JPH04265863A - Probe needle - Google Patents

Abstract

PURPOSE:To enhance the isolation between conductor needles by coating one conductor needle among two conductor needles with a dielectric film excepting the tip part thereof and coating the dielectric film and the conductor surface of the other conductor needle with a dielectric substance. CONSTITUTION:In a probe needle, a dielectric film 7 is formed to one conductor needle 1 among two conductor needles 1 and a conductive substance 3 is applied to both conductor needles by vapor deposition excepting the tip parts thereof. By bringing the conductor needle 1 whose conductor surface is directly coated with the conductive substance 3 into contact with the high frequency earth electrode of an element to be measured, the element to be measured can be connected to the earth electrode on the probe needle with low parasitic inductance and the isolation between the conductor needles 1 is enhanced and the oscillation of the element to be measured is prevented and the reflection of an unnecessary signal can be suppressed.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is particularly applicable to microwave band ICs.
The present invention relates to probe needles used in the evaluation of high-speed devices such as the following.

0002

2. Description of the Related Art FIG. 8 is a block diagram showing an example of a conventional probe needle. In this figure, 1 is a conductor needle, 2 is a device to be measured, and 4 is a probe card board. Each conductor needle 1 and blade 5 are fixed on this probe card board 4. The blade 5 is generally a ceramic plate on which a microstrip line having a characteristic impedance of 50 ohms 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 the device under test 2 from oscillating.

Next, the operation will be explained. Generally, the device under test 2 is a high-speed device such as a microwave band IC,
A probe needle through which a high frequency signal can pass is used. For high frequency signals in the microwave band, a blade 5 is used on the probe card board 4 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 50Ω microstrip line, it becomes a distributed constant line with clear characteristics at high frequencies, and unnecessary reflections do not occur. Also, blade 5
Since the ground electrode of 5 is on the back side of the signal line, each blade 5
Another advantage is that the isolation between them is improved. However, in the part where the probe card board 4 and the device under test 2 are connected, such a brake is required due to dimensional constraints.
Therefore, the conductor needle 1 is used. However, in some cases, the conductor needle 1
Because the distance between them is about 10 μm, each conductor needle 1
There is a problem in that a parasitic capacitance is generated between the two. Particularly in the microwave band, the influence of this 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 schematically shows a cross-sectional view of the probe needle in FIG. There is. Generally, a signal needle that passes a microwave signal and a bias needle that applies a DC bias are used. In FIG. 8, the conductor needle 1 on the left side is a bias needle, and the conductor needle 1 on the right side is a signal needle. Even with a bias needle that applies a DC bias, the microwave signal of the device under test 2 leaks to the bias needle, so the microwave signal must be sufficiently high in the microwave band to prevent this leaked microwave signal from leaking to other conductor needles 1. Isolation is required. Furthermore, a chip capacitor 6 is added as a bypass capacitor for high frequency removal so that the device under test 2 is stable at high frequencies.

[0005]

[Problems to be Solved by the Invention] However, since the conductor needle 1 with a length of several mm is inserted between the chip capacitor 6 and the device to be measured 2, the inductance of the conductor needle 1 is introduced, and the high frequency It no longer necessarily functions as a good bypass capacitor. For this reason, a problem has arisen in that the device under test 2 oscillates in some cases.

In the conventional example described above, 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 resistance capacitor), microwave stability can be achieved. It is known that accurate measurements can be made. In this case as well, the inductance of the conductor needle 1 weakens the oscillation prevention effect, posing a problem. In addition, although the part of the blade 5 was a distributed constant line with a constant characteristic impedance, the part of the conductor needle 1 no longer functioned as a distributed constant line, and the characteristic impedance was constant.
The dance will be different. Therefore, unnecessary reflection occurs at the conductor needle 1 in the high frequency band. Furthermore, in the configuration of the conventional probe needles as described above, a parasitic capacitance C occurs between the conductor needles 1, and the isolation between the conductor needles 1 deteriorates. In addition, since the conductor needle 1 is inserted between the chip capacitor 6 used as a bypass capacitor for high frequency removal and the device under test 2, the inductance of the conductor needle 1 is introduced, which may cause the device under test 2 to oscillate. I end up. Further, there were other problems such as the conductor needle 1 portion not functioning as a distributed constant line and causing unnecessary reflections in high frequency bands.

The present invention has been made in order to solve the above-mentioned problems, and provides a project that can reduce the parasitic capacitance between the conductor needles and improve the isolation between the conductor needles.
The purpose is to obtain a needle.

[0008]

[Means for Solving the Problems] The invention as set forth in claim 1 of the present invention is to cover at least one of the conductor needles with a dielectric film except for the tip, and to cover the surface of the dielectric film with a dielectric film. The conductor surface of another conductor needle is covered with a conductive material and electrically connected.

[0009] Furthermore, the invention according to claim 2 provides a method for covering at least one of the conductor needles with a dielectric film or a resistor film except for the tip, and covering the top with a resistor film or a dielectric film. The upper film surface of the resistor film or dielectric film and the conductor surface of another conductor needle are covered with a conductive material and electrically connected.

[0010] The invention according to claim 3 also provides a conductor needle covered with a dielectric film, and a conductor whose conductor surface is covered with a conductive material and which is electrically connected to the dielectric film surface. The needles are arranged alternately.

[0011]

[Function] The probe needle according to claim 1 of the present invention covers the conductor needle with a dielectric film, and further covers the surface of the dielectric film and the conductor surface of the other conductor needle with a conductive material. As a result, a so-called coaxial line can be formed up to just before the device to be measured, and the isolation between the conductor needles is improved.

Further, the probe needle according to claim 2 of the present invention is electrically compatible with a state in which a resistive capacitor is added immediately before the element to be measured by covering the conductive needle with a dielectric film and a resistive film. An equivalent state can be realized, 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.

Further, the probe needle according to claim 3 of the present invention includes a conductor needle covered with a dielectric film, and a conductor surface covered with a conductive material, and an electrical connection between the dielectric film surface and the conductor needle. By alternately providing a required number of conductor needles that are connected to each other, the characteristic impedance of the conductor needles is good even in a high frequency band, and unnecessary reflections do not occur.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of the configuration of a probe needle showing an embodiment of the invention according to claim 1, in which 3 is a conductive material covering the conductor needle 1, and other symbols are This figure 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, and 7 is a dielectric film. In manufacturing, after forming the dielectric film 7 on the conductor needle 1 by vapor deposition using a method such as sputtering, both conductor needles 1 are fixed to the blade 5 on the probe card substrate 4. Each blade 5 is fixed to the probe card board 4 by a method such as soldering according to the pad arrangement of the device to be measured 2. Thereafter, a conductive substance 3 is deposited or applied onto each conductor needle 1 except for the tip of the conductor needle 1, thereby forming a probe needle having the cross-sectional shape shown in FIG. In the semiconductor device evaluation method of the present invention, the conductor needle 1
By directly contacting the probe covered with conductive substance 3 on the conductor surface of the probe to the high-frequency ground electrode of the device under test 2, it is possible to connect the probe needle with the ground electrode with low parasitic inductance. Improved isolation between needles 1,
It is possible to prevent oscillation of the device under test 2 and suppress reflection of unnecessary signals.

3 to 5 are sectional views similar to FIG. 2 showing embodiments of the invention according to claim 2 of the present invention, and 8 is a resistor film, and the dielectric film of FIG. It can be formed by the same process as the film 7.

Hereinafter, first, an embodiment of the invention according to claim 1 shown in FIGS. 1 and 2 will be described in detail. As shown in FIG. 1, the conductor needle 1 is covered with a conductive substance 3 up to the vicinity of the device to be measured 2, and as can be seen from the A-A' cross section shown in FIG. surface and the right conductor needle 1
It is electrically connected to the surface of the upper dielectric film 7. By connecting the left conductor needle 1 to the ground electrode of the device to be measured 2 or a power supply terminal equivalent to the ground electrode in terms of high frequency, the right conductor needle 1 becomes a so-called coaxial line. Since the coaxial line is configured in this way, the parasitic capacitance C with other conductor needles 1 is eliminated, and the characteristic impedance of the line is kept constant, so that unnecessary reflection of high frequency signals 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. As shown in FIGS. That is, in FIG. 3, one conductor needle 1 is covered with a dielectric film 7, which is covered with a resistor film 8. FIG. 4 shows a configuration opposite to that of FIG. 3, that is,
One of the conductor needles 1 is covered with a resistor film 8, which is covered with a dielectric film 7. Further, FIG. 5 shows an example in which two layers of the dielectric film 7 and the resistor film 8 of FIG. 3 are alternately provided.

In this way, the dielectric film 7 and the resistor film 8
By providing them alternately, a series capacitor and a resistor are added to the conductor needle 1. This is equivalent to the conventional example in which a resistor is connected in series to the chip capacitor 6 (resistance capacitor), and is effective in preventing oscillation of the circuit under test. Furthermore, as shown in FIG. 1, by forming the capacitor and resistor close to the device under test 2, the parasitic inductance between the device under test 2 and the device under test 2 can be reduced, resulting in good oscillation even in high frequency bands. Prevention is 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, a conductor needle 1 covered with a dielectric film 7 and a conductor needle 1 whose conductor surface is covered with a conductive substance 3 and which are electrically connected to the dielectric film 7 surface are used. Since the ground wires of the distributed constant line in the device under test 2 and the ground wire on the probe needle can be connected with low inductance, disturbances in the characteristic impedance of the line are reduced and unnecessary. signal reflection is less likely to occur. 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 is not covered by the conductive substance 3.
Because the ground electrode is nearby at the tip of the line, it can be seen as a distributed constant line, and reflection of high-frequency signals can be reduced.

[0021]

[Effect of the invention] As explained above, claim 1 of the present invention
In the invention described in , at least one of the conductor needles is covered with a dielectric film except for the tip, and the surface of the dielectric film and the conductor surfaces of the other conductor needles are covered with a conductive material and electrically conductive. Since the wires are connected directly, a so-called coaxial line can be formed up to just before the device to be measured, which has the effect of reducing parasitic capacitance between the conductor needles, that is, improving isolation.

[0022] Furthermore, the invention according to claim 2 of the present invention includes:
At least one of the conductor needles is covered with a dielectric film or a resistor film except for the tip, and the upper film surface of the resistor film or dielectric film is covered with a resistor film or a dielectric film. Since the conductor surface of the conductor needle and the conductor surface of the other conductor needle are covered with a conductive material and electrically connected, this is equivalent to adding a resistive capacitor just before the device to be measured, and has the effect of preventing oscillation of the device to be measured.

[0023] Furthermore, the invention according to claim 3 of the present invention includes:
Since conductor needles covered with a dielectric film and conductor needles whose conductor surface is covered with a conductive substance and which are electrically connected to the dielectric film surface are provided alternately, the characteristic impedance of the conductor needles is −
This makes it possible to connect wires with less disturbance even in high-frequency dance bands, reducing unnecessary signal reflections.

[Brief explanation of the drawing]

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. 1;

FIG. 3 is a sectional view corresponding to the sectional view taken along line AA' in FIG. 1, showing another embodiment of the present invention.

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

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

FIG. 6 A-A in FIG. 1 showing still another embodiment of the present invention.
FIG.

FIG. 7 A-A in FIG. 1 showing still another embodiment of the present invention.
FIG.

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

9 is a sectional view taken along line BB' in FIG. 8;

[Explanation of symbols]

1 Conductor needle 2 Element to be measured 3 Conductive substance 4 Probe card board 5 Blade 6 Chip capacitor 7 Dielectric film 8 Resistor film

Claims (3)

[Claims] 1. A probe needle having at least two conductor needles arranged according to the pad arrangement of an object to be measured,
At least one of the conductor needles is covered with a dielectric film except for the tip, and the surface of the dielectric film and the conductor surface of the other conductor needles are covered with a conductive material and electrically connected. A probe needle characterized by: 2. A probe needle having at least two conductor needles arranged according to the pad arrangement of the object to be measured,
At least one of the conductor needles is covered with a dielectric film or a resistor film except for the tip, and the top thereof is covered with a resistor film or a dielectric film, and the upper part of the resistor film or dielectric film is covered with a resistor film or a dielectric film. A probe needle characterized in that the membrane surface and the conductor surface of another conductor needle are covered with a conductive material and electrically connected. 3. A probe needle having a conductor needle arranged according to the pad arrangement of the 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 characterized in that conductor needles electrically connected to the surface of the dielectric film are provided alternately.