CLEANING APPARATUS FOR A PROBE

Abstract

The present invention provides a cleaning apparatus capable of removing foreign matters attached to a tip of a probe effectively without impairing the durability of the probe. The cleaning apparatus for the probe comprises a base plate having a rough surface and a surface layer formed to conform to and cover the rough surface for the purpose of providing a polishing surface for the probe and having lower hardness than hardness of the probe tip of the probe.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a cleaning apparatus for removing foreign matters from a probe tip of a probe card used in an electrical test of a semi conductor device such as an integrated circuit formed on a semiconductor wafer.

In an electrical test of semiconductor devices collectively formed on a semiconductor wafer, an electrical connecting apparatus such as a probe card connected to a tester is used in general to connect the tester used in the test to a device under test. The tip of each probe provided on this electrical connecting apparatus contacts an electrode pad formed on each semiconductor device of the semiconductor wafer to cause the semiconductor device as a device under test to be electrically connected to the aforementioned tester.

At the time of the mutual connection, the tip of the probe of the electrical connecting apparatus slides on the surface of the corresponding electrode pad and abuts on this electrode pad so as to slightly scrape the surface of the electrode pad so that the probe can be connected to the corresponding electrode pad reliably. At this time, scrapes of the electrode pad may attach to the tip of the probe as foreign matters. Since attachment of such foreign matters to the probe tip interferes with subsequent accurate electrical connection for other semiconductor devices, it interferes with accurate tests.

It is proposed that a cleaning member having an elastic layer containing polishing agent on the rough surface of a base plate is used to remove foreign matters attached to the probe tip (for example, refer to Patent Document 1). According to this cleaning member, by letting the probe tip slide on the elastic layer of the cleaning member as needed, the foreign matters attached to the probe can be removed.

[Patent Document 1] Japanese Patent No. 3766065

BRIEF SUMMARY OF THE INVENTION

However, since the elastic layer contains the polishing agent having higher hardness than hardness of the probe, the tip of the probe significantly abrades away per cleaning of the probe. Thus, the durability of the probe may be impaired.

It is an object of the present invention to provide a cleaning apparatus enabling to remove foreign matters attached to a tip of a probe effectively without impairing the durability of the probe.

The present invention is a cleaning apparatus for removing foreign matters attached to a probe, and comprises a base plate having a rough surface, and a surface layer formed to conform to and cover the rough surface for the purpose of providing a polishing surface for the probe and having lower hardness than hardness of a probe tip of the probe.

The surface layer is lower in hardness than the probe and is formed on the rough surface to conform to the base plate. Accordingly, by letting the probe tip of the probe slide on the surface layer, foreign matters attached to the probe can be removed effectively without causing significant abrasion of the probe.

The surface layer may be formed to have a smooth surface along the rough surface.

The thickness of the surface layer may be 0.05 to 1.0 micrometers.

The arithmetic mean roughness (Ra) of the rough surface may be 0.02 to 1.00 micrometers. In this case, the arithmetic mean roughness (Ra) value of the rough surface of the surface layer is approximately 10% smaller than the arithmetic mean roughness value of the rough surface of the base plate.

For the base plate, a silicon plate whose surface is formed to be a rough surface by sandblast may be used, for example. As the base plate, an amorphous carbon plate, a silicon carbide plate, or a ceramic plate can be used instead of the silicon plate.

When the Vickers hardness (Hv) of the probe tip of the probe is 800 to 1000, a metal material having the Vickers hardness (Hv) of 400 to 600 may be used for the surface layer.

For example, in a case where a hard metal such as rhodium or ruthenium is used as the probe tip, nickel or a nickel alloy may be used for the metal material of the surface layer. The surface layer can be formed by deposition of copper, a copper alloy, tungsten, a tungsten alloy, chromium, or a chromium alloy, instead of the nickel material.

With the present invention, since foreign matters such as aluminum scraps attached to the probe tip can be removed without using a conventional surface layer containing polishing agent as described above, the tip of the probe will not abrade away as significantly as in the conventional case in cleaning of the probe.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view schematically showing a cleaning apparatus according to the present invention.

FIG. 2 is a schematic view partially showing a probe assembly that undergoes cleaning by using the cleaning apparatus shown in FIG. 1.

FIG. 3 is a front view of a probe in the probe assembly shown in FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a cross-sectional view schematically showing a cleaning apparatus according to the present invention. Prior to description of the cleaning apparatus shown in FIG. 1, an example of a probe assembly having a probe that undergoes cleaning processing by the cleaning apparatus will be described with reference to FIGS. 2 and 3.

A probe assembly 10 according to the present invention is used for an electrical test of a plurality of integrated circuits (not shown) formed on a semiconductor wafer 12 as shown in FIG. 2. The semiconductor wafer 12 is removably held on a vacuum chuck 14, for example, with a plurality of electrodes 12a formed on its one surface directing upward. The probe assembly 10 is supported by a not shown frame member to be movable relatively to the vacuum chuck 14 in directions toward and away from the semiconductor wafer 12 on the vacuum chuck 14 for the electrical test of the aforementioned integrated circuits of the semiconductor wafer 12 on the vacuum chuck 14.

The probe assembly 10 comprises a printed wiring board 16 and a probe board 18 piled up on the printed wiring board. The probe board 18 is a layered body made of a ceramic board 18a and a multi-layered wiring board 18b whose upper surface is connected to the ceramic board, as is conventionally well known. On the lower surface of the probe board 18, that is, the multi-layered wiring board 18b, are aligned and mounted a plurality of probes 20 according to the present invention.

The probe board 18 is attached integrally with the printed wiring board 16 so as to be piled on the lower surface of the printed wiring board 16 via a conventionally well-known attachment ring assembly 22 made of a dielectric material such as a ceramic and not shown combining members similar to conventional ones such as bolts so that the probes 20 may be directed downward. In the example shown in the figure, on the upper surface of the printed wiring board 16 is integrally arranged a reinforcement member 24 that is made of a metal material and allows partial exposure of the aforementioned upper surface of the printed wiring board 16.

On the multi-layered wiring board 18b of the probe board 18 are formed conventionally well-known plural conductive paths 26 as shown in FIG. 3. The respective probes 20 are attached to the probe board 18 by being fixedly connected to probe lands 26a of the respective corresponding conductive paths 26.

The aforementioned conductive paths on the probe board 18 corresponding to the respective probes 20 are electrically connected to sockets (not shown) arranged in an area exposed from the reinforcement member 24 on the upper surface of the printed wiring board 16 via respective conductive paths (not shown) respectively penetrating the ceramic board 18a and the printed wiring board 16 as in a conventionally well-known manner and are connected to a circuit of a not shown tester main body via the sockets.

Accordingly, by letting the probe assembly 10 and the vacuum chuck 14 move so as to approach each other so that the respective probes 20 of the probe assembly 10 may abut on the corresponding electrodes 12a on the semiconductor wafer 12 as a device under test, the electrodes 12a can be connected to the circuit of the aforementioned tester main body, and thus an electrical test of the device under test 12 can be performed.

Referring to FIG. 3, which is an enlarged view of each probe 20, each probe 20 comprises a plate-shaped probe main body 20a and a probe tip 20b part of which is buried in the probe main body. They exhibit relatively good conductivity.

The probe main body 20a may be made of a highly flexible metal material with relatively excellent flexibility such as nickel, a nickel alloy including a nickel-phosphorus alloy, a nickel-tungsten alloy, a nickel-cobalt alloy, and a nickel-chromium alloy, or phosphor bronze. Also, the probe tip 20b is made of a metal material whose Vickers hardness (Hv) is 800 to 1000 such as rhodium or ruthenium. The probe tip 20b made of such a metal material is higher in hardness and more excellent in abrasion resistance than the probe main body 20a.

In the example shown in the figure, the probe main body 20a comprises an attachment region 28 whose flat surface shape is a rectangular shape, a strip-shaped connection region 30 extending downward from one side of the attachment region, arm regions 32, 32 extending in a lateral direction from the connection region, and a probe tip region 34 continuing into the arm regions. An upper edge 28a of the attachment region 28 is an attachment end portion to the probe land 26a. In the example shown in the figure, the arm regions 32 continue into the attachment region 28 extending downward from the upper edge or the attachment end portion 28a via the connection region 30.

The arm regions 32 extend in a lateral direction with a space from a lower edge 28b of the attachment region 28. In the example shown in the figure, the arm regions 32 are a pair of arm regions 32, 32 extending in parallel with each other at a distance from each other in an up-down direction. The probe tip region 34 extends from the tip ends of both the arm regions to the opposite side of a side where the attachment end portion 28a is located, that is, to the lower side, so as to connect both the arm regions 32.

Each probe 20 is fixed to the probe land 26a of the conductive path 26 at the attachment end portion 28a of the probe main body 20a, and as shown in FIG. 2, the plurality of probes 20 are arranged in series to be close to one another with their probe tips 20b aligned on a straight line.

According to the probe assembly 10, when the probe tip 20b of the probe 20 abuts on the electrode 12a of the aforementioned semiconductor wafer 12, the probe assembly 10 further receives an action force in a direction in which the semiconductor wafer 12 and the probe assembly 10 approach each other. Due to this action force, arc-like retroflexion opened upward occurs in the arm regions 32, 32 of the probe assembly 10 by the elasticity. This action force causing the retroflexion is generally referred to as an overdriving force. The probe tip 20b of each probe 20 slightly slides on the electrode 12a by the overdriving force and scrapes the surface of the electrode 12a by this slide. Generally, since the surface of the electrode 12a is covered with oxide (electrical insulating substance) of the electrode, non-conductivity may occur, and it is thought that reliable electrical contact can be attained by scraping of the surface.

However, when scrapes of the electrode 12a occurring at this time attach to the probe tip 20b, these attachments cause a failure such as non-conductivity by residing between the probe tip 20b and the electrode 12a at the time of subsequent tests of other integrated circuit areas of the semiconductor wafer 12 or another semiconductor wafer 12.

Under such circumstances, the cleaning apparatus according to the present invention shown in FIG. 1 is used for removal of foreign matters attached to the probe tip 20b of the probe 20.

The cleaning apparatus 40 according to the present invention comprises a base plate 42 and a surface layer 44 formed on the base plate as shown in FIG. 1. As the base plate 42, a silicon plate such as a silicon crystal substrate can be used. A surface 42a of the base plate 42 undergoes miltor processing by e.g., surface polishing as needed and thereafter is processed to become a rough surface by e.g., sandblast processing.

By this surface roughening, the surface 42a of the base plate 42 is formed so that the arithmetic mean roughness (Ra) may become 0.02 to 1.00 micrometers.

On the surface 42a of the base plate 42 that has undergone the surface roughening, the surface layer 44 is formed. This surface layer 44 is made of a metal material whose Vickers hardness (Hv) value is 400 to 600, which is smaller than that of the probe tip 20b. Such a metal material is represented by nickel or a nickel alloy.

This metal material for the surface layer 44 is deposited on the surface 42a to have a thickness of 0.05 to 1.0 micrometers by using, e.g., a spattering technique. By this deposition of the metal material, the surface layer 44 having a surface 44a approximately conforming to convexo-concave of the surface 42a of the base plate 42 is formed. This surface 44a of the surface layer 44 forms a smoother curve surfaced than the surface 42a of the base plate 42 does, and the arithmetic mean roughness (Ra) value of the surface 44a of the surface layer 44 is approximately 10% smaller than the arithmetic mean roughness value of the surface 42a of the base plate 42. Also, although convexo-concave corresponding to the corners of the convexo-concave of the surface 42a of the base plate 42 is formed on the surface 44a of the surface layer 44 in the schematic view of FIG. 1, the surface 44a with these corners is in fact a smooth curved surface. Thus, even in a case where corners are formed on the surface 42a of the base plate 42, no corner-like parts occur on the surface 44a of the surface layer 44. The surface layer 44 of the cleaning apparatus 40 according to the present invention does not contain conventional highly hard polishing agent at all, is lower in hardness (Hv) than the probe tip 20b of the probe 20, and has the surface 44a conforming to the surface 42a of the base plate 42. Accordingly, by letting the probe tip 20b of the probe 20 slide on the surface 44a of the surface layer 44 of the cleaning apparatus 40, foreign matters can be removed effectively without causing significant abrasion of the probe tip 20b.

As the base plate 42, an amorphous carbon plate, a silicon carbide plate, a ceramic plate, or the like can be used instead of the aforementioned silicon plate.

Also, the surface layer 44 can be formed by deposition of copper, a copper alloy, tungsten, a tungsten alloy, chromium, or a chromium alloy. The surface layer 44 is preferably one that is hard enough for the probe tip 20b of the probe 20 not to stick in the surface layer 44 when the probe tip 20b of the probe 20 is thrust toward the surface layer 44 at the time of cleaning of the probe 20 and that is less harder than the probe tip. Therefore, the material for the surface layer is determined by the relation with the hardness of the material for the probe tip.

Also, the surface layer 44 can be formed by deposition of an insulating material such as a gelled material or a silicon nitride film as well.

The present invention is not limited to the above embodiments but may be altered in various ways without departing from the spirit and scope of the present invention.

Claims

1. A cleaning apparatus for removing foreign matters attached to a probe, comprising:

a base plate having a rough surface; and

a surface layer formed to conform to and cover said rough surface for the purpose of providing a polishing surface for said probe and having lower hardness than hardness of a probe tip of said probe.

2. The cleaning apparatus according to claim 1, wherein said surface layer has a smooth surface along said rough surface.

3. The cleaning apparatus according to claim 1 or 2, wherein the thickness of said surface layer is 0.05 to 1.0 micrometers.

4. The cleaning apparatus according to claim 1, wherein the arithmetic mean roughness (Ra) of said rough surface is 0.02 to 1.00 micrometers.

5. The cleaning apparatus according to claim 1, wherein said base plate comprises a silicon plate whose surface is formed to be a rough surface by sandblast.

6. The cleaning apparatus according to claim 1, wherein the Vickers hardness (Hv) of the probe tip of said probe is 800 to 1000, and said surface layer is formed by depositing a metal material having the Vickers hardness (Hv) of 400 to 600 to cover said rough surface.

7. The cleaning apparatus according to claim 6, wherein said metal material is nickel or a nickel alloy.

8. The cleaning apparatus according to claim 2 wherein the arithmetic mean roughness (Ra) of said rough surface is 0.02 to 1.00 micrometers.

9. The cleaning apparatus according to claim 3 wherein the arithmetic mean roughness (Ra) of said rough surface is 0.02 to 1.00 micrometers.

10. The cleaning apparatus according to claim 2, wherein said base plate comprises a silicon plate whose surface is formed to be a rough surface by sandblast.

11. The cleaning apparatus according to claim 3, wherein said base plate comprises a silicon plate whose surface is formed to be a rough surface by sandblast.

12. The cleaning apparatus according to claim 4, wherein said base plate comprises a silicon plate whose surface is formed to be a rough surface by sandblast.