JP3901324B2 - Magnetic sensor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a magnetic sensor used for a control element of a brushless motor.
[0002]
[Prior art]
Magnetic sensors typified by semiconductor Hall elements have become one of the most important sensors in the fields of home appliances and industrial machinery, such as control elements in brushless motors. Development is desired. Since the sensitivity of semiconductor magnetic sensors depends on the mobility of electrons in semiconductors, attempts have recently been made to use cold cathode solid-state vacuum devices as magnetic sensors based on the principle of field emission as a measure to improve sensitivity. It has been broken. Further, it is said that this apparatus can be used even in a high temperature or radioactive environment, and expansion of the application range can be expected (Japanese Patent Laid-Open No. 6-308207).
A typical example of such an apparatus is shown in FIG. A vertical field emission type emitter electrode 1 provided on an insulating or semi-insulating substrate 5 for emitting electrons, and the number of electrons emitted from the emitter electrode 1, that is, for controlling an emitter current. A gate electrode 2, a deflection electrode 4 for controlling the trajectory of electrons emitted from the emitter electrode 1, and an anode electrode 3 for collecting electrons emitted from the emitter electrode 1. Note that element fabrication is performed using a semiconductor process.
[0003]
[Problems to be solved by the invention]
However, such a conventional magnetic sensor has the following problems.
(1) In the conventional magnetic sensor, the electron beam has a uniform line width to obtain a linear output characteristic with respect to the magnetic field. However, by arranging the emitter electrodes in a linear form, the linear electron beam can be obtained. As a result, the line width of the electron beam fluctuates, the sensor output exhibits a non-linear characteristic with respect to the external magnetic field, the accuracy of the element is lowered, and the application range is narrowed.
(2) In the conventional magnetic sensor, if the length of the arm of the linear electron beam is uniform, a linear output characteristic is obtained with respect to the magnetic field. Not provided. Therefore, the length of the arm of the electron beam fluctuates due to fluctuations in the field emission current, and the sensor output characteristics with respect to the external magnetic field exhibit nonlinearity, reducing the accuracy of this element and narrowing the application range.
(3) In the conventional magnetic sensor, the function is satisfied because the divided deflection electrode and the gate electrode are insulated. However, when actually used, the insulation between each deflection electrode and the gate electrode is lowered. This is presumably because the electron beam is ionized by the atmospheric gas and is attracted to the emitter electrode by electrostatic attraction, thereby modifying the surface of the insulating layer located above the emitter electrode. When the insulation between each deflection electrode and the gate electrode is lowered, the potential of the gate electrode is lowered and the amount of emitted electrons is reduced, so that the sensor becomes impossible to measure and the reliability is reduced, and the application range is narrowed.
(4) In the conventional magnetic sensor, since the electron beam has a uniform line width, a linear output characteristic is obtained with respect to the magnetic field. However, since the linear electron beam is generated by the deflection electrode, the electric field The line width of the electron beam fluctuates due to non-uniformity of the non-uniformity and the like, showing non-linear characteristics, reducing the accuracy of this element, and narrowing the application range.
Accordingly, an object of the present invention is to provide a magnetic sensor with high accuracy and a wide application range.
[0004]
[Means for Solving the Problems]
In order to achieve the above object, the present invention controls a field emission type emitter electrode arranged to emit a linear electron beam in a package whose inside is evacuated, and the number of electrons emitted from the emitter electrode. A gate electrode that deflects the electron beam, and a four-part deflecting electrode that deflects the electron beam, and the electron beam that is divided into at least two parts via an insulating layer on a substrate facing the emitter electrode via a gap An anode electrode that collects the electrons of the cross-section , and the formed cross-shaped electron beam is changed by the external magnetic field to be measured, and the intensity of the external magnetic field is changed based on the change in the number of electrons incident on the anode electrode a magnetic sensor for detecting a, the 4 divided an insulating layer formed on each of the deflection electrodes, the cross-shaped electronic Bee provided at a boundary of the outer end portion of the insulating interlayer Line segments are provided with masks adjusted to be equal. The insulating layer between the deflection electrode and the gate electrode is removed.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be specifically described below based on examples.
First Embodiment FIG. 1 is a perspective view showing the overall configuration of a magnetic sensor according to a first embodiment of the present invention, FIG. 2 is an enlarged sectional view in the vicinity of the emitter electrode, and FIG. 3 is a plan view seen from the upper part in the vicinity of the emitter electrode. .
The magnetic sensor of this embodiment is a field emission type emitter electrode 1 provided to emit electrons into the package 8 and the number of electrons emitted from the emitter electrode 1, that is, an emitter current. A gate electrode 2, an anode electrode 3 for collecting electrons emitted from the emitter electrode 1, and a deflection electrode 4 for controlling the trajectory of electrons emitted from the emitter electrode 1 are provided. Further, an activation correction mask 9 made of an insulating material is laminated on the upper part of each deflection electrode.
The deflection electrode 4 is equally divided into four 90 ° portions around the emitter electrode 1. Note that the same potential is applied to these deflection electrodes 4. Further, the anode electrode 3 is divided into four parts at the same position as the deflection electrode 4 when viewed from above the sensor. By measuring the current reaching each anode electrode 3, the arrival position of the electron beam deflected in a cross shape to the anode electrode 3 can be determined. The equipotential shielding electrode 7 is provided on the outer periphery 360 degrees of these structures.
All the electrodes described above are arranged radially and symmetrically from the center of the cross-shaped electron beam so that the trajectory of electrons does not have anisotropy.
Here, in the conventional structure as shown in FIG. 14, the arm length of the electron beam has an uneven arm length with time as shown in FIGS. 4B and 4C, for example. Since it becomes a cross-shaped electron beam, the output with respect to the external magnetic field becomes non-linear as shown by the broken line in FIG. However, if the mask for limiting the electron beam end is provided as shown in FIGS. 1 and 2 of this embodiment, the end is limited by the mask as shown in FIG. Since an electron beam having the length of the arm of the electron beam is obtained, a linear output with respect to the external magnetic field can be obtained as shown by a solid line in FIG.
[0006]
Second Embodiment FIG. 6 is a perspective view showing the overall configuration of a magnetic sensor according to a second embodiment of the present invention.
The magnetic sensor of this embodiment is the same as that shown in FIGS. 1 and 2 in appearance. The emitter electrode 1 provided for emitting electrons, the number of electrons emitted from the emitter electrode 1, that is, the gate electrode 2 for limiting the emitter current, and the electrons emitted from the emitter electrode 1 are collected. An insulator 6 is laminated in place of the deflection electrode 4 at the position of the anode electrode 3 and the deflection electrode 4 provided in the first embodiment, and for trajectory correction for limiting the excreted electron beam on the upper portion thereof. The mask 9 is held and fixed.
These components are disposed in the package 8 and, like the first embodiment, the equipotential shielding electrode 7 is provided on the outer periphery 360 degrees of these structures.
Also in this embodiment, since an electron beam having a uniform beam length can always be obtained by providing a mask, the improvement in linearity of the sensor output with respect to the external magnetic field similar to the solid line in FIG. 5 can be seen. Become.
[0007]
Third Embodiment FIG. 7 is a perspective view showing the overall configuration of a magnetic sensor according to a third embodiment of the present invention, and FIG. 8 is an enlarged sectional view of the vicinity of the emitter electrode.
The magnetic sensor of this embodiment includes a field emission type emitter electrode 1 provided for emitting electrons, a gate electrode 2 for controlling the number of electrons emitted from the emitter electrode 1, that is, an emitter current, An anode electrode 3 for collecting electrons emitted from the emitter electrode 1 and a deflecting electrode 4 arranged on the same plane as the gate electrode for controlling the trajectory of the electrons emitted from the emitter electrode 1 are configured. Yes. Further, a trajectory correcting mask 9 made of an insulating material is laminated on each deflection electrode.
These components are arranged inside the package 8 as shown in FIG. The deflection electrodes 41 and 42 are equally divided into four by 90 degrees with the emitter electrode 1 as the center. Note that the same potential is applied to the deflection electrodes 41 and 42. Further, the anode electrode 3 is divided into four parts at the same position as the deflection electrode 4 when viewed from above the sensor. By measuring the current reaching each anode electrode 3, the arrival position of the electron beam deflected in a cross shape to the anode electrode 3 can be determined. The equipotential shielding electrode 7 is provided on the outer periphery 360 degrees of these structures.
Here, in the conventional structure as shown in FIG. 14, since the line width of the electron beam is not constant, the state when the electron beam reaches the anode electrode 3 is a non-uniform line as shown in FIG. It becomes a cross-shaped electron beam having a width, and the output with respect to the external magnetic field becomes nonlinear as shown by the broken line in FIG. However, if orbital correction masks 91 and 92 are provided as shown in FIGS. 7 and 8 of this embodiment, a cross-shaped electron beam having a uniform line width as shown in FIG. 9B can be obtained. Therefore, as shown by the solid line in FIG. 10, a linear output can be obtained with respect to the external magnetic field. In addition, what is necessary is just to provide in the upper part so that the insulating layer 9 may be covered, when using a conductor as a mask.
[0008]
Fourth Embodiment FIG. 11 is a perspective view showing the overall configuration of a magnetic sensor according to a fourth embodiment of the present invention.
In the magnetic sensor of this embodiment, five emitter electrodes 1 provided for emitting electrons are arranged in a cross shape, and a gate electrode for controlling the number of electrons emitted from the emitter electrode 1, that is, an emitter current. 2, an anode electrode 3 for collecting electrons emitted from the emitter electrode 1, and a deflecting electrode 4 on the same plane as the gate electrode 2 for controlling the trajectory of electrons emitted from the emitter electrode 1. Configured. Further, a trajectory correcting mask 9 made of an insulating material is laminated on each deflection electrode 4.
These components are arranged inside the package 8 as shown in FIG. The deflection electrode 4 is equally divided into four portions by 90 degrees with the emitter electrode 1 as the center. Note that the same potential is applied to these deflection electrodes 4. Further, the anode electrode 3 is divided into four parts at the same position as the deflection electrode 4 when viewed from above the sensor. By measuring the current reaching each anode electrode 3, the arrival position of the electron beam deflected in a cross shape to the anode electrode 3 can be determined. The equipotential shielding electrode 7 is provided on the outer periphery 360 degrees of these structures.
Since the present embodiment also provides a trajectory correcting mask 9 as in the third embodiment, a cross-shaped electron beam having a uniform line width as shown in FIG. 9B can be obtained. As shown by the solid line in FIG. 10, a linear output can be obtained with respect to the external magnetic field. Also, as shown in FIG. 12, the same effect can be obtained by providing a mask 9 around each emitter element 1.
[0009]
Fifth Embodiment FIG. 13 shows the structure of a magnetic sensor according to a fifth embodiment of the present invention, and is an enlarged cross-sectional view taken along a plane perpendicular to the substrate along the line AA 'in FIG. FIG. The external appearance is almost the same as that of the conventional example shown in FIG.
The magnetic sensor of this embodiment includes a field emission type emitter electrode 1 provided for emitting electrons, a gate electrode 2 for controlling the number of electrons emitted from the emitter electrode 1, that is, an emitter current, An anode electrode 3 for collecting electrons emitted from the emitter electrode 1 and a deflection electrode 4 on the same plane as the gate electrode 2 for controlling the trajectory of electrons emitted from the emitter electrode 1 are configured. ing.
These components are arranged inside the package 8 as shown in FIG. The deflection electrode 4 is equally divided into four portions by 90 degrees with the emitter electrode 1 as the center. Note that the same potential is applied to these deflection electrodes 4. Further, the anode electrode 3 is divided into four parts at the same position as the deflection electrode 4 when viewed from above the sensor. By measuring the current reaching each anode electrode 3, the arrival position of the electron beam deflected in a cross shape to the anode electrode 3 can be determined. The equipotential shielding electrode 7 is provided on the outer periphery 360 degrees of these structures.
Here, in the conventional structure as shown in FIG. 15, the deflection electrode electrodes 41 and 42 divided by the insulation deterioration of the exposed portion of the insulating layer 6 are electrically in common with the gate electrode 2, and the potential of the gate electrode 2 is Decreases, and the amount of emitted electrons decreases. Therefore, by etching the exposed portion with buffered hydrofluoric acid and forming it as shown in FIG. 13, it is possible to avoid deterioration of the insulating layer and to prevent potential fluctuation of the gate electrode 2. Further, it is preferable to perform over-etching because deterioration of the insulating layer can be further prevented.
[0010]
【The invention's effect】
As described above, the present invention has the following effects.
(1) A linear electron beam emitted from a vertical field emission type emitter electrode is provided with a trajectory correction mask for correcting an end portion and a line width of the electron beam, so that the arm length and the line width are uniform. An electron beam can be obtained. Furthermore, since the fluctuation of the current flowing into the divided anode becomes linear due to the fluctuation of the external magnetic field, the accuracy of the magnetic sensor is improved, and a magnetic sensor with high accuracy, practicality, and wide application range can be provided.
(2) The divided insulating layer between the deflection electrode and the gate electrode is removed, so that the insulation between the deflection electrode and the gate electrode can be prevented from deteriorating, thereby preventing the potential fluctuation of the gate electrode. The reliability of the magnetic sensor is improved, and a magnetic sensor with a wide application range can be provided.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an overall configuration of a magnetic sensor according to a first embodiment of the present invention.
FIG. 2 is an enlarged cross-sectional view in the vicinity of an emitter electrode according to the first embodiment.
FIG. 3 is a plan view seen from the upper part in the vicinity of the emitter electrode of the first embodiment.
FIG. 4 is a schematic view of an electron beam when reaching the anode for explaining the first embodiment, as viewed from above.
FIG. 5 is a characteristic diagram of an external magnetic field and sensor output for explaining the first embodiment.
FIG. 6 is a perspective view showing an overall configuration of a magnetic sensor according to a second embodiment of the present invention.
FIG. 7 is a perspective view showing an overall configuration of a magnetic sensor according to a third embodiment of the present invention.
FIG. 8 is an enlarged cross-sectional view in the vicinity of an emitter electrode according to a third embodiment.
FIG. 9 is a schematic view of a cross-shaped electron beam as viewed from above, explaining the second and third embodiments of the present invention.
FIG. 10 is a characteristic diagram of an external magnetic field and sensor output for explaining second and third embodiments of the present invention.
FIG. 11 is a perspective view showing an overall configuration of a magnetic sensor according to a fourth embodiment of the present invention.
FIG. 12 is a perspective view showing the overall configuration of another example of the fourth embodiment of the present invention.
FIG. 13 is an enlarged sectional view showing a configuration of a magnetic sensor according to a fifth embodiment of the present invention.
FIG. 14 is a perspective view showing an overall configuration of a conventional magnetic sensor.
FIG. 15 is a perspective view showing an overall configuration of a conventional magnetic sensor.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Emitter electrode 2, 21, 22 Gate electrode 3, 31, 32 Anode electrode 4, 41, 42 Deflection electrode 5 Substrate 6, 61, 62, 63, 64 Insulating layer 7 Shielding electrode 8 Package 9, 91, 92, 93, 94 Orbit Correction Mask

Claims (2)

A field emission type emitter electrode arranged to emit a linear electron beam, a gate electrode for controlling the number of electrons emitted from the emitter electrode, and the electron beam are deflected in a package having a vacuum inside . A four-divided deflection electrode; and an anode electrode for collecting electrons of the electron beam provided on the substrate at a position facing the emitter electrode via a gap and divided into at least two via an insulating layer In the magnetic sensor for detecting the intensity of the external magnetic field based on the fact that the formed cross-shaped electron beam is changed by the external magnetic field to be measured and the number of electrons incident on the anode electrode is changed.
An insulating layer provided on each of the four-divided deflection electrodes, and a mask provided at the boundary of the outer end between the insulating layers and adjusted so that the line segment of the cross-shaped electron beam is equally divided Magnetic sensor characterized by the above.   The magnetic sensor according to claim 1, wherein an insulating layer between the deflection electrode and the gate electrode is removed.

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