Probe polishing method and probe polishing member

In a probe polishing method, a plurality of probes, which are arranged on a probe card for performing an inspection of electrical characteristics of a target object, are polished by using a polishing member. Further, the probes are polished over plural times, while changing a relative position of the abrasive sheet with respect to the probe card.

FIELD OF THE INVENTION

The present invention relates to a probe polishing method and a probe polishing member employed in a probe apparatus; and, more particularly, to a probe polishing method and a probe polishing member capable of reducing time required for polishing probes without increasing the size of the probe apparatus, thus improving a throughput of inspection with a small probe apparatus.

BACKGROUND OF THE INVENTION

As illustrated inFIG. 7, a conventional probe apparatus includes, in a probe chamber, a mounting table1for mounting thereon an object to be inspected (e,g., a wafer W) and incorporating therein an elevation mechanism and a rotation mechanism; an X-stage2supporting the mounting table1and movable in an X direction; a Y-stage3supporting the X stage2and movable in a Y direction; a probe card4disposed above the mounting table1; and an alignment mechanism5for aligning probes4A of the probe card4with the wafer W. In the probe chamber, after aligning the wafer W and the probes4A by using the alignment mechanism5, the mounting table1is moved in X, Y, Z directions on a base6by means of the X-stage2, the Y-stage3and the elevation mechanism to bring the wafer W into an electric contact with the probes4A, whereby electrical characteristics of the wafer W are inspected by the probes4A. The X-stage2and the Y-stage3are individually moved in the X and Y directions, by driving mechanisms connected to ball screws, respectively.FIG. 7shows a ball screw2B included in the driving mechanism of the X-stage2and a motor3A included in the driving mechanism of the Y stage3.

Further, as shown inFIG. 7, the alignment mechanism5includes a lower charge coupled device (CCD) camera5A and an upper CCD camera5B and is operated under the control of a controller. The lower CCD camera5A is installed at the mounting table1to capture an image of the probes4A of the probe card4from below, while the upper CCD camera5B is disposed at the center of an alignment bridge5C to capture an image of the wafer W on the mounting table1from above. The alignment bridge5C is moved from an innermost side in the probe chamber to a probe center in a direction marked by an arrow inFIG. 7along a pair of guide rails (not shown) that are extended in the Y direction (front-rear direction).

In performing an inspection of the wafer W, the alignment mechanism5aligns electrode pads of the wafer W with the probes4A. Then, by moving the mounting table1in the X, Y, and Z directions, the electrode pads of the wafer W are brought into electric contact with the probes4A to inspect the electrical characteristics of the wafer W. As the inspection is repeated, metal oxides on the surface of the electrode pad are worn away and adhered to needle tips of the probes4A, which would hinder following inspections. Thus, the needle tips of the probes4A are polished by using a polishing member7shown inFIG. 7to remove the particles adhered to the needle tips.

Meanwhile, if the number of devices simultaneously measured by the probes4increases as the size of the probe card4is increased, the area of the probe card4occupied by the probes4A (hereinafter, simply referred to as “probe area”) gets larger than the size of the polishing member7, so that it becomes impossible to polish the probes4A with the conventional polishing member7. In such a case, though the probes4A may be polished after separating the probe card4from the probe apparatus, a considerable amount of time is required for the separation and reinstallation of the probe card4, which results in deterioration of a polishing efficiency.

Japanese Patent Laid-open Application No. 2000-164649 (Reference 1) discloses a method for polishing probes by using a polishing member of a wafer size mounted on the mounting table1without separating the probe card from the probe apparatus. Further, Japanese Patent Laid-open Application No. 2000-183119 (Reference 2) describes a probe apparatus using a polishing member having a size suitable for a probe area of a probe card, wherein the polishing member can be rotated to correspond to a direction of the probe area which varies depending on the type of the probe card.

In Reference 1, though the polishing member can be changed in accordance with the type of the probe card, the polishing member has to be newly installed every time a polishing of probes is conducted. Thus, a considerable amount of time is required for the installation of the polishing member, so that the efficiency of the polishing work is deteriorated. Further, an additional device for installing the polishing member is required, thereby increasing a cost. Besides, in case of a large probe card capable of contacting with the entire region of a wafer at one time, although it is possible to polish all of the probes of the probe card simultaneously, it is inevitable that the same portions of the polishing member are used repetitively because the polishing member cannot be index fed. Thus, the polishing member cannot be utilized efficiently. Moreover, due to the large size of the polishing member, an extra space is required for the accommodation of the polishing member, which increases the entire size of the probe apparatus.

In Reference 2, to change the direction of the polishing member having a size suitable for a probe area to correspond to the direction of the probe area, the polishing member sometimes needs to be elevated higher than a mounting surface of the mounting table depending on the direction of the probe area. Thus, a rotation mechanism and an elevation mechanism for the polishing member are additionally needed, which makes the entire mechanism of the probe apparatus complicated. Further, since the same portions of the polishing member are repetitively used to polish probes as similar to the case of Reference 1, the work efficiency of the polishing member is poor. Moreover, there are required the extra space for accommodating the polishing member having the size suitable for the probe area and a space for allowing the direction change of the polishing member, so that the entire size of the probe apparatus is increased.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide a probe polishing method and a probe polishing member capable of polishing probes of a probe card reliably and efficiently even when the arrangement region of the probes is not fully covered by the polishing member because the number of the probes increases as a size of the probe card becomes larger, thus improving inspection throughput.

In accordance with an embodiment of the present invention, there is provided a probe polishing method for polishing, by using a polishing member, a plurality of probes arranged on a probe card for performing an inspection of electrical characteristics of a target object,

wherein the probes are polished over plural times, while changing a relative position of the polishing member with respect to the probe card.

Preferably, the same probes are polished more than one time with different portions of the polishing member each time by changing the relative position of the polishing member with respect to the probe card.

Preferably, the polishing member is installed on a movable mounting table for mounting the target object thereon, and the polishing member is moved by using the mounting table.

Preferably, an abrasive sheet is used as the polishing member, and the abrasive sheet has a slant portion at a peripheral portion thereof, the slant portion being inclined outwardly downwardly.

Preferably, the abrasive sheet includes an abrasive layer and a cushion layer formed under the abrasive layer.

In accordance with one aspect of the present invention, a polishing member used to polish probes for performing an inspection of electrical characteristics of a target object, the polishing member being mounted on a support, the polishing member including: a slant portion at a peripheral portion of the polishing member, the slant portion being inclined outwardly downwardly.

Preferably, the support is installed at a mounting table for mounting the target object thereon, and the support has a slant surface at a peripheral portion thereof, the slant surface being inclined outwardly downwardly.

Preferably, the polishing member is formed of an abrasive sheet including an abrasive layer and a cushion layer formed under the abrasive layer.

In accordance with the present invention of any one of claims1to8, there can be provided a probe polishing method and a probe polishing member capable of polishing probes of a probe card certainly and efficiently even when the arrangement region of the probes is not fully covered by the polishing member because the number of the probes increases as a size of the probe card becomes larger, thus improving a throughput of inspection.

DETAILED DESCRIPTION OF THE EMBODIMENTS

As schematically illustrated inFIG. 1, for example, a polishing member10in accordance with the embodiment of the present invention is formed to have a size smaller than an arrangement area of a plurality of probes21attached on a probe card20(hereinafter, simply referred to as “probe area”). That is, the probe area is larger than the size of the polishing member10such that the entire region of the probe area is not fully covered by the polishing member10. As shown inFIG. 2, for example, the polishing member10is disposed on a support31installed at a periphery of a mounting table30for supporting a to-be-inspected object such as a wafer (not shown). The mounting table30is configured to be movable in X, Y, Z and θ directions as in the conventional cases. The support31is horizontally protruded from a part of the periphery of the mounting table30, and supports the polishing member10thereon such that the surface of the polishing member10is positioned slightly higher than a mounting surface of the mounting table30.

Since the polishing member10cannot polish all the probes21in the probe area at one time, as shown inFIG. 1, the probes21in the probe area divided into plural groups (e.g., three groups bordered by dashed dotted lines inFIG. 1), and a polishing operation is individually performed for each group (over three times in total inFIG. 1) by index feeding the polishing member10by means of the mounting table30.

Further, the planar shape of the polishing member10can be appropriately set as desired. For example, as illustrated inFIG. 2, the polishing member10is formed to have a rectangular shape. Further, since the polishing member10is a consumptive member, it is attachably and detachably mounted on the top surface of the support31so that it can be replaced with a new one. The polishing member10may be formed of a flexible abrasive sheet or an abrasive plate made up of, e.g., an alumina ceramic. In this embodiment, the polishing member10is formed of a flexible abrasive sheet. Thus, in the following description, the polishing member10will be explained as an abrasive sheet10. In this embodiment, the polishing member10has a hard abrasive, so that it is particularly effective to polish probes with the surface of the abrasive. Here, the surface hardness of the polishing member10is set to be higher than that of a material forming the probes21. For example, in case the probes21are made up of tungsten which has a Mohs hardness of 7.5 and, thus, an abrasive whose Mohs hardness is more than a value of 8, e.g., 9 is used for the polishing member10, alumina whose particle diameter ranging from 0.5 to 10 μm can be used as the abrasive.

As shown inFIG. 1, the top surface of the support31has a slant surface31A provided at the peripheral portion of the support31, the slant portion being inclined outwardly downwardly. Here, the abrasive sheet10is formed to have a size enough to cover the slant surface31A of the support31. The abrasive sheet10is attached on the support31having the slant surface31A, so that the abrasive sheet10is made to conform to the contour of the top surface of the support10and the peripheral portion of the abrasive sheet10has a slant portion10A inclined outwardly downwardly. Here, the abrasive sheet10may be configured to have a size covering the entire region of the flat surface portion or just covering a part of slant surface31A as shown inFIG. 1. The slant portion10A of the abrasive sheet10is designed to have a length of, e.g., 5 mm (5 mm or above is preferable) and to have a degree of inclination of, e.g., 10% (10% or less is preferable). By configuring the abrasive sheet10to have the slant portion10A at the peripheral portion thereof, leading ends of the probes21located outside the boundaries (marked by dashed dotted lines inFIG. 1) of a polishing region of the probe area, which is being polished by the abrasive sheet, are increasingly distanced away from the abrasive sheet10as they are located farther from the polishing region. Thus, during the index feeding of the abrasive sheet10for the polishing of the probes21, the probes21located adjacent to the polishing region are prevented from being bent or damaged by the peripheral portion of the abrasive sheet10, thereby keeping the arrangement of the probes21in order.

Further, as shown inFIG. 3, for example, the abrasive sheet10includes an abrasive layer11; a film layer12supporting the abrasive layer11; and a cushion layer13supporting the film layer12. The abrasive layer11is formed by coating fine powder of, e.g., alumina, which is employed as the abrasive, on the film layer12. The film layer12is made up of, e.g., a polyethylene terephthalate (PET) resin or the like and the cushion layer13is made up of an expandable resin (e.g., acryl foam) having a high elasticity. Further, an adhesive layer14made up of, e.g., an acryl-based resin material is formed on the top and the bottom surface of the cushion layer13. Further, reference numeral15represents a liner film which is removed when attaching the abrasive sheet10to the support31. The thickness of the abrasive sheet10can be appropriately set as desired. For example, the thickness of the abrasive sheet10(excepting for the liner film15) is set to be, e.g., about 500 μm, wherein the sum of the thicknesses of the abrasive layer11and the film layer12is set to be, e.g., about 200 μm; and the sum of the thicknesses of the cushion layer13and the adhesive layers14is set to be, e.g., about 300 μm. It is preferable that the fine powder of the abrasive such as alumina or the like is set to have a particle diameter smaller than the diameter of leading ends of the probes21. The diameter of the leading ends of the probes21is set to range, e.g., from about 10 to 20 μm; the length of probe tips is set to be, e.g., about 200 μm; and the interval between the probes21is set to be about 50 to 200 μm.

Below, an embodiment of the polishing method in accordance with the present invention will be described with reference toFIGS. 4 to 6B.FIGS. 5A,5B and6A,6B illustrate a polishing method wherein the probe area is divided into two.

In an inspection process of a wafer, after the wafer is loaded on the mounting table30, the wafer is aligned with the probes21of the probe card by an alignment mechanism (not shown). Then, the wafer is horizontally moved to a first inspection position by using the mounting table30, and the wafer is elevated and overdriven by a specific amount by means of the mounting table30to be brought into contact with the probes21. Accordingly, electrode pads of the wafer and the probes21are brought into electric contact with each other and electrical characteristics of the wafer are inspected. Thereafter, the mounting table30is moved downward, and the wafer is index fed through the mounting table30to a next inspection position, where the same inspection process as described above is repeated. During the inspection of the wafer, the probes21pick oxide films formed on the electrode pads to make electric connections therebetween. Thus, as the inspection is repeated, particles of the oxide films are adhered to leading ends of the probes21, which would hinder following inspections.

Thus, the probe polishing method in accordance with the present invention is performed to remove the particles from the probes21. The probes21in the probe area are polished by the abrasive sheet10, while index feeding the abrasive sheet10by means of the mounting table30.FIG. 4shows a polishing region of the abrasive sheet10that can be covered by the index feeding of the mounting table30, which is hatched inFIG. 4. The probe card20is installed in a probe apparatus E in a manner that the center of its probe area coincides with a probe center C of the probe apparatus E. The probe area is within the polishing region, and all the probes21can be polished through the index feeding of the mounting table30.

The polishing process of the probes21is performed as follows. First, prior to the polishing, each size of the probe area of the probe card20and the abrasive sheet10is registered in a controller of the probe apparatus, whereby the controller determines whether to polish the whole probe area at one time or to polish the probe area over plural times by grouping it into plural sections based on the sizes of the probe area and the abrasive sheet10. In case the probe area is larger than the abrasive sheet10, the controller automatically calculates the number of the polishing operations to be performed based on the registered size information of the probe area and the abrasive sheet10. Alternatively, an operator may set the number of the polishing operations to be performed. In the examples shown inFIGS. 5A,5B and6A,6B, the probe area is polished over two times. Further, the probe area will be explained by providing reference numeral23to the probe area blow.

As shown inFIGS. 5A and 5B, in case a probe area23is elongated in a X-direction in the drawings, the probe area23is divided into, e.g., two, an upper and a lower portion in the drawings. Then, by moving a mounting table (not shown), the abrasive sheet10is moved to a position, e.g., where the upper portion of the probe area23is positioned above a lower left side of the abrasive sheet10, as shown inFIG. 5A. In this state, the abrasive sheet10is elevated by the mounting table to come into contact with the probes21at the upper portion of the probe area23, and the abrasive sheet10is overdriven by about 50 to 100 μm, e.g., 50 μm, whereby leading ends of the probes21collide with the abrasive layer11(seeFIG. 3). The abrasive contained in the abrasive layer11scratches or peels particles adhered to the leading ends of the probes21. Thereafter, the abrasive sheet10is descended down to its lowermost position to be separated from the probe area21. In this way, the particles attached on the leading ends of the probes21can be removed, and the removed particles are left on the abrasive layer11. By setting a contact area of the probes with the slant portion10A of the abrasive sheet10, which is determined by an overdriving amount and a degree of inclination of the slant portion10A, not to exceed ½ of the slant portion10A in a horizontal direction, any damage on probes can be reliably prevented.

Though the particles adhered on the leading ends of the probes21can sometime be removed by a single polishing operation, some particles may remain after the single polishing operation. In such cases, the abrasive sheet10is index fed by a specific distance δ by moving the mounting table, so that the abrasive sheet10is displaced in a horizontal direction (Y direction) marked by an arrow inFIG. 5A. Then, as described above, the abrasive sheet10is overdriven; and the remaining particles on the probes can be removed by using a separate new portion of the abrasive sheet10; and then, the abrasive sheet is descended. By changing the polishing portion of the abrasive sheet10as described above, the efficiency of removing the particles from the probes can be improved. That is, by shifting the abrasive sheet10in the Y direction as many time as necessary, the same portion of the probe area23can be polished plural times, so that the particles adhered to the probe areas23can be completely removed.

After polishing the upper portion of the probe area23, the abrasive sheet10is moved downward in the X direction by means of the mounting table to allow the lower portion of the probe area23to be positioned above the abrasive sheet10. Then, the lower portion of the probe area23is polished in the same manner as that for polishing the upper portion of the probe area23. If necessary, the probes21on the lower portion of the probe area are polished repetitively by index feeding the abrasive sheet10over plural times.

Further, as shown inFIGS. 6A and 6B, in case the probe area23is elongated in a Y-direction, a right half of the probe area23is first polished, e.g., as shown inFIG. 6A, and if necessary, the same probes21are polished repetitively by index feeding the abrasive sheet10downward through the mounting table by a distance δ, as shown by an arrow inFIG. 6A. Then, the abrasive sheet10is moved as shown inFIG. 6Bto polish the remaining left half of the probe area23in the same manner as that of the right half.

In accordance with the embodiment of the present invention as described above, since the abrasive sheet10has the slant portion10A inclined outwardly downwardly, the peripheral portion of the abrasive sheet10can hardly make a contact with the probes21even in case the probe area23is not fully covered by the abrasive sheet10. Thus, it is possible to polish the probe area23completely and effectively by dividing it into plural regions without disordering the arrangement of the probes21. Accordingly, even if the size of the probe card20is increased and the probe area23cannot be completely covered by the abrasive sheet10, the probe area23can be polished by using the same abrasive sheet10without having to separate the probe card20, by way of dividing the probe area23into plural polishing regions and moving the abrasive sheet10by means of the mounting table30. Therefore, the probe area23can be polished completely in a shorter period of time, thereby improving a throughput of inspection. Moreover, since the polishing member10only needs attaching to and detaching from the top surface of the support31installed at the mounting table30, its structure can be simplified and costs can be reduced. Further, since a separate space for the polishing operation is not required, a size increase of the probe apparatus can be prevented.

Further, in accordance with the embodiment of the present invention, since the same probes21on the probe area can be polished plural times with different portions of the abrasive sheet10by index feeding the abrasive sheet10by means of the mounting table30, the particles on the probes21can be removed completely and efficiently. In addition, since the abrasive sheet10has the abrasive layer11and the cushion layer13, the probes21are allowed to collide with the abrasive layer11elastically, so that the damage on the probes21can be prevented.

Furthermore, the present invention is not limited to the embodiments described above, but the design of each component can be varied appropriately if necessary. For example, though the embodiments have been described for the case where the slant portion10A of the abrasive sheet10is formed by attaching the abrasive sheet10on the slant surface31A of the support31, it is also possible to form a slant surface portion at the peripheral portion of the abrasive sheet10itself. In such a case, it is preferable to provide the slant surface at the cushion layer13. In addition, although the embodiments have been described for the case where the probe area is not fully covered by the abrasive sheet, the polishing method of the present invention can also be applied to a case where the abrasive sheet can cover the entire probe area.

While the invention has been shown and described with respect to the embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the following claims.