JPH0961469A - Electric field detector - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To adjust an optical system with respect to a position shift of an EO probe by a simple operation. An element whose physical state changes due to a leakage electric field from a wiring of an integrated circuit is arranged close to an integrated circuit substrate, and a change in the physical state of the element is optically measured to detect a leakage electric field. In the electric field detecting device,
A position detection unit that obtains a signal corresponding to a positional deviation in the axial direction, receives a signal from this position detection unit, and moves the entire detection optical system that optically measures a change in the physical state of the element,
A moving means for adjusting the position of the element so as to compensate the positional deviation of the element is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention arranges an element whose physical state changes due to a leakage electric field from a wiring inside the integrated circuit in the vicinity of the integrated circuit substrate, and changes the physical state optically. The present invention relates to an electric field detection device that measures a leak electric field by measuring the electric field, and particularly relates to adjustment of an optical system.

[0002]

2. Description of the Related Art When an electro-optic crystal whose refractive index changes according to electric field strength is placed in a leakage electric field from an integrated circuit and a laser beam is applied to the electro-optic crystal, the laser beam passing through the crystal is The polarization changes depending on the electric field strength. 2. Description of the Related Art Conventionally, electric field detection devices that utilize this characteristic to detect an electric field at an arbitrary place in an integrated circuit without contact have been well known.

[0003]

By the way, the EO (Electro-Optic) probe section having the electro-optic crystal may be displaced. The cause of the positional deviation includes positional deviation due to replacement of the probe itself, positional deviation of the holder for the EO probe (accompanying temperature change, vibration, etc.). Since the tip of an EO probe is usually as small as several hundreds of microns and its mass is also small, it is difficult to attach a position shift compensation mechanism or the like thereto. Therefore, it is general to adjust the positional deviation of the EO probe section with an optical system.
In the conventional electric field detection device, there are many adjustment points of the optical system, the operation thereof is complicated, and there is a drawback that it takes a lot of effort to perform the optimum adjustment of the positional deviation.

In view of such a point, an object of the present invention is E
An object of the present invention is to provide an electric field detection device capable of adjusting the optical system with respect to the displacement of the O probe by a simple operation.

[0005]

In order to achieve such an object, according to the present invention, an element whose physical state is changed by a leakage electric field from a wiring of an integrated circuit is arranged close to the integrated circuit substrate, In an electric field detecting device for optically measuring a change in a physical state of an element to detect a leakage electric field, a position detecting section that obtains a signal corresponding to a positional deviation of the element in two axial directions, and a position detecting section of the position detecting section. It is characterized by further comprising moving means for receiving the signal, moving the entire detection optical system for optically measuring the change of the physical state of the element, and adjusting the position so as to compensate the positional deviation of the element.

[0006]

[Function] The position detecting unit shifts the position of the element in two axial directions (X,
A signal corresponding to the inclination in the Y direction) is obtained. This signal is given to the moving means to drive. The moving means moves the entire detection optical system that optically measures the change in the physical state of the element to detect the leakage electric field in two axial directions. This automatically adjusts the position of the detection optical system so that the tilt of the element is compensated (cancelled).

[0007]

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in detail below with reference to the drawings. FIG. 1 is a configuration diagram showing one embodiment of an electric field detection device according to the present invention. In the figure, 1 is a laser beam (here, linearly polarized light), 2 is an objective lens, 3 is an element whose physical state changes due to a leakage electric field, and here is an EO (Electro-Optic) probe having an electro-optic crystal. Reference numeral 10 is a detection optical system, 20 is a moving means, and 30 is a position detection unit.

In the detection optical system 10, 11 is a prism, which reflects the reflected light from the EO probe 3 which has passed through the objective lens 2. Reference numeral 12 denotes a beam splitter which divides the reflected light from the prism 11 into two parts, one of which is a four-division photodiode 18 and the other of which is a polarized beam splitter 1.
Enter 3.

Reference numeral 14 is a first lens for focusing the light beam that has passed through the polarization beam splitter 13, 15 is a first photodiode for detecting the intensity of the light beam focused by the first lens 14, and 16 is a polarized light beam. A second lens for converging the beam light reflected by the splitter 13 and a second photodiode 17 for detecting the intensity of the beam light focused by the second lens 16. The light incident on the lens 16 has its plane of polarization rotated by 90 ° with respect to the light incident on the lens 14.

Taking the difference between the outputs of the first photodiode 15 and the second photodiode 17, the difference is the rotation angle of the deflection surface of the reflected light reflected by the EO probe 3, in other words, the tip of the EO probe 3. Corresponding to the electric field strength of.

Reference numeral 18 denotes a four-division photodiode, which receives the beam spot of the reflected light split by the beam splitter 12. The beam spot diameter is smaller than the size of the light receiving surface for four photodiodes, and the beam spot normally hits the center of the four divisions. EO probe 3
When tilts, the spot shifts from the center of the photodiode,
There is a difference in the output of the photodiode.

The position detecting section 30 includes adders 31 to 34 that sum the outputs of the photodiodes of the four-divided photodiodes 18 and a differential amplifier that amplifies the difference between two of the adders 31 to 34. EO probe 3 equipped with amplifiers 35 and 36
The signals corresponding to the inclinations in the two axis directions (X and Y directions in the plane perpendicular to the paper surface of FIG. 1) of the differential amplifier 35,
It can be obtained from 36.

The moving means 20 is driven by the output of the position detecting section 30, and moves the entire detection optical system 10 in a vertical direction in a plane parallel to the paper surface of FIG. 1 and in a direction perpendicular to the paper surface. For example, an actuator is used as the linear movement mechanism.

The operation in such a configuration will be described. The EO probe 3 is irradiated with the laser light 1 through the objective lens 2. The reflected light from the EO probe 3 passes through the objective lens 2 again, enters the detection optical system 10, is redirected by the prism 11, and enters the beam splitter 12. The reflected light branched by the beam splitter 12 enters a four-division photodiode 18 for position detection.

When the EO probe 3 is tilted to the left by δθ as shown, the light incident on the detection optical system 10 (shown by the broken line) is f × sin (2δθ), where f is only the focal length of the objective lens. Move in parallel.
As a result, a difference occurs in the output of the four-division photodiode 18, and the differential amplifier of the position detector 30 outputs an output signal according to the difference. The actuator 20 is driven by this output signal, and the entire detection optical system 10 is moved downward until the output of the differential amplifier becomes zero. In this way, the actuator 20 operates so that the output of the differential amplifier is always zero, and the position of the detection optical system 10 is automatically adjusted.

Although the above description is for the case where the EO probe 3 is tilted in the direction of rotation within the plane of the drawing, the rotation of the EO probe 3 in the direction perpendicular to the plane of the drawing is performed by the actuator 20 in the same manner as described above so that the entire detection optical system 10 is rotated. The tilt of the EO probe 3 can be canceled by moving in a direction perpendicular to the direction.

It should be noted that the present invention is not limited to the embodiments, and appropriate changes and modifications can be made. For example, a two-divided photodiode may be used as the four-divided photodiode 18, and the positional deviation of the EO probe 3 in only one axis direction may be compensated.

[0018]

As described above, according to the present invention, E
Even if the position of the O probe shifts, the position of the EO probe itself cannot be compensated, and the entire detection optical system can be easily adjusted by moving in the biaxial directions.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of an electric field detecting device according to the present invention.

[Explanation of symbols]

 1 Laser Light 2 Objective Lens 3 EO Probe 10 Detection Optical System 11 Prism 12 Beam Splitter 13 Polarizing Beam Splitter 14, 16 Lens 15,17 Photodiode 18 4 Split Photodiode 20 Moving Means 30 Position Detecting Unit 31-34 Adder 35, 36 differential amplifier

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location H01L 21/66 G01R 31/28 L (72) Inventor Kiyoaki Koyama 2-9 Nakamachi, Musashino-shi, Tokyo No. 32 Yokogawa Electric Co., Ltd. (72) Inventor Tsutomu Yamazaki 2-932 Nakamachi, Musashino City, Tokyo No. 32 Yokogawa Electric Co., Ltd. (72) Inventor Jiro Minohaku 2-932 Nakamachi, Musashino City, Tokyo Yokogawa Electric Co., Ltd. (72) Inventor Mitsuhiro Suzuki 2-932 Nakamachi, Musashino-shi, Tokyo Yokogawa Electric Co., Ltd. (72) Naonori Hayashi 2-932 Nakamachi, Musashino-shi, Tokyo Yokogawa Electric Co., Ltd.

Claims (2)

[Claims] 1. An element, the physical state of which is changed by a leakage electric field from a wiring of an integrated circuit, is arranged close to an integrated circuit substrate, and the element is irradiated with light to optically change the physical state of the element. In an electric field detection device for measuring and detecting a leakage electric field, a position detection unit that obtains a signal corresponding to a positional deviation of the element in two axial directions, and a signal of the position detection unit to receive a signal of the physical state of the element. An electric field detecting apparatus comprising: a moving unit that moves the entire detection optical system that optically measures a change and adjusts the position so as to compensate for the positional deviation of the element. 2. The detection optical system includes a two-divided photodiode or a four-divided photodiode that receives a spot of reflected light from the element, and in the position detection unit, the detection optical system includes a two-divided photodiode. In this case, a signal corresponding to the displacement of the element in the uniaxial direction is obtained based on the output of the two-division photodiode, and when the detection optical system includes a four-division photodiode, the output of the four-division photodiode. 2. The electric field detecting device according to claim 1, wherein a signal corresponding to the positional deviation of the element in the biaxial directions is obtained based on the above.