JPH0432049A - Recording medium - Google Patents

Abstract

PURPOSE:To increase a recording capacity and to allow writing and reading out of information by forming <=3mum ruggedness at <=1mum bit intervals on the surface of the recording medium which records information by utilizing the magnitude in oxygen quantity. CONSTITUTION:The <=3mum ruggedness is formed at <=1mum bit intervals on the surface of the recording medium 3 which records the information by utilizing the magnitude in the oxygen quantity. The projecting part 3a of an oxide conductor layer 3 is partly heated and the diffusion of oxygen arises to change the oxygen quantity when the distance between the tip of a needle-like electrode 4 and the projecting part 3a of the oxide conductor layer 3 is set to 10 to 20Angstrom and 10V voltage pulse is impressed between the needle-like electrode 4 and the oxide conductor layer 3. The electric resistivity of the oxide conductor layer 3 in this part is then changed. The writing of the large capacity and many valued information is executed in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a recording medium for a file recording device such as a computer, and is particularly suitable for high density and large storage capacity, and can be used over a wide temperature range. The present invention relates to a usable rewritable recording medium.

(Prior Art) Magnetic materials are often used as recording media for conventional mass storage devices. Regarding such recording media,
For example, Ohmsha, "Magnetic Material Ceramics", Sakurai,
It is described in the complete edition, page 143 (1986).

Further, as an example of using an oxide as the recording medium, Japanese Patent Laid-Open No. 63-268087 discloses that an oxide superconductor is used to perform recording and reproduction at a temperature lower than the superconducting critical temperature. . However, this recording medium is required to be used at a low temperature below the superconducting critical temperature.

(Problem to be solved by the invention) In the above-mentioned conventional technology, when using a magnetic material, the magnetization state of the magnetic material is used. A pit period of about several μm is considered to be the limit, and there is a problem that high density cannot be achieved.

On the other hand, in recording media using oxide superconductors,
The medium is cooled to a temperature that indicates a superconducting state, and in this state, oxygen ions and hydrogen ions are irradiated from a needle-shaped ion irradiation source to convert the two states of superconducting state and normal conducting state into binary signals of the binary system. Therefore, although this method can increase the storage capacity, there are practical problems. In other words, the critical temperature of all currently known superconductors is lower than about 160 degrees Celsius, and in order to actually record data, it must be cooled to a temperature lower than about 160 degrees Celsius. A major problem is that either a cooling medium must be used, or a special cooling device such as a cryopump must be used.

Therefore, an object of the present invention is to provide a recording medium that has a larger recording capacity than when magnetic materials are used, and on which information can be written and read without using a special cooling medium or cooling device. .

(Means for solving problems) The above objects are achieved by the present invention as described below.

That is, the present invention provides a recording medium in which the amount of oxygen contained in an oxide is controlled and information is recorded using the amount of oxygen.
This is a recording medium characterized by having the following unevenness formed thereon.

(Function) The amount of oxygen contained in the oxide is controlled, the state of the oxygen content in the oxide is used, and this change in state is made to correspond to a signal to write and read information.

For example, YBa2Cu2O7-X (0<X<
1) For materials, if the X value is greater than about 0.5,
The crystal structure is a tetragonal structure, and the X value is 0.
．． If it is smaller than 5, it takes on an orthorhombic structure, but the electrical resistivity changes with this change in oxygen content.
The electrical resistivity near room temperature is higher in the tetragonal structure. Furthermore, even with the same tetragonal structure, if the amount of oxygen is reduced, the electrical resistivity becomes even higher.

In addition, the optical properties also change as the amount of oxygen changes, and for example, the reflectance decreases as the amount of oxygen decreases, that is, the X value increases. Similar to the reflectance, the absorption rate also changes depending on the amount of oxygen. Such physical property changes occur when the X value is small.
The same thing occurs in the horhombic structure, and changes in the amount of oxygen can be controlled by applying an electric field or current to the oxide at any temperature, or by irradiating it with light. , can be changed continuously depending on the intensity of the input signal called light.

The present invention records various information by utilizing changes in electrical or optical physical quantities such as electrical resistivity, light absorption, and reflectance caused by changes in the amount of oxygen in oxides as described above. It is.

Furthermore, by forming irregularities of 3 μm or less with a pit interval of 1 μm or less on the surface of the oxide conductor, the deviation of the recording position can be reduced and the accuracy of writing and reading can be improved. Furthermore, positioning of the needle becomes easier.

The optimum pit shape can be determined depending on the type of oxide conductor and the type of protective film formed on the oxide conductor layer.

(Example) The details of the present invention will be explained below with reference to Examples.

Example 1 FIG. 1 shows an embodiment of the present invention.

On a quartz substrate (substrate: 1), Cr was laminated to a thickness of 100 layers and Au was laminated to a thickness of 1,000 layers using a resistance heating method (electrode: 2 layers).
). Next, a 1 μm thick Er-Ba-Cu-0 film was deposited thereon by RF magnetron sputtering (oxide conductor layer: 3). The film forming conditions at this time were Er:Ba:Cu=
E adjusted to be 1:2:3 (atomic ratio)
The r-Ba-Cu-0 sintered body was used as a sputtering target, the gas pressure was Ar5Pa, the power was 100W, and the substrate temperature was 300°C. As shown in Fig. 1, this was processed using ordinary photolithography technology, with a pitch of 1 μm and 6.0 μm.
It was processed into an uneven shape with a height of 0.00 people. When the electrical resistivity of the Er-Ba-Cu-0 film thus prepared was measured, it was found to be 3 x 10-'' Ω·cm.

Furthermore, an example of writing information to this recording medium is shown in FIG.

Reference numeral 4 indicates a needle-like electrode, and tungsten is used.

The distance between the tip of the needle electrode 4 and the convex portion 3a of the oxide conductor layer 3 is set to 10 to 20 people. Next, when a voltage pulse of 10 cm is applied between the needle electrode 4 and the oxide conductor layer 3, a part of the convex part 3a of the oxide conductor layer is heated, oxygen is diffused, and the amount of oxygen is decreased. As a result, the electrical resistivity of the oxide conductor layer 3 in that portion changes (three films are shown). FIG. 3 shows the change in electrical resistivity as a function of the number of times this voltage pulse is applied.

Furthermore, by scanning the needle electrode 4 in the XY force direction, a portion 3 with a changed electrical resistivity is formed on the oxide conductor layer.
A large number of data b can be created, and as a result, large-capacity and multi-value 1 writing can be performed.

Note that information can be erased by performing heat treatment at 250° C. in an oxygen atmosphere to return the oxide conductor layer to its original state.

Example 2 FIG. 4 shows a schematic diagram of a second embodiment of the invention.

In this example, MgO was used as the substrate 1, and a Y-Ba-Cu-0 film was deposited thereon by a cluster ion beam method to form an oxide conductor layer 3. The film forming conditions at this time are:
Y, BaO, and Cu were used independently as vapor deposition sources, and the ionization conditions were ionization current of 50 mA for Y, acceleration voltage of 0.5 KV%BaO, and ionization current of 10 for Cu.
The acceleration voltage was 0 mA, the acceleration voltage was IKV, and the substrate temperature was 420°C. During film formation, while blowing oxygen gas at 4 x 10-' Torr near the substrate, the composition ratio of the three metal elements on the substrate was adjusted to Y: Ba: Cu = 15:30:55 (atomic ratio). A film was formed.

The film thickness was set at 6,000 people.

Furthermore, 1,000 people formed an upper layer 5 of silver, which is an oxygen-permeable substance, on this layer by a conventional resistance heating method. This is then processed to a thickness of 0.5 μm as shown in Figure 4 using a normal microfabrication process.
It was processed into an uneven shape with a pitch of 0.5 μm in height.

The electrical resistivity in this case was measured to be 1×10-”Ω.
・It was cIll.

Writing on the recording medium created in this manner can be performed in the same manner as in Example 1, except that the distance between the upper layer 5 of the recording medium and the needle electrode 4 was 50 people, and the applied voltage was 50V. Ta. The relationship between the number of pulse applications and electrical resistivity in this case is shown in FIG.

Note that information could also be erased using the same method as in Example 1. In this example, by providing the upper layer, it was possible to physically protect the oxide conductor layer 3.

Examples 3-6 FIG. 6 is a schematic diagram of Examples 3 to 6.

A recording medium was prepared in the same manner as in Examples 1 and 2 using the materials shown in Table 1 for the substrate, electrodes, oxide conductor, and upper layer. At that time, the electrodes were created using a normal vapor deposition method. Further, the oxide conductor layer 3 was formed using the cluster beam method as in Example 2, with Y, Ho, and Yb each accounting for about 1% of the total metal composition.
It was created by adjusting it to be 5 to 16%. This was processed into an uneven shape with a pitch of 0.4 μm and a height of 1 μm as shown in FIG. 6 using a microfabrication process. These uneven pits are arranged in a spiral shape from the center of the substrate.

The upper layer 5 was created by appropriately selecting a vapor deposition method, a spin code method, etc. depending on the material. As the upper layer 5, in Example 3, silicone oil, which is an oxygen permeable substance, was used, and in Example 4, Aj, which is a substance that absorbs oxygen, was used. Also, Example 5.
In 6, the upper layer 5 is made of Au, which is a material that does not pass oxygen.
a-3i was used respectively.

When information was written and erased using the recording medium thus prepared, in Example 3, information could be written and erased in the same manner as in Example 1.

In Example 4, when writing was performed in the same manner as in Example 2, oxygen in the oxide conductor film was diffused by heating and absorbed into the upper layer 5, changing the electrical resistivity and writing could not be performed. Ta. However, the information could not be deleted.

In Examples 5 and 6, when writing was performed in the same manner as in Example 2, oxygen was suppressed in the upper N5, moved to the substrate 1 side of the oxide conductor layer, and writing could be performed.

Furthermore, information could be erased in the same manner as in Example 1.

(Effects of the Invention) As described above, the present invention records information by utilizing changes in the amount of oxygen in an oxide, and the recording capacity is significantly increased compared to the case where a magnetic material is used.

Furthermore, even when superconducting oxide is used, it can be used at room temperature.

Furthermore, in the present invention, since the oxide conductor is processed to have an uneven shape of 3 μm or less with a pit interval of 1 μm or less, the accuracy of writing and reading is improved compared to the case of a planar shape. Positioning of the needle electrode and the recording medium is also easy.

[Brief explanation of drawings]

1, 2, 4 and 6 are schematic diagrams showing embodiments of the present invention; FIGS. 3 and 5 are diagrams showing the relationship between the number of pulse applications and electrical resistivity; Table 1 is a table showing the materials of Examples 3 to 6. 1: Substrate 2.4: Electrode 3: Oxide conductor 5: Upper layer Fig. 1 Fig. 2 Fig. 3

Claims (9)

[Claims] (1) In a recording medium that controls the amount of oxygen contained in an oxide and records information using the amount of oxygen, irregularities of 3 μm or less are formed on the surface of the recording medium with pit intervals of 1 μm or less. A recording medium characterized by: (2) The recording medium according to claim 1, wherein the oxide is an oxide that transitions to a superconducting state at low temperatures due to the temperature inherent to the material. (3) The recording medium according to claim 1 or 2, wherein the oxide is an oxide whose crystal structure changes when the amount of oxygen is around a certain value. (4) Claims 1, 2, and 3 in which the state of the amount of oxygen is changed by irradiating light, applying an electric field, or flowing an electric current.
Recording medium described in . (5) The oxide has the formula Ln-Ba-Cu-O (Ln is Sc,
Represents elements belonging to group III a subgroup of the periodic table such as Y, La, Ac, etc., and the total amount of metal elements Ln, Ba, Cu is 10
5. The recording medium according to claim 1, wherein the recording medium is a metal oxide having an Ln ratio of 10 to 20 when 0. (6) The recording medium according to any one of claims 1 to 5, wherein the oxide is formed on a substrate provided with an electrode. (7) The recording medium according to claim 6, wherein an oxygen permeable film is provided on the oxide. (8) The recording medium according to claim 6, wherein a film that absorbs oxygen is provided on the oxide. (9) The recording medium according to claim 6, wherein an oxygen-impermeable film is provided on the oxide.