JP5386127B2 - Contact probe and manufacturing method thereof - Google Patents

Description

The present invention relates to a contact probe and a method for manufacturing the same, and more particularly, a contact probe that performs electrical property testing of an inspection object by contacting and making contact with a fine electrode pad on the inspection object such as a semiconductor wafer. Regarding improvements.

  In general, in the manufacturing process of a semiconductor device, an electrical characteristic test is performed on an electronic circuit formed on a semiconductor wafer. Such an electrical characteristic test for an inspection object is performed using a contact probe that is brought into contact with an electrode pad on the inspection object to conduct. The contact probe includes, for example, a beam portion having a cantilever structure, and a contact portion for contacting an inspection object is formed on the beam portion. Since the contact portion needs to be repeatedly contacted with the inspection object, the contact portion is formed of a metal having high wear resistance, for example, a hard metal such as rhodium (Rh). In general, the contact portion is formed by laminating two types of metal layers in consideration of contactability, conductivity, cost, ease of manufacture, and the like. For example, a first metal layer made of a metal such as nickel (Ni) and a second metal layer made of a metal such as rhodium are stacked. Usually, these metal layers constituting the contact portion are formed by electroplating.

  FIGS. 7A and 7B are cross-sectional views showing a conventional contact probe. FIG. 7A shows a state in which a contact portion is formed in a region on a beam portion surrounded by a resist. FIG. 7B shows the contact portion after the resist is removed. In this contact probe, a contact portion is formed at the tip of a beam portion made of an alloy layer of nickel and cobalt. The contact portion is formed by removing a part of the photoresist applied on the beam portion and laminating a metal layer on the region where the resist is removed by electroplating. Specifically, first, a nickel layer is formed on the beam portion using an electrolytic solution containing nickel ions as a plating solution. Next, a rhodium layer is formed on the nickel layer using an electrolytic solution containing rhodium ions as a plating solution. Therefore, when the rhodium layer is formed, the surface of the rhodium layer and the surrounding resist are covered with a rhodium plating solution.

  In general, the rhodium plating solution penetrates the resist before it is removed from the surface of the rhodium layer, or enters between the resist and the rhodium layer and reaches the vicinity of the interface between the rhodium layer and the nickel layer. Since rhodium and nickel have greatly different standard electrode potentials, if a plating solution exists near the interface between the rhodium layer and the nickel layer, a local battery is formed through the plating solution, and nickel with a small standard electrode potential is used as the plating solution. In some cases, the strength of the contact portion may decrease.

  The present invention has been made in view of the above circumstances, and an object thereof is to suppress a decrease in strength of a contact probe having a contact portion in which a second metal layer is laminated on a first metal layer. In particular, it is an object of the present invention to provide a contact probe, a probe card, and a method for manufacturing a contact probe that can suppress a decrease in strength of a contact portion in which two types of metal layers having greatly different standard electrode potentials are stacked.

A contact probe according to a first aspect of the present invention is a contact probe having a contact portion in which a second metal layer is laminated on a first metal layer, and a standard electrode between the first metal layer and the second metal layer. A conductive intermediate metal layer having a higher potential than the first metal layer and lower than the second metal layer is provided , the first metal layer is mainly composed of nickel, and the second metal layer is mainly composed of rhodium. It is comprised so that . According to such a configuration, the intermediate metal layer having the standard electrode potential between these metal layers is provided between the first metal layer and the second metal layer. In addition, the difference in the standard electrode potential between the metal layers can be reduced as compared with the case where the second metal layer is directly formed. Thereby, compared with the conventional thing which forms a 2nd metal layer on a 1st metal layer, it can suppress that a metal elutes by the local cell effect | action in the interface vicinity between metal layers.

Moreover , since the 2nd metal layer contacted with a test object is formed with a metal harder than a 1st metal layer, the abrasion resistance of a contact part can be improved.

The contact probe according to the second aspect of the present invention is configured such that, in addition to the above configuration, the second metal layer is thinner than the first metal layer.

In a contact probe according to a third aspect of the present invention, in addition to the above configuration, the intermediate metal layer is composed of a metal layer mainly composed of two kinds of metals having different standard electrode potentials. The metal layer having a high standard electrode potential is monotonously increased toward the metal layer side. According to such a configuration, a gradient can be given to the mixing ratio between two types of metals having different standard electrode potentials in the intermediate metal layer formed between the first metal layer and the second metal layer. Therefore, the difference in the standard electrode potential between the metal layers can be reduced as compared with the case where the mixing ratio is constant. Therefore, it can suppress effectively that a metal elutes by the local battery action in the interface vicinity between metal layers.

The contact probe according to the fourth aspect of the present invention is configured such that, in addition to the above- described configuration, the intermediate metal layer is composed mainly of palladium and nickel or cobalt.

A contact probe manufacturing method according to a fifth aspect of the present invention is a method of manufacturing a contact probe having a beam portion and a contact portion, wherein the first metal layer is formed on the beam portion by electroplating. A second step of forming an intermediate metal layer having a higher standard electrode potential on the first metal layer than the first metal layer by electroplating; and a standard electrode potential on the intermediate metal layer of the intermediate metal layer. have a third step of forming by electroplating the second metal layer is higher than the first metal layer is composed mainly of nickel, configured as the second metal layer is composed mainly of rhodium Is done.

In the contact probe manufacturing method according to the sixth aspect of the present invention, in addition to the above configuration, the second step includes a step of forming a metal layer mainly composed of two kinds of metals having different standard electrode potentials as the intermediate metal layer. In this case, the intermediate metal layer is formed while the current density during electroplating is monotonously increased. According to such a configuration, since the intermediate metal layer is formed while the current density is monotonously increased, 2 different standard electrode potentials are present in the intermediate metal layer from the first metal layer side to the second metal layer side. It is possible to provide a gradient in the mixing ratio between kinds of metals.

  According to the contact probe, probe card, and contact probe manufacturing method of the present invention, an intermediate metal layer having a standard electrode potential between these metal layers is provided between the first metal layer and the second metal layer. Since it is provided, the difference in the standard electrode potential between the metal layers can be reduced as compared with the case where the second metal layer is formed directly on the first metal layer. Therefore, it is possible to suppress the metal from eluting due to the local cell action near the interface between the metal layers as compared with the conventional one in which the second metal layer is directly formed on the first metal layer. It is possible to suppress a decrease in strength of the contact portion in which two types of metal layers having greatly different electrode potentials are stacked.

Embodiment 1 FIG.
<Probe card>
FIGS. 1A and 1B are views showing an example of a probe card 10 according to Embodiment 1 of the present invention, and FIG. 1A is a plan view seen from the inspection object side. (B) in a figure is a side view. The probe card 10 includes a main board 14 attached to a probe device (not shown), a probe board 12 held by the main board 14, and a plurality of contact probes 11 fixed on the probe board 12. Each contact probe 11 is provided on one main surface of the probe substrate 12.

  In this probe card 10, contact probes 11 are arranged on a straight line at a predetermined pitch, and two rows of such contact probes 11 are formed with their beam tips facing each other. Usually, the probe card 10 is held horizontally and is arranged with the main surface of the probe substrate 12 on which the contact probe 11 is formed facing downward in the vertical direction.

  When performing an electrical property test on the inspection object, the alignment of the inspection object and the probe card 10, that is, the main for the inspection object, so that each contact probe 11 faces the electrode pad on the inspection object. The substrate 14 is aligned. With the inspection object and the probe card 10 properly aligned, the tip of the contact probe 11 is brought into contact with the electrode pad 1 on the inspection object by bringing the probe substrate 12 and the inspection object closer to each other. Can do.

  The main board 14 is a circular printed board that can be attached to and detached from the probe device, and has an external terminal 13 for performing signal input / output with the tester device. The peripheral portion of the main board 14 is held by the probe device and supported so as to be horizontal. For example, a multilayer printed circuit board mainly composed of glass epoxy is used as the main board 14.

  The probe substrate 12 is a wiring substrate formed of silicon or the like, and is wired to the main substrate 14 via the connecting member 16. The connecting member 16 connects the main board 14 and the probe board 12 and electrically connects the main board 14 and the probe board 12 as conductive wires. Here, a flexible printed circuit board (FPC) in which a wiring pattern is printed on a flexible film is used as the connecting member 16. One end of the flexible substrate is fixed to the peripheral edge of the probe substrate 12, and the other end is connected to the main substrate 14 via a detachable connector 15.

  The contact probe 11 is a probe (probe) that is elastically brought into contact with a fine electrode pad formed on an object to be inspected. A large number of contact probes 11 are arranged and arranged on the probe substrate 12. Yes. Each contact probe 11 is electrically connected to the external terminal 13 via each wiring of the probe substrate 12, and by bringing the contact probe 11 into contact with each other, a minute electrode pad can be electrically connected to the tester device.

<Contact probe>
FIG. 2 is a side view showing a configuration example of the contact probe 11 in the probe card 10 of FIG. The contact probe 11 includes a beam portion 1 having a cantilever structure and a contact portion 3 for contacting an electrode pad on an inspection object.

  The beam portion 1 is formed of a structure having the extending direction in the left-right direction in FIG. The contact portion 3 is formed on the tip portion of such a beam portion 1 and is composed of a structure projecting from the surface of the beam portion 1 that faces the inspection object.

<Contact part>
FIG. 3 is a diagram showing a configuration example of a main part of the contact probe 11 of FIG. 2, and shows the contact part 3 formed on the beam part 1. The contact portion 3 is configured by providing an intermediate metal layer 32 between a first metal layer 31 formed on the beam portion 1 and a second metal layer 33 for contacting the object to be inspected. Yes. These metal layers 31 to 33 are all laminated by electroplating.

  In this example, the beam portion 1 is formed of an elongated flat plate-like structure, and the contact portion 3 is formed on the main surface facing the inspection object. Further, the contact portion 3 is an elongated columnar body whose end face shape is substantially circular. The beam portion 1 is made of, for example, a conductive metal layer mainly composed of nickel and cobalt (Co), that is, a nickel-cobalt alloy layer.

  The first metal layer 31 is made of, for example, a plating layer (nickel plating layer) containing nickel as a main component. The second metal layer 33 is harder and higher in wear resistance than the first metal layer 31 and has a high corrosion resistance. For example, a plating layer (rhodium plating) mainly composed of rhodium. Layer).

  The intermediate metal layer 32 is made of a conductive plating layer having a standard electrode potential higher than that of the first metal layer 31 and lower than that of the second metal layer 33. Here, the standard electrode potential, also called standard potential or standard reduction potential, is a standard of a battery made by combining a standard hydrogen electrode and a measurement target electrode with the standard hydrogen electrode potential as a reference (0 volts). It is the electromotive force in the state.

  The standard electrode potential of nickel is −0.257V, and the standard electrode potential of rhodium is + 0.799V. Therefore, the intermediate metal layer 32 is formed as a plating layer whose main component is a metal having a standard electrode potential higher than −0.257V and less than 0.799V. For example, the intermediate metal layer 32 is formed as a metal layer mainly composed of palladium (Pd) and nickel, that is, a palladium-nickel alloy layer. Alternatively, the intermediate metal layer 32 may be formed as a metal layer mainly composed of palladium and cobalt, that is, a palladium-cobalt alloy layer.

  That is, the intermediate metal layer 32 is formed of a plating layer mainly composed of two kinds of simple metals having different standard electrode potentials. The standard electrode potential of palladium is + 0.915V. Here, the mixing ratio between single metals in the intermediate metal layer 32 is uniform in the thickness direction of the intermediate metal layer 32, that is, constant from the first metal layer 31 side to the second metal layer 33 side. And

  Further, the difference in standard electrode potential between the nickel-cobalt alloy constituting the beam portion 1 and the nickel constituting the first metal layer 31 is the difference between the nickel of the first metal layer 31 and the second metal layer. This is sufficiently smaller than the difference in standard electrode potential (1.056 V) with rhodium constituting 33.

  Here, by making the thickness of the second metal layer 33 thinner than that of the first metal layer 31, the ratio of the rhodium plating layer in the contact portion 3 is made smaller than that of the nickel plating layer. Thereby, the contact property and electrical conductivity of the contact part 3 can be improved.

  Specifically, the thickness of the beam portion 1 is 27 μm, the thickness of the first metal layer 31 is about 30 μm, the thickness of the intermediate metal layer 32 is 3 μm, and the second The thickness of the metal layer 33 is 15 μm. That is, the intermediate metal layer 32 is the thinnest and the first metal layer 31 is the thickest.

  According to the experiments by the applicants of the present application, the first metal layer 31 and the second metal layer 33 are provided with a palladium-nickel alloy layer or by providing a palladium-cobalt alloy layer. It was confirmed that the elution amount of nickel constituting the metal layer 31 was reduced. That is, it was found that the metal elution amount due to the local cell action near the interface between the metal layers is lower than in the conventional case where the second metal layer 33 is formed on the first metal layer 31. According to the present embodiment, the elution of the metal from the first metal layer 31 can be suppressed in this way, so that the strength reduction of the contact portion 3 can be suppressed.

<Contact probe formation process>
4 and 5 are cross-sectional views schematically showing the process of forming the contact probe 11 of FIG. FIG. 4A shows a conductive substrate 40 serving as a pedestal for forming the contact probe 11. As such a substrate 40, for example, a copper plate is used.

  FIG. 4B shows a state in which a sacrificial layer 41 is formed on the substrate 40 of FIG. 4A, and then a part of the sacrificial layer 41 is removed. As the sacrificial layer 41 laminated on the substrate 40, for example, a conductive layer such as copper is formed by electroplating. After the sacrificial layer 41 is formed on the substrate 40, a part of the sacrificial layer 41 is removed by etching or the like in order to form the fixed end 2 of the beam portion 1 through a masking process such as photolithography (photoengraving). The

  FIG. 4C shows a state in which the conductive layer 42 is formed on the substrate 40 in FIG. 4B, and then the surfaces of the conductive layer 42 and the sacrificial layer 41 are polished. As the conductive layer 42 laminated on the substrate 40 after removing a part of the sacrificial layer 41, a nickel-cobalt alloy layer is formed by electroplating. The excess conductive layer 42 is removed by polishing the surface.

  FIG. 4D shows a state in which a sacrificial layer 43 is formed on the substrate 40 in FIG. 4C, and then a part of the sacrificial layer 43 is removed. As the sacrificial layer 43 stacked on the sacrificial layer 41 and the conductive layer 42, the same conductive layer as the sacrificial layer 41 is formed by electroplating. After the sacrificial layer 43 is formed, a part of the sacrificial layer 43 is removed to form the beam portion 1 through a masking process.

  FIG. 4E shows a state in which the conductive layer 44 is formed on the substrate 40 in FIG. 4D, and then the surfaces of the conductive layer 44 and the sacrificial layer 43 are polished. As the conductive layer 44 to be laminated after removing a part of the sacrificial layer 43, a layer made of the same metal as the conductive layer 42 is formed by electroplating. The excess conductive layer 44 is removed by polishing the surface to form a beam portion of the beam portion 1 joined to the fixed end 2.

  FIG. 5A shows a state in which a resist layer 45 is formed on the substrate 40 in FIG. 4E, and then a part of the resist layer 45 is removed. The resist layer 45 laminated on the sacrificial layer 43 and the conductive layer 44 is formed by applying a photoresist. After forming the resist layer 45, a part of the resist layer 45 is removed in order to form the contact part 3 through a masking process.

  FIG. 5B shows a state in which the first metal layer 46 is formed on the substrate 40 of FIG. After removing a part of the resist layer 45, a nickel plating layer is formed by electroplating as the first metal layer 46 laminated in the region on the conductive layer 44 from which the resist has been removed. This electroplating process is performed using an electrolytic solution containing nickel ions, for example, a nickel sulfate solution as a plating solution.

  FIG. 5C shows a state in which the intermediate metal layer 47 is formed on the substrate 40 in FIG. As an intermediate metal layer 47 laminated on the first metal layer 46, a palladium-nickel alloy layer is formed by electroplating. This electroplating process is performed using an electrolytic solution containing palladium and nickel ions as a plating solution. This plating solution contains palladium and nickel in a weight ratio of 7: 3 in consideration of the property that nickel is more likely to precipitate than palladium.

  FIG. 5D shows a state in which the second metal layer 48 is formed on the substrate 40 in FIG. As the second metal layer 48 laminated on the intermediate metal layer 47, a rhodium plating layer is formed by electroplating. This electroplating process is performed using an electrolytic solution containing rhodium ions as a plating solution. After the formation of the second metal layer 48, the surface of the second metal layer 48 is polished, and the resist layer 45 and the sacrificial layers 41 and 43 are removed, whereby the contact probe 11 is completed.

  A step of polishing the surface of the metal layer is provided when the intermediate metal layer 47 is formed on the first metal layer 46 and when the second metal layer 48 is formed on the intermediate metal layer 47. May be.

  According to the present embodiment, since the intermediate metal layer 32 having the standard electrode potential between these metal layers is provided between the first metal layer 31 and the second metal layer 33, Compared with the case where the second metal layer 33 is formed on the metal layer 31, the difference in the standard electrode potential between the metal layers can be reduced. Thereby, compared with the conventional thing which forms the 2nd metal layer 33 on the 1st metal layer 31, it can suppress that a metal elutes by the local cell action of the interface vicinity of metal layers.

Embodiment 2. FIG.
In the first embodiment, an example in which the mixing ratio between single metals constituting the intermediate metal layer 32 is uniform in the thickness direction of the intermediate metal layer 32 has been described. On the other hand, in the present embodiment, in the intermediate metal layer 32, the ratio of the single metal having a high standard electrode potential monotonously increases from the first metal layer 31 side to the second metal layer 33 side. A case where a gradient is given to the mixing ratio between single metals will be described.

  FIG. 6 is a diagram showing a configuration example of the contact probe according to the second embodiment of the present invention. The change in current density when the intermediate metal layer 32 is formed on the first metal layer 31 by electroplating. The appearance and the change of the mixing ratio of palladium are shown. In the present embodiment, when the intermediate metal layer 32 is stacked on the first metal layer 31, the first metal layer has a high standard electrode potential, i.e., the proportion of palladium increases monotonously. From the 31 side to the second metal layer 32 side, the mixing ratio between single metals is provided with a gradient.

Specifically, with respect to the current density a ₁ at the start of plating (time t ₁ ), the current density is monotonously increased with the passage of time, so that the mixture ratio of palladium to nickel is increased at the start of plating (mixing). The ratio b ₁ %) is monotonously increased. That is, the intermediate metal layer 32 is formed while monotonously increasing the current density during electroplating so that the proportion of palladium having a high standard electrode potential monotonously increases.

  Generally, during electroplating, the voltage applied between the metal layer and the plating solution is controlled to adjust the current density, thereby changing the mixing ratio of the metal to be plated. In particular, when the current density is increased, the proportion of the metal having a high standard electrode potential can be increased.

In this example, assuming that the current density at the end of plating (time t ₂ ) is a ₂ , the current density is represented by a straight line with a constant upward slope, whereas the palladium mixing ratio is the mixing ratio at the end of plating. It is represented by a straight line with a constant upward slope of b ₂ %. In the intermediate metal layer 32 formed by such an electroplating process, the end portion on the first metal layer 31 side is in a high nickel mixing ratio (nickel rich) state, and the end portion on the second metal layer 33 side is , The mixture ratio of palladium becomes high (palladium rich).

  According to the present embodiment, the current density is monotonously increased so that the ratio of the single metal having a high standard electrode potential monotonously increases from the first metal layer 31 side to the second metal layer 33 side. However, since the intermediate metal layer 32 is formed, the mixing ratio between the single metals in the intermediate metal layer 32 can be given a gradient. As a result, since the mixing ratio between the single metals in the intermediate metal layer 32 formed between the first metal layer 31 and the second metal layer 33 is given a gradient, the mixing ratio has a gradient. The difference in standard electrode potential between the metal layers can be reduced as compared with the case where it is not.

  In the first and second embodiments, the example in which the intermediate metal layer 32 is formed of one type of metal layer and formed by one electroplating process has been described. It is not limited. For example, the intermediate metal layer 32 may be formed by laminating two or more kinds of metal layers, or may be formed through two or more electroplating processes.

It is the figure which showed an example of the probe card 10 by Embodiment 1 of this invention. It is the side view which showed the structural example of the contact probe 11 in the probe card 10 of FIG. FIG. 3 is a diagram illustrating a configuration example of a main part of the contact probe 11 in FIG. 2, in which a contact portion 3 formed on the beam portion 1 is illustrated. FIG. 4 is a cross-sectional view schematically showing a process of forming the contact probe 11 of FIG. 2, showing a process until a beam portion of the beam portion 1 is formed on a substrate 40. FIG. 3 is a cross-sectional view schematically showing a process of forming the contact probe 11 of FIG. 2 and shows a process until a second metal layer 48 is formed after the beam portion is formed. It is the figure which showed one structural example of the contact probe by Embodiment 2 of this invention, and the current density at the time of forming the intermediate metal layer 32 and the mixing ratio of palladium are shown. It is sectional drawing which showed the conventional contact probe.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Beam part 2 Fixed end 3 Contact part 10 Probe card 11 Contact probe 12 Probe board 13 External terminal 14 Main board 15 Connector 16 Connection member 31 1st metal layer 32 Intermediate metal layer 33 2nd metal layer

Claims (6)

In a contact probe having a contact portion in which a second metal layer is laminated on a first metal layer,
A conductive intermediate metal layer having a standard electrode potential higher than that of the first metal layer and lower than that of the second metal layer is provided between the first metal layer and the second metal layer ;
A contact probe characterized in that the first metal layer contains nickel as a main component and the second metal layer contains rhodium as a main component .   The contact probe according to claim 1, wherein the second metal layer is thinner than the first metal layer.   The intermediate metal layer is composed of a metal layer mainly composed of two kinds of metals having different standard electrode potentials, and a ratio of a metal having a high standard electrode potential from the first metal layer side to the second metal layer side is The contact probe according to claim 1, wherein the contact probe increases monotonously. The contact probe according to claim 1, wherein the intermediate metal layer contains palladium and nickel or cobalt as main components. In a method of manufacturing a contact probe having a beam portion and a contact portion,
Forming a first metal layer on the beam portion by electroplating;
A second step of forming, by electroplating, an intermediate metal layer having a standard electrode potential higher than that of the first metal layer on the first metal layer;
The standard electrode potential intermediate metal layer is perforated and a third step of forming by electroplating the second metal layer is higher than the intermediate metal layer,
A method of manufacturing a contact probe, wherein the first metal layer contains nickel as a main component and the second metal layer contains rhodium as a main component . The second step is a step of forming, as the intermediate metal layer, a metal layer mainly composed of two kinds of metals having different standard electrode potentials, while increasing the current density during electroplating monotonously. The method of manufacturing a contact probe according to claim 5 , wherein the method is a step of forming an intermediate metal layer.

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