Probe and probe card

Abstract

A probe (20) has: a contact unit (20C) at one end; and a terminal unit (20T), which is in contact with a circuit board, at the other end. The probe (20) comprises: a low / high-resistance unit (20LH) in which a low-resistance unit (20L) made of a first metal is covered by a high-resistance unit (20H) made of a second metal having a higher resistivity than the low-resistance unit (20L); a medium-resistance unit (20M) that is connected to the low-resistance unit (20L) in the lengthwise direction (X) of the probe (20), and that is made of a third metal having a lower resistivity than the high-resistance unit (20H) and a higher resistivity than the low-resistance unit (20L); and a medium-high-resistance unit (20MH) having a high-resistance unit (20H) connected to the high-resistance unit (20H) of the low / high-resistance unit (20LH) on both side surfaces in one direction of the medium-resistance unit (20M).

Description

Probes and Probe Cards

[0001] The present disclosure relates to probes and probe cards.

[0002] A probe card is a card (substrate) with probes (probe needles) attached. A probe card connects each of the electrodes (power input electrode, signal output electrode, and ground electrode) of the electronic circuit of a semiconductor device formed on a semiconductor wafer to a tester device using probe pins. The electrical characteristics of the electronic circuit of a semiconductor device are tested by supplying a current to the semiconductor device to operate it and checking whether the semiconductor device outputs a predetermined signal. During this test, a large current flows through the power supply probe (power probe) and the ground probe (ground probe). If a large current flows through the power supply probe or ground probe during semiconductor device testing, the probe may burn out. Therefore, probes with a high allowable current value are desirable for probe cards. In order to increase the allowable current value while maintaining the mechanical strength of the probe, it has been proposed to use a probe in which an inner member is made of a conductive material with low resistance (e.g., copper, silver, gold, and alloys thereof), and the outer periphery of this inner member is provided with a conductive material with high resistance and mechanical strength (e.g., a conductive material selected from rhodium, platinum, iridium, and alloys thereof, palladium-cobalt alloy, palladium-nickel alloy, and nickel-phosphorus alloy, preferably rhodium) (see, for example, Patent Document 1).

[0003] Special table 2018-501490 publication

[0004] A problem with probes is that the tip that contacts the electrode gradually wears with repeated use. Conventional probes have a Cu surface plated with PdCo, ​​and as the tip wears, the internal Cu becomes exposed. This causes the Cu to oxidize, changing the state of the probe when it contacts the electrode. To prevent the Cu from being exposed, a predetermined portion of the tip is made of PdCo. In this way, by making the tip of the probe PdCo, ​​the probe becomes resistant to wear. However, a new problem has arisen: heat is generated in this portion due to the high resistance of the PdCo portion.

[0005] Therefore, in order to develop a probe that can withstand wear and eliminate the problem of heat generation, for example, the replacement of PdCo with NiB was considered. However, simply replacing PdCo with NiB resulted in peeling at the interface between the Cu and NiB plating layers, which posed a problem in that the adhesion between the plating layers had to be strengthened.

[0006] The present disclosure discloses a technique for solving the above-mentioned problems, and aims to provide a probe and a probe card that can withstand wear, reduce heat generation, and have high adhesion between components.

[0007] The probe according to the present disclosure has a contact portion at one longitudinal end that is brought into contact with an electrode to be tested, and a terminal portion at the other longitudinal end that is brought into contact with a circuit board, the probe comprising: a low-high resistance portion in which a low resistance portion made of a conductive first metal is covered with a high resistance portion made of a conductive second metal having a resistivity higher than that of the low resistance portion; a medium resistance portion on the contact portion side of the low-high resistance portion, connected to the low resistance portion in the longitudinal direction of the probe, and made of a third metal having a low resistivity lower than that of the high resistance portion and a resistivity higher than that of the low resistance portion; and a medium-high resistance portion having high resistance portions on both side surfaces in one direction of the medium resistance portion that are connected to the high resistance portion of the low-high resistance portion.

[0008] According to the probe and probe card of the present disclosure, it is possible to provide a probe and probe card that can withstand wear, reduce heat generation, and have high adhesion between components.

[0009] 2A is a diagram schematically illustrating a state in which an electronic circuit is being tested using a probe card according to embodiment 1. FIG. 2A is a perspective view of a probe according to embodiment 1. FIG. 2B is a diagram of the probe shown in FIG. 2A as viewed from the buckling direction Z+ side. FIG. 3A is a cross-sectional schematic diagram of a probe, an upper guide, an intermediate guide, and a lower guide. The probe corresponds to the A-A cross section of FIG. 2A. FIG. 3B is a B-B cross section of FIG. 2A, which is a cross section perpendicular to the longitudinal direction of the low-high resistance section of the probe. FIG. 3C is a C-C cross section of FIG. 2A, which is a cross section perpendicular to the longitudinal direction of the middle-high resistance section of the probe. A cross-sectional view of the probe and guide in a buckled state according to embodiment 1.

[0010] First Embodiment. A probe and a probe card according to the first embodiment will be described below with reference to the drawings. FIG. 1 is a diagram schematically illustrating an electronic circuit being inspected by a probe card 100 according to the first embodiment. 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." That is, the side to be inspected as viewed from the probe card 100 will be referred to as "bottom." For convenience, the left-to-right direction of the paper in FIG. 1 will be referred to as the buckling direction Z. When distinguishing between left and right, the left side of FIG. 1 will be referred to as the buckling direction Z+ side, and the right side of FIG. 1 will be referred to as the buckling direction Z- side. For convenience, the direction from the front of the paper to the back and the opposite direction will be referred to as the direction Y perpendicular to the buckling direction Z.

[0011] The probe card 100 includes a large number of probes 20 that are brought into contact with electrodes C on electronic circuits of semiconductor devices formed on a semiconductor wafer W, respectively.

[0012] The probe card 100 includes a frame 10, an upper guide 11U attached to the upper end of the frame 10, a lower guide 11L attached to the lower end of the frame 10, an intermediate guide 11M attached between the upper guide 11U and the lower guide 11L, and a wiring board 14. At least two guides are required.

[0013] The upper guide 11U has a plurality of guide holes 11Uh that penetrate in the vertical direction, and the middle guide 11M and the lower guide 11L also have a plurality of guide holes 11Mh, 11Lh that penetrate in the vertical direction. A wiring board 14 is disposed above the frame 10. The wiring board 14 has, on its lower surface, a plurality of probe connection pads 14P that come into contact with the terminal portions 20T at the upper ends of the probes 20.

[0014] A plurality of probes 20 are inserted and guided through the guide holes 11Uh, 11Mh, and 11Lh, respectively. The probes 20 are vertical probes that are disposed perpendicular to the test object (electronic circuits formed on the semiconductor wafer W).

[0015] FIG. 2A is a perspective view of the probe 20. FIG. 2B is a view of the probe 20 shown in FIG. 2A as seen from the buckling direction Z+ side. The left-right direction in FIG. 2A is the buckling direction Z of the probe 20, i.e., the direction in which the probe 20 elastically deforms when the probe card 100 is overdriven. FIG. 3A is a cross-sectional schematic diagram of the probe 20, the upper guide 11U, the intermediate guide 11M, and the lower guide 11L. The probe 20 corresponds to the A-A cross section in FIG. 2A. FIG. 3B is a B-B cross-sectional view of FIG. 2A, which is a cross-sectional view perpendicular to the longitudinal direction X of the low-high resistance section 20LH of the probe 20. FIG. 3C is a CC cross-sectional view of FIG. 2A, which is a cross-sectional view perpendicular to the longitudinal direction X of the medium-high resistance section 20MH of the probe 20. FIG. 4 is a cross-sectional schematic diagram of the probe 20, the upper guide 11U, the intermediate guide 11M, and the lower guide 11L, which is a cross-sectional view showing the probe 20 in a buckling-deformed state.

[0016] The probe 20 has an elongated shape. The central portion is curved, and the upper and lower portions extend linearly in the vertical direction. The curved central portion is an elastically deformable portion 20D. The probe 20 has a contact portion 20C at its lower end (one end). A terminal portion 20T is formed at its upper end (the other end).

[0017] The contact portion 20C is a contact portion that comes into contact with the test object. The terminal portion 20T is provided at the upper end of the probe 20 and is pressed against the probe connection pad 14P of the wiring board 14 during testing. The elastically deforming portion 20D is a portion that easily buckles and deforms as shown in FIG. 4 when a compressive force is applied to it in the longitudinal direction X during overdriving. During overdriving, the elastically deforming portion 20D buckles and deforms in the buckling direction Z in response to a reaction force from the test object, and the contact portion 20C retreats toward the terminal portion 20T.

[0018] The probe 20 is made of three types of conductive metals with different resistivities. First, there is a first metal with low resistivity, such as Cu, Au, or Ag (copper, gold, or silver). The portion of the probe 20 made of the first metal is the low-resistivity portion 20L. The other is a second metal, such as a PdCo alloy (palladium cobalt), which has a higher resistivity and lower conductivity than the first metal but high mechanical strength. The portion of the probe 20 made of the second metal is the high-resistivity portion 20H. The other is a third metal, such as a NiB alloy, whose hardness and resistivity are intermediate between those of the first and second metals. The portion of the probe 20 made of the third metal is the medium-resistivity portion 20M.

[0019] The low resistance portion 20L has high conductivity and functions to increase the allowable current value of the probe 20. However, because Cu oxidizes, the probe 20 cannot be constructed using only the first metal. Therefore, the low resistance portion 20L is covered by the high resistance portion 20H. The high resistance portion 20H functions to maintain the mechanical strength of the probe 20. The medium resistance portion 20M has a lower resistance than the high resistance portion 20H but a higher resistance than the low resistance portion 20L, and functions to suppress heat generation at the contact portion 20C of the probe 20.

[0020] 3A and 3B, the probe 20 has a low-high resistance section 20LH that is located below the intermediate guide 11M and above the lower guide 11L, and extends from the lower end (boundary K) toward the terminal section 20T, with the periphery of the low resistance section 20L being a rectangular pillar and covered with a high resistance section 20H. This section is referred to as the low-high resistance section 20LH. The low-high resistance section 20LH is inserted into the guide hole 11Lh of the lower guide 11L that is closest to the contact section 20C.

[0021] The section from the lower end (boundary K) of the low-high resistance section 20LH to the contact section 20C at the tip has a rectangular cross section perpendicular to the longitudinal direction X of the probe 20. As shown in FIG. 3C, it has an irregular three-layer structure in the buckling direction Z. That is, in the cross section shown in FIG. 3C, thin plate-like high resistance sections 20H are present on both sides of the medium resistance section 20M in the buckling direction Z, with the medium resistance section 20M sandwiched between them. This section is referred to as the medium-high resistance section 20MH. The medium resistance section 20M is connected to the low resistance section 20L in the longitudinal direction X of the probe 20. Note that the high resistance sections 20H are not provided on both side surfaces of the medium-high resistance section 20MH in the direction Y perpendicular to the buckling direction Z.

[0022] The widths of the two high resistance portions 20H of the medium-high resistance portion 20MH in the Y direction differ between the buckling direction Z+ side and the buckling direction Z- side. The width of the high resistance portion 20H on the buckling direction Z- side is the same as the width of the medium resistance portion 20M in the Y direction, but the width of the high resistance portion 20H on the buckling direction Z+ side is smaller than the width of the medium resistance portion 20M in the Y direction. Therefore, when the medium-high resistance portion 20MH is viewed from the buckling direction Z- side, it appears as if the medium resistance portions 20M are present on both sides in the Y direction, with the high resistance portion 20H sandwiched between them. The high resistance portion 20H of the medium-high resistance portion 20MH is formed flush with the high resistance portion 20H in a recess 20MR formed on the surface of the medium resistance portion 20M on the buckling direction Z+ side so as to be embedded in the longitudinal direction X of the probe 20. Note that a recess 20MR may also be provided on the buckling direction Z- side, with the same configuration as on the buckling direction Z+ side.

[0023] 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, 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, forming layers that constitute the structure on top of it, and then removing only the sacrificial layer by etching.

[0024] Well-known plating techniques can be used to form each layer, including the sacrificial layer. For example, a substrate serving as a cathode and a metal piece serving as an anode are immersed in an electrolyte, and a voltage is applied between the two electrodes to deposit metal ions in the electrolyte onto the substrate surface. 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.

[0025] The mutually adjacent low resistance portion 20L, high resistance portion 20H, and medium resistance portion 20M are laminated by the above-mentioned plating process.

[0026] According to the probe 20 and probe card 100 of embodiment 1, heat generation at the tip of the probe can be suppressed by providing a medium-high resistance section 20MH having a NiB alloy layer below the low-high resistance section 20LH of the probe 20, which has a low resistance section 20L surrounded by a high resistance section 20H.

[0027] Furthermore, in the medium-high resistance section 20MH of the probe 20, by sandwiching the medium resistance section 20M between the high resistance sections 20H in the buckling direction Z, peeling can be prevented from occurring at the plating interface between the low resistance section 20L and the medium resistance section 20M.

[0028] Furthermore, the second metal constituting the high resistance portion 20H of the low-high resistance portion 20LH of the probe 20 and the second metal constituting the high resistance portion 20H of the medium-high resistance portion 20MH are formed in a connected state, so that the rigidity of the probe 20 can be maintained.

[0029] Furthermore, in the medium-high resistance section 20MH of the probe 20, one of the high resistance sections 20H of the medium-high resistance section 20MH is formed flush with the high resistance section 20H so as to be embedded in a recess 20MR formed on the surface of the medium resistance section 20M on the + side of the buckling direction Z, thereby ensuring sufficient strength not only against mechanical strength in the buckling direction Z but also against forces acting in the direction Y perpendicular to the buckling direction Z.

[0030] In the first embodiment, the two high resistance portions 20H of the medium-high resistance portion 20MH have different widths in the Y direction, but they may be the same. In this case, the widths may be the same on the right side of FIG. 3C or on the left side, and the high resistance portions 20H on both sides in the buckling direction Z may be embedded flush with the medium resistance portion 20M.

[0031] Although exemplary embodiments are described in the present disclosure, the various features, aspects, and functions described in the 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 variations not illustrated are anticipated within the scope of the technology of the present disclosure. For example, this includes modifying, adding, or omitting at least one component.

[0032] 100 probe card, 10 frame, 11U upper guide, 11L lower guide, 11M intermediate guide, 11Uh, 11Mh, 11Lh guide holes, 14 wiring board, 14P probe connection pad, 20 probe, 20C contact portion, 20D elastic deformation portion, 20H high resistance portion, 20M medium resistance portion, 20L low resistance portion, 20LH low-high resistance portion, 20MH medium-high resistance portion, 20MR recess, 20T terminal portion, C electrode, W semiconductor wafer, X longitudinal direction, Y direction, Z buckling direction, K boundary.

Claims

1. A probe having a contact portion at one end in the longitudinal direction that contacts the electrode to be inspected, and a terminal portion at the other end in the longitudinal direction that contacts a circuit board, The probe comprises a low-resistance portion made of a first conductive metal, A high-resistance section made of a second metal having conductivity with a resistivity higher than that of the low-resistance section, The device comprises a medium-resistivity section made of a third metal whose resistivity is lower than that of the high-resistivity section and higher than that of the low-resistivity section, The probe has a low-to-high resistance portion in which the low-resistance portion is surrounded by the high-resistance portion in a cross section perpendicular to the longitudinal direction, Displaced on the contact portion side of the low-to-high resistance portion, and having a medium-to-high resistance portion having the medium resistance portion and the high resistance portion in a cross section perpendicular to the longitudinal direction of the probe, In the aforementioned medium-high resistance section, the medium resistance section is connected to the low resistance section in the longitudinal direction of the probe. Furthermore, the probe is such that both sides of the probe in the buckling direction are sandwiched between the high-resistance portion of the low-to-high-resistance portion, which extends continuously from the high-resistance portion.

2. The probe according to claim 1, wherein the high-resistance portion of the medium-to-high-resistance portion is embedded in the medium-resistance portion in the longitudinal direction of the probe when viewed in the buckling direction.

3. The probe according to claim 2, wherein the high-resistance portion of the medium-to-high-resistance portion is formed in a recess formed on at least one side surface of the medium-resistance portion in the buckling direction.

4. The probe according to any one of claims 1 to 3, wherein the first metal is gold, silver, or copper, the second metal is a PdCo alloy, and the third metal is a NiB alloy.

5. A plurality of probes according to claim 4, It comprises at least two guides, each having multiple guide holes for inserting and guiding the respective probe, The medium-to-high resistance section is a probe card inserted into the guide hole of the guide, which is located closest to the contact section.