in the vertical direction.

Description

Technical Field

[0001] This invention relates to a probe card, and more specifically, to an improvement of a probe card having a vertical probe supported by two guide plates and generating elastic force through buckling deformation. Prior Technology

[0002] A probe card is a device consisting of many probes erected on a wiring board, used to inspect the electrical characteristics of semiconductor devices formed on semiconductor wafers. Semiconductor device inspection is performed by contacting the tips of the probes with the electrode pads on the semiconductor wafer, thereby establishing electrical conductivity between the semiconductor device and external devices.

[0003] During inspection, the probe card is brought close to the semiconductor wafer. Once the probes begin to contact the electrode pads, an overspeed drive is performed to bring the probe card and semiconductor wafer even closer. The probes elastically deform due to the overspeed drive, applying force to the electrode pads. Therefore, by ensuring a certain amount of overspeed drive, height discrepancies between the probes and the electrode pads can be absorbed, ensuring that all probes reliably conduct to the electrode pads.

[0004] In recent years, with the increasing speed of semiconductor devices, there has been a demand for probe cards capable of performing inspections using high-frequency signals. To improve the high-frequency characteristics of the probe card, it is necessary to shorten the probe length as much as possible and reduce its inductance. However, to shorten the probe length while ensuring a certain overspeed transmission, the probe needs to be bent more significantly during overspeed transmission. This results in the probe exceeding its stress limit and undergoing plastic deformation, failing to maintain its elastic force. The bent probe experiences maximum stress on the outer side of its bend. Therefore, by reducing the thickness of the probe in the bending direction, the stress generated during overspeed transmission can be suppressed, thus inhibiting plastic deformation.

[0005] Figure 10 is a schematic diagram showing one configuration example of a conventional probe card 300. This probe card 300 includes a vertical probe 15 supported by two guide plates 13 and 14. The upper end of the probe 15 is connected to a probe electrode 102 on a main substrate 10, and the lower end contacts the object to be inspected. Furthermore, the probe 15 is inserted through two guide holes 131 and 141 formed in the two guide plates 13 and 14 spaced apart, and elastically deforms between the guide plates 13 and 14. The corresponding two guide holes 131 and 141 are offset, so the probe 15 bends slowly even when not being inspected, and bends more significantly and buckles during inspection, maintaining elasticity (e.g., Patent Document 1).

[0006] Figure 11 is a schematic diagram showing one configuration example of the probe card 301 with improved high-frequency characteristics. Compared with the case in Figure 10, the high-frequency characteristics are improved by shortening the insertion interval of the shorter probe 15 through the guide plates 13 and 14. Furthermore, by reducing the thickness of the probe 15 in the bending direction D, the elastic force during inspection can be maintained even if the probe 15 is shortened. However, since the thickness of the probe 15 is reduced, its cross-sectional area is also reduced, resulting in new problems such as reduced current capacity and reduced current withstand characteristics.

[0007] To address this, a probe with a longitudinally elongated slit formed in the middle region excluding both ends of the probe, and two or more layers arranged separately, has been proposed (e.g., Patent Document 2). By having two or more layers through the slit, plastic deformation can be suppressed and the current capacity can be increased. However, a new problem arises: the slit and the boundaries at both ends are prone to breakage due to stress concentration during elastic deformation. [Previous Technical Documents] [Patent Literature]

[0008] Patent Document 1: Japanese Patent Application Publication No. 2001-050982 Patent Document 2: Japanese Patent Application Publication No. 2009-272308 Summary of the Invention

[0009] [The problem the invention aims to solve]

[0010] Conventional probes conduct electricity by having their tips contact the electrode pads of the object being inspected. Therefore, there is a risk that the contact area may be reduced if the electrode pads are uneven, or that contact may be impossible if there are minute foreign objects on the electrode pads.

[0011] Figure 12 illustrates the case where the tip of the conventional probe 15 contacts the protrusion 202 on the electrode pad 201. When there are uneven surfaces on the electrode pad 201, the tip of the probe 15 may only contact the protrusion 202, which may not ensure sufficient contact area and could reduce current capacity.

[0012] Figure 13 illustrates the situation where the tip of the conventional probe 15 contacts a foreign object 203 on the electrode pad 201. When a foreign object 203 is present on the surface of the electrode pad 201, there is a risk that the tip of the probe 15 may only contact the foreign object 203, and the probe 15 may not be able to conduct electricity with the electrode pad 201.

[0013] Furthermore, the same problem may arise regarding the connection between the upper end of probe 15 and probe electrode 102.

[0014] This invention is made in view of the above-mentioned issues, with the aim of improving the reliability of probe cards. In particular, it aims to provide probe cards that are less prone to poor contact. Furthermore, it aims to provide probe cards with good high-frequency characteristics, good current withstand characteristics, and good conductivity. [Solutions]

[0015] The probe card of the first embodiment of the present invention comprises: a wiring substrate having one or more probe electrodes; an upper guide plate separated downward from the wiring substrate and disposed opposite to the wiring substrate, having one or more upper guide holes; a lower guide plate separated downward from the upper guide plate and disposed opposite to the upper guide plate, having one or more lower guide holes; and a probe group consisting of two or more probes inserted into the same upper guide holes and the same lower guide holes, and connected to the same probe electrodes and the same electrodes of the object being inspected; each probe constituting the probe group can be independently bent and deformed between the upper guide plate and the lower guide plate, and its lower end can move independently in the vertical direction.

[0016] By employing this configuration, even when the surface of the electrode pad on the object being inspected is uneven, or when there are foreign objects in a portion of the electrode pad, the probe and the electrode pad can still maintain reliable conductivity. Furthermore, since the reduction in probe cross-sectional area can be mitigated by increasing the number of probes, the decrease in current capacity can be suppressed, and high-frequency characteristics can be improved.

[0017] In addition to the above-described configuration, the probe card of the second embodiment of the present invention has a friction-inhibiting film formed on the side of the probe.

[0018] By adopting this configuration, it is possible to prevent adjacent probes from interfering with each other due to friction.

[0019] In addition to the above-described configuration, the probe card of the third embodiment of the present invention has a locking portion that locks onto the upper surface of the upper guide plate to prevent it from falling off the upper guide plate.

[0020] In addition to the above-described configuration, the probe card of the fourth embodiment of the present invention has a probe configuration in which its side faces the inner wall of the upper guide hole, and the locking part is a protruding part that locks onto the upper guide plate on the side including the part facing the inner wall.

[0021] By adopting this configuration, even when the probe group consists of three or more probes, it is possible to prevent each probe from falling off.

[0022] In addition to the above-described configuration, the probe card of the fifth embodiment of the present invention is configured such that the lower guide hole is formed in a manner offset relative to the upper guide hole, and the probe is bent between the upper guide plate and the lower guide plate when not being inspected.

[0023] By adopting this configuration, probes belonging to the same probe group can bend and deform in the same direction, thus preventing adjacent probes from interfering with each other. [Effects of the Invention]

[0024] According to the present invention, the reliability of probe cards can be improved. In particular, probe cards that are less prone to poor contact can be provided. Furthermore, probe cards with good high-frequency characteristics, good current withstand characteristics, and good conductivity can be provided. Simple Explanation of the Diagram

[0025] [Figure 1] is a diagram showing an example of the configuration of a probe card 100 according to Embodiment 1 of the present invention. [Figure 2] is a perspective view showing one example of the detailed configuration of probe group 15G. [Figure 3] is a diagram showing the condition of each probe 15 during inspection. It is a cross-sectional view when cut from the same vertical plane as in Figure 1. [Figure 4] is a cross-sectional view of each probe 15 when it is cut through the horizontal plane of the upper guide plate 13 or the lower guide plate 14. [Figure 5] is a cross-sectional view of each probe 15 when it is cut with a vertical plane that intersects the cross-section of Figure 1. [Figure 6] is a diagram showing the inspection situation when the electrode pad 201 has unevenness. [Figure 7] is a diagram showing the inspection process when there is a foreign object 203 on the electrode pad 201. [Figure 8] is a diagram showing other configuration examples of probe group 15G. [Figure 9] is a diagram showing an example of one of the main parts of the probe group 15G of Embodiment 2 of the present invention. It is a cross-sectional view of each probe 15 cut through the horizontal plane of the upper guide plate 13 or the lower guide plate 14. [Figure 10] is a schematic diagram showing a typical example of the structure of a conventional probe card. [Figure 11] is a schematic diagram showing one example of a conventional probe card for enhancing high-frequency characteristics. [Figure 12] is a diagram showing the situation where the tip of the conventional probe 15 contacts the protrusion 202 on the electrode pad 201. [Figure 13] is a diagram showing the situation where the tip of the conventional probe 15 contacts a foreign object 203 on the electrode pad 201. Implementation

[0026] Implementation Form 1. Figure 1 is a diagram showing one configuration example of the probe card 100 according to Embodiment 1 of the present invention. It is a cross-sectional view of the horizontally arranged probe card 100 when cut vertically. The probe card 100 is mounted on the card holder 21 with the mounting surface of the probe 15 facing the semiconductor wafer 200 on the platform 20. By moving the platform 20 up and down, the probe 15 can contact the electrode pad 201 on the semiconductor wafer 200.

[0027] The probe card 100 consists of a main substrate 10, a reinforcing plate 11, a probe guide 12, and two or more probes 15.

[0028] The main substrate 10 is a wiring substrate detachably mounted on the wafer detector, for example, using a circular glass epoxy board. The outer periphery of the lower surface of the main substrate 10 is supported by the wafer detector's retainer 21 and is horizontally positioned. A reinforcing plate 11 for suppressing strain on the main substrate 10 is mounted at the center of the upper surface of the main substrate 10, and two or more external terminals 101 for connecting signal terminals of a test device (not shown) are provided at the outer periphery of the upper surface. Furthermore, a probe electrode 102 for connecting a probe 15 is provided at the center of the lower surface.

[0029] The probe guide 12 is a support member that can move up and down to support the probe 15 and position the probe 15 in the horizontal plane. The probe guide 12 consists of two guide plates 13 and 14 that support the probe 15, and guide plate mounting portions 130 and 140 that mount the guide plates 13 and 14 to the main substrate 10.

[0030] The upper guide plate 13 is a plate-shaped component, such as a ceramic plate, with an upper guide hole 131 formed thereon. It is arranged parallel to the main substrate 10 via a guide plate mounting portion 130. The upper guide plate 13 separates downward from the main substrate 10 and is arranged facing the main substrate 10. The upper guide hole 131 is a hole that passes through the upper guide plate 13 in the thickness direction, through which the probe 15 is inserted and supports the base of the probe 15.

[0031] The lower guide plate 14 is a plate-shaped component, such as a ceramic plate, with a lower guide hole 141 formed thereon. It is arranged parallel to the main substrate 10 via the guide plate mounting part 140. The lower guide plate 14 is separated from the upper guide plate 13 and is arranged opposite to the upper guide plate 13. The lower guide hole 141 is a hole that passes through the lower guide plate 14 along the thickness direction of the plate, through which the probe 15 is inserted, and supports the tip of the probe 15 in a way that allows it to move up and down.

[0032] The probe 15 extends along a direction intersecting the main substrate 10 and is a vertical probe that bends and deforms through high-speed transmission. The probe 15 is made of a conductive material with an elongated shape, its upper end connected to the probe electrode 102, and its lower end contacting the electrode pad 201 on the object being inspected. Furthermore, the probe 15 passes through the upper guide hole 131 and also through the lower guide hole 141. The probe 15 is made of metallic materials with excellent elasticity and conductivity, such as nickel (Ni) alloys and palladium (Pd) alloys. The probe 15 can be formed from a single conductive material or by layering different conductive materials. For example, gold (Au) and copper (Cu), which have particularly high conductivity, can also be used in parts.

[0033] The probe group 15G consists of two or more independent probes 15, and each probe 15 on the probe card 100 belongs to any probe group 15G. Probes 15 belonging to the same probe group 15G are inserted through the same upper guide hole 131 and connected to the same probe electrode 102. Furthermore, probes 15 belonging to the same probe group 15G are inserted through the same lower guide hole 141 and contact the same electrode pad 201 on the semiconductor wafer 200. Moreover, adjacent probes 15 belonging to the same probe group 15G are arranged in a manner that allows them to contact each other laterally, or are arranged facing each other with a slight gap between them. That is, the probe group 15G in the probe card 100 of this embodiment is equivalent to the probes in a conventional probe card.

[0034] Figures 2-5 illustrate an example of the detailed configuration of the probe group 15G, showing three probes 15 constituting one probe group 15G. Figure 2 is a perspective view showing the external shape of each probe 15. Figure 3 is a cross-sectional view showing the state of each probe 15 during inspection, cut with the same vertical plane as in Figure 1. Figure 4 is a cross-sectional view showing each probe 15 cut with a horizontal plane passing through the upper guide plate 13 or the lower guide plate 14. Figure 5 is a cross-sectional view showing each probe 15 cut with a vertical plane intersecting the cross-section of Figure 1.

[0035] The probe 15 is composed of a needle base 151 as the upper end, a needle tip 152 as the lower end, and an elastically deformable part 150 clamped by the needle base 151 and the needle tip 152. Furthermore, the probe 15 is provided with a locking part 155 for preventing it from falling off.

[0036] An elastically deformable portion 150 is disposed between the upper guide plate 13 and the lower guide plate 14, and bends and deforms by high-speed transmission during inspection. A connecting chip 153 for connecting to the probe electrode 102 of the main substrate 10 is provided at the tip of the needle base 151. Furthermore, a contact chip 154 ​​for contacting the electrode pad 201 of the semiconductor wafer 200 is provided at the tip of the needle tip 152.

[0037] The upper guide hole 131 is offset relative to the lower guide hole 141 in the buckling direction D (see Figure 3). The buckling direction D is a predetermined direction in the horizontal plane. For example, with the guide plates 13 and 14 arranged in a manner that makes the horizontal positions of the guide holes 131 and 141 consistent, after inserting the probe 15 through the two guide holes 131 and 141, the guide plates 13 and 14 slide relative to each other in the buckling direction D by a specific distance, thereby offsetting the guide holes 131 and 141. The buckling direction D is the horizontal direction on the vertical plane (buckling surface) that causes the probe 15 to buckle and deform. By performing this offset configuration, even if the probe 15 is an unbent straight shape, the elastic deformation portion 150 can bend gently in the buckling surface when not under inspection. Therefore, by overspeed transmission during inspection, the elastic deformation portion 150 bends more in the buckling surface, thereby buckling and deforming. By offsetting the guide plates 13 and 14, the buckling direction D of the probe 15 can be predetermined, ensuring that the buckling directions D of each probe 15 belonging to the same probe group 15G are consistent. Therefore, each probe 15 can buckle and deform independently without interfering with each other.

[0038] The probe 15, for example, comprises a generally quadrangular prism (see Figure 4). In this case, the cross-section of the elastically deformable portion 150 is rectangular, having a thickness H aligned with the buckling direction D and a width W orthogonal to the buckling direction D. The thickness H of the cross-section is shorter than the width W. Reducing the thickness H can suppress plastic deformation and shorten the length of the probe 15, thereby improving high-frequency characteristics.

[0039] However, since the thickness H is reduced, the cross-sectional area of ​​the probe 15 is reduced, and the current capacity is also reduced. Therefore, by making the width W longer than the thickness H, the reduction in cross-sectional area can be suppressed, thus suppressing the reduction in current capacity. Furthermore, by arranging two or more probes 15 in a manner along the buckling direction D, the increase in the number of probes 15 can mitigate or compensate for the reduction in the cross-sectional area of ​​a single probe 15, ensuring current capacity.

[0040] The locking portion 155 is a protrusion extending horizontally from the needle base 151, locking onto the upper surface of the upper guide plate 13 to prevent the probe 15 from falling off the upper guide plate 13 (see Figure 5). The locking portion 155 is formed as the protrusion shown below, that is, on the side not facing other probes 15 in the same probe group 15G, that is, the side including the part facing the inner wall of the upper guide hole 131, protruding in such a way as to lock onto the upper guide plate 13. Furthermore, the locking portion 155 is preferably provided in a direction intersecting the bending direction D, so that the locking condition will not become shallow due to bending deformation and thus prevent it from falling off the upper guide plate 13.

[0041] Figure 6 illustrates the inspection process when the electrode pad 201 has unevenness. In the probe card 100 of this embodiment, each probe 15 belonging to the same probe group 15G is configured to operate independently. Specifically, the probe tip 152 moves up and down independently, and the elastic deformation portion 150 can bend and deform independently. Therefore, when unevenness is formed on the upper surface of the electrode pad 201, the lower end of each probe 15 can be made to have different heights according to the shape of the upper surface, allowing all probes 15 to contact the electrode pad 201. Thus, sufficient contact area is ensured, improving the reliability of the inspection.

[0042] The electrode pad 201 has a protrusion 202 formed in a portion of its area, which is higher than other areas. The three probes 15 shown in the figure belong to the same probe group 15G. The central probe 15 contacts the protrusion 202, while the probes 15 at both ends contact the area other than the protrusion 202. That is, since the three probes contact the electrode pad 201 respectively, sufficient contact area can be ensured between the probes and the electrode pad 201.

[0043] Figure 7 illustrates the inspection process when there is a foreign object 203 on the electrode pad 201. Similar to Figure 6, because the lower ends of the probes 15 belonging to the same probe group 15G can be made at different heights, even when there is a foreign object 203 on the electrode pad 201 and some probes 15 are in contact with the foreign object, other probes 15 can still contact the electrode pad 201. Therefore, even when there is an insulating foreign object on the electrode pad 201, the probes 15 can reliably conduct electricity to the electrode pad 201, improving the reliability of the inspection.

[0044] Figures 8(a) to (f) show other configuration examples of the probe group 15G. Similar to the case in Figure 4, they are cross-sectional views of each probe 15 cut through the horizontal plane of the upper guide plate 13 or the lower guide plate 14.

[0045] The probe group 15G in (a) and (b) consists of two probes 15 arranged in a row. In (a), the two probes 15 are arranged in the buckling direction D, and in (b), the two probes 15 are arranged in a direction intersecting the buckling direction D.

[0046] (c) The probe group 15G consists of four probes 15 arranged in a lattice pattern. In this probe group 15G, two probes 15 are arranged in the buckling direction D, and two probes 15 are also arranged in the direction intersecting the buckling direction D.

[0047] (d) The probe group 15G consists of six probes 15 arranged in a lattice pattern. In this probe group 15G, three probes 15 are arranged in the buckling direction D, and two probes 15 are arranged in the direction intersecting the buckling direction D.

[0048] The probe groups 15G in (e) and (f) include wide probes 15A and narrow probes 15B with different widths as probes 15. The width 2W of the wide probe 15A is twice the width W of the narrow probe 15B. The combined width 2W of the two narrow probes 15B arranged in a direction intersecting the buckling direction D is the same as the width 2W of the wide probe 15A. For convenience, the two narrow probes 15B arranged in a direction intersecting the buckling direction D are referred to as segmented probes 15C. In the probe groups 15G in (e) and (f), the wide probes 15A and segmented probes 15C are arranged in the buckling direction D. In the probe group 15G in (e), two wide probes 15A are arranged in the buckling direction D with a segmented probe 15C between them. On the other hand, in the probe group 15G in (f), two segmented probes 15C are arranged in the buckling direction D with a wide probe 15A between them. (e) and (f) are examples of situations in which one or more wide probes 15A and one or more segmented probes 15C are mixed together and arranged in the buckling direction D.

[0049] The probes 15 shown in (a) to (f) each have a locking portion 155 for preventing them from falling off. Therefore, the probe 15 needs to have a locking portion 155 protruding from the side of the portion facing the inner wall of the guide holes 131 and 141 so as to lock onto the upper guide plate 13. Therefore, when the locking portion 155 is arranged in a direction intersecting the bending direction D, it is arranged such that no more than three probes 15 are arranged in the direction intersecting the bending direction D. That is, one or two or more probes 15 are arranged in the bending direction D, and one or two probes 15 are arranged in the direction intersecting the bending direction D.

[0050] Furthermore, in (a) to (f), the thickness H of all probes 15 belonging to the same probe group 15G is the same, and the total width of all probes 15 in the direction intersecting the buckling direction D is the same. Therefore, the buckling deformation of each probe 15 does not produce significant differences, and interference between adjacent probes 15 can be suppressed.

[0051] Implementation Form 2. Figure 9 is a diagram showing an example of a main part of the probe group 15G of Embodiment 2 of the present invention. Similar to Figure 4, it is a cross-sectional view of each probe 15 cut through a horizontal plane passing through the upper guide plate 13 or the lower guide plate 14. A friction-inhibiting film 156 is formed on the side of the probe 15.

[0052] The friction suppression film 156 is a film used to prevent interference between adjacent probes 15, and is formed on the opposing sides of the probes 15. For example, it is preferably formed in a manner that covers the entire side of the probes 15 except for the connecting wafer 153 and the contact wafer 154.

[0053] The friction-inhibiting film 156 can be obtained by forming a film made of a material with a coefficient of friction lower than that of the probe 15 on the side surface, such as a DLC (diamond-like carbon) film or a PTFE (polytetrafluoroethylene) film. The DLC film is an amorphous hard film made of hydrocarbons or carbon, and its durability is higher than that of the PTFE film. Therefore, it is preferable to use a DLC film as the friction-inhibiting film 156.

[0054] Since probes 15 belonging to the same probe group 15G are connected to the same probe electrode 102 and the same electrode pad 201, it is not necessary to insulate probes 15 from each other. The friction suppression film 156 does not need to be an insulating material, but it prioritizes reducing the coefficient of friction and can use a material with lower conductivity than probe 15.

[0055] By forming a friction-inhibiting film 156 on the side of the probe 15, friction between adjacent probes 15 can be suppressed, preventing interference between independently operating probes 15.

[0056] 10: Main base board 11: Reinforcing plate 12: Probe guide 13: Upper guide plate 14:Lower guide plate 15: Probe 15A: Wide probe 15B: Narrow probe 15C: Segmentation probe 15G: Probe Cluster 20: Platform 21: Card Holder 100: Probe Card 101:External terminal 102: Probe electrode 130: Guide plate mounting section 131:Upper guide hole 140: Guide plate mounting section 141:Lower guide hole 150: Elastic deformation section 151: Needle base 152: Needle tip 153: Connecting Chip 154: Contact chip 155: Locking part 156: Friction-inhibiting film 200: Semiconductor wafers 201: Electrode pad 202:convex part 203: Foreign object D: Flexion direction

Claims

1. A probe card comprising: a wiring substrate having one or more probe electrodes; an upper guide plate separated downward from the wiring substrate and disposed opposite to the wiring substrate, having one or more upper guide holes; a lower guide plate separated downward from the upper guide plate and disposed opposite to the upper guide plate, having one or more lower guide holes; and a probe group comprising two or more probes; wherein the two or more probes constituting the probe group are commonly inserted into one of the upper guide holes and commonly inserted into one of the lower guide holes, and are commonly connected to one of the probe electrodes and one electrode of the object being inspected; each probe constituting the probe group is independently bendable in a predetermined direction between the upper guide plate and the lower guide plate, and its lower end is independently movable in a vertical direction; and the two or more probes constituting the probe group are arranged in the predetermined direction.

2. As in request item 1, the probe card, wherein, A friction-inhibiting film is formed on the side of the probe.

3. As in request item 1, the probe card, wherein, The probe has a locking part that locks onto the upper surface of the upper guide plate to prevent it from falling off the upper guide plate; the locking part protrudes from the upper end of the probe, i.e. the base of the probe, in a direction orthogonal to the predetermined direction.

4. As in request item 1, the probe card, where, The cross-section of the buckling and deformed portion of the probe, i.e. the elastically deformed portion, is a rectangle formed by the short side in the predetermined direction and the long side orthogonal to the predetermined direction.

5. The probe card requested in any of items 1 to 4, wherein... The lower guide hole is formed offset relative to the upper guide hole, and the probe is bent between the upper guide plate and the lower guide plate when not in use.

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