JPH0694807A - Voltage signal measuring device for integrated circuit - Google Patents

Abstract

PURPOSE:To provide a voltage signal measuring device for an integrated circuit which can determine the spacing between a probe and a circuit to be measured precisely without damaging the probe and circuit, presents an enhanced reproducibility of measuring, and is capable of precision measurement. CONSTITUTION:An air guide 6 is moved by a vertical coarse motion mechanism 11 so as to approach a circuit to be measured 1, and a cylinder 5 and accordingly a probe 3, which is supported thereby through a probe holder 4, is approached to the circuit 1. The probe 3 is moved by a piezo actuator 8 toward the circuit 1 and touched therewith with no risk of damaging through the action of a balance mechanism 9, and with the contact point as reference, the probe 3 is separated. Upon determination of the distance generated, the cylinder 5 is fixed by a cylinder lock 12 along with securing of the probe 3, and thereupon the distance between the probe 3 and the circuit measured 1 is determined precisely.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention utilizes an electro-optical effect and laser light by bringing a probe formed of an electro-optical material whose birefringence index changes by an electric field into proximity to a circuit to be measured such as an integrated circuit. The present invention relates to an integrated circuit voltage signal measuring device for measuring a voltage signal of an integrated circuit.

[0002]

2. Description of the Related Art An electro-optic material whose birefringence is changed by an electric field is brought close to an integrated circuit, placed in an electric field generated by the operation of the integrated circuit, and laser light is incident on the electro-optic material. The change changes the polarization of the laser light. When the laser light that has undergone this polarization change is passed through a generally well-known polarization detection optical system that uses a polarizer,
The polarization change of the laser light can be converted into the light intensity change of the laser light. By measuring the change in light intensity of the laser light (hereinafter referred to as change in light intensity), the electric field coupled to the electro-optical material, that is, the voltage signal at the measurement point can be measured.

The above-described voltage signal measuring technique for integrated circuits is called electro-optical sampling. In this electro-optic sampling, the amount of coupling between the electro-optic material and the electric field differs depending on the distance between the probe and the circuit under measurement (hereinafter referred to as the distance), so that the detected light intensity change strongly depends on the distance.
In order to improve / N (signal to noise ratio), it is necessary to bring the probe as close as possible to the circuit under test.
However, when the probe and the circuit under test are in close proximity to each other, signal changes are sensitive to changes in the distance, so in order to improve the measurement accuracy, the distance between the probe and the circuit under test is determined with high reproducibility and high accuracy. There is a need.

[0004]

Conventionally, as described above, there is no technique relating to probe positioning for determining the distance between the probe and the circuit to be measured, and it has been sufficient to measure a voltage signal until now. The probe was brought close to or in contact with the circuit under measurement until the S / N was obtained. Therefore, there is a problem in that the separation distance varies with repeated positioning of the probe, and the reproducibility of measurement is poor.

The present invention has been made in view of the above,
Its purpose is to integrate the probe and the circuit under test without damaging the probe and the circuit under test with high accuracy, improving the reproducibility of the measurement and enabling highly accurate measurement. An object is to provide a voltage signal measuring device for a circuit.

[0006]

In order to achieve the above object, a voltage signal measuring device for an integrated circuit according to the present invention is provided so as to be close to a circuit under test, and the birefringence is changed by an electric field. A probe that is formed of a material and that electro-optically measures the voltage signal of the circuit under measurement by being irradiated with laser light, and a cylinder that supports the probe so that the probe can be brought into contact with and separated from the circuit under measurement. A guide that has an inner diameter slightly larger than the outer diameter of the cylinder and into which the cylinder is inserted so as to guide the movement of the cylinder; A fine movement means for flowing a gas between the guide and the cylinder so that the guide can be finely moved; a guide movement means for moving the guide to move to and away from the circuit to be measured; Cylinder moving means for moving the cylinder to and from the circuit to be measured to move the lobe to and from the circuit to be measured, position measuring means for measuring the position of the cylinder, and effective weights of the cylinder and the probe. The gist of the present invention is to have a lightening balance mechanism and cylinder fixing means for fixing the cylinder.

[0007]

In the integrated circuit voltage signal measuring apparatus of the present invention, the guide moving means moves the guide so as to approach the circuit to be measured, and the cylinder, and thus the probe supported by the cylinder, approaches the circuit to be measured. Furthermore, the probe is moved toward the circuit to be measured by the cylinder moving means, and the probe mechanism is brought into contact with the circuit to be measured without damage by the action of the balance mechanism.The probe is separated based on this contact point, and the separation distance is set. After the determination, the cylinder is fixed by the cylinder fixing means and the probe is also fixed, and the separation distance between the probe and the circuit to be measured is determined with high accuracy.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing the overall configuration of a voltage signal measuring device for an integrated circuit according to an embodiment of the present invention.

In FIG. 1, 1 is a circuit to be measured, 2 is a vertical fine movement mechanism, 3 is a probe for measuring a voltage signal, 4 is a probe holder, 5 is a cylinder, 6 is an air guide, 7 is air in the cylinder and the air guide. Inlet 8 for pouring in, a piezo actuator 8 for finely moving the cylinder up and down with high precision, 9 a balance mechanism for reducing the effective weight of the probe 3 and probe holder 4 fixed to the cylinder 5, 1
0 is a position scale that measures the position of the cylinder, 1
1 is a vertical coarse movement mechanism capable of moving the air guide up and down, 12
Is a cylinder lock for fixing the cylinder.

More specifically, the probe 3 is formed by fixing an electro-optic material with a transparent material and processing the tip into a needle shape for measuring an integrated circuit. The electro-optical material used for the probe 3 is, for example, LiNbO ₃ , LiTaO ₃ , KTP,
Crystals such as GaAs, KD ^* P, ZnTe, CdTe, or organic optical materials are used.

The probe 3 is fixed to the cylinder 5 via a probe holder 4. Further, the cylinder 5 is inserted into the air guide 6 having an inner diameter slightly larger than the outer diameter of the cylinder 5 and air is sent from the inflow port 7 into the gap between the cylinder 5 and the air guide 6 so that the cylinder 5 has very little friction. It has a mechanism that can be slid vertically. Further, the effective weight of the probe 3 and the probe holder 4 fixed to the cylinder 5 by the balance mechanism 9 is reduced.

When the measurement is not performed, the air guide 6 is raised by the vertical coarse movement mechanism 11 as shown in FIG. 2 so that the cylinder 5 is separated from the balance mechanism 9 and is in a retracted state. In this state, the cylinder 5 has a weight of several hundred grams, which is the total weight of the probe 3 and the probe holder 4, so that the cylinder 5 does not move up and down even if a slight impact is applied to the device. Can prevent damage. Further, the cylinder may be fixed by the cylinder lock 12.

In the measurement, when the cylinder 5 is fixed by the cylinder lock 12, the fixation is released, the vertical coarse movement mechanism 11 lowers the air guide, and the measurement point (contact point) is set in the state as shown in FIG. The probe 3 is arranged above the point). The vertical fine movement mechanism 2 is fixed, and the cylinder 5 is gradually lowered by the piezo actuator 8,
The probe 3 is brought close to the circuit to be measured. The manner in which the probe 3 descends can be seen by monitoring the position scale 10 connected to the cylinder 5. When the probe 3 is continuously lowered, as shown in FIG. 4, the probe 3 comes into contact with the circuit to be measured 1 at a certain position, the probe 3 stops, and the display of the position scale 10 stops changing. With this position as the contact point, the downward movement by the piezo actuator 8 is stopped. Here, since the effective weight of the probe 3 and the probe holder 4 fixed to the cylinder 5 by the balance mechanism 9 is reduced to 0.1 to 0.2 g, the probe 3
Thus, damage to the probe 3 and the circuit under test 1 can be reduced when the circuit under test 1 contacts. Further, even if the probe 3 is lowered too much after the contact, the inclination of the balance does not change from that at the time of contact, so that the inclination of the probe and the contact pressure do not change. Furthermore, since there is no sliding friction between the cylinder and the air guide, damage when the probe 3 contacts the circuit under test 1 is reduced,
Contact can be detected with high sensitivity.

After the contact, the probe 3 is raised by the piezo actuator 8 to determine the separation distance. At this time, if the position scale 10 is reset in the contact state,
The distance between the probe 3 and the circuit under test 1 can be arbitrarily set based on the displayed value on the position scale 10. After the separation distance is determined, the cylinder 5 is fixed by the cylinder lock 12 in order to maintain the stability of the probe 3 against vibration so that the probe 3 cannot move up and down as shown in FIG.

[0016]

As described above, according to the present invention,
The guide moving means moves the guide so as to approach the circuit to be measured, the cylinder, and thus the probe supported by the cylinder, approaches the circuit to be measured, and the cylinder moving means moves the probe toward the circuit to be measured. After the probe is brought into contact with the circuit under test by the action of the balance mechanism without damage, the probe is separated based on this contact point, the separation distance is determined, and then the cylinder is fixed by the cylinder fixing means and the probe is also fixed. Therefore, the distance between the probe and the circuit under measurement can be set with high accuracy without damaging the probe and the circuit under measurement, and as a result, the variation in the detection signal intensity due to repeated positioning of the probe can be reduced. It is possible to measure electric signals with high reproducibility and high accuracy.

[Brief description of drawings]

FIG. 1 is a perspective view showing an overall configuration of a voltage signal measuring device for an integrated circuit according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a state in which a cylinder is retracted in the voltage signal measuring device of the integrated circuit of FIG.

FIG. 3 is a cross-sectional view showing a state immediately before a probe and a circuit under measurement come into contact with each other in the voltage signal measuring device of the integrated circuit of FIG.

FIG. 4 is a cross-sectional view showing a state where a probe and a circuit under measurement are in contact with each other in the voltage signal measuring device of the integrated circuit of FIG.

5 is a cross-sectional view showing a state in which a distance between a probe and a circuit to be measured is set in the voltage signal measuring device for integrated circuit of FIG.

[Explanation of symbols]

 1 Circuit to be Measured 3 Probe 5 Cylinder 6 Air Guide 7 Inlet 8 Piezo Actuator 9 Balance Mechanism 10 Position Scale 11 Vertical Coarse Mechanism 12 Cylinder Lock

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Tatsuo Sato Marunouchi 3-chome 3-2, Chiyoda-ku, Tokyo Nikon Corporation (72) Inventor Kunio Uchiyama Marunouchi 3-chome 2-3, Chiyoda-ku, Tokyo Company Nikon

Claims (1)

[Claims] 1. A voltage signal of a circuit to be measured is electro-optically provided by being irradiated with laser light, the electro-optical material being provided so as to be close to the circuit to be measured and having a birefringence changing by an electric field. A probe to be measured, a cylinder for supporting the probe so that the probe can be brought into and out of contact with a circuit to be measured, and an inner diameter slightly larger than the outer diameter of the cylinder to guide the movement of the cylinder. A guide in which the cylinder is inserted into the inner diameter, fine movement means for flowing gas between the guide and the cylinder so that the cylinder can finely move in the guide in a state where friction is extremely small, Guide moving means for moving the guide so as to move toward and away from the circuit to be measured, and the cylinder for moving away from and to the circuit to be measured so as to move the probe toward and away from the circuit to be measured. A stacking means comprising: a cylinder moving means for moving the position, a position measuring means for measuring the position of the cylinder, a balance mechanism for reducing the effective weight of the cylinder and the probe, and a cylinder fixing means for fixing the cylinder. Circuit voltage signal measuring device.