JP2765247B2 - Probe needle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention particularly relates to a microwave band IC.
And the like, which relates to a probe needle used for evaluating a high-speed device such as the one shown in FIG.

[0002]

2. Description of the Related Art FIG. 8 is a structural view showing an example of a conventional probe needle. In this figure, 1 is a conductor needle, 2 is an element to be measured, 4 is a probe card board, The conductor needles 1 and the blades 5 are fixed on the probe card substrate 4. The blade 5 is generally a ceramic plate on which a microstrip line having a characteristic impedance of 50Ω is formed. Reference numeral 6 denotes a chip capacitor, which generally has a capacitance of several tens of μF to several μF, and is used to prevent oscillation of the device under test 2.

Next, the operation will be described. Generally, the device under test 2 is a high-speed device such as a microwave band IC,
A probe needle that can pass a high-frequency signal is used. In the microwave band high frequency signal, a blade 5 is used on the probe card substrate 4 in order to prevent signal interference between the conductor needles 1 and to avoid unnecessary reflection in the microwave band. . Since the blade 5 is generally a 50 Ω microstrip line, it is a distributed constant line whose characteristics are clearly high-frequency, and does not cause unnecessary reflection. Further, since the ground electrode of the blade 5 is located on the back surface of the signal line, there is an advantage that the isolation between the blades 5 is improved.
However, in the portion where the probe card substrate 4 and the device under test 2 are connected, such a breakage occurs due to dimensional restrictions.
And the conductor needle 1 is used. However, in the vicinity of the element 2 to be measured, the conductor needle 1
Since the distance between them is close to about 10 μm, each conductor needle 1
There is a problem that a parasitic capacitance occurs between them. In particular, in the microwave band, the effect of the parasitic capacitance is large, and in some cases, the characteristics of the device under test 2 may change due to interference between the conductor needles 1, which is a problem.

FIG. 9 is a schematic cross-sectional view taken along the line BB 'of the probe needle of FIG. 8, showing that a parasitic capacitance C is generated between the conductor needles 1. As shown in FIG. I have. Generally, a signal needle for passing a microwave signal and a bias needle for applying a DC bias are used. In FIG. 8, the conductor needle 1 on the left is a bias needle, and the conductor needle 1 on the right is a signal needle. Even with a bias needle that applies a DC bias, since the microwave signal of the device under test 2 leaks to the bias needle, the microwave signal in a microwave band sufficient to prevent the leaked microwave signal from leaking to another conductor needle 1 Isolation is required. Further, a chip capacitor 6 is added as a high-frequency removing bypass capacitor so that the device under test 2 is stable at high frequencies.

[0005]

However, since the conductor needle 1 having a length of about several mm is inserted between the chip capacitor 6 and the device under test 2, the inductance of the conductor needle 1 is included, and the frequency is reduced in terms of high frequency. It did not always function as a good bypass capacitor. For this reason, there has been a problem that the device under test 2 oscillates in some cases.

In the above conventional example, a chip capacitor 6 is added as shown in FIG. 8, but by adding a capacitor and a resistor connected in series (hereinafter, referred to as a resistor capacitor), microwave stability is obtained. It is known that various measurements can be made. In this case, the inductance of the conductive needle 1 also weakens the oscillation prevention effect, which is a problem. The distributed constant line having a constant characteristic impedance is provided at the blade 5 portion, but does not function as the distributed constant line at the conductor needle 1 portion.
The dance is different. Therefore, in the high frequency band, unnecessary reflection occurs at the portion of the conductor needle 1. Furthermore, in the conventional probe needle configuration as described above, a parasitic capacitance C is generated between the conductor needles 1 and the isolation between the conductor needles 1 is deteriorated. In addition, since the conductor needle 1 enters between the chip capacitor 6 used as a high-frequency removal bypass capacitor and the device under test 2, the inductance of the conductor needle 1 enters, and in some cases, the device under test 2 oscillates. Would. Further, there is a problem that the portion of the conductor needle 1 does not function as a distributed constant line and unnecessary reflection occurs in a high frequency band.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and can reduce the parasitic capacitance between the conductor needles and improve the isolation between the conductor needles.
The purpose is to get the needle.

[0008]

According to a first aspect of the present invention, at least one of the conductive needles is covered with a dielectric film except for a tip portion, and the conductive needle is covered with a dielectric film. Conductive substance by vapor deposition or coating on the conductor surface of another conductor needle
And electrically connected.

According to a second aspect of the present invention, at least one of the conductive needles is covered with a dielectric film or a resistive film except for a tip portion, and a resistive film or a dielectric film is formed thereon. , And the upper film surface of the resistor film or the dielectric film and the conductor surface of another conductor needle are covered with a conductive substance and electrically connected.

According to a third aspect of the present invention, there is provided a conductive needle covered with a dielectric film, and a conductor covered on a conductive surface with a conductive material and electrically connected to the dielectric film surface. Needles are provided alternately.

[0011]

The probe needle according to the first aspect of the present invention covers the conductor needle with a dielectric film, and further covers the dielectric film surface and the conductor surface of another conductor needle with a conductive material. Thus, a so-called coaxial line can be formed immediately before the element to be measured, and the isolation between the conductor needles is improved.

In the probe needle according to the present invention, the conductor needle is covered with a dielectric film and a resistance film, so that the probe needle is electrically connected to a state in which a resistance capacitor is added immediately before the element to be measured. An equivalent state can be realized, the parasitic inductance generated between the device under test and the device under test can be reduced, and oscillation of the device under test can be prevented.

According to a third aspect of the present invention, there is provided a probe needle having a conductor needle covered with a dielectric film, and a conductor surface covered with a conductive material. Since the required number of conductive needles are alternately provided, the characteristic impedance of the conductive needles is good even in a high frequency band, and unnecessary reflection does not occur.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing the structure of a probe needle according to an embodiment of the present invention. In FIG. 1, reference numeral 3 denotes a conductive material covering the conductor needle 1, and other reference numerals designate the same. 10 shows the same components as those in FIGS. 8 and 9.

FIG. 2 shows a cross section taken along the line AA 'in FIG. 1. Reference numeral 7 denotes a dielectric film. In manufacturing, a dielectric film 7 is formed by vapor deposition on the conductor needle 1 by a method such as sputtering, and then both the conductor needles 1 are fixed to a blade 5 on a probe card substrate 4. The blades 5 are fixed to the probe card substrate 4 according to the pad arrangement of the device under test 2 by soldering or the like. Thereafter, a probe needle having a cross-sectional shape shown in FIG. 2 can be formed by depositing or applying a conductive material 3 on each of the conductive needles 1 except for the tip of the conductive needle 1. In this case, deposit or apply a highly viscous material
As shown in FIGS. 10 (a), (b) and (c),
The space between the conductor needles 1 gradually fills as the film thickness increases.
The conductive material 3 fills the space as shown in FIG.
Is done. In the method for evaluating a semiconductor device according to the present invention, a probe having a conductor surface directly covered with a conductive material 3 is brought into contact with a high-frequency ground electrode of the device under test 2 by a probe. Can be connected to the ground electrode with low parasitic inductance, the isolation between the conductor needles 1 can be improved, the oscillation of the device under test 2 can be prevented, and unnecessary signal reflection can be suppressed.

FIGS. 3 to 5 are sectional views similar to FIG. 2 showing an embodiment of the invention according to the second aspect of the present invention. Reference numeral 8 denotes a resistor film, and FIG. It can be formed by a process similar to that of the film 7.

First, an embodiment of the invention described in claim 1 shown in FIGS. 1 and 2 will be described in detail. As shown in FIG. 1, the conductive needle 1 is covered with a conductive substance 3 up to the vicinity of the device 2 to be measured. As can be seen from the cross section AA 'shown in FIG. Face and conductor needle 1 on the right
The surface of the upper dielectric film 7 is electrically connected. By connecting the left conductive needle 1 to a ground electrode of the device under test 2 or a power supply terminal equivalent to the ground electrode in high frequency, the right conductive needle 1 becomes a so-called coaxial line. As described above, the coaxial line configuration eliminates the parasitic capacitance C between the conductor needles 1 and the other conductor needles 1. Further, the characteristic impedance of the line becomes constant, so that unnecessary high-frequency signal reflection is reduced.

Next, an embodiment of the invention according to claim 2 shown in FIGS. 3 to 5 will be described. In these examples,
As shown in FIGS. 3 to 5, the conductor needle 1 is covered with a dielectric film 7 and a resistor film 8. That is, in FIG. 3, one of the conductor needles 1 is covered with a dielectric film 7 and the other is covered with a resistor film 8. FIG. 4 shows a configuration opposite to that of FIG.
One of the conductor needles 1 is covered with a resistor film 8, and the other is covered with a dielectric film 7. FIG. 5 shows a structure in which the dielectric film 7 and the resistor film 8 of FIG. 3 are alternately provided in two layers.

As described above, the dielectric film 7 and the resistor film 8
Are alternately provided, which means that a series capacitor and a resistor are added to the conductor needle 1. This is equivalent to the one in which a resistor is connected in series to the chip capacitor 6 shown in the conventional example (resistor capacitor), and is effective in preventing oscillation of the circuit under test. Further, as shown in FIG. 1, since the capacitor and the resistor can be formed in the vicinity of the device under test 2, the parasitic inductance interposed between the device and the device under test 2 can be reduced. Prevention becomes possible.

Next, an embodiment of the invention according to claim 3 shown in FIGS. 6 and 7 will be described. In the embodiment of FIG. 6, the conductor needle 1 covered with the dielectric film 7 and the conductor needle 1 covered on the conductor surface with the conductive substance 3 and electrically connected to the surface of the dielectric film 7 are combined. Since the grounding line of the distributed constant line in the device under test 2 and the grounding line on the probe needle can be connected with low inductance, the characteristic impedance of the line is less disturbed and unnecessary. Signal reflection hardly occurs. In the embodiment shown in FIG. 7, the dielectric film 7 of FIG. 6 is further covered with a resistor film 8. In these embodiments, the conductor needle 1 not covered by the conductive substance 3
Since the ground electrode is also in the vicinity of the tip of the device, it can be regarded as a distributed constant line, and the reflection of high-frequency signals can be reduced.

[0021]

As described above, according to the first aspect of the present invention,
According to the invention described in (1), at least one of the conductor needles is covered with a dielectric film except for the tip, and the conductive film is formed on the dielectric film surface and the conductor surface of another conductor needle by vapor deposition or coating . Since it was covered with a substance and electrically connected,
A so-called coaxial line can be used to reduce the parasitic capacitance between the conductor needles, that is, to improve the isolation. Also, since the conductive material is formed by vapor deposition or coating, no mechanical stress is applied , and the pitch is narrow. , Many
There is an effect that even those having needles and those having complicated shapes can be easily formed. After fixing the conductor needle,
Protects the needle tip by using a conductive material such as resin containing Ag paste.
By spraying an electrically conductive and highly viscous substance onto the needle,
A conductive substance can be applied without applying stress.
In the case of vapor deposition, it can be formed similarly. Also, this method uses a needle
Since only the tip needs to be protected, several tens to
Position can be covered with a conductive material.
It can be significantly shorter than the conventional method of several mm
To realize a conductive needle that can be used up to higher frequencies
There is.

[0022] The invention described in claim 2 of the present invention provides:
At least one of the conductive needles is covered with a dielectric film or a resistive film except for a tip portion, and is covered with a resistive film or a dielectric film, and an upper film surface of the resistive film or the dielectric film is covered. And the conductor surface of another conductor needle are covered with a conductive material and electrically connected, which is equivalent to a state in which a resistance capacitor is added immediately before the device under test, and has the effect of preventing oscillation of the device under test.

[0023] The invention according to claim 3 of the present invention provides:
Since the conductor needle covered with the dielectric film and the conductor needle covered with the conductive material on the conductor surface and electrically connected to the dielectric film surface are provided alternately, the characteristic impedance of the conductor needle is provided. −
Even if the dance is in a high frequency band, connection with less disturbance can be performed, and unnecessary signal reflection can be reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a probe needle according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA 'of the embodiment of FIG.

FIG. 3 is a cross-sectional view corresponding to a cross-sectional view taken along line AA ′ of FIG. 1 showing another embodiment of the present invention.

FIG. 4 is a cross-sectional view corresponding to a cross-sectional view taken along line AA ′ of FIG. 1, showing another embodiment of the present invention.

FIG. 5 is a sectional view corresponding to a sectional view taken along line AA ′ of FIG. 1 showing another embodiment of the present invention.

FIG. 6 is a cross-sectional view showing a still further embodiment of the present invention;
It is sectional drawing equivalent to the sectional view by the A 'line.

FIG. 7 is a cross-sectional view showing a still further embodiment of the present invention.
It is sectional drawing equivalent to the sectional view by the A 'line.

FIG. 8 is a perspective view showing an example of a conventional probe needle.

FIG. 9 is a cross-sectional view taken along line BB ′ of FIG.

FIG. 10 is a view illustrating a process of forming the conductive material of FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Conductor needle 2 Device under test 3 Conductive substance 4 Probe card substrate 5 Blade 6 Chip capacitor 7 Dielectric film 8 Resistor film

Claims (3)

(57) [Claims] 1. A probe needle having at least two conductor needles arranged according to a pad arrangement of an object to be measured,
It said at least one conductor needles of conductive needles except tip covered by a dielectric film, covered with a conductive material by vapor deposition or coating and over said dielectric layer surface on the conductor surface of the other conductors needle electric A probe needle characterized by being electrically connected. 2. A probe needle having at least two conductor needles arranged according to a pad arrangement of an object to be measured,
At least one of the conductive needles is covered with a dielectric film or a resistive film except for a tip portion, and is covered with a resistive film or a dielectric film. A probe needle, wherein a film surface and a conductor surface of another conductor needle are covered with a conductive substance and electrically connected. 3. A probe needle having a conductor needle arranged according to a pad arrangement of an object to be measured, wherein the conductor needle is covered with a dielectric film, and the conductor surface is covered with a conductive substance;
A probe needle , wherein the conductive needle and the electrically conductive needle are alternately provided on the surface of the dielectric film.