JPH0632208B2 - Non-volatile high recording density random access memory - Google Patents

Description

The present invention relates to a nonvolatile high recording density random access memory using a ferromagnetic material.

The present invention provides a recording device that is superior to a conventional magnetic recording device or a recording device using a semiconductor in terms of recording density as compared with the former and in non-volatility as compared with the latter. The purpose is to provide.

In order to achieve the above object, according to the present invention, ferromagnetic ultrafine particles are regularly and correctly landed / fixed on a predetermined lattice point in a non-magnetic substance, and writing is performed at any time through the lattice point. A nonvolatile high recording density random access memory provided with a read line is provided.

Desirably, the non-magnetic material is a substrate, and the lattice points are lattice points on the plane of the substrate. Then, the ultrafine particles of the ferromagnetic material are set in and fixed in the holes regularly formed at the lattice points on the plane of the substrate. The grid points are, for example, grid points of a square grid. Further, the ferromagnetic ultrafine particles are fixed by a first insulating film such as Si or SiO ₂ . Writing / reading lines are provided on the first insulator film via the second insulator film such as Si or SiO ₂ mutually as needed. The writing line is composed of two groups of lines which intersect each other without touching each other at the lattice points. The read line from time to time consists of one line.
Then, a current below the critical current necessary for reversing the magnetization of the ferromagnetic ultrafine particles is fed to the two writing lines that intersect each other and pass through the lattice points to be written. In addition, a current is sent to a write line that passes through a grid point to be read at any time during and after reading. Furthermore, the ferromagnetic ultrafine particles are implanted and fixed in holes that are regularly formed at lattice points on the plane of the non-magnetic substrate, and lines for writing and reading that pass through the lattice points at any time are provided. A plurality of the constructed ones are superposed and integrated.

Next, one embodiment of the present invention will be described with reference to FIGS. 1 to 4.

FIG. 1 is an exploded perspective view of the nonvolatile high recording density random access memory of this embodiment, in which reference numeral 1 is a non-magnetic substrate of Si or SiO ₂ . Code 1
Reference numeral b is a hole formed on the substrate 1 for implanting ferromagnetic ultrafine particles such as iron, nickel, and cobalt, which is a normal lithographic technique using light, electron beams or X-rays. Thus, the hole 1b is formed on the substrate 1 in a predetermined shape, depth and position. In FIG. 1, the cross section 1a of the hole 1b is shown in order to make it appear three-dimensional. The holes 1b are regularly formed on fixed grid points, and the symmetry of the arrangement of the grid points is shown as an example of a square grid, but other symmetry is also possible. After forming the hole 1b, the ferromagnetic ultrafine particles are applied to the carrier gas (N ₂ or N ₂ while applying a strong magnetic field perpendicular to the substrate 1).
H ₂ ), and spraying, the ultrafine particles are implanted in the hole 1 b. At that time, the surface of the substrate 1 other than the holes 1b is covered with a resist film, and the resist film is removed after the implantation of the ultrafine particles. After that, Si or Si shown by reference numeral 2 on the surface of the substrate 1
An insulating film such as O ₂ is vapor-deposited to form a film for fixing the implanted ultrafine particles. The read line 2a is formed thereon by using the above-mentioned lithographic technique. The arrangement of the read lines 2a is, for example, a group of parallel lines passing through diagonal lines of a square lattice as shown in FIG. 2, and they are connected to one line as shown by a dotted line 2b. The readout line 2a does not necessarily have to pass through the diagonal of the square lattice,
Various modifications are possible. Also, of course, hole 1
It also depends on the symmetry of the lattice points of b. In FIG. 2, the shape of the upper surface of the hole 1b in contact with the lower surface of the Si or SiO ₂ film 2 is shown by a dotted line. After the read line 2a is formed, an insulating film 3 such as Si or SiO ₂ is vapor-deposited on the read line 2a, and the first write line 3a is similarly formed thereon (FIG. 3). Further, another insulating film 4 such as Si or SiO ₂ is vapor-deposited thereon, and the second write line 4a is similarly prepared (FIG. 4). In the case of a square lattice, the first write line 3a extends in parallel to the horizontal direction, and the second write line 4a extends in parallel to the vertical direction intersecting with this. The intersections of the first and second writing lines coincide with the lattice points. In the above embodiment, the write lines 3a and 4a are arranged on the read line 2a, but the write lines 3a and 4a are first formed on the substrate 1.
It will be apparent that modifications such as arranging a and providing the read line 2a thereon can be made. The size of the holes and the width of the lines should be as fine as possible with current lithography technology.

The memory of the above embodiment operates as follows. First,
Before writing, it is assumed that all the ultrafine particles have, for example, an upward magnetization direction at each lattice point. At this time, of the first write line 3a and the second write line 4a, the line passing through the lattice point to be written is determined, and at the same time, the line below the critical sea current required for reversing the magnetization of the ferromagnetic ultrafine particles is determined. When a current is sent, the magnetization does not reverse because all the currents passing through the other lattice points are below the critical current, but the sum of the two currents is the critical current only at the lattice point at the intersection of the selected lines 3a and 4a. After reaching the above, the magnetization of only the ultrafine particles at the lattice point is reversed. That is, it is possible to perform recording corresponding to 0 before inversion and 1 after inversion. For reading, write lines 3a, 4
Depending on whether the selected lattice point is in the state of 0 or in the state of 1 when performing the same operation on a,
Since the reversal of magnetization occurs or does not occur and the current induced in the read line 2a is different, it is possible to know the stored content (0 or 1) of the ultrafine particles at the lattice point. It depends on what you can do. However, the reversal of the magnetization caused by the reading at that time needs to be restored again, and this is performed by sending a necessary current to the write lines 3a and 4a.

According to the present invention, the effect of the present invention is to provide a conventional semiconductor LSI.
It is possible to manufacture relatively easily by directly using the technology used in the above, and it is possible to obtain a recording density larger by one digit or more than the memory such as the conventional tape or disk. Further, it is expected that the recording density of the memory of the present invention will inevitably increase with the development of fine processing technology. Further, the memory of the present invention is non-volatile as compared with a RAM using a semiconductor, and the memory content can be stored, which is a significant advantage over a semiconductor memory.

It will be apparent that modifications such as a three-dimensional memory can be configured by superimposing a plurality of single-layer memories configured as described above and integrating them. In that case, the write line can be formed by three or more groups of lines having different directions.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a nonvolatile high recording density random access memory according to an embodiment of the present invention, FIG. 2 is a detailed view of a portion related to a read line of the memory of FIG. 1, and FIGS. 3 is a detailed view of a portion of the memory of FIG. 1 relating to first and second write lines. FIG. 1: non-magnetic substrate, 1b: hole, 2, 3, 4: insulating film,
2a: read line, 3a, 4a: write line

Claims (13)

[Claims] 1. A non-magnetic substrate made by a lithographic technique and having holes on lattice points, ultrafine particles of a ferromagnetic material embedded in the holes on said lattice points, and said lattice points made by a lithographic technique. Non-volatile high recording density random access memory characterized by having mutually insulated wiring for occasional writing and reading through 2. The nonvolatile high recording density random access memory according to claim 1, wherein the ferromagnetic ultrafine particles are produced by using a gas evaporation method and a lithography technique. 3. A nonvolatile high recording density random access memory according to claim 2, wherein a magnetic field is applied when the ultrafine particles of the ferromagnetic material are produced by the gas evaporation method. 4. The non-volatile high recording density random access memory according to claim 1, wherein the lattice points on the non-magnetic substrate are lattice points on a plane of the substrate. 5. Nonvolatile according to claim 4, wherein the ultrafine ferromagnetic particles are landed and fixed in holes regularly formed at lattice points on the plane of the substrate. High recording density random access memory 6. The nonvolatile high recording density according to claim 4 or 5, wherein the lattice points are square lattices, parallelograms, honeycombs or triangular lattices. Random access memory 7. The nonvolatile high recording according to any one of claims 4 to 6, wherein the ferromagnetic fine particles are fixed by a first insulating film such as Si or SiO _2. Density random access memory 8. A line for writing / reading at any time is provided on the first insulator film via a second insulator film such as Si or SiO _{2 with} respect to each other. Nonvolatile high recording density random access memory according to item 7. 9. The non-volatile high recording density according to any one of claims 4 to 8, characterized in that the write line at any time is composed of two groups of lines which intersect without touching each other at lattice points. Random access memory 10. The non-volatile high recording density random access memory according to claim 4, wherein the read line at any time comprises one line. 11. A configuration is such that a current below a critical current required for reversing the magnetization of ferromagnetic ultrafine particles is sent to each of two write lines that intersect each other and pass through a lattice point to be written. Non-volatile high recording density random access memory according to any one of claims 8 and 9 characterized by 12. The present invention according to claim 8, characterized in that a current is sent to the write line passing through the grid point to be read at any time during and after reading.
Non-volatile high recording density random access memory according to any one of items 9 and 11 13. Ferromagnetic ultrafine particles are landed and fixed in holes regularly formed at lattice points on the surface of a non-magnetic substrate, and lines for writing and reading are provided at any time passing through the lattice points. A nonvolatile high recording density random access memory according to claim 1, characterized in that a plurality of the thus constituted ones are superposed and integrated.