KR20130070895A - Probe card and fabricating method thereof - Google Patents

Abstract

PURPOSE: A probe card and a manufacturing method thereof increase the leakage distance between signal conductors, and suppress leakage current. CONSTITUTION: An insulating substrate (10) has multiple signal conductors (20). The insulating substrate is a ceramic substrate. The ceramic substrate is a low temperature co-fired ceramic substrate. A groove (30) is formed on the insulating substrate to surround the signal conductor. The sectional shape of the groove is u-shaped or V-shape.

Description

Probe card and fabrication method

The present invention relates to a probe card and a method of manufacturing the same, and more particularly, to a probe card having excellent leakage current characteristics and a method of manufacturing the same.

A general semiconductor test apparatus includes a tester, a performance board, and a probe card to test electrical characteristics of chips manufactured on a wafer.

A probe card used in a test apparatus such as a semiconductor IC is a device including a predetermined substrate and probes arranged on the substrate, and is used to measure electrical characteristics of a microelectronic device such as a semiconductor device.

The probe card of the semiconductor test apparatus receives a signal generated by the tester through the performance board and delivers it to the pads of the chip in the wafer, and transmits the signal output from the pads of the chip to the tester through the performance board. do.

The probe card forms an electrical path between the semiconductor device and an external electronic device (eg, a test device), thereby enabling electrical testing of the semiconductor device.

After the semiconductor wafer process, a test pattern is inserted into an empty space or a scribing space of the semiconductor wafer to examine the yield and process accuracy of the substrate. At this time, in order to inspect these test patterns, a test is performed using a probe card like a normal wafer.

In these tests, the inspection equipment or probe card must also have good electrical properties because the test patterns that are planted on the wafer are examined with very small currents.

In the past, a probe card was connected to a probe station to inspect a test pattern on a wafer, a signal was input to a wafer through a semiconductor inspection device, and a signal output from the wafer was input back to the inspection device through a probe card. .

At this time, the components constituting the probe card are probe tip (probe rod), space transformer, interposer pin, printed circuit board (PCB), straw It is in the order of ZIP connector.

These probe cards are used to test memory ICs and select ICs by checking overall timing performance, simple read and write performance, and DC characteristics.

However, in the case of logic ICs that are not memory ICs, but perform direct operations, the test items are mainly DC parameters and frequency characteristics. Especially when measuring DC parameters, there should be almost no disturbance component of the probe card.

In particular, the leakage current (leakage current) of the items to measure the current of hundreds of femto amps (fA) level of the leakage current on the probe card can be measured only the leakage current of the actual IC.

An object of the present invention is to provide a probe card having excellent leakage current characteristics and a method of manufacturing the same.

 One aspect of the invention is an insulating substrate formed with a plurality of signal conductors; And a groove formed in the insulating substrate to surround the signal conductor.

In one embodiment, the insulating substrate may include a ceramic substrate.

In one embodiment, the ceramic substrate may be a low temperature cofired ceramic substrate.

In one embodiment, the cross-sectional shape of the groove may be U-shaped or V-shaped.

In one embodiment, the groove may further include a fine groove.

In one embodiment, the cross-sectional shape of the microgroove may be U-shaped or V-shaped.

In one embodiment, the groove may be formed in a lattice shape on the insulating substrate.

In one embodiment, the leakage distance between the signal conductors may be 30 μm or more.

In one embodiment, the material of the signal conductor may include one or more selected from the group consisting of gold, silver, tin, lead, nickel, titanium, and alloys thereof.

Another aspect of the invention provides a method for manufacturing an insulating substrate including a signal conductor; Forming a groove between the signal conductors; And forming a fine groove in a portion of the groove.

In one embodiment, the insulating substrate may include a ceramic substrate.

In one embodiment, the ceramic substrate may be a low temperature cofired ceramic substrate.

In one embodiment, the cross-sectional shape of the groove may be U-shaped or V-shaped.

In one embodiment, the cross-sectional shape of the microgroove may be U-shaped or V-shaped.

In one embodiment, the groove may be formed in a lattice shape on the insulating substrate.

In one embodiment, the leakage distance between the signal conductors may be 30 μm or more.

In one embodiment, the material of the signal conductor may include one or more selected from the group consisting of gold, silver, tin, lead, nickel, titanium, and alloys thereof.

The probe card according to the present invention has excellent leakage current characteristics.

1 is a perspective view of a probe card according to an embodiment of the present invention.
2 is a plan view of FIG. 1.
3 is a cross-sectional view taken along line XX 'of FIG. 1.
4 is an enlarged view of a portion Z of FIG. 3.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

The embodiments of the present invention can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below.

Furthermore, embodiments of the present invention are provided to more fully explain the present invention to those skilled in the art.

The shape and the size of the elements in the drawings may be exaggerated for clarity and the same elements are denoted by the same reference numerals in the drawings.

1 is a perspective view of a probe card according to an aspect of the present invention. 2 is a plan view of FIG. 1. 3 is a cross-sectional view taken along line XX 'of FIG. 1. 4 is an enlarged view of a portion “Z” of FIG. 3.

1 to 4, a probe card, which is an aspect of the present invention, includes an insulating substrate 10, a plurality of signal conductors 20 formed on the insulating substrate 10, and a signal conductor 20 on the insulating substrate 10. It may include a groove 30 formed to surround the.

The insulation substrate 10 refers to a substrate having electrical insulation, and the insulation substrate may be a ceramic substrate made of a ceramic material. The insulating substrate may include a substrate made of a polymer resin or the like, but a ceramic substrate made of a ceramic material is preferable.

Ceramic substrates may include ceramic materials (HTCC, High Temperature Co-fired Ceramics) that sinter alumina, zirconia, etc. at high temperature, but are referred to as Low Temperature Co-fired Ceramics (LTCC). A substrate is preferable.

Alumina substrates have good electrical characteristics, but the thermal expansion coefficient is larger than that of silicon wafers, so that the temperature of the probe pad and the IC pads on the wafer can be displaced due to temperature changes.

In order to solve this problem, an LTCC ceramic substrate having a thermal expansion coefficient similar to that of a silicon wafer may be used.

However, LTCC ceramic substrates are difficult to apply to probe cards that test logic ICs because of their poor leakage current characteristics due to differences in crystallization structure.

Conventional ceramic multilayer substrates (HTCC) mainly composed of alumina or the like require a firing temperature of about 1500 ° C. or higher, whereas LTCC ceramic substrates can be “low temperature” at 1000 ° C. or lower by adding glass-based materials.

The biggest feature of LTCC is that by lowering the firing temperature, metals such as silver (Ag) or copper (Cu), which are inexpensive, have a low melting point and high electrical conductivity, can be used as the inner wiring material.

In addition, the addition of glass-based materials reduces the electromagnetic characteristics, but it can maintain the inherent characteristics of HTCC, which cannot be obtained in resin-based multilayer substrate technology such as high dielectric constant, low dielectric loss, high thermal conductivity, and thermal expansion coefficient similar to that of silicon.

In particular, LTCC has a similar thermal expansion coefficient to silicon, which is effective for mounting bare-chips and has high thermal conductivity, which may be used as an ideal semiconductor mounting substrate.

The green sheet for forming the LTCC substrate may be formed using a glass ceramic material.

For example, the green sheet may be SiO ₂ -CaO-Al ₂ O ₃ -based glass, SiO ₂ -MgO-Al ₂ O ₃ -based glass, SiO ₂ -B ₂ O ₃ -CaO-R ₂ O-based glass (here, R may be formed using at least any one of Li, Na, and K)

U-shaped and V-shaped grooves 30 may be formed in the insulating substrate 10. In addition, a U-shaped, V-shaped fine groove 40 may be further formed on the bottom surface of the groove 30.

However, it is not necessarily limited to U and V-shapes, and may be mixed for adjusting the leakage distance, or may be other shapes such as semicircles.

The leakage distance may vary according to the cross-sectional shape of the groove 30 and the fine groove 40, and may be appropriately selected or mixed according to design criteria.

The groove 30 may be formed in the insulating substrate 10 between the signal conductors 20. In order to prevent the disturbance of the signal by increasing the leakage distance 40 between the signal conductors 20 to suppress the leakage current.

As the groove 30 is deeply formed, the leakage distance 50 may increase.

The leakage distance 40 may mean a surface distance of the insulating substrate 10 existing between the signal conductor 20 and the signal conductor 20. If there is curvature on the surface of the insulating substrate 10, the distance measured along the curved surface can be said.

That is, referring to FIG. 4, the grooves 30 and the fine grooves 40 are formed between the signal conductors 20, and the distance measured along the curves may be referred to as “leakage distance 50”.

Since no current flows into the insulating substrate 10, current may flow along the surface of the insulating substrate 10 having a relatively lower insulating strength than the insulating substrate 10, which may be referred to as a “leakage current”. have.

If the leakage distance 50 is large, the path of the current becomes long, and thus the leakage current value may decrease.

The leakage distance between neighboring signal conductors may be 30um or more.

If the leakage distance is less than 30um, the signal may be disturbed by the leakage current flowing between the signal conductors.

The groove 30 may be formed to surround the signal conductor 20. In addition, the groove 30 may be formed in a lattice shape on the insulating substrate 10. Each signal conductor 20 may be completely isolated by a groove. This is to reduce the leakage current by increasing the leakage distance 50 between each signal conductor 20.

The insulating substrate 10 may be a low temperature cofired ceramic substrate having a similar thermal expansion coefficient to that of the silicon wafer. Although alumina and the like are excellent in insulating properties, it is not preferable to use alumina as an insulating substrate because there is a considerable difference from the silicon wafer in the coefficient of thermal expansion.

However, LTCC ceramic substrates may have lower leakage current characteristics than substrates such as alumina due to the crystal structure. It is necessary to supplement the leakage current characteristics of the LTCC ceramic substrate, and in the present invention, the grooves 30 and the fine grooves 40 are formed to complement the leakage current characteristics of the LTCC ceramic substrate.

The signal conductor 20 may refer to a conductive conductor capable of transmitting a signal. That is, the signal generated from the semiconductor inspection equipment may be transmitted to the semiconductor device, and the signal from the semiconductor device may be transferred to the semiconductor inspection equipment.

The signal conductor 20 is sufficient if it can transmit a signal. Specifically, the material of the signal conductor may include one or more selected from the group consisting of gold, silver, tin, lead, nickel, titanium, and alloys thereof.

Another aspect of the invention Manufacturing an insulating substrate 10 having a signal conductor 20 formed thereon; Forming a groove (30) between the signal conductors (20); And forming a fine groove 40 on the bottom surface of the groove 30.

The insulating substrate may be a ceramic substrate. A conductive paste may be printed on the ceramic green sheet to form a conductive internal circuit pattern, and then laminated and sintered to manufacture a ceramic substrate.

The ceramic substrate may be a low temperature cofired ceramic substrate. In this case, it can be sintered together with the internal circuit pattern at a low temperature of less than 1000 ℃. A plurality of signal conductors 20 may be formed on the ceramic substrate.

Grooves 30 may be formed in the insulating substrate between the signal conductors 20. The groove 30 can be formed by removing a portion of the insulating substrate using a laser or other mechanical punching process. The leakage distance 50 may be adjusted by adjusting the depth of the groove 30.

Fine grooves 40 may be additionally formed on the bottom surface of the grooves 30. The fine groove 40 may be used to more precisely adjust the leakage distance 50.

The cross section of the groove 30 may be U-shaped or V-shaped, the cross-sectional view of the fine groove 40 may be U-shaped or V-shaped.

The groove 30 may be formed in a lattice shape on the insulating substrate. The groove 30 may be formed to surround the signal conductor 20. Each signal conductor 20 may be completely isolated by the groove 30.

This is to reduce the leakage current by increasing the leakage distance 50 between each signal conductor 20.

The leakage distance between signal conductors may be 30um or more.

If the leakage distance is less than 30um, the signal may be disturbed by the leakage current flowing between the signal conductors.

The signal conductor 20 is sufficient if it can transmit a signal. Specifically, the material of the signal conductor may include one or more selected from the group consisting of gold, silver, tin, lead, nickel, titanium, and alloys thereof.

Other matters related to the insulated substrate, signal conductor and groove are the same as described above.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples.

The probe card according to the embodiment was prepared according to the following method.

First, ceramic powder for LTCC, ethanol as an organic solvent, polyvinyl butyral as a binder, and the like were mixed and ball milled to prepare a ceramic slurry. Ball milling was performed for 100 hours using zirconia balls.

A ceramic green sheet having a thickness of about 100 μm was manufactured from the ceramic slurry through the doctor blade method. Via holes penetrating the ceramic green sheet were formed.

The conductive paste was printed to print a circuit pattern on the ceramic green sheet. In the via hole, a conductive paste was filled to form a via conductor.

The via conductor was formed so as to connect the circuit pattern to each other through the ceramic green sheet. The thing containing silver (Ag) was used for the electrically conductive paste.

50 ceramic green sheets on which conductor circuit patterns and via conductors were formed were laminated, and then co-fired at 950 ° C. to prepare a ceramic substrate.

Next, grooves were formed in the sintered substrate using a laser. The grooves were formed in a U shape and fine grooves were also formed.

The comparative example was also prepared by the same method as the above example, except that no grooves or fine grooves were formed.

The distance between the conductors was constant at 30 μm, and when the grooves and the micro grooves were formed, the probes were prepared by dividing the grooves into only the grooves and not the micro grooves or the grooves.

After measuring the leakage current with respect to each probe card, the leakage distance was measured at the cut surface, and the result is shown in Table 1.

Leakage current was measured using a femto ammeter instrument. The leakage distance was determined by measuring the surface distance of the substrate between signal conductors. Specifically, the cross section of the substrate was photographed under a high magnification microscope, and then the surface distance of the substrate between signal conductors was measured.

The case where signal distortion occurred was determined to be defective.

division Distance between conductors
(um) home Fine groove Leakage distance
(um) Leakage current
(nA) Judgment Comparative Example 1 30 Unformed Unformed 30 1.3 Bad Comparative Example 2 formation Unformed 70 0.7 Bad Comparative Example 3 formation formation 75 0.6 Bad Example 1 formation formation 150 0.25 Good Example 2 formation formation 155 0.2 Good

Referring to Table 1, in Comparative Example 1, the distance between the signal conductors was 30 μm, and no grooves and fine grooves were formed. The leakage distance was 30 μm, the leakage current was 1.2 nA, and signal distortion occurred.

It is inferred that the leakage distance is large and the leakage current is large, resulting in signal distortion.

In Comparative Example 2, the distance between the signal conductors was 30 μm, the grooves were formed and the fine grooves were not formed. The leakage distance was 70 μm, the leakage current was 0.7 nA, and signal distortion occurred.

It is inferred that the leakage distance is large and the leakage current is large, resulting in signal distortion.

In Comparative Example 3, the distance between the signal conductors was 30 um, the grooves and the fine grooves were formed, the leakage distance was 75 um, the leakage current was 0.6 nA, and signal distortion occurred.

In Comparative Example 3, although both the grooves and the fine grooves are formed, it is inferred that the leakage distance is short, so that the leakage current is large and signal distortion occurs.

In Example 1, the distance between the signal conductors was 30 μm, the grooves and the fine grooves were formed, and the leakage distance was 150 μm. The leakage current value was 0.25 nA, and no signal distortion occurred.

In Example 2, the distance between the signal conductors is 30 μm, the grooves and the fine grooves are formed, and the leakage distance is 155 μm. The leakage distance is larger and the leakage current is smaller than that of the first embodiment. No distortion of the signal occurred.

In conclusion, according to Table 1, the leakage current can be reduced by increasing the leakage distance by forming the groove and the fine groove, it can be seen that the distortion of the signal can be prevented.

The terms used in the present invention are intended to illustrate specific embodiments and are not intended to limit the invention. The singular presentation should be understood to include plural meanings, unless the context clearly indicates otherwise.

Terms such as "comprises" or "having" mean that there is a feature, number, step, operation, component, or combination thereof described in the specification, but not intended to exclude it.

The present invention is not limited by the above-described embodiments and the accompanying drawings, but is intended to be limited only by the appended claims.

It will be apparent to those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. something to do.

10: ceramic substrate
20: signal conductor
30: home
40: fine groove
50: leakage distance
60: Distance between signal conductors

Claims (17)

An insulating substrate on which a plurality of signal conductors are formed; And
A groove formed in the insulating substrate to surround the signal conductor;
Probe card comprising a.
The method of claim 1,
And the insulating substrate is a ceramic substrate.
The method of claim 2,
The ceramic substrate is a low temperature cofired ceramic substrate.
The method of claim 1,
Probe card of the cross-sectional shape of the groove is U-shaped or V-shaped.
The method of claim 1,
The groove of the probe card further comprises a fine groove.
The method of claim 5,
The cross-sectional shape of the fine groove is a U-shaped or V-shaped probe card.
The method of claim 1,
And the groove is formed in a lattice shape on an insulating substrate.
The method of claim 1,
Probe card leakage distance between the signal conductor is more than 30um.
The method of claim 1,
And a material of the signal conductor comprises at least one selected from the group consisting of gold, silver, tin, lead, nickel, titanium and alloys thereof.
Manufacturing an insulating substrate having a signal conductor formed thereon;
Forming grooves in the insulating substrate between the signal conductors; And
Forming a fine groove in a portion of the groove;
Method of manufacturing a probe card comprising a.
The method of claim 10,
And the insulating substrate is a ceramic substrate.
The method of claim 10,
The ceramic substrate is a low temperature cofired ceramic substrate.
The method of claim 10,
A cross-sectional shape of the groove is a U-shaped or V-shaped probe card manufacturing method.
The method of claim 10,
The cross-sectional shape of the fine groove is a manufacturing method of the probe card U-shaped or V-shaped.
The method of claim 10,
The groove is a method of manufacturing a probe card formed in a grid shape on an insulating substrate.
The method of claim 10,
The leakage distance between the signal conductor is 30um or more method of manufacturing a probe card.
The method of claim 10,
And the material of the signal conductor comprises at least one selected from the group consisting of gold, silver, tin, lead, nickel, titanium and alloys thereof.

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