JPH11101862A - Minute region observation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve measurement with a high space resolution without damaging a first sensor and an object to be measured by providing a second sensor for measuring the distance between a first sensor and an object to be measured and the traveling mechanism of a probe and controlling the interval between the first sensor and the object to be measured without any contact. SOLUTION: A SQUID 11 is used as a first sensor. A micro cantilever 81, a laser oscillator 91, and a laser detector 92 are combined as a second sensor. The micro cantilever 81 is a cantilever beam with a minute needle at its tip. Since the micro cantilever 81 is deformed owing to force being generated between an object 20 to be measured and the minute needle, the micro cantilever 81 can detect the distance between itself and the object to be measured by detecting the deformation. For measurement, the optical axis of laser beams after transporting a liquid He is aligned and the interval between the object 20 to be measured and the SQUID 11 is reduced by an Z-axis traveling mechanism 35 and a scanner 70. Z-axis control is made by the scanner 70 so that the displacement of the micro cantilever 81 becomes constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a micro-area observation for scanning a surface of a magnetic material, a semiconductor material, a superconducting material, and the like, detecting physical properties such as magnetism and charges generated from an object to be measured, and displaying a distribution. The present invention relates to a distance control mechanism between an object to be measured and a sensor for detecting physical properties and a control method thereof.

[0002]

2. Description of the Related Art When a defect is present in an object such as a magnetic material, the magnetic flux density on the surface of the object changes. for that reason,
By measuring the magnetic flux density by scanning the vicinity of the surface of the measured object with a magnetic sensor, a defective portion of the measured object can be detected. When signals such as magnetism and electric charge output from the device under test are detected using the first sensor, the distance between the device under test and the first sensor is increased in order to improve the spatial resolution and SN ratio. Need to be set close. The conventional micro-area observation apparatus has a configuration in which an object to be measured and a first sensor are brought into contact with each other, and the first sensor can be moved up and down due to unevenness of the object to be measured.

FIG. 2 is a block diagram showing an example of a conventional minute area observation apparatus using a superconducting magnetic sensor (SQUID) as a first sensor. At least the SQUID 11, the probe 31, and the scanning stage 4
1. Cryostat 51, analysis display system 60,
It consists of. The cryostat 51 is a container having a vacuum heat insulating layer and holding a refrigerant 52. This is a device that can keep the SQUID 11 in a superconductive state by inserting the probe 31 holding the SQUID 11 into the cryostat 51.

[0004] The analysis display system 60 uses the SQUID 11
This system analyzes and displays the magnetic flux density data measured by using averaging and Fourier transform. The scanning stage 41 is a device that scans while placing the device under test 20 on the device. The scanning stage 41 includes the SQUID 11 and the DUT 2
This is a mechanism for changing the position relative to 0. In the XY directions, the SQUID 11 is used to scan an arbitrary range of the DUT 20, and in the Z-axis direction, the distance between the SQUID 11 and the DUT 20 is changed depending on the thickness of each DUT 20. Used for

[0005] The scanning stage controller 42 is a device for controlling the operation of the scanning stage 41. Probe 31
The SQUID 11 is attached to the probe 31 by fixing the SQUID 11 to a hinge 36 fixed to the probe 31.
The hinge 36 is in contact with the spring 37, and the angle changes depending on the surface shape of the DUT 20.

[0006] The first sensor driving device 12 is an SQUID.
This is a device that drives D11 and outputs a detected magnetic signal as a voltage signal. The measurement of the DUT 20 is performed by scanning the surface of the DUT with the SQUID 11. The scanning is performed by bringing the SQUID 11 into contact with the surface of the object to be measured. DUT 20
Even if the surface has a tilt or irregularities, the object to be measured 20 and the SQUID 11 are always in contact by changing the angle of the hinge fixing the SQUID 11.

[0007] The obtained data is analyzed and displayed by the analysis and display system 60 to detect a defect of the device under test 20.

[0008]

In the above-described conventional micro-area observation apparatus, since the object to be measured contacts the first sensor, there is a possibility that the object to be measured and the first sensor may be damaged. Also, the angle of the first sensor with respect to the DUT changes depending on the position of the DUT in order to offset the distance between the DUT and the first sensor caused by the tilt and unevenness of the DUT by the change in the hinge angle. However, there is a problem that the detection sensitivity of the first sensor changes.

[0009]

[Means for Solving the Problems]

(First Means) In order to solve the above-mentioned problems, the present invention provides a second sensor for measuring a distance between a first sensor and an object to be measured and a probe moving mechanism, and a first sensor. The distance between the object and the object to be measured can be controlled in a non-contact manner. (Second Means) The first means is further provided with a mechanism for automatically adjusting the relative position between the first sensor and the second sensor. (Third Means) The second sensor and the first sensor are integrally formed. (Fourth Means) The first sensor is provided with a hole, and the second sensor made of a magnetic material is installed through the hole of the first sensor.

[0010] According to the structure of the micro area observation apparatus according to the first means, it is possible to measure the distance between the first sensor and the object to be measured and to control the distance so as to be constant. One sensor can scan the measured object without contact,
It is possible to measure the physical properties of the measured object with high spatial resolution without damaging the first sensor and the measured object. Even if the surface shape of the device under test has an inclination or irregularities, the distance between the first sensor and the device under test is always kept constant by vertically moving the first sensor by the moving mechanism. The angle of the first sensor with respect to the measurement object does not change, and measurement can be performed with the same sensitivity at any position on the measurement object.

By the second means, it is possible to adjust a minute relative position which is difficult to manually perform. In addition, for example, even in a measurement environment such as cryogenic temperature, the distance between the first sensor and the second sensor with respect to the measured object can be equalized, so that the heat shrinkage rate between the first sensor and the second sensor is reduced. Even in the case of being different, it is possible to accurately measure and control the interval between the first sensor and the object to be measured.

According to the third means, since the distance measurement and the physical property detection are performed at the same position, the distance between the object to be measured and the first sensor can always be kept accurately and constant. It is possible to measure physical properties with high spatial resolution without damaging the object. According to the fourth means, when the magnetic sensor is used as the first sensor, even when the detection unit of the magnetic sensor is large or when the interval between the magnetic sensor and the object is wide, the magnetic sensor is generated from the object. Since the magnetic flux passes through the inside of the second sensor, the magnetic flux passes through the magnetic sensor as a result, and the measurement can be performed with high sensitivity and high spatial resolution.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 is a view showing the structure of a micro area observation apparatus according to Embodiment 1 of the present invention. Although the SQUID was used as the first sensor, other sensors such as a superconducting magnetoresistive element and a charge sensor may be used.

The cryostat 51 is a container having a vacuum heat insulating layer, which holds the refrigerant 52 and has a SQUA in the refrigerant.
This is a device for inserting and holding the ID 11, the DUT 20, the scanning stage 41, and the like. SQUID11 has Nb-based L
Using the ow-Tc-SQUID, the cryostat 51
By storing liquid helium as refrigerant 52
D11 is kept in a superconducting state. However, a Hi-Tc-SQUID such as an yttrium-based material may be used for the SQUID 11, and in that case, liquid nitrogen may be used as the refrigerant 52.

The first sensor driving device includes a SQUID
This is a device that drives D11 and outputs a detected magnetic signal as a voltage signal. The analysis display system 60 is a device that analyzes and displays a voltage signal output from the first sensor driving device 12. A measurement chamber 32 is provided inside the cryostat. The measurement chamber 32 has a structure suspended from a flange 53 fixed to the upper part of the cryostat.
The measurement chamber 32 can be divided into a ceiling part 33 and a side part 34. The connection between the ceiling portion 33 and the side portion 34 can be vacuum-sealed so that air and liquid helium do not enter the measurement chamber. The vacuum valve 38 is in the measuring chamber 3
2 is a valve for evacuating and inserting He gas. A scanning stage 41 that fixes and moves the device under test 20 is provided inside the measurement chamber 32.

The scanning stage 41 is suspended from the ceiling 33 of the measuring chamber 32 and fixed. Stainless steel is used as the material of the cryostat 51 and the measurement chamber 32,
Materials such as aluminum and FRP may be used. Probe 3
A Z-axis moving mechanism 35 is provided at the upper end of 1. The Z-axis moving mechanism 35 includes a motor and a rotation-linear motion conversion mechanism. The rotation axis of the motor is connected to the rotation-linear motion conversion mechanism, and the rotation-linear motion conversion mechanism is connected to the probe 31. When the motor is rotated, the rotation is converted into linear motion by a rotation-linear motion conversion mechanism, and the probe 31 moves up and down.

A scanner 70 is connected to the lower end of the probe 31, and the SQUID 11 and the microcantilever 81 are fixed to the scanner 70. The scanner 70 is a piezoelectric actuator, and can scan the SQUID 11 and the microcantilever 81 at a resolution of nm within a range of several tens μm at the maximum. The scanning stage controller 42 is a device that controls the operations of the scanning stage 41 and the scanner 70.

The micro cantilever 81, the laser transmitter 91 and the laser detector 92 are combined and used as a second sensor. The micro cantilever 81 is a cantilever having a fine needle at the tip. The force generated between the object to be measured and the minute needle causes the micro cantilever 8 to move.
Since 1 is deformed, the distance between the microcantilever 81 and the object to be measured can be detected by detecting the deformation. The microcantilever 81 is provided with a mirror surface, and the mirror surface is irradiated with laser light by a laser transmitter 91 and the reflected light is detected by a laser detector 92 to measure the displacement of the microcantilever 81.

The measurement is performed according to the following procedure. Measurement room 32
The side part 34 is removed from the ceiling part 33, and the DUT 20
Is set on the scanning stage 41. Z axis moving mechanism 35
After roughly adjusting the distance between the SQUID 11 and the DUT 20, the ceiling portion 33 and the side portion 34 of the measurement room 32 are connected. After the measurement chamber 32 is evacuated by the vacuum valve 38, He gas is inserted. The measurement chamber 32 is installed in the cryostat 51, and the liquid He of the refrigerant 52 is transferred into the cryostat 51 to cool the measurement chamber 32.

After the liquid He is transferred, the optical axis of the laser beam is aligned, and the distance between the object 20 and the SQUID 11 is reduced by the Z-axis moving mechanism 35 and the scanner 70. The Z-axis control is performed by the scanner 70 so that the displacement of the micro cantilever 81 becomes constant. SQUID 11 with the distance between the microcantilever and the DUT 20 kept constant.
Scans the device under test 20 for signal detection.

(Embodiment 2) FIG. 3A is a view showing the structure of a microscopic region observation apparatus according to Embodiment 2 of the present invention. FIG. 3B is a diagram illustrating the structure of the first sensor and the second sensor used in the microscopic region observation device according to the second embodiment of the present invention. There is no difference from the first embodiment except for the method of detecting the distance between the first sensor and the object to be measured.

A second sensor for measuring the distance between the first sensor and the object to be measured includes a bimorph 82 and a quartz oscillator 8.
3 in combination. The micro probe 84 is brought into contact with the quartz oscillator 83, and the quartz oscillator 83 is fixed on the bimorph 82. When the micro probe 84 is brought close to the device under test 20 in a state where the crystal resonator 83 is resonated by the bimorph 82, the resonance frequency of the crystal resonator 83 changes due to the force generated between the micro probe 84 and the device under test. Occurs. By detecting the resonance frequency, the distance between the object to be measured and the minute probe 84 can be measured. The distance between the first sensor and the object to be measured is made constant by controlling the distance between the object to be measured and the micro probe 84 by the scanner 70 so as to keep the resonance frequency constant.

The distance between the object to be measured and the minute probe 84 can also be controlled by the Z-axis moving mechanism 35. Since the change in the resonance frequency of the crystal resonator 83 can be obtained even without the minute probe 84, the crystal resonator 83 may be brought directly close to the DUT 20 without using the minute probe 84. (Embodiment 3) FIG. 4 is a view showing a structure of a relative position adjusting mechanism of a first sensor and a second sensor used in a micro area observation apparatus according to Embodiment 3 of the present invention. There is no difference from the second embodiment except that a displacement adjustment mechanism for adjusting the relative position between the second sensor and the first sensor is provided.

In order to adjust the relative position between the second sensor and the SQUID 11, a displacement adjusting mechanism 90 is provided, and the displacement adjusting mechanism 90 is composed of a combination of a bimorph 82, a quartz oscillator 83, and a fine probe 84. Fix the second sensor. The displacement adjusting mechanism 90 is made of a piezoelectric element. As a method of adjusting the relative position, the scanner 70 is gradually extended while the displacement adjusting mechanism 90 is extended and the micro probe 84 is closer to the object to be measured than the SQUID 11. When the minute probe 84 tries to contact the object, the displacement adjusting mechanism 90 is contracted to prevent the minute probe 84 from contacting the object. The state in which the SQUID 11 is to come into contact with the object to be measured is detected by a change in force generated between the microprobe 84 and the object to be measured. With the SQUID 11 in contact with the object to be measured in advance, the minute probe 84 is
May be extended to a position approaching the object to be measured. Further, the displacement may be adjusted by the displacement adjusting mechanism while observing the micro probe 84 and the SQUID 11 with a microscope.

Instead of the piezoelectric element, a displacement adjusting mechanism composed of a motor and a screw may be used. (Embodiment 4) FIG. 5 is a view showing the structure of a first sensor and a second sensor used in a microscopic region observation apparatus according to Embodiment 4 of the present invention. There is no difference from the second embodiment except that the charge sensor is used as the first sensor and the first sensor is mounted on the second sensor.

Crystal oscillator 83 fixed to bimorph 82
, A charge sensor 13 as a first sensor is mounted. The charge sensor 13 uses a single electron transistor or the like which is very sensitive to an electric field. It is necessary to drive at a very low temperature of several K in order to obtain the performance. The distance detection method is the same as in the second embodiment. While measuring the resonance frequency of the crystal resonator 83 resonated by the bimorph 82,
When the charge sensor 13 is brought close to the device under test 20, the resonance frequency changes when the charge sensor 13 and the device under test 20 come close to each other. By controlling the distance with the scanner 70 so that the resonance frequency is constant, the charge sensor 13 is controlled.
The distance between the device and the device under test 20 can be kept close to each other.

Although the charge sensor 13 is used as the first sensor, a SQUID or other physical property detection sensor may be used. (Embodiment 5) FIG. 6 is a view showing the structure of a first sensor and a second sensor used in a micro area observation apparatus according to Embodiment 5 of the present invention. There is no difference from the fourth embodiment except for the mounting method of the first sensor.

Crystal oscillator 83 fixed to bimorph 82
The optical fiber 85 is in contact with the optical fiber 85, and the charge sensor 13 as the first sensor is mounted on the optical fiber 85.
The distance detection method is the same as in the fourth embodiment. When the charge sensor 13 is brought close to the device under test 20 while measuring the resonance frequency of the crystal resonator 83 resonated by the bimorph 82, the resonance frequency changes when the charge sensor 13 and the device under test 20 come close to each other. The distance between the charge sensor 13 and the device under test 20 can be kept close by controlling the distance with the scanner 70 so that the resonance frequency is constant.

Although the optical fiber 85 is used here, a small piece of glass or sapphire may be used. The first sensor may be a SQUID or another physical property detection sensor. (Embodiment 6) FIG. 7 is a view showing the structure of a first sensor and a second sensor used in a micro area observation apparatus according to Embodiment 6 of the present invention. The micro magnetic probe 86 is brought into contact with the quartz oscillator, a hole is provided in the signal detection portion of the SQUID 11 as the first sensor, and the micro magnetic probe 86 is passed through the hole. There is nothing to change.

The distance detecting method is the same as that of the second embodiment, except that a bimorph 82 and a quartz oscillator 83 are used.
Is detected by measuring the resonance frequency of The micromagnetic probe 86 is made of an iron-nickel alloy, but may be another magnetic material, or may be a needle in which an optical fiber is coated with a magnetic film such as Ni. (Embodiment 7) FIG. 8 is a view showing the structure of a first sensor and a second sensor used in a microscopic region observation apparatus according to Embodiment 7 of the present invention. The method of detecting the distance between the first sensor and the measured object is the same as that of the second embodiment except that the distance between the electrode of the second sensor unit and the measured object is measured.

A microelectrode 87 is installed near the SQUID 11 as the first sensor, and the microelectrode 87 and the DUT 2
The capacitance between 0 is measured and controlled, and the distance between the microelectrode 87 and the object to be measured is controlled and measured. As the first sensor, a charge sensor or another physical property detection sensor may be used.

(Eighth Embodiment) FIG. 9 is a view showing the structure of a first sensor and a second sensor used in a micro area observation apparatus according to an eighth embodiment of the present invention. There is no difference from the first embodiment except for the method of detecting the distance between the first sensor and the object to be measured. The second sensor is the micro cantilever 81
And a strain resistance element 89. Strain resistance element 89
Is mounted on the microcantilever 81, the deformation of the microcantilever caused by the force generated when the object to be measured comes close to the microcantilever is detected by the strain resistance element 89, and the distance is controlled by the scanner 70 for measurement.

Although the SQUID is used as the first sensor, it may be a charge sensor or another physical property detection sensor. (Embodiment 9) FIG. 10 is a view showing the structure of a first sensor and a second sensor used in a micro area observation apparatus according to Embodiment 9 of the present invention. There is no difference from the first embodiment except for the method of detecting the distance between the first sensor and the object to be measured.

The second sensor comprises only the quartz oscillator 83. An AC signal is input to the crystal oscillator 83 and vibrated, and an output signal is measured. The distance is detected by detecting a change in the amplitude of the output signal when approaching the device under test. Although the SQUID is used as the first sensor, it may be a charge sensor or another physical property detection sensor.

[0035]

According to the present invention, the first sensor and the object to be measured can be brought into close proximity to each other without contact, and the angle of the first sensor can be kept constant.
It is possible to always measure with the same sensitivity and high spatial resolution without damaging the first sensor and the object to be measured.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a minute area observation apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a conventional small area observation device using a SQUID.

FIG. 3A is a diagram illustrating a minute region observation apparatus according to a second embodiment of the present invention. (B) It is the figure which showed the structure of the 1st sensor and 2nd sensor used by the micro area observation apparatus of Example 2 of this invention.

FIG. 4 is a diagram showing the structure of a first sensor and a second sensor used in a micro area observation device according to a third embodiment of the present invention.

FIG. 5 is a diagram showing the structure of a first sensor and a second sensor used in a micro area observation device according to a fourth embodiment of the present invention.

FIG. 6 is a diagram showing a structure of a first sensor and a second sensor used in a micro area observation device according to a fifth embodiment of the present invention.

FIG. 7 is a diagram showing a structure of a first sensor and a second sensor used in a micro area observation device according to a sixth embodiment of the present invention.

FIG. 8 is a diagram showing the structure of a first sensor and a second sensor used in a micro area observation device according to a seventh embodiment of the present invention.

FIG. 9 is a diagram showing a structure of a first sensor and a second sensor used in a micro area observation device according to an eighth embodiment of the present invention.

FIG. 10 is a diagram showing a structure of a first sensor and a second sensor used in a micro area observation device according to a ninth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 SQUID 12 First sensor drive device 13 Charge sensor 20 DUT 31 Probe 32 Measurement chamber 33 Ceiling part 34 Side part 35 Z-axis moving mechanism 36 Hinge 37 Spring 38 Vacuum valve 41 Scanning stage 42 Scanning stage controller 51 Cryostat 52 Refrigerant 53 Flange 60 Analysis display device 70 Scanner 81 Micro cantilever 82 Bimorph 83 Quartz vibrator 84 Micro probe 85 Optical fiber 86 Micro magnetic probe 87 Micro electrode 89 Strain resistance element 90 Displacement adjusting mechanism 91 Laser transmitter 92 Laser detector

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kazuo Chine 1-8-8 Nakase, Mihama-ku, Chiba-shi, Chiba Seiko Instruments Inc.

Claims (18)

[Claims] 1. An apparatus having a first sensor for detecting physical properties of an object to be measured and a moving mechanism for changing a distance between the first sensor and the object to be measured. A second sensor for detecting a distance of the small area. 2. The microscopic region observation device according to claim 1, wherein the first sensor and the second sensor are separate bodies. 3. An apparatus according to claim 1, wherein said first sensor and said second sensor are integrated. 4. The microscopic region observation device according to claim 1, wherein the first sensor and the second sensor are installed in a cryostat. 5. The microscopic region observation apparatus according to claim 2, wherein a microcantilever and a deformation detecting means of the microcantilever are used in combination as the second sensor. 6. An apparatus according to claim 5, wherein an optical lever system is used as said deformation detecting means. 7. A combination of a quartz oscillator and a vibrating element is used as said deformation detecting means.
The microscopic region observation apparatus according to the above. 8. The microscopic region observation apparatus according to claim 5, wherein a distortion resistance element is used as said deformation detecting means. 9. The micro-region observation apparatus according to claim 2, wherein a micro-electrode is used as the second sensor, and the distance is detected based on a capacitance between the micro-electrode and an object to be measured. 10. The microscopic region observation apparatus according to claim 2, wherein a quartz oscillator is used as the second sensor. 11. The microscopic region observation apparatus according to claim 3, wherein the crystal sensor and the vibration element are used in combination as the second sensor, and the first sensor is mounted on the crystal resonator. . 12. A micro probe is mounted on the quartz oscillator as the second sensor.
The microscopic region observation apparatus according to the above. 13. A micro-tip is mounted on the crystal unit,
The micro area observation device according to claim 11, wherein the first sensor is mounted on the micro probe. 14. The microscopic region observation apparatus according to claim 2, further comprising a relative position adjustment mechanism between the first sensor and the second sensor. 15. The small area observation device according to claim 4, wherein the first sensor is a superconducting quantum interference device. 16. The microregion observation apparatus according to claim 12, wherein a hole is provided in a signal detection portion of the first sensor, and the microprobe is inserted into the hole portion. 17. The microscopic region observation apparatus according to claim 16, wherein the microprobe is a magnetic material. 18. The small area observation device according to claim 4, wherein the first sensor is a charge sensor.