Patent Grant
8378705
The present invention relates to a wiring substrate and a probe card that includes the wiring substrate and that is used for an electrical characteristics test for a semiconductor wafer.
In a semiconductor test process, an electrical characteristics test for detecting a defective product is performed by bringing probes having conductivity into contact with a semiconductor wafer before dicing (wafer level test). When the wafer level test is performed, to transfer a test signal to the semiconductor wafer, a probe card housing a large number of probes is used. In the wafer level test, the probes are individually brought into contact with each of dies on the semiconductor wafer while the dies are scanned by the probe card. Because hundreds to tens of thousands of dies are formed on the semiconductor wafer, it takes considerable time to test one semiconductor wafer. Thus, an increase in the number of dies causes higher cost.
To solve the problems of the wafer level test described above, in recent years, a method (full wafer level test) is also used in which hundreds to tens of thousands of probes are collectively brought into contact with all or at least about ¼ to ½ of dies on a semiconductor wafer (see, for example, Patent Document 1). In this method, to accurately bring the probes into contact with electrodes on the semiconductor wafer, there are proposed a technology for maintaining positional accuracy of tips of probes by accurately keeping the parallelism or the flatness of a probe card with respect to a surface of the semiconductor wafer and a technology for highly accurately aligning a semiconductor wafer (see, for example, Patent Document 2 or 3).
In general, the coefficient of thermal expansion (3.4×10−6/° C.) of a semiconductor wafer composed mostly of silicone is significantly smaller than the coefficient of thermal expansion (12×10−6 to 17×10−6/° C.) of a wiring substrate composed mostly of resin such as glass epoxy or polyimide. Therefore, in the conventional probe card, the space transformer is formed of material having a coefficient of thermal expansion that is larger than the coefficient of thermal expansion of the semiconductor wafer and is smaller than the coefficient of thermal expansion of the wiring substrate in order to alleviate a difference between the coefficient of thermal expansion of the semiconductor wafer and the coefficient of thermal expansion of the wiring substrate, and to prevent misalignment between a tip position of a probe and an electrode of the semiconductor wafer when an electrical characteristics test is performed under a wide temperature environment (about 25 to 125° C.).
Because the space transformer requires inner wiring, it takes time to manufacture the space transformer, and, because a number of layers need to be stacked, cost is increased inevitably. In this circumstance, a demand is growing for a wiring substrate that allows wiring at a fine pitch of about 100 μm and has a coefficient of thermal expansion close to the coefficient of thermal expansion of silicone, as a wiring substrate that allows construction of a probe card without using the space transformer.
The present invention has been made in view of the above, and it is an object of the present invention to provide a wiring substrate that allows wiring at a fine pitch and has a coefficient of thermal expansion close to the coefficient of thermal expansion of silicone, and a probe card that includes the wiring substrate.
To solve the problem described above and achieve the object, a wiring substrate according to the present invention includes: a ceramic substrate having a coefficient of thermal expansion of 3.0×10−6 to 5.0×10−6/° C.; and one or more thin-film wiring sheets stacked on one surface of the ceramic substrate.
In the wiring substrate according to the present invention as set forth in the invention described above, the ceramic substrate has a through hole that pierces through the ceramic substrate in a thickness direction.
In the wiring substrate according to the present invention as set forth in the invention described above, a plurality of zero insertion force type connectors, each of which is electrically connected to the thin-film wiring sheet, is further included.
In the wiring substrate according to the present invention as set forth in the invention described above, one or more metals that are stacked on other surface of the ceramic substrate and that have coefficients of thermal expansion smaller than the coefficient of thermal expansion of the ceramic substrate is further included.
In the wiring substrate according to the present invention as set forth in the invention described above, a thin-film multilayer wiring sheet stacked on other surface of the ceramic substrate is further included.
A probe card according to the present invention that electrically connects a semiconductor wafer and a circuit structure that generates a signal to be output to the semiconductor wafer, by using a conductive probe that is extendable in a longitudinal direction, includes: the wiring substrate according to any one of the invention as set forth; and a probe head on which a plurality of probes is arranged in accordance with wiring on the thin-film wiring sheet, which holds individual probes while preventing the probes from coming off and allowing both ends of each probe to be exposed, and which is stacked on the wiring substrate while allowing one end of each probe to be brought into contact with the thin-film wiring sheet.
According to the present invention, because a ceramic substrate having the coefficient of thermal expansion of 3.0×10−6 to 5.0×10−6/° C. and one or more thin-film wiring sheets stacked on one surface of the ceramic substrate are provided, it is possible to provide a wiring substrate that allows wiring at a fine pitch and has a coefficient of thermal expansion close to the coefficient of thermal expansion of silicone, and a probe card that includes the wiring substrate.
Best modes for carrying out the present invention (hereinafter, “embodiments”) are explained below with reference to the accompanying drawings. It should be noted that the drawings are schematic and a relation between the thickness and the width of each portion, a ratio of the thicknesses of the respective portions, and the like may be different from realistic ones. It goes without saying that the drawings may depict some portion as having different relations and ratios of dimensions.
The plunger 21 includes a tip portion 21a having a sharp tip end, a boss portion 21b which is formed on a base end side of the tip portion 21a and has a diameter smaller than the diameter of the tip portion 21a, and a shaft portion 21c which extends from a surface on the opposite side of a surface that comes into contact with the tip portion 21a among the surfaces of the boss portion 21b. The plunger 22 includes a tip portion 22a having a sharp tip end, a flange portion 22b which is formed on a base end side of the tip portion 22a and has a diameter larger than the diameter of the tip portion 22a, and a boss portion 22c which protrudes from the surface of the flange portion 22b in a direction opposite to the tip portion 22a and has a diameter smaller than the diameter of the flange portion 22b. The coil spring 23 is structured such that one side attached to the plunger 21 is a loosely wound portion 23a, and the other side attached to the plunger 22 is a tightly wound portion 23b. The end portion of the loosely wound portion 23a is press fitted onto the boss portion 21b, while the end portion of the tightly wound portion 23b is press fitted onto the boss portion 22c.
In the probe 2 in the state illustrated in
The configuration of the probe 2 described above is just an example, and any of various types of conventionally-known probes may be used in the configuration.
The probe head 3 is formed by using insulating material. On the probe head 3, hole portions 31 that individually house the probes 2 are arranged in accordance with an array of the electrodes 101 of the semiconductor wafer 100 such that the hole portions 31 pierce through the probe head 3 in a thickness direction (a vertical direction of
The number and an arrangement pattern of the probes 2 housed in the probe head 3 are determined depending on the number of semiconductor chips and an arrangement pattern of the electrodes 101 formed on the semiconductor wafer 100. For example, when the semiconductor wafer 100 having a diameter of 8 inches (about 200 millimeters) is the test object, tens to thousands of the probes 2 are necessary. When the semiconductor wafer having a diameter of 12 inches (about 300 millimeters) is the test object, hundreds to tens of thousands of the probes 2 are necessary.
The wiring substrate 4 includes a ceramic substrate 41 having the coefficient of thermal expansion of 2.5×10−6 to 5.0×10−6/° C., or more preferably, 2.9×10−6 to 3.9×10−6/° C., three thin-film wiring sheets 42a, 42b, 42c stacked on one surface of the ceramic substrate 41, and a thin-film multilayer wiring sheet 43 stacked on the other surface of the ceramic substrate 41. The value of the coefficient of thermal expansion of the ceramic substrate 41 is close to the value of the coefficient of the thermal expansion of silicone (3.4×10−6/° C.). The thin-film wiring sheets 42a, 42b, 42c and the thin-film multilayer wiring sheet 43 are, for example, Cu/PI thin-film multilayer wiring sheets and allow wiring at a fine pitch of about 100 μm. The thin-film wiring sheets 42a, 42b, 42c and the thin-film multilayer wiring sheet 43 are fixed to the ceramic substrate 41 by adhesive bonding or the like. In
On the ceramic substrate 41 is formed a plurality of through holes 411 piercing through in a plate thickness direction. The through holes 411 are formed by any of machining methods such as drilling, punching, laser machining, electron beam machining, ion beam machining, wire electrical discharge machining, or etching, and the surfaces thereof are subjected to plating with a conductive material 412 such as silver or copper.
As a wiring substrate 44 illustrated in
According to the first embodiment described above, because the ceramic substrate having the coefficient of thermal expansion of 3.0×10−6 to 5.0×10−6/° C. and one or more thin-film wiring sheets stacked on one surface of the ceramic substrate are included, it is possible to provide a wiring substrate that allows wiring at a fine pitch and has a coefficient of thermal expansion close to the coefficient of thermal expansion of silicone, and a probe card that includes the wiring substrate.
Furthermore, according to the first embodiment, because the coefficient of thermal expansion of the wiring substrate is close to that of the silicone and wiring at a fine pitch is available on the wiring substrate, it is not necessary to use a space transformer, unlike a conventional probe card. Therefore, an interposer that electrically connects the space transformer and the wiring substrate is also not necessary, so that a problem can hardly occur in that electrical characteristics are deteriorated due to increase in contact points as in the conventional probe card. As a result, it is possible to provide a wiring substrate and a probe card having excellent transmission characteristics for a high-frequency electrical signal.
Moreover, according to the first embodiment, because the space transformer and the interposer are not needed, the number of components is decreased, making the assembly easy and making it possible to reduce manufacturing time. Therefore, it is possible to reduce costs for manufacturing, resulting in reduced prices.
Furthermore, according to the first embodiment, the coefficient of thermal expansion of the wiring substrate is made close to the coefficient of thermal expansion of a semiconductor wafer, so that the wiring substrate is prevented from being misaligned or warping at the time of a test. Therefore, it is possible to uniformly bring all probes into contact with the semiconductor wafer, making it possible to prevent a difference in the degree of abrasion between the probes and improve durability of each probe.
The wiring substrate 9 includes a ceramic substrate 91 made of the same material as the ceramic substrate 41 of the first embodiment described above, three thin-film wiring sheets 92a, 92b, 92c which are fixedly stacked on one surface of the ceramic substrate 91 and interposed between the ceramic substrate 91 and the probe head 3, and a resin substrate 93 which is composed mostly of resin such as glass epoxy or polyimide and has a concave portion in which the ceramic substrate 91 is fitted. The resin substrate 93 has a surface which becomes flush with the surface of the ceramic substrate 91 when the ceramic substrate 91 is fitted, and on which the thin-film wiring sheets 92a, 92b, 92c are stacked. In
According to the probe card 8 having the above configuration, it is possible to easily adjust the flatness of the ceramic substrate 91 by reducing the volume of the ceramic substrate 91 to the requisite minimum. Furthermore, because the resin substrate 93 which is lower in cost than the ceramic substrate 91 is used as remaining part of the wiring substrate 9, it is possible to further reduce costs.
It is possible to mount the mounted component 11 on the probe card 1 described above.
The wiring substrate 13 includes a ceramic substrate 131 made of the same material as the ceramic substrate 41 described above (with the coefficient of thermal expansion of 2.5×10−6 to 5.0×10−6/° C., or more preferably, 2.9×10−6 to 3.9×10−6/° C.), and four thin-film wiring sheets 132a, 132b, 132c, 132d which are fixedly stacked on one surface of the ceramic substrate 131 on a side opposing the probe head 3. In
The surfaces of the first flange portion 14b and the second flange portion 14d opposing each other have substantially the same areas. On the first flange portion 14b is formed a plurality of hole portions 142. On the second flange portion 14d is formed a plurality of hole portions 143 which is coaxially positioned with respect to any one of the plurality of hole portions 142 formed on the first flange portion 14b and which allows insertion of screws.
When the connector 14 is attached to the wiring substrate 13, as illustrated in
According to the second embodiment described above, because a ceramic substrate having the coefficient of thermal expansion of 3.0×10−6 to 5.0×10−6/° C. and a plurality of thin-film wiring sheets stacked on one surface of the ceramic substrate are included, it is possible to provide a wiring substrate that allows wiring at a fine pitch and has a coefficient of thermal expansion close to the coefficient of thermal expansion of silicone, and a probe card that includes the wiring substrate.
Furthermore, according to the second embodiment, because a space transformer and an interposer are not needed, it is possible to provide a probe card that has excellent transmission characteristics for a high-frequency electrical signal, requires less cost, and is cost-effective.
Moreover, according to the second embodiment, because an electrical connection is established by applying a ZIF-type connector, it is possible to surely obtain the electrical connection without causing any stress even when the number of probes is large and stress on the probe card or a tester may be increased due to enormous reflection force that occurs on a spring-action terminal. Therefore, even in the probe card having a large number of probes and complicated wiring, electrical connection failure or damage on the probes is less likely to occur, resulting in improved durability of the probe card.
The wiring substrate 16 includes a ceramic substrate 161 made of the same material as the ceramic substrate 41 described above (with the coefficient of thermal expansion of 3.0×10−6 to 5.0×10−6/° C.), and a plurality of thin-film wiring sheets which are fixedly stacked on one surface of the ceramic substrate 161 on a side opposing the probe head 3. In
The first connector 171 includes a first joint portion 171a which has a convex shape and is mounted to be combined with the female connector that forms a pair, a third flange portion 171b which is placed on one surface (the top surface in
When the connector 17 is attached to the wiring substrate 16, the engagement portion 172b of the second connector 172 is mounted on the opening portion 163, and thereafter, the second joint portion 171c of the first connector 171 is engaged with the engagement portion 172b and screws 301 are attached to hole portions 175 formed on the first connector 171, hole portions 164 formed on the wiring substrate 16, and hole portions 176 formed on the second connector 172 (in
According to the third embodiment described above, it is possible to achieve the same advantages as those of the second embodiment described above. In addition, according to the third embodiment, a male connector is constructed of separated two connectors, so that only an opening portion needs to be formed on the wiring substrate instead of forming the cutout part on the wiring substrate as in the second embodiment described above. Therefore, it is possible to increase the rigidity of the wiring substrate. Furthermore, because connection of a ground layer or a power layer of the wiring substrate can be maintained without disconnection at the outer peripheral portion of the wiring substrate, it is possible to ensure a path of a return current. Therefore, it is possible to achieve desirable transmission characteristics for transmitting a high-frequency electrical signal.
The first to third embodiments are explained in detail above as best modes for carrying out the present invention; however, the present invention should not be limited to the embodiments. For example, depending on the coefficient of thermal expansion of the ceramic substrate, as in a wiring substrate 18 illustrated in
Furthermore, as illustrated in
In the second and third embodiments described above, an example is explained in which a ZIF-type male connector is mounted on the wiring substrate. However, it is possible to mount a ZIF-type female connector on the wiring substrate.
As is apparent in the above description, the present invention can include various embodiments and the like not described here, and various design changes and the like can be made in the range without departing from the technical idea as specified by the claims.
As described above, the wiring substrate and the probe card according to the present invention is useful for an electrical characteristics test for a semiconductor wafer.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2008-050888 | Feb 2008 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2009/053602 | 2/26/2009 | WO | 00 | 8/26/2010 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2009/107747 | 9/3/2009 | WO | A |
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