JP2001356135A - Probe head and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a probe head capable of surely showing the deflecting direction of a plurality of probe pins. SOLUTION: This probe head 10 comprises a substrate 12 having a wiring 11 for transmitting an electric signal to an object to be inspected and a plurality of metallic probe pins 13 connected to the wiring 11 and protruded from the substrate 12. Each probe pin 13 is inclined in the same direction to the direction vertical to the essential surface 12a of the substrate 12. The inclination is 1-10 deg.. The section parallel to the substrate essential surface 12a of each probe pin 13 is anisotropic, for example, rectangular or elliptic. All the probe pins 13 are deflected in the same direction in the inspection due to such inclination and sectional shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a probe head which is a jig used for performing an electrical test of an electronic device such as a semiconductor wafer chip, an IC, an LSI, a liquid crystal display device, and a method of manufacturing the same. The present invention relates to a jig called a contact probe or a probe card and a manufacturing method thereof.

[0002]

2. Description of the Related Art A probe card or a contact probe attached to a prober is used in accordance with miniaturization, high integration or diversification of an electronic device to be inspected.
Various things have been developed. For example, Japanese Unexamined Patent Publication
No. 123174 discloses a probe card in which a probe electrode for contacting an electrode of an integrated circuit is formed of silicon whiskers subjected to a conductive treatment. In this conventional technique, an attempt is made to increase the aspect ratio of a probe electrode by using whiskers, and to produce a bump having a height sufficient to absorb variations in height even at a fine pitch. Typically, such silicon whiskers are VLS
(Vapor-Liquid-Solid) growth method.

[0003] When a probe pin (inspection electrode) having a relatively high aspect ratio as described above is brought into contact with an electrode of an inspection object, the probe pin bends considerably. In the prior art, the probe pins stand perpendicular to the probe card substrate, and since the cross section of the probe pins is generally circular, the direction in which the plurality of probe pins bend at the time of contact differs for each probe pin. Probability is high. Therefore, if each probe pin bends greatly at the time of contact, adjacent probe pins may come into contact with each other. In order to avoid such a situation, it is necessary to increase the arrangement pitch of the probe pins, and it becomes difficult to obtain a probe card in which the probe pins are arranged at a high density in a two-dimensional pin arrangement.

A probe pin made of a conductive silicon whisker has a relatively small effective cross-sectional area of a conductor, and therefore can have a relatively high electric resistance.

[0005] Stroke (deflection) required for contact
In order to obtain the above, it is necessary to lengthen the probe pin to some extent, and the inductance becomes large. In such a case, the high frequency characteristics deteriorate. Further, it is difficult to form a coaxial structure that can obtain good high-frequency characteristics in the related art.

[0006]

SUMMARY OF THE INVENTION One object of the present invention is to provide a probe head in which the direction of deflection of a probe pin can be reliably determined.

Another object of the present invention is to provide a probe head structure which can increase the arrangement density of probe pins.

It is a further object of the present invention to provide a probe head with low contact resistance.

It is a further object of the present invention to provide a probe head that can have good high frequency characteristics.

[0010]

According to the present invention, there is provided a probe head comprising a substrate having a wiring for transmitting an electric signal to an inspection object, and a plurality of metal probe pins connected to the wiring and projecting from the substrate. Prepare. In the present invention, the plurality of probe pins are inclined in the same direction with respect to a direction perpendicular to the main surface of the substrate, and the cross section of each probe pin parallel to the main surface of the substrate is anisotropic. . The length L ₁ of the cross section is the length L ₂ of the cross section (here, L ₁
Is the length of the cross section in the direction of displacement of the probe pin with respect to the direction perpendicular to the main surface of the substrate, and L ₂ is the length of the cross section in the direction perpendicular to the direction of displacement.

In the present invention, the inclination angle of each probe pin with respect to a direction perpendicular to the main surface of the substrate is 1 ° to 10 °.
In the range. In the present invention, the cross section of the probe pin is preferably rectangular or elliptical. In this case, L ₁ is a rectangular or elliptical short side or minor axis, and L ₂ is a rectangular or elliptical long side or major axis.

In the present invention, the substrate preferably further has a ground line. The probe head according to the present invention
It is preferable to further include a ground sheath made of a conductive material surrounding the probe pin and connected to the ground line. Further, in the present invention, it is preferable that the tip portion of each probe pin is covered with a material having higher conductivity than the body portion.

A method of manufacturing a probe head according to the present invention includes a step of forming a plurality of probe pins on a substrate having wirings by using lithography and plating. In this manufacturing method, lithography uses light emitted from a direction inclined with respect to a direction perpendicular to the main surface of the substrate.

[0014]

FIG. 1 shows a specific example of a probe head according to the present invention. Typically, the probe head is a jig called a contact probe or a probe card. Referring to FIG. 1, a probe head 10 includes a substrate 12 having a wiring 11 for transmitting an electric signal to an inspection object,
And a plurality of metal probe pins 1 extending from substrate 12
3 The probe pins 13 are, for example, Ni, C
It is made of a highly conductive metal such as u, Ni alloy, Rh alloy, Cu alloy, Au alloy or the like, but is not limited thereto. Each probe pin 13 is connected to the wiring 11.
As the substrate 12, a ceramic substrate or a silicon substrate on which circuits are integrated with high density by multilayer wiring is preferably used. The ceramic substrate can support a high frequency of, for example, 1 GHz or more.

All the probe pins 13 extending from the substrate 12 are inclined in the same direction with respect to a direction perpendicular to the main surface 12a of the substrate. Typically, the tilt angle θ is 1 ° to 10 °
Range. As shown in an enlarged manner in FIGS. 2A and 2B, a cross section of each probe pin 13 (substrate main surface 12a
Is anisotropic (rather than square or circular), for example, rectangular (FIG. 2 (a)) or elliptical (FIG. 2 (b)). That is, as shown in FIG. 3, the length of the cross section in the direction (shown by the arrow) of the displacement of the probe pin 13 with respect to the direction perpendicular to the main surface 12a of the substrate is L ₁ , and the length of the cross section in the direction perpendicular to the direction of the displacement the When L _2, L ₁ is significantly shorter than L _2. FIG.
In the cases (a) and (b), L ₁ is the shorter side of the rectangle or the shorter diameter of the ellipse, and L ₂ is the longer side of the rectangle or the longer diameter of the ellipse. Such a cross-sectional shape controls the direction of deflection of the probe pin. For example, as shown in FIGS. 2 (a) and 2 (b), when the cross section of the probe pin is rectangular or elliptical, the probe pin easily bends in the direction of its short side or short diameter, while bending in other directions. Hateful.
Relates the probe pins, the ratio of L ₂ for _{L 1 (L 2 / L 1} )
(Aspect ratio) is, for example, 1.5 to 10.
The height (h) of each probe pin 13 is 10 μm to 500 μm.
μm, preferably 50 μm to 200 μm
m. The plurality of probe pins are, for example, 5 μm to
Can be provided at intervals of 50 μm, up to 6000
It can be provided with a density of mm ² .

At the time of inspection, the probe head 10 shown in FIG.
Is brought closer to the inspection object 40 as shown in FIG. The inspection object 40 is, for example, a silicon wafer on which an IC circuit is patterned. Probe head 10
The probe pins 13 are arranged at an appropriate pitch and pattern so as to be able to contact each electrode (pad) 41 of the inspection object 40. As shown in FIG. 4B, all the probe pins 13 bend in the same direction when they come into contact with the electrodes 41. This is because the probe pins 13 are
2a is inclined with respect to the direction perpendicular to the direction (the direction in which the probe head is brought closer to the inspection object), and as described above, the cross section of the probe pin 13 is anisotropic and easily bends in the inclined direction. Because it is. As described above, since the probe pin of the present invention bends in a fixed direction, contact between the probe pins due to variations in the bending direction as in the related art is avoided. By controlling the deflection direction at the time of contact in this way, even when the probe pins are arranged at a narrow pitch of 10 μm or less, contact between adjacent probe pins at the time of contact can be avoided. Further, the probe pin of the present invention can bend in a predetermined direction and apply an appropriate contact pressure. Further, the probe pin of the present invention is made of metal, and can provide higher conductivity than a conventional conductive whisker.

The probe head according to the present invention can be typically manufactured by the following process. First, as shown in FIG. 5A, light (X-rays or U-rays) is applied to a resist 52 applied on a substrate 51 through a mask 53.
V light). The substrate 51 is, for example, a ceramic substrate or a silicon substrate on which circuits are integrated with high density by multilayer wiring. As shown in FIG. 5A, the substrate 51 is arranged at an angle so that the irradiation light enters the resist 52 obliquely. This inclination angle is an appropriate angle in the range of, for example, 1 ° to 10 °. In the mask 53, a portion 5 that blocks light.
The shape of 3a is anisotropic, for example, a rectangle or an ellipse. Here, the ratio of the long side / short side or the long diameter / short diameter is, for example, 2 or more, and can be 2 to 10. This shape determines the cross-sectional shape of the probe pin to be formed. Next, development is performed to obtain a resist pattern 54 as shown in FIG. Resist pattern 54
Is, for example, 1 ° to 10 ° with respect to a direction perpendicular to the substrate surface.
It has a plurality of inclined holes 54a. The cross section of the hole 55 is, for example, rectangular or oval. For example, the height of the hole 54a is 100 μm, its long side or major axis is 10 μm, its short side or minor axis is 5 μm, and a plurality of holes are arranged at a pitch of 15 μm. However, these sizes and pitches are not limited to these, and can be various. Hole 54
The position a corresponds to the position of the electrode of the inspection object. The above process can be performed by a general lithography method. Deep lithography using synchrotron radiation may be performed by the LIGA method. According to lithography using X-rays, the cross-sectional shape of the hole can be controlled with high accuracy, which is advantageous.

Next, as shown in FIG. 5C, a metal 55 is deposited on the substrate 51 along the resist pattern 54 by plating. The metal 55 is deposited in the holes 54a and takes the required shape. In order to promote plating, a conductive layer may be provided in advance on the wiring layer of the substrate 51 by sputtering. Plating proceeds through such a conductive layer. The conductive layer is made of, for example, Ti, but is not limited thereto. Here, the plating metal is, for example, Ni, Ni-Co, Ni-W, or Cu, but is not limited thereto. In this way, a metal pillar serving as a probe pin is formed by plating. After completion of the plating, if the resist pattern is removed as shown in FIG. 5D, a probe head 60 in which the probe pins 63 extend from the substrate 51 is obtained.
When a conductive layer is formed on the substrate surface, it is preferable to remove an unnecessary conductive layer with an acid. Also, after the above plating,
Further, another plating may be performed, and a metal having higher conductivity and good electrical contact, such as Au or Rh, may be attached to the tip of the metal pillar. Thereafter, if the resist is removed, a probe head is obtained. In this case, the electric resistance of the probe pin can be further reduced.

FIG. 6 shows another embodiment of the probe head according to the present invention. In the probe head 70, the substrate 7
2 has a ground line 71b in addition to the signal line 71a connected to the probe pin 73. On the substrate 72, these wirings have a multilayer structure and are three-dimensionally arranged. Further, a metal sheath 77 extends from the substrate 72 so as to surround the probe pin 73, and the sheath 77 is connected to a ground wire 71b. The sheath 77 is shorter than the probe pin 73, and the tip of the probe pin 73 protrudes from the sheath 77 by a length necessary for contact. The sheath 77 may be made of the same material as the probe pin or a different material. The sheath 77 is, for example,
It is made of a highly conductive metal such as Ni, Cu, Ni alloy, Rh alloy, Cu alloy, and Au alloy, but is not limited thereto. Probe pin 73 surrounded by sheath 77
Is, for example, as shown in an enlarged manner in FIGS. 7A and 7B. In the structure shown in FIG.
A probe pin 73a having a rectangular cross section is surrounded by a rectangular parallelepiped hollow sheath 77a. In the structure shown in FIG.
A probe pin 73b having an elliptical cross section is surrounded by a sheath 77b shaped like a cylindrical tube. In any case, the probe pin and the sheath have a coaxial structure. With such a coaxial structure, the probe head 70 can have good high-frequency characteristics, and can cope with a measurement at a high frequency exceeding 1 GHz.

Such a probe head can also be manufactured by using lithography and plating, as described above. For example, as shown in FIG. 8A, first, a resist pattern 84 is formed on a substrate 82 by oblique lithography. Next, as shown in FIG.
Power is supplied from the signal line 81a and the ground line 81b to grow the plating metal. Next, as shown in FIG. 8C, power is supplied only from the signal line 81a, and the probe pins 83 are further extended. Then, if the resist pattern 84 is removed, a probe head is obtained.

[0021]

As described above, according to the present invention, it is possible to provide a probe head in which a plurality of probe pins all bend in the same direction at the time of contact. Such probe pins can be provided with a high placement density. Further, according to the present invention, a probe head having lower contact resistance can be provided. The probe head of the present invention having a coaxial structure can have good high-frequency characteristics. Further, according to the manufacturing method of the present invention, a probe pin with a narrow pitch can be formed with high accuracy, particularly by using X-ray lithography. The cross-sectional dimension of a probe pin greatly affects its spring characteristics (the repulsive force of the spring is proportional to the short side of the cross-section or the cube of the short diameter). According to lithography, control can be performed with high accuracy.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a specific example of a probe head according to the present invention.

FIGS. 2A and 2B are perspective views showing a specific example of the shape of the probe pin shown in FIG.

FIG. 3 is a schematic cross-sectional view for explaining the shape of the probe pin shown in FIG.

FIGS. 4A and 4B are schematic cross-sectional views showing a state where the probe head shown in FIG. 1 is brought into contact with an electrode of an inspection object.

FIGS. 5A to 5D are schematic cross-sectional views showing a method for manufacturing the probe head shown in FIG.

FIG. 6 is a schematic sectional view showing another specific example of the probe head according to the present invention.

FIGS. 7A and 7B are diagrams showing a specific example of a cross-sectional structure of a probe pin and a sheath shown in FIG. 6;

8A to 8C are schematic cross-sectional views illustrating another method for manufacturing a probe head according to the present invention.

[Explanation of symbols]

10, 70 probe head, 11 wiring, 12, 72
Board, 13, 73 probe pin, 71a signal line, 7
1b Ground wire.

Continued on the front page F term (reference) 2G011 AA10 AA16 AB06 AB09 AC14 AC32 AE03 AF07 4M106 AA02 AA04 BA01 CA01 DD06 DD10 DD15 DD30

Claims (7)

[Claims] 1. A substrate having a wiring for transmitting an electric signal to an inspection target, and a plurality of metal probe pins connected to the wiring and protruding from the substrate, wherein the plurality of probe pins are: with respect to the direction perpendicular to the major surface of the substrate is inclined in the same direction, cross section parallel to the major surface of the substrate of each probe pin is anisotropic, the length L ₁ of the cross section The length L _{2 of the} cross section (where L ₁
Is the length of the cross section in the direction of displacement of the probe pins with respect to a direction perpendicular to the main surface of the substrate, and L ₂
Is the length of the cross section in a direction perpendicular to the shift direction). 2. The probe head according to claim 1, wherein an inclination angle of each probe pin with respect to a direction perpendicular to a main surface of the substrate is in a range of 1 ° to 10 °. 3. The cross section of the probe pin is rectangular or elliptical, L ₁ is the shorter side or minor diameter of the rectangle or elliptical, and L ₂ is the rectangular or elliptical. 3. The probe head according to claim 1, which has a long side or a long diameter. 4. The probe head according to claim 1, wherein the substrate further has a ground line. 5. The probe head according to claim 4, further comprising a grounding sheath made of a conductive material surrounding the probe pin and connected to the grounding wire. 6. The probe head according to claim 1, wherein a tip portion of each probe pin is covered with a material having higher conductivity than a body portion thereof. 7. The method of manufacturing a probe head according to claim 1, further comprising a step of forming a plurality of probe pins on a substrate having wiring by using lithography and plating. The method of manufacturing a probe head, wherein the lithography uses light irradiated from a direction inclined with respect to a direction perpendicular to a main surface of the substrate.