JPH05302939A - Method for measuring probe card and high-frequency element - Google Patents

Abstract

PURPOSE:To measure a high-frequency element highly accurately by inclining the tips of probes, which are connected to the electrodes of a material to be measured, and arranging the input and output probes at angles so that the probes are hardly affected by electromagnetic induction. CONSTITUTION:In a probe card, wirings 4 (4a-4d) are formed on the surface of a substrate 1. Interconnection connector parts 6 to a testing apparatus are connected to probes 2 (2a-2d), which are attached to the rear surface. Oscillation preventing circuits 5a and 5b, each comprising capacitor having the specified capacitance, are connected between the output probe 2b and the grounding probe 2d and between the power-supply probe 2c and the grounding probe 2d. Thus, the oscillation at a low frequency is prevented. A resin ring 3, which is attached to the rear surface of the substrate 1, is in contact with the side surfaces of the probes 2. The probes 2 are positioned so as to extend downward obliquely. The probes 2 comprise the probes 2a-2d for input, output, power supply and grounding. The probes 2a and 2b form the angle of about 91.8 deg. at the horizontal plane to each other and are arranged at the solid angle of 40 deg.. The probes are hardly affected by electromagnetic induction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a probe card and a method of measuring a high frequency element. More specifically, the present invention relates to a probe card that prevents generation of noise due to an induced current and a method for measuring a high frequency element.

[0002]

2. Description of the Related Art Conventionally, when investigating the performance of a high-frequency element such as a high-frequency FET in a manufacturing process, etc., in the state of a chip or a semiconductor wafer before dicing, a probe is brought into contact with an electrode pad of each element to make a direct current. The characteristics such as input / output characteristics (static characteristics) when flowing is measured. The measurement using this kind of probe is carried out, for example, in JP-A-1-20.
A probe card as disclosed in 1166 or Japanese Patent Laid-Open No. 2-285264 is used. FIG. 9 shows a plan view of a probe card of this type which has been conventionally used, and its X-
A cross-sectional view taken along the line X is shown in FIG. 10, and a plan view of the electrode pad portion of the high frequency FET is shown in FIG.

This probe card has electrical wiring 4 (4a, 4a, 4a) on the surface of a substrate 1 made of glass or epoxy resin.
b, 4c, 4d), and the probe 2 (2a, 2b, 2c, 2d) is provided on the back surface of the substrate 1 with the electrical wiring 4
And is formed in a radial shape. The tip of the probe 2 is obliquely arranged so as to be separated from the substrate 1, or is bent so as to be completely in contact with the DUT 7. In order to ensure the contact of the probe 2 with the object to be measured 7, the probe 2 is provided with a spring property by the fixing ring 3 made of resin. Each electrical wiring 4
An oscillation prevention circuit 5 (5a, 5b) formed of a capacitor C and a resistor R is formed between a, 4b, 4c, and 4d, and the end of each electrical wiring 4 is connected to a test device. A connector 6 is formed on the. Each probe 2 of this probe card is brought into contact with each electrode of the object to be measured to measure static characteristics and the like. For example, when examining the characteristics of a high-frequency FET as the device under test 7, the gate electrode G of the FET,
Each electrode pad of the source electrode S and the drain electrode D is shown in the figure.
11, the gate electrode probe 2f, the source electrode probe 2g, and the drain electrode probe 2h are connected in a positional relationship as shown in FIG. Therefore, the gate electrode probe 2f for input
And the drain electrode probe 2h for output is almost 18
They are arranged in a 0 ° relationship.

[0004]

When the characteristic test of the high frequency element is conducted with the above-mentioned configuration of the probe card, there is a problem that abnormal oscillation occurs and accurate measurement cannot be performed.

In order to stop this oscillation, as described above, the oscillation preventing circuit 5 including the capacitance C and the resistor R is formed between the electrical wirings 4 to prevent the oscillation. Although the prevention of oscillation by R is effective for a relatively low frequency of several hundred MHz or less, it has no effect for a high frequency of 2 to 5 GHz, and there is a problem that high frequency oscillation is likely to occur.

In particular, when the input probe and the output probe are in a positional relationship close to 180 °, there is a problem that noise is generated in the input probe due to electromagnetic induction due to the output current, which is amplified and oscillates.

In view of the above problems, it is an object of the present invention to provide a probe card which has low noise and does not oscillate even in a high frequency region, and to provide a method for measuring a high frequency element efficiently and accurately. ..

[0008]

A probe card according to the present invention has a plurality of probes which are electrically connected to a substrate and which are connected to the wires and whose tips are connected to electrodes of an object to be measured. The probe is tilted so that the tip of the probe is separated from the substrate, and at least two probes for input and output are arranged so as to form an angle less susceptible to electromagnetic induction.

The measuring method of the high-frequency element according to the present invention is a measuring method of a high-frequency element in which a plurality of probes are brought into contact with each electrode of the high-frequency element to measure high-frequency characteristics. It is characterized in that it is arranged obliquely with respect to the horizontal plane, and at least the input and output probes are arranged at an angle that is less likely to be affected by electromagnetic induction.

[0010]

According to the present invention, at least the input probe and the output probe of the plurality of probes connected to the respective electrodes of the high frequency element are formed so as to have an angle that is not easily influenced by electromagnetic induction. The phenomenon that an induced current is generated in another probe by the magnetic field generated by the current flowing in one probe does not occur.

From this point of view, it is most preferable that each probe makes an angle of 90 ° so that the interaction of electromagnetic induction does not completely appear, but it is not necessarily 90 °.
In the range of 60 to 120 °, the interaction due to electromagnetic induction is greatly reduced and oscillation can be suppressed.

Further, in this probe, particularly, the relation between the input probe and the output probe is arranged at the above-mentioned angle, so that the oscillation particularly due to the feedback can be prevented. This is because when the output noise is coupled to the input, it is amplified by the high-frequency element and appears at the output, and it is coupled to the input as large noise, leading to oscillation, but both probes are affected by electromagnetic induction. This is because the vicious cycle does not occur because the output and the input are not combined at a certain angle.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a probe card of the present invention will be described with reference to the drawings. 1 is an explanatory plan view showing an embodiment of a probe card of the present invention, FIG. 2 is a sectional view taken along the line II-II of FIG. 1, FIG. 3 is a schematic diagram showing a three-dimensional arrangement of the probes of FIG.
4 is an explanatory plan view showing another embodiment of the probe card of the present invention, FIG. 5 is a sectional view taken along the line VV of FIG. 4, FIG. 6 is a schematic view showing the three-dimensional arrangement of the probe of FIG. 4, and FIGS. 8 is a graph showing static characteristics of a high frequency FET measured using the probe card of the present invention. 1 and 2 show the structure of a probe card for measuring a high-frequency amplifier having a four-terminal probe. Like the conventional probe card, the probe card shown in FIG. 1 has wirings 4 (4a, 4a, 4a, 4a) on the surface of a substrate 1 made of glass or an epoxy printed board.
b, 4c, 4d) are formed, the probe 2 (2a, 2b, 2c, 2d) attached to the back surface is connected to the connector portion 6 for connecting to the test apparatus, and the output probe 2b and the ground are connected. 10 between the probe for power supply 2d and between the probe for power supply 2c and the probe for ground 2d, respectively.
Oscillation prevention circuits 5a and 5b composed of capacitors of 00 pF and 10,000 pF are connected to prevent low frequency oscillation.

The wiring 4 and the like may be formed on the back surface of the substrate 1. Further, the probes 2 are radially attached to the back surface of the substrate 1, and the tips are bent downward so that they can be separated from the substrate. The resin ring 3 attached to the back surface of the substrate 1 contacts the side surface of the probe 2 to position and fix the probe 2 so as to extend obliquely downward. In this embodiment, the probe 2 is mounted on the substrate 1.
It is positioned so that it forms an angle of about 10 ° downward from.

The probe 2 comprises four probes 2a, 2b, 2c, 2d for input, output, power supply, and ground. The input probe 2a and the output probe 2b are provided.
Form an angle of about 91.8 ° with respect to each other in the horizontal plane (projection onto the substrate 1). Two probes 2 arranged by this
The angles a and 2b are stereoscopically 90 °.

According to the present invention, the input probe 2a and the output probe 2b are arranged so as to have a three-dimensional relationship of 90 °, so that the mutual relationship due to electromagnetic induction is eliminated. In addition, each probe has a certain downward angle (or upward direction) so as to make sure contact with the object to be measured 7 and to prevent the root of the probe from contacting the object to be measured 7. Must have Therefore, in this embodiment, the probe is tilted downward at an angle of about 10 °. The mutual relationship for the probes tilted downward at about 10 ° to have a 90 ° relationship with each other will be described in more detail with reference to FIG.

In FIG. 3, 2a and 2b are from the substrate surface A, respectively.
The position of the probe is shown tilted by 10 °.
B and C are connection points of the probe with the substrate 1, and D and
E indicates the tips of the probes 2a and 2b, respectively, and the intersection of the extensions is P. In the present invention, the angle at which the two intersect is set to 90 ° as much as possible. Now BP = CP =
If m is m and the projection length BO = CO on the substrate surface A is n, the angle θ formed by the two probes projected on the substrate surface can be obtained as follows.

The relationship between m and n is cos 10 ° = n / m.

Further, if the second cosine law is applied to the triangular BOC to solve for θ, 2m ² = n ² + n ² -2n · n cos θ cos θ = 1- (1 / cos 10 °) ² Therefore θ = 91.7817 ° is obtained. available.

In this way, the input probe and the output probe are arranged on the substrate so as to have a relation of about 92 °,
The input probe 2a and the output probe 2b form an angle of 90 ° by bending downward so as to have an inclination of, and a magnetic field is generated around the probe 2b as a central axis by the current flowing through the output probe 2b. However, since the input probe 2a is orthogonal to the axis connecting the rotation centers of the magnetic fields, no induced current is generated. For this reason, no signal is fed back from the output side to the input side, and oscillation in the high frequency region does not occur.

Next, a probe card for measuring a high frequency FET will be described as another embodiment of the probe card.

FIG. 4 is a plan view of the FET probe card, and FIG. 5 is a sectional view taken along line VV of FIG. In these figures, 2f, 2g, and 2h are probes for the gate electrode, the source electrode, and the drain electrode, respectively. The tips of the probes 2f, 2g, and 2h are tilted downward and are arranged so as to form a three-dimensional angle of 90 ° with the other probes. That is, the probes 2f, 2g, 2h form an angle of 120 ° with each other on the plane of the substrate 1, and
It is arranged on the back surface of the substrate 1 so as to extend obliquely downward at an angle of 35.3 °. With this arrangement, the probe needles 2f, 2g, 2
As shown in FIG. 6, h has a three-dimensional arrangement relationship of three sides which share one vertex among the sides forming a cube. Therefore, although there are three measuring probes, each of them makes a three-dimensional angle of 90 ° with the other probes. Therefore, similarly to the above-described embodiment, it is possible to suppress the generation of noise and the oscillation at high frequency due to the influence of the magnetic field generated by another probe. Further, as in the above-mentioned embodiment, as the low frequency oscillation prevention circuits 5c and 5d, ferrite beads are connected in series with the source electrode probe 2g to form an inductance component, and the gate electrode probe 2f and the drain electrode are used. A circuit consisting of a 100 pF capacitor and a 220 Ω resistor is connected to the probe 2h to suppress oscillation in the low frequency range of 1 to 500 MHz.

7 to 8 show the results of measuring the static characteristics of the high frequency FET using the probe card of this embodiment. FIG. 7 shows the relationship between the drain-source voltage V _DS (V) and the drain current Id (mA). The characteristics measured using the probe card according to this embodiment are shown in (a) and (b).
The characteristics measured using the conventional probe card described in the related art are shown in FIG. Further, FIG. 8 shows the relationship between the base voltage V _B (V) and the drain current Id (mA). Similar to FIG. 7, (a) shows the measurement result according to the present embodiment, and (b) shows the conventional example. Shows the measurement results by.

As is clear from these measurement results, it can be understood that the measurement according to the present invention has no influence of noise and can be accurately measured, and whether the quality is good or not can be accurately determined in the performance test and the measurement can be performed quickly.

In each of the above-mentioned embodiments, at least the input probe (gate electrode in the case of FET) and the output probe are arranged in the vicinity of 90 °.
It is most preferable that the angle becomes 0 ° because noise due to electromagnetic induction is completely eliminated, but even if the angle that is hard to receive electromagnetic induction according to the present invention is not 90 °, it is fed back to the input side as long as it is in the range of 60 to 120 °. The noise is reduced to less than half and the effect is produced. However, in order to reduce the feedback to ⅕, it is sufficient to set it in the range of 78 to 102 °, and this range is more preferable because there is almost no influence of noise.

[0026]

According to the present invention, in order to measure a high frequency element, the output and input probes are arranged in a three-dimensional angle so that they are less susceptible to electromagnetic induction. It is possible to suppress noise generation and oscillation due to electromagnetic induction between the probes. As a result, the accuracy of measurement of static characteristics is significantly improved, and the high-frequency element can be measured accurately and accurately in a short time. In addition, since it is composed of the same components as the conventional probe card, it can be used by connecting it to the existing test equipment as usual and has high versatility.

[Brief description of drawings]

FIG. 1 is an explanatory plan view showing an embodiment of a probe card of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG.

FIG. 3 is a schematic diagram showing the configuration of the probe of FIG.

FIG. 4 is a plan view showing another embodiment of the probe card of the present invention.

5 is a sectional view taken along line VV of FIG.

FIG. 6 is a schematic diagram showing the configuration of the probe of FIG.

FIG. 7 is a diagram showing a relationship between a drain-source voltage and a drain current of a high-frequency FET, where (a) is a measurement example according to the present invention and (b) is a measurement example according to a conventional method.

FIG. 8 is a diagram showing a relationship between a base voltage and a drain current of a high-frequency FET, (a) is a measurement example according to the present invention,
(B) is an example of measurement by the conventional method.

FIG. 9 is an explanatory plan view of a conventional probe card.

10 is a cross-sectional view taken along line XX of FIG.

FIG. 11 is a layout view of electrode portions of a high-frequency FET.

[Explanation of symbols]

 1 substrate 2a input probe 2b output probe 2f gate electrode probe 2h drain electrode probe

Claims (2)

[Claims] 1. A substrate is provided with electrical wiring, which has a plurality of probes connected to the wiring and whose tip is connected to an electrode of an object to be measured, so that the tip of the probe is separated from the substrate. A probe card in which the probes are tilted, and at least two probes for input and output are arranged so as to form an angle that is unlikely to be affected by electromagnetic induction. 2. A method for measuring a high frequency element, wherein a plurality of probes are respectively brought into contact with each electrode of the high frequency element to measure high frequency characteristics, wherein the plurality of probes are arranged obliquely with respect to a horizontal plane, and A method for measuring a high-frequency element, characterized in that at least input and output probes are arranged at an angle that is unlikely to be affected by electromagnetic induction.