JPH0820470B2 - Voltage detector - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage detecting device for detecting a voltage of a predetermined portion of an object to be measured, for example, an integrated circuit or the like, and in particular, to a voltage of a predetermined portion of the device to be measured. The present invention relates to a voltage detecting device of a type that detects a voltage by utilizing the fact that the polarization state of a light beam changes due to the change.

[Conventional technology]

Conventionally, various voltage detection devices have been used to detect the voltage of a predetermined portion of an object to be measured such as an integrated circuit.

Among this type of voltage detecting device, a type of voltage detecting device has been recently developed which detects the voltage of the DUT by utilizing the fact that the polarization state of the light beam changes depending on the voltage of a predetermined portion of the DUT. There is.

For example, in the voltage detection device described in the patent application filed on May 30, 1987 by the applicant of the present application under the name of “voltage detection device”, an electro-optic material whose refractive index changes depending on the voltage of a measured object is used. It is housed in an optical probe with a minute cross section,
By injecting a light beam having a predetermined polarization component into the electro-optical material of this optical probe and detecting the amount of change in the polarization state of the light beam due to the change in the refractive index of the electro-optical material, It is designed to detect the voltage at one position.

[Problems to be solved by the invention]

By the way, there are cases where the user desires to select a specific plurality of positions from all positions of an object to be measured such as an integrated circuit and simultaneously measure only the voltages at these specific plurality of positions. However, the voltage detection device using the optical probe as described above has a problem that it is not possible to arbitrarily select the position of the object to be measured and simultaneously detect the voltages at a plurality of selected specific positions.

An object of the present invention is to provide a voltage detection device capable of simultaneously detecting voltages at specific plural positions of an object to be measured.

A further object of the present invention is to provide a voltage detection device capable of simultaneously detecting the voltage at a specific two-dimensional position of the object to be measured.

[Means for solving problems]

The present invention relates to a voltage detecting device of a type using an electro-optical material whose refractive index changes when a voltage is applied,
The electro-optical material is positioned so as to cover a plurality of positions of the measured object whose voltage is to be detected, and a specific portion of the electro-optical material corresponding to a specific position of the measured object is provided with a light source. Incident light obtained by dividing a light beam into a plurality of desired patterns is made incident respectively, and a change in the polarization state of the emitted light from the specific portion of the electro-optical material is detected by a detector. SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art by the voltage detection device characterized by the above.

[Action]

In the present invention, the electro-optical material is positioned so as to cover a plurality of positions of the measured object where the voltage is to be detected, and the light from the light source is emitted to each of the specific portions of the electro-optical material corresponding to the specific position of the measured object. The beam is divided into a desired pattern by a microlens array, a holographic lens, or a spatial light modulator, and is made incident. Since the refractive index of each part of the electro-optical material changes depending on the voltage at each position of the measured object corresponding to each part, it is divided into a plurality of desired patterns and is incident on each specific part of the electro-optical material. The polarization state of the light beam changes with the change in the refractive index of each specific portion of the electro-optical material, and is output as output light from the electro-optical material and enters a detector, such as a two-dimensional photodetector array or streak camera. To do. Thus, the detector can simultaneously detect the voltage at a specific position of the measured object, for example, a specific two-dimensional position.

〔Example〕

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

FIG. 1 is a configuration diagram of a first embodiment of a voltage detecting device according to the present invention.

In the voltage detecting device 1 shown in FIG. 1, the electro-optical material 2 is fixed by approaching the device under test 3 such as an integrated circuit or by contacting the device 3 under test. This electro-optic material 2
Has a cross section cut into a size that covers a plurality of two-dimensional positions of the DUT 3. A reflecting mirror 8 made of a metal or a dielectric multilayer film is formed on the bottom surface of the electro-optical material 2.

Further, the voltage detection device 1 includes a polarizer 4 for extracting a predetermined polarization component from a light beam BM from a light source (not shown), and a light beam having the predetermined polarization component extracted by the polarizer 4 in a grid pattern. the number of the micro-lens array 5 for dividing the light beam BM _ij, electrooptic material causes incident as the incident light a plurality of light beams BM _ij of the grid-shaped pattern which is divided by the microlens array 5 in the electro-optic material 2 2
The electro-optic material 2 is reflected by the reflecting mirror 8 formed on the bottom surface of the
The beam splitter 6 that splits a large number of emitted light SG _ij having a lattice pattern output from the beam splitter 6 for voltage detection, and the detection light that passes only the light beam of a predetermined polarization component of the emitted light SG _ij from the beam splitter 6. It comprises a photon 7 and a detector 9 on which the emitted light that has passed through the analyzer 7 is incident.

The microlens array 5 is configured by stacking a plurality of first rod lenses 10 aligned in a specific direction and a plurality of second rod lenses 11 aligned in a direction orthogonal to the first rod lenses. As a result, the light beam is divided into a grid.

The detector 9 is composed of a two-dimensional photodetector such as a CCD camera, a photodiode array, a vidicon camera or a high-speed response detector such as a streak camera.

In the voltage detection device 1 having such a configuration, the electro-optic material 2 has a cross section cut into a size that covers a plurality of two-dimensional positions of the DUT 3, so that the plurality of DUTs 3 of the DUT 3 are cut. The refractive index of the local portion of the electro-optical material 2 corresponding to these two-dimensional positions is changed by the voltage of the two-dimensional positions. Therefore, when a large number of light beams BM _ij of the grid-shaped pattern having a predetermined polarization component split by the microlens array 5 proceeds a grid portion of the electro-optical material 2, the number of these light beams BM _ij is Electro-optical material 2 by the voltage at the grid-like position of DUT 3 directly below the grid-like portion
The polarization state is changed due to the change in the refractive index of the inner lattice portion, and the light is output from the electro-optic material 2 as emitted light.
These emitted lights are further added to the analyzer 7 via the beam splitter 6. Assuming that the analyzer 7 is configured to pass only a light beam having a polarization component orthogonal to the polarization component of the polarizer 4, the polarization state changes and the analyzer 7
Each emitted light SG _ij incident on the
It is added to the detector 9 in proportion to n ² [(π / 2) · V _ij / V ₀ ]. Here, V _ij is the voltage at the two-dimensional lattice position (i, j) of the DUT 3, and V ₀ is the half-wave voltage.

As described above, the intensity of each emitted light changes depending on the change in the refractive index of the local portion of the electro-optical material 2 associated with the change in the voltage at each lattice-shaped position of the DUT 3, and accordingly, in the detector 9, Of all the two-dimensional positions of the DUT 3 such as an integrated circuit, only the voltages at the two-dimensional grid-like positions can be detected at the same time.

In the first embodiment, a large number of light beams BM _ij having a two-dimensional grid pattern are formed by using the microlens array 5, and these light beams are made incident on the electro-optical material 2 so that the measured object 3 Although the voltage at the two-dimensional grid-like position is detected, it may be desired to further detect the voltage at any two-dimensional position of the DUT 3.

2 to 4 are configuration diagrams of second to fourth embodiments of the voltage detecting device according to the present invention, which are capable of detecting the voltages at arbitrary two-dimensional positions of the DUT 3. is there.
2 to 4, the same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

In the voltage detection device of FIG. 2, the microlens array 5 is used.
A plate-shaped mask 12 is installed behind the. This mask 12 has openings 13 in a lattice shape, but unnecessary openings are closed in order to obtain a desired light beam pattern. This mask
Since only the desired light beam can be extracted and made incident on the electro-optic material 2 by 12, the voltage at any two-dimensional position of the measurement object 3 can be detected.

Further, in the voltage detection device 20 of FIG. 3, instead of the microlens array 5, specific two-dimensional portions (i ₀ , j ₀ ), (i ₁ , j ₀ ), (i ₀ , j) of the electro-optic material 2 are used. A holographic lens 21 is used which is hologram-recorded so that the light beam is focused only on ₁ ) and (i ₁ , j ₁ ). Here, a good optical system can be obtained by increasing the distance between the holographic lens 21 and the electro-optical material 2 and decreasing the distance between the electro-optical material 2 and the beam splitter 6 and the detector 9.

When such a holographic lens 21 is used, upon reproduction of a light beam BM having a predetermined polarization component extracted by the polarizer 4, reproduced images HG _{1 to} HG ₄ are emitted from the holographic lens 21 according to the hologram recording. The obtained electro-optical materials 2 are incident as incident light through the beam splitter 6.
Specific two-dimensional part of (i ₀ , j ₀ ), (i ₁ , j ₀ ), (i ₀ ,
It is incident on j ₁ ) and (i ₁ , j ₁ ) respectively. Electro-optical material 2
The two-dimensional part of (i ₀ , j ₀ ), (i ₁ , j ₀ ), (i ₀ , j ₁ ),
Reconstructed image incident on (i ₁ , j ₁ ), that is, incident light HG _{1 to} HG ₄
The polarization state changes due to the change in the refractive index of the two-dimensional portion due to the voltage at the two-dimensional position of the DUT 3 immediately below these two-dimensional portions. Reconstructed images with changed polarization state HG ₁
To HG ₄ are emitted from the electro-optical material 2 as emitted lights SG _{1 to} SG ₄ , and these emitted lights SG _{1 to} SG ₄ are split by the beam splitter 6 and passed through the imaging optical system 22 and the analyzer 7. Join detector 9. As a result, the voltage at a specific two-dimensional position of the DUT 3 can be detected. By changing the hologram recording of the holographic lens 21, it is possible to easily detect the voltage of the DUT 3 at a desired arbitrary two-dimensional position.

In the voltage detection device 30 of FIG. 4, a spatial light modulator 31 is used instead of the microlens array 5.

When the input image IG is input to the input surface 32 of the spatial light modulator 31, the light beam incident on the output surface 33 is output from the output surface 33 as a pattern corresponding to the input image IG. That is, in FIG. 4, when the light beam BM having a predetermined polarization component extracted by the polarizer 34 enters the output surface 33 of the spatial light modulator 31 via the beam splitter 35, the light beam BM corresponds to the input image IG. The reflected light is reflected by the spatial light modulator 31 and output, and is divided by the beam splitter 35 to extract a predetermined polarization component by the polarizer 4, and the electro-optics is transmitted through the reduction optical system 36 and the beam splitter 6. It is adapted to be incident on the material 2.

In the voltage detection device 30 having such a configuration, the parts IG _{1 to} I
When the incident image IG consisting of G ₆ is applied to the input surface 32, the light beam reflected from the output surface 33 of the spatial light modulator 31 becomes a pattern corresponding to each part IG _{1 to} IG ₆ of the incident image IG. Corresponding two-dimensional parts P _{1 to} P ₆ of the electro-optical material 2 in a pattern
Incident as incident light. Since only a predetermined polarization component of each incident light incident on each two-dimensional portion P _{1 to} P ₆ of the electro-optical material 2 is extracted by the polarizer 4, the incident light is converted into the electro-optical material. The polarization state is changed by the change in the refractive index of the two-dimensional portions P _{1 to} P ₆ due to the voltage at the two-dimensional position of the DUT 2 immediately below each of the two-dimensional portions P _{1 to} P ₆ of the electro-optical device. The material 2 outputs the emitted light. The emitted light from the electro-optical material 2 is split by the beam splitter 6 and added to the detector 9 via the analyzer 7. This allows
The voltage of each two-dimensional position of the DUT 3 corresponding to each part IG _{1 to} IG ₆ of the input image IG can be detected. Input image IG
Since the pattern can be changed arbitrarily, the voltage at any desired two-dimensional position of the DUT 3 can be detected.

As described above, according to the second to fourth embodiments, the incident light can be incident on an arbitrary two-dimensional portion of the electro-optical material 2, so that the desired light can be obtained from all the two-dimensional positions of the DUT 3. It is possible to arbitrarily select only the two-dimensional position and simultaneously detect only the voltage of the selected two-dimensional position.

In the above-described first to fourth embodiments, as the detector 9, a two-dimensional photodetector array such as a CCD camera, a photodiode array, or a vidicon camera is used, or a high-speed response detector such as a streak camera is used. However, when using a two-dimensional photodetector array such as a CCD camera, a pulse light source such as a laser diode that outputs a light pulse having a very short pulse width is used as a light source (not shown). The high-speed voltage change of the DUT 3 is sampled and measured in a very short time width. At this time, the voltage change of the DUT 3 must be periodically repeated. When using a high-speed response detector such as a streak camera, a pulse light source or a DC light source is used as a light source, and voltage information at the two-dimensional position of the DUT 3 is converted into one-dimensional information by a bundle of optical fibers. Measure with high time resolution. When using the streak camera, the voltage change of the DUT 3 can be measured even if it is a single-shot phenomenon.

Furthermore, in the above-described first to fourth embodiments, the DUT 3
Although the case where the voltage of a specific two-dimensional position of the object 3 is detected at the same time has been described, when the voltage detecting devices shown in these embodiments detect the voltage of a specific one-dimensional position of the DUT 3 at the same time. Can also be applied.

〔The invention's effect〕

As described above, according to the present invention, the light beam from the light source is divided into a plurality of desired patterns and incident on each specific portion of the electro-optical material corresponding to the specific position of the object to be measured. Since the change in the polarization state of the light emitted from each specific portion of the material is detected by the detector, it is possible to simultaneously detect the voltage at specific plural positions of the measured object.

[Brief description of drawings]

1 is a configuration diagram of a first embodiment of a voltage detection device according to the present invention, FIG. 2 is a configuration diagram of a second embodiment of a voltage detection device according to the present invention, and FIG. 3 is related to the present invention. Third of voltage detection device
FIG. 4 is a block diagram of a fourth embodiment of the voltage detecting device according to the present invention. 1,20,30 …… Voltage detector, 2 …… Electro-optical material, 3 ・ ・ ・
… Object to be measured, 5… Microlens array, 9… Two-dimensional detector, 21… Holographic lens, 31… Spatial light modulator, BM… Light beam, IG… Input image

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location H01L 21/66 C 7514-4M

Claims (8)

[Claims] 1. A voltage detecting device of a type using an electro-optical material, the refractive index of which changes when a voltage is applied,
The electro-optical material is positioned so as to cover a plurality of positions of the measured object whose voltage is to be detected, and a specific portion of the electro-optical material corresponding to a specific position of the measured object is provided with a light source. Incident light obtained by dividing a light beam into a plurality of desired patterns is made incident respectively, and a change in the polarization state of the emitted light from the specific portion of the electro-optical material is detected by a detector. The voltage detection device is characterized by being. 2. The voltage detection device according to claim 1, wherein the light beam from the light source is divided by a microlens array into a large number of incident lights in a grid pattern. apparatus. 3. A light beam from a light source is divided into a large number of incident lights having a desired pattern by a microlens array and a plate-shaped mask superposed on the microlens array. The voltage detection device according to claim 1. 4. The voltage according to claim 1, wherein the light beam from the light source is divided into a large number of incident lights having a desired pattern by a holographic lens. Detection device. 5. A light beam from a light source is divided by a spatial light modulator into a large number of incident lights having a desired pattern corresponding to an input image. The voltage detection device according to the item. 6. The light source is a pulsed light source, and the detector is a two-dimensional detector of a photodetector array, and the voltage is detected by sampling a voltage at a specific position of the object to be measured. The voltage detection device according to claim 1. 7. The voltage detection device according to claim 1, wherein the light source is a pulse light source or a DC light source, and the detector is a fast response detector. 8. The voltage detection device according to claim 7, wherein the fast response detector is a streak camera.