JP2775969B2 - Pickup coil for squid vector magnetometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application> The present invention relates to a pickup coil for a squid magnetometer, and more particularly, to facilitate manufacturing by forming a large number of pickup coils using semiconductor process technology. It relates to a pickup coil.

<Conventional technology> A squid magnetometer includes a superconducting ring having a Josephson junction, an input coil forming a superconducting closed loop together with the coil, and a pick-up coil coupled to the input coil. The flux quantum φ ₀ (2.07 × 10
^It outputs a voltage signal with a cycle of ^-15 wb), and can measure magnetic flux with high sensitivity.

FIG. 5 is a general configuration diagram showing such a squid magnetometer (DC type). ,, 1 superconducting ring with Josephson junctions JC in FIG, 2 is the inductance L ₁ of the input coil to bind to the superconductive ring 1, 21 and 22 of the input coil 2 made of a superconducting material terminals, Reference numeral 3 denotes a pickup coil having an inductance Lp, and terminals 21 and 2 are formed so as to form a superconductive closed loop together with the input coil 2.
Are connected in series via two. 7 is a superconducting ring 1
An amplifier, which amplifies the output voltage from, is a current source that supplies current to the superconducting ring. Here, the superconducting ring 1, the input coil 2, the terminals 21, 22 and the pickup coil 3 are all stored in the cryostat 8 and maintained in a superconducting state in liquid helium.

6 (a) and 6 (b) are perspective views showing a conventional example of pickup coils arranged in three axial directions for detecting a magnetic field as a vector. (A) is a diagram in which three wires (40a, 40b, 40c) are wound around a spherical bobbin 40 at right angles to each other, and the diameter of the bobbin is, for example, about 30 mm. FIG. 5B shows a case where substrates (51a, 51b, 51c) each having a coil pattern formed on three surfaces of a cube 50 having a side of about 30 mm are fixed.

<Problems to be solved by the invention> However, the method shown in (a) has a problem that productivity is poor because the wire must be manually wound.
(B) In the case shown in the figure, it is difficult to improve the dimensional accuracy when attaching the substrate to the cube, and the positions of the detected magnetic fields are all three axes apart, so x, y, z at different positions There is a problem of detecting the component and ending. That is, if the diameter of the bobbin and the length of one side of the cube are reduced, the coil can be approached, but the workability deteriorates. For example, when measuring the brain magnetic field of the human head, the greater the number of channels of the magnetometer, the more information that can be obtained. was there.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems of the prior art. By using a semiconductor process technology, a pickup coil for detecting a magnetic field vector at a position having almost the same detection position with high dimensional accuracy can be manufactured at low cost. The purpose is to do.

<Means for Solving the Problems> A configuration of the present invention for solving the above problems includes a pickup coil for detecting a magnetic flux to be measured, and an input coil connected to the pickup coil and forming a superconducting closed loop together with the coil. And a pickup coil of a squid magnetometer including a superconducting ring coupled to the input coil, wherein the pickup coil is formed by an anisotropic etching on a substrate and has an inverted base having a flat bottom surface and a fixed side wall. A hole having a shape is formed, and a thin film coil pattern is provided at at least two places of the bottom part and the side wall.

<Operation> Since pickup coils are formed on the bottom and side walls of the inverted trapezoidal fine holes formed by anisotropic etching, the pickup coils formed in one hole can be regarded as being substantially at the same position. In addition, since the semiconductor device is manufactured using a semiconductor process, productivity can be increased and dimensional accuracy can be improved.

<Embodiment> FIG. 1 is a configuration perspective view showing an embodiment of the present invention.
In the figure, reference numeral 30 denotes a silicon substrate. Reference numeral 31 denotes a fine hole formed on the silicon substrate and having a side of, for example, 100 μm and a depth of about 40 μm. Reference numerals 3a, 3b, and 3c denote pickup coils formed in the fine hole.

Such microscopic holes should be aligned on the (100) surface in the <110> direction, and anisotropic etching solution using potassium hydroxide solution, EDP etching solution, etc. to expose (111) surface Is formed. In this case, the angle of the side wall of the hole is 54.7 ° with respect to the horizontal direction. Therefore, the area of the base is 44
If it is about μm, the length of the side wall from the edge of the hole to the bottom is
It is about 50 μm, and the same size coil pattern can be formed on the bottom and side surfaces.

FIG. 2 is a sectional view showing a state in which a resist 32 is applied to the surface of the silicon substrate including the fine holes 31 and patterned into a coil shape using a mask 33.

FIG. 3 is a plan view showing an example in which coils are formed at two places on the bottom and the wall of the fine hole 31. FIG. Although a large number of such holes are formed on the same substrate, it is possible to increase the effective area for picking up magnetic flux by connecting the pickup coils at the same position. When exposing micro holes using a mask pattern, the resist is patterned using X-rays with little diffraction, and a coil is formed by sputtering or vapor deposition using a superconducting material. It is also possible to form a coil directly. It is also possible to form a coil pattern by laminating a superconducting thin film on the entire surface of the substrate and then etching it with a focus ion beam. Further, the number of pickup coils and the dimensions of the holes can be arbitrarily changed as necessary.

FIG. 4 shows a state in which a substrate on which a number of pickup coils are formed is arranged on the head of a human body, and it is possible to efficiently detect a magnetoencephalogram vector.

<Effects of the Invention> As described above in detail with the embodiments, according to the present invention, there is no need to manually wind a superconducting wire or attach a substrate to a cube as in the related art. A pickup coil for measuring an extremely close magnetic field vector can be realized.

Further, since the pattern is formed by using a semiconductor process, the dimensional accuracy can be drastically improved, the size can be reduced, and a large number of pickup coils can be manufactured efficiently.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of the pickup coil of the present invention, FIG. 2 is a sectional view showing a state in which a coil pattern is formed on a resist using a mask, and FIG. FIG. 4 is a plan view showing an example in which coils are formed at two places, FIG. 4 is a view showing a state in which a substrate is placed on the head of a human body, FIG. 5 is a general configuration diagram of a squid magnetometer, and FIG.
FIG. 1 is a perspective view showing a conventional pickup coil. 30 …… Substrate, 31 …… Micro hole, 3a, 3b, 3c …… Pickup coil.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01R 33/035 H01L 39/22

Claims (1)

(57) [Claims] A pickup coil for detecting a magnetic flux to be measured; an input coil connected to the pickup coil to form a superconducting closed loop together with the coil;
In a pickup coil of a squid magnetometer including a superconducting ring coupled to the input coil, the pickup coil has an inverted trapezoidal shape having a flat bottom surface and a fixed angle side wall by anisotropic etching on a substrate. A pickup coil for a squid magnetometer, wherein a hole is formed and a thin-film coil pattern is provided at at least two places on the bottom part and the side wall.