JPH07101514B2 - Recording / reproducing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention is a method for performing high-density recording / reproduction using a beam selected from an electron beam, a charged particle beam and a neutral particle beam in a vacuum in a recording medium. Regarding

[Conventional technology]

As a high-density recording medium and a recording / reproducing method for the medium, various media and methods for using the medium have been known, and typical methods include magnetic recording and optical recording.

The recording density of each of magnetic recording and optical recording is about 1.0 to 0.5 μm in terms of recording wavelength. In magnetic recording, the minimum particle size that can exist as a ferromagnetic material, about 100Å, is considered to be the minimum recording wavelength that is possible in principle, but currently, the device side such as a magnetic head used for recording and reproducing is used. Due to restrictions, the shortest wavelength of recording is about 1 μm to 0.7 μm. On the other hand, in optical recording, the recording density is limited by the diameter of the light beam used for recording and reproduction, and the shortest wavelength of recording is about 1 μm to 0.5 μm.

[Problems to be solved by the invention]

Therefore, in place of these, demands for a method for realizing a higher recording density are increasing in various technical fields.

It is an object of the present invention to provide a new recording / reproducing method which meets these needs and enables recording / reproducing at a higher density than conventional magnetic recording or optical recording.

[Means for solving problems]

The present invention firstly provides a recording medium having a multilayer structure in which atomic layers are alternately stacked on a support, and a recording beam selected from an electron beam, a charged particle beam and a neutral particle beam in a vacuum atmosphere. By irradiating the surface of the recording medium with the atoms of the lower layer and Ag-Mg, Cs-Te, Sb-Cs, Cu-Be, Ga.
Information is recorded by forming a mixture selected from the group consisting of -As-P, and the surface of the recording medium on which the information has been recorded is irradiated with a reproducing beam, which is an electron beam. Emit secondary electrons from the surface, 2
The present invention relates to a recording / reproducing method characterized by reproducing recorded information by reading a difference in secondary electron emission characteristics depending on a location.

Secondly, a recording medium having a multilayer structure in which atomic layers are alternately stacked on a support is used, and a recording beam selected from an electron beam, a charged particle beam and a neutral particle beam is used in a vacuum atmosphere. The surface of the recording medium is irradiated with the atoms of the lower layer and Ag-Mg, Cs-Te, Sb-Cs, Cu-Be, Ga.
Information is recorded by forming a mixture selected from the group consisting of -As-P, and the recorded information is erased by removing the formed portion of the mixture by plasma etching or chemical sputtering. Of the recorded information by irradiating the surface of the recording medium on which is recorded with a reproducing beam, which is an electron beam, to emit secondary electrons from the surface of the recording medium, and reading the difference in secondary electron emission characteristics depending on the location. The present invention relates to a recording / reproducing method characterized by performing reproduction.

The present invention will be described in detail below.

FIG. 1 is a cross-sectional view showing a structure of a recording medium and a state of the recording medium at the time of recording / erasing as one embodiment of the present invention. (A) ... Recording medium structure, (b) ... Recording, (c) ) ... Recording part erased, (d) ... Record addition correction, (e) ... Record entire surface erased.

FIG. 1 (a) shows an example of the recording medium of the present invention. The first atomic layer 2 and the second atomic layer are formed on the support 1 as atomic layers.
3, a first atomic layer 4 and a second atomic layer 5 are repeatedly stacked alternately, each atomic layer being a combination of atomic layers forming a mixture between adjacent atomic layers by a recording beam, and a four-layer structure Recording medium.

In FIG. 1 (b), a recording beam is used to irradiate a part of the uppermost second atomic layer 5 on the surface of the recording medium to form a mixture with the lower first atomic layer 4. A sectional view of the recording portion 6a is shown. The surface of the recording medium on which this information is recorded is irradiated with a reproducing beam selected from an electron beam, a charged particle beam and a neutral particle beam, and the recording portion 6a
The recorded information can be reproduced by reading the difference in the emission characteristics between the secondary electrons emitted from the mixed portion of and the secondary electrons emitted from the uppermost second atomic layer 5 of the recording medium. I can.

FIG. 1 (c) shows a state in which the recording portion 6a of FIG. 1 (b) is erased. The recording portion 6a is irradiated with an erasing beam, and the second atomic layer 5 and the first atomic layer 5 are erased. By removing 4 and forming the erased portion 7, the surface of the erased portion 7 becomes the second atomic layer 3 and therefore there is no difference in the radiation characteristics from the secondary electrons emitted from the uppermost second atomic layer 5 during reproduction. It will disappear, and partial erasure will be completed.

FIG. 1 (d) shows a recording portion in the same manner as in FIG. 1 (b).
It shows that the recording part 6b can be added to 6a.

In FIG. 1 (e), the second atomic layer 5 and the first atomic layer 4 are completely removed by using an erasing beam in order to erase all the recorded portions 6a and 6b to form a new recording surface. The uppermost layer is changed to the second atomic layer 3.

The above is a summary, and next, each element of the present invention will be described.

The support in the present invention is preferably one that does not release harmful gas for use in a vacuum, a metal and its oxide having a smooth surface, glass or plastic film, etc. are used, and the shape thereof is a plate, It may be a thin film.

The secondary electron emission characteristic in the present invention means, for example, the secondary electron emission efficiency or the energy spectrum of secondary electrons. The secondary electrons mentioned here are a general term for electrons generated from an object when a reproducing beam selected from an electron beam, a charged particle beam and a neutral particle beam hits the object, and also includes Auger electrons.

As a reading method for reproducing the recorded information, it is preferable to detect the secondary electron emission efficiency from the strength of the output and a method to detect the energy spectrum because it is not affected by the unevenness of the solid surface.

The atomic layer of the present invention is formed using a vacuum vapor deposition method or a sputtering method.

In the alternately laminated atomic layers of the present invention, the element forming each atomic layer may be composed of a single element, or may be composed of two or more kinds of elements.

In addition, at least two kinds of atomic layers in the present invention mean that two kinds are the most general, but three or four kinds of atomic layers may be used if necessary.

As a layer structure, it is necessary that a layer containing a mixture having different secondary electron emission characteristics from a single layer can be formed by forming a mixture between elements of two adjacent layers.

The present invention, when mixed between the upper and lower atomic layers, the elements contained in the atomic layer are selected so that the difference in electron emission efficiency between the atomic layer of a simple substance and the alloy is shown as much as possible, and the mixture is Ag. -Mg, Cs-Te, Sb-Cs, Cu-Be, Ga-As-P.

Therefore, it is preferable that the adjacent layers are formed of one or two of the respective component elements so that the mixture is formed by the irradiation of the recording beam.

Further, when detecting the energy spectrum of secondary electrons, it is desirable that the mixture produced has an amorphous (amorphous) structure in order to reduce noise from grain boundaries during reproduction.

In the present invention, to have a multilayer structure in which atomic layers are alternately stacked is not limited to four layers, but it is preferable to have a multilayer structure for applications in which recording and erasing are performed many times.

The thickness of the atomic layer in the present invention is such that if the layer is too thin, secondary electrons will be emitted from the layer below the surface layer and S / N will not be sufficient. It is preferably 10 to 100 Å because it takes a lot of time to remove a necessary portion.

As the element of the charged particles or the neutral particles for generating the recording beam used in the present invention, an element which is a gas at room temperature and is inactive is used. For example, Ar, N.

As the recording beam in the present invention, a beam selected from an electron beam, a charged particle beam and a neutral particle beam is used,
It is necessary to have an energy intensity for mixing a part of the uppermost atomic layer on the surface of the recording medium and the atomic layer thereunder.

In the present invention, recording is erased by plasma etching or chemical sputtering so that the mixing of the upper and lower atomic layers does not proceed. Chemical spattering refers to spattering that is carried out with the reaction of the discharge gas and the target.

The elements for generating the charged particle beam or neutral particle erasing beam used in the present invention are Cl, C, O, S, F, H, Ar,
Those containing N, etc., such as CF (+ O ₂ , H ₂ ), CCl _4, etc. are preferable. In order to erase the mixed gas without alloying the upper and lower atomic layers, it is preferable to irradiate the beam while cooling the recording medium.

Also, the electron beam, neutral particle beam, or charged particle beam focused on the surface of the recording medium can be narrowed down to approximately 300 Å or less. Therefore, it is possible to record with a high recording density of about 10 ¹⁰ bits / cm ² .

The intensity of the reproducing beam energy by the electron beam in the present invention is adjusted to the extent that secondary electrons are emitted from the surface of the atomic layer without promoting formation of a mixture on the surface of the recording medium. Further, these beams can be used by narrowing them down to a narrow beam diameter as described above.

An electron beam was selected because of its controllability and ease of focusing the beam.

[Action]

The present invention has a multi-layer structure in which at least two kinds of atomic layers having different secondary electron emission characteristics are alternately stacked, and each atomic layer has a combination of elements forming a mixture between adjacent atomic layers by a recording beam. Since it is a recording medium having, by irradiating a part of the uppermost atomic layer on the surface of the recording medium with a recording beam, and by mixing with the lower heteroatom layer,
When the recording portion is formed and the recording medium is irradiated with the reproducing beam, secondary electrons having emission characteristics different from those of the uppermost layer are emitted from the mixed portion. Therefore, the recorded information can be reproduced by reading the difference in the secondary electron characteristics emitted according to the location.

Further, since the element for generating the charged particle beam or the neutral particle beam as the recording beam used in the present invention is a gas at room temperature and an inert gas such as Ar or N is used, a solid or liquid element is used. The operation of the device becomes extremely stable as compared with.

The recording density of the present invention can be increased up to the beam diameter of an electron beam, a neutral particle beam, or a charged particle beam focused on a solid surface, so that the recording density is about 300.
By using a neutral particle beam or a charged particle beam that can be narrowed down to Å or less, it is possible to record at a high recording density of about 10 ¹⁰ bits / cm ² or more.

In addition, the present invention, when correcting or erasing the record,
Since the recording medium has a multi-layer structure in which two or more kinds of atomic layers are alternately stacked, the uppermost second atomic layer and the lower first atomic layer are mixed. By removing with the erasing beam and exposing the second atomic layer therebelow, that portion becomes an atomic layer of the same type as the uppermost layer, so the recording is erased.

In addition, in order to erase all records, the top layer and the first layer below
The uppermost layer becomes the next second atomic layer by removing the entire atomic layer of
There is no difference in the location of secondary electron emission characteristics, and the new second
The recording surface will be created by the atomic layer of. In the case of the next recording, the recording will be made by alloying the second atomic layer and the first atomic layer thereunder.

〔Example〕

A Be atomic layer as the first atomic layer and a Cu atomic layer as the second atomic layer were alternately formed on the support Cu plate cooled in a vacuum by the magnetron sputtering method, two layers each having a thickness of 100 Å. A recording medium having four layers as a whole was formed.

While cooling the recording medium, Ar ⁺ ions were squeezed to a dot shape by squeezing it to 500 Å to form a mixed layer Cu-Be of the uppermost second atomic layer Cu and the underlying first atomic layer Be, and recording and did.

Using a field emission scanning electron microscope, the film surface was observed by scanning with an electron beam at an accelerating electric field of 25 KV, and a bright dot-like pattern with a diameter of about 500Å was read.

〔The invention's effect〕

The present invention has a multilayer structure in which at least two kinds of atomic layers are alternately stacked on a support, and each atomic layer is a combination of atomic layers which is alloyed between the upper and lower atomic layers by a recording beam. The recording medium is irradiated with a recording beam selected from an electron beam, a charged particle beam and a neutral particle beam in a vacuum atmosphere to irradiate a part of the uppermost atomic layer on the surface of the recording medium, and the lower layer Information is recorded by forming a mixed layer with an atomic layer, the recording is erased by removing the portion of the mixed layer by plasma etching or chemical sputtering, and further information is recorded on the surface of the recording medium. The recorded information is reproduced by irradiating a reproducing beam, which is an electron beam, to emit secondary electrons from the surface of the recording medium and reading the difference in secondary electron emission characteristics depending on the location. In recording and reproducing method, characterized in that, the ultra-high density not to until now, the recording of information, additions, corrections,
A recording medium that can be erased freely and a recording / reproducing method thereof have been obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the structure of a recording medium as one embodiment of the present invention and a state at the time of recording / erasing using the recording medium. (A) ... Structure of recording medium, (b) ... recording, (c) ... recording portion deletion, (d) ... recording addition, (e) ...
Indicates the state of erasing the entire recording surface. 1 ... Support, 2 ... First atomic layer 3 ... Second atomic layer 4 ... First atomic layer 5 ... Second atomic layer 6a, 6b ... Recording portion 7 ... Erase portion

Claims (2)

[Claims] 1. A recording medium having a multilayer structure in which atomic layers are alternately stacked on a support, and a recording beam selected from an electron beam, a charged particle beam and a neutral particle beam in a vacuum atmosphere. The surface of the recording medium is irradiated with the atoms of the lower layer and Ag-Mg, Cs-Te, Sb-Cs, Cu-Be, Ga.
Information is recorded by forming a mixture selected from the group consisting of -As-P, and the surface of the recording medium on which the information is recorded is irradiated with a reproducing beam, which is an electron beam, A recording / reproducing apparatus which reproduces recorded information by emitting secondary electrons from the device and reading the difference in secondary electron emission characteristics depending on the location. 2. A recording medium having a multilayer structure in which atomic layers are alternately stacked on a support, and a recording beam selected from an electron beam, a charged particle beam and a neutral particle beam in a vacuum atmosphere. The surface of the recording medium is irradiated with the atoms of the lower layer and Ag-Mg, Cs-Te, Sb-Cs, Cu-Be, Ga.
Recording information by forming a mixture selected from the group consisting of -As-P, and erasing the record by removing the formed portion of the mixture using plasma etching or chemical sputtering. Information recorded by irradiating the surface of the recording medium on which information is recorded with a reproducing beam, which is an electron beam, to emit secondary electrons from the surface of the recording medium and reading the difference in secondary electron emission characteristics depending on the location. A recording / reproducing method characterized by performing reproduction of.