JPS61500238A - Improvements in data storage and recording - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Improvements in data storage and recording The present invention relates to data storage, media, and to recording data on such media. The present invention relates to a method for reading recorded data from such a medium. In particular, the original His research interests include magneto-optical technology.

Information storage and retrieval systems are desired to have the following characteristics.

This is the “bit”). (2) Minimize the energy required to write 1 bit Make it. (3) Maximize the write speed, ie, the number of bits written per second.

(4) Maximize the reading speed of recorded information. (5) Read recorded information Maximize the signal level obtained when reading. (6) Signal-to-noise ratio during reading Maximize. [71” between reading 1” bit and reading “0” bit Maximize the contrast between

There are a number of magneto-optical techniques that are theoretically suitable for use in information storage. These are magnetic Thermomagnetism is a technology that optically reads recorded material after it has been written (i.e., recorded) optically. Includes writing/magnetic reading techniques and thermomagnetic writing/optical reading techniques.

In particular, the present invention uses optical reading or thermomagnetic writing (or both). Regarding the system that was used. If the writing phase is a thermomagnetic phase, the writing ( i.e., the physical effects on the medium caused by the recording process are at least partially magnetic effects, and for example, when a medium is locally affected by the absorption of incident electromagnetic radiation. This includes being heated to. One object of the invention is to against write radiation to reduce energy and increase write speed. An object of the present invention is to provide a magneto-optic memory structure having high sensitivity.

When reading out a magneto-optic memory structure optically, the This is done by observing changes in the polarization state of electromagnetic radiation. The above scattering is , direct transmission or reflection, or scattering in other directions. It's okay. When the readout radiation is linearly polarized, the change in the polarization state of the scattered light is usually strictly defined as a rotation of the polarization direction. This causes the scattered beam to is exactly the same as adding a polarization component perpendicular to the incident polarization (added This component is the so-called "magneto-optic" component).

This magneto-optic component in the direct polarization state “retains” the readout information; generally have very low strength. However, the scattered component with a polarization state parallel to the incident radiation, Not holding any information is a very big deal. Due to these factors, The readout signal-to-noise ratio is low (and the readout contrast is also low). Therefore, in the case of known magneto-optical memories, the extraction performance of stored information is low. This will limit the usefulness of the memory. “Bits” are memories In digital storage, a "bit error rate" is often desired. Become something bigger than anything. Therefore, the second object of the present invention is to improve the readout signal pair. Improve readout “bit error rate” by improving noise ratio and contrast The third objective of the present invention is to provide a means for By using magneto-optical structures formed by The goal is to improve the "reduction rate".

A number of multilayer magneto-optical structures are known that improve recording sensitivity and readout reliability. It is. These structures combine magneto-optic layers, dielectric layers and metal layers, It consists of deposited in strictly flat thin film form. These are the bulk of the write radiation It absorbs minutes and gives high writing sensitivity. Also, these are magneto-optical components of scattered radiation. while increasing the intensity of the ``normal'' reflected radiation (i.e., which carries information). The component of the eccentric state parallel to the incident radiation) is weakened to increase the reliability of the readout. The purpose is to However, in many cases, especially computer memo Further improvements are desired when applied to other industries. In addition, it can be produced with high yield, and this Accordingly, it is also desirable to provide a structure that can reduce manufacturing costs. . The above multilayer structure has the required uniformity within the entire storage area of each structure and for each structure. It is difficult to manufacture such materials with such characteristics.

According to one feature of the invention, optical reading using optical reading radiation of wavelength W /An optical data storage medium used in a writing system which has a raised surface area and A region that retains a surface texture in which concave areas are arranged in a regular arrangement. The period (pitch) measured transversely to the average surface level is the wave A medium whose length is less than W and whose depth (peaks and valleys) is 10 to 1000 nanometers. In the body, (al base and (bl) The above-mentioned surface texture structure is small (both are located on top of the peaks and valleys, and these a regular array of zones of compatible magneto-optic material; A storage medium is provided.

Unless otherwise specified, wavelength values stated herein refer to wavelengths in vacuum. (which, for all practical purposes, is the same as the wavelength in air).

If zones of magneto-optic material extend over all surface textures, they It constitutes a pneumatic film or layer.

−4= The data storage medium of the invention can be used, especially if the magneto-optic material itself is not optically reflective. Contains a layer or zones of light reflective material.

Such a reflective layer is placed above or below (relative to the substrate) the magneto-optic layer.

Where there are zones of light-reflecting material, these locations are aligned with zones of magneto-optic material. They may or may not match.

The substrate is generally a dielectric, and in many embodiments the top surface has the above-mentioned texture. constitute a surface.

(+) magneto-optic zone or layer and (11) optically reflective zone or layer (-if any) Superimposed on the top layer is a further zone or layer of dielectric material. like this If the dielectric material is present as a layer, its lower surface (relative to the substrate) is 1. base and Surface texture pattern as long as material can be present between the dielectric layer and the dielectric layer. must match. The top surface of the dielectric layer may be flat or have a surface texture. May match a pattern. The dielectric material constituting the zone or layer may be e.g. , - silicon oxide, silicon dioxide or aluminum nitride. magneto-optic layer Aluminum nitride has protective properties that reduce the oxidation tendency of its constituent materials. is preferred. If a dielectric layer is present and this layer matches the surface texture pattern is the thickness of the dielectric layer and the wavelength of the read radiation W measured in the dielectric material itself. is preferably about A (where the refractive index of the material and the wavelength of the radiation passing through this material (Due to the relationship, the wavelength is different from the value of W measured in air or vacuum).

The thickness of the magneto-optical material is generally 200 nanometers or less, preferably 5 to 5 nanometers thick. Within the range of 150 nanometers (nm).

Furthermore, the present invention provides a method for recording (writing) and reading data on such data storage media. We also provide a method for doing so. Furthermore, the present invention has the above-mentioned structure, and also has the above structure. Pre-recorded data storage media on which recording is performed by the method described above are also provided. Ru.

For example, thermomagnetic In embodiments of the invention where the writing step includes optical radiation, the writing The H region, which includes (but is not limited to) the bit to be scanned, is subjected to the magnetic field. this magnet The field is not as strong as the device. In order to write bits, magneto-optical materials are used is heated, a magnetic field is applied that affects its magnetization, and light is applied to the Hi region.

In many embodiments of the present invention, the pitch (P) of the texture of one surface is the peak-to-valley of the surface texture. The depth of D> is 2 or more and 8 times or less. In many embodiments, Pinch and depth are equal.

The magneto-optic material is in the form of a thin film disposed on a suitably textured substrate. and this thin film is a highly reflective material (or the magneto-optic material is silver or placed on an intermediate thin film of highly reflective material such as a metal such as aluminum. It has been found that radiation is sometimes absorbed very efficiently. This high absorption efficiency is the incident energy required to raise the temperature of the magneto-optic material to its cue point. Lugi will be smaller than in other cases. This allows ζlower power to be used and Therefore, low cost radiation sources and/or short exposure times and thus fast writing speeds are required. can be used. Further, in a medium constructed according to the present invention, a magneto-optic material is used. The thickness of the layer and the associated metal layer are similar to the thickness of the corresponding layer of known magneto-optical recording media. This further promotes the above effect. The surface texture is relatively deep. If the be done. Depends on the combination of the depth of the surface texture and the thickness of the film being applied. Thus, the energy required for writing is further reduced. When using thermomagnetic writing , the substrate becomes resilient to the action of heating to the temperature required for recording. . Suitable substrates for this are, for example, glass, thermosetting plastics, and softening temperature It is a highly thermoplastic material.

Use magneto-optic films such as GdCo or TbFe alloys at low recording temperatures In some cases, a wide variety of materials can be used as the substrate.

When using the material according to the invention in systems based on optical reading, the It is preferable to utilize changes in the polarization state of the emitted beam. For example, the read head , the plane-polarized light is arranged to be incident on the focus to be read. Conveniently , the E vector of the incident light lies in the plane of incidence, and this plane includes grooves and overhangs in the surface texture. perpendicular to the longitudinal direction of the section. (Other polarizations can also be used, but these It turns out that it is not very effective. ) The depth of the grain is greater than its pitch (i.e. period) On the significantly smaller implementation side, the preferred magnetization direction is in the region of a large number of recording bits. substantially perpendicular to the plane of the media portion containing the media. This is because magnetic light A preferred material for the layer is MnB1. GdCo, TbFe, GdTbFe, and This is because rare earth-transition element alloys and other rare earth-transition element alloys can be used.

The surface texture takes the form of alternating overhangs and grooves. These are linear and They may be parallel and parallel, for example in the form of concentric rings or concentric spirals. It may be in a state. The surface texture consists of two series of straight grooves and overhangs. They may be arranged at an angle to each other, the angle being defined by two series of grooves and overhangs. can be set to 1906 so that they are orthogonal to each other.

For convenience, the surface texture is referred to as a lattice. The cross-section of the texture is a sinusoidal shape. (Due to the manufacturing method, it is difficult to obtain a completely sinusoidal cross section). Or again The texture may be square wave-like or serrated.

In embodiments where the grain depth is at least 115 pinches of the grid, the magnetization The direction is parallel to the longitudinal direction of the groove and the overhang.

In another configuration, the direction of magnetization is perpendicular to the plane of the media portion containing the large number of recorded bits. (i.e., as in the case of a shallow grid). In yet another embodiment, the direction of magnetization is perpendicular to the longitudinal direction of the groove and overhang and at any point within the bit area. The direction of magnetization changes within the region of one bit in that it is perpendicular to the surface element at the point do.

In other words, the direction of magnetization changes at each point on the contour of the groove and overhang.

In embodiments where the depth of the grating is at least 115 times the pitch of the grating, this There are a large number of suitable magneto-optic materials.

When using linearly polarized incident radiation, the plane of polarization of the reflected radiation is rotated relative to the beam. When the direction of magnetization is reversed, the polarization plane of the reflected beam The direction of rotation of is also reversed with respect to the incident beam. As a result, the magnetization directions are opposite to each other. It is possible to distinguish between binary characters 1 and 0, which are represented in the opposite direction.

The Kerr component of the reflected beam (i.e., the direction of polarization is perpendicular to the incident beam) (resolved component) is usually much smaller than the component whose polarization direction does not change, and is actually contains noise in the polarization state of the scattered radiation, so the phase between the written l and 0 is The difference is easily distinguishable from high background noise (component with no change in polarization state). Not stick.

When using a recording medium configured according to the present invention, reading is difficult for the following two reasons. It's easier and more reliable.

(al) The intensity of the component of the reflected beam whose polarization state does not change is significantly reduced.

(b) The strength of the Kerr component is significantly increased.

For example, when we measured the textured surface of a shallow lattice, we found that the Kerr component was more than 7.5 times It has been found that the unrotated polarization component is reduced to two as the number of rotations increases. similar For deep lattice-grained surfaces, the Kerr component increases by a factor of 10 and the unrotated polarization increases by a factor of 10. A decrease in the intensity of the light component was shown. The phase of the Kerr component changes relative to the unchanged component. resulting in an elliptical polarization of the reflected beam. This oval polarization can be can be removed by a suitable phase plate.

In order to provide a thorough understanding of the invention, a number of specific embodiments are set forth below with reference to the accompanying drawings. explain. − FIG. 1 is an enlarged sectional view of the first embodiment, and FIG. 2 is a preferred embodiment of the embodiment of FIG. Figure 3(a), Figure 3) and Figure 3(C) are the same as those in Figure 1. FIG. FIG. 4 is a graph showing the reflected output for various media, and FIG. (Figures b1 and 5(C) show a deep-textured medium according to a second embodiment of the invention. is a diagram, Figures 6(a) to 6(e) illustrate a deep-textured medium according to a third embodiment of the present invention. It is a diagram showing Figures 7(a) to 7(d) illustrate the texture according to the fourth and fifth embodiments of the present invention. A diagram showing a deep medium, FIG. 8 is a diagram showing a medium according to a sixth embodiment of the present invention, and FIG. 9 is a diagram showing a second medium according to a sixth embodiment of the present invention.

The various embodiments shown in the accompanying drawings are shown schematically and may be drawn to appropriate scale. isn't it.

According to an embodiment of the present invention, a substrate having a slightly textured surface coated with a thin metal film is provided. the thin film of metal is compatible with the texture of the surface, and further , on the metal thin film, there is also a magneto-optical material that is compatible with the texture of the substrate surface. A data storage medium is provided which is provided with a thin film of material. magneto-optical materials If the film inner body is highly reflective, a thin film of metal can be removed. magneto-optical Preferably, the thickness of the membrane is in the range of 5 to i'oonm (nanometers). child One such structure is shown by way of example in FIG. An example of depth of texture For example, if the surface is in the form of a grid, the peak-to-valley dimension) is very much 1 ( Generally speaking, if the wavelength of readout radiation is W (nanometer), it is less than W/4 nm. For example, it is in the range of 10 to 50 nm. The wavelength of readout radiation is 633n For m, the preferred depth is 10=150 nm. Alternatively, the depth of texture is W/4 to Wnm, for example, in the range of 50 to 200 nm. Kimenotaira The uniform pitch is typically less than or equal to the wavelength of the writing or reading radiation. Substrate and magnetic light The metal constituting the thin film between the film and the film is preferably silver, gold, copper or aluminum. Delicious. The thickness of this film is, for example, in the range of 10 to 1100 nm; Preferably it is smaller. For example, silver, gold, copper, or A thin metal film of aluminum is deposited. The thickness of such a thin film is between 5 and 3 It is in the range of 0 nm.

The surface texture is a series of substantially parallel alternating valleys and peaks that are uniform in shape and shape. , but this is not important. Such surfaces are well known from spectroscopic techniques. Since it is similar to a surface relief diffraction grating, it will be referred to as a grating hereafter.

The texture consists of two such lattices arranged at an angle to each other. .

The grids are arranged perpendicular to each other. This kind of textured surface is called an intersecting lattice. do. There are many known ways to create such gratings, including photographs of interference fields. This includes lithography, mechanical scoring, and reproduction from existing surfaces.

The media of many embodiments of the present invention can be relatively easily mass-produced.

These media are processed through appropriate processing steps from a master that retains the desired surface texture. can be formed by Generally, embossing, casting, and molds from masters A method such as pushing is appropriate. The master itself exhibits the desired surface profile. It is formed using an instrument precisely shaped to do so. Data recording according to the present invention One technique for manufacturing storage media is described below. This begins with the formation of the appliance.

1) Attach a thin resist film to a flat surface.

2) exposing this resist - in a pattern corresponding to the desired surface relief;

3) Develop the resist.

4) First, form a thin conductive layer on the resist, then fill it to obtain durability. By electroplating another metal layer of sufficient thickness on top of the above layer, a negative image on the resist surface is created. form.

5) Peel the electroplated metal layer from the resist, which is important That's not the point.

6) Electroplated metal positive (which constitutes a reproduction instrument) from a metal negative (which constitutes a reproduction instrument) form (acting as a master).

7) Make a plastic copy directly from this positive or metal negative. .

8) Overlay the desired material layer or region, such as a thin metal film, to act as a mirror layer. A thin film of magneto-optic material is then applied. this money Attached plastic reproductions present a strong absorbent surface that is easy to write on, e.g. For example, it constitutes a data storage medium that acts as a digital or analog information storage medium.

In a mass production process, steps (7) and (8) above are repeated.

Many variations are possible within the scope of the process described above.

Step 1) The resist may be, for example, a photoresist or an electron beam It may also be a resist. This resist can be applied, for example, by spin technology, dip technology , by spraying techniques or other suitable techniques.

The surface to which this resist is applied may be flat or curved, e.g. , cylindrical, conical, spherical or any other suitable shape.

Step 2/3) The pattern is related to the surface texture pattern of the data storage medium. The above requirements must be met. The pinch does not have to be uniform, but The patterns must be regular, ie, repeatable. The pattern is created using an electron beam. Write or create parallel halves or angles to each other (possibly Interference fringes are formed as one of the two haberturns set at 90°. The image is imaged onto the resist by one of a number of methods, including imaging. crossing An important technique for forming an array of grooves or a string of concentric grooves is the layer technique. The interference. For example, two laser beams are focused one-dimensionally into a series of spots. An interference pattern in the form of a cut is formed. Group coated with resist -13-1 The body is moved under this interference pattern (e.g. rotation or translation or (2), the desired exposure is performed. Recording by electron beam is another important technique that can be used for single spot recording or multi-spot recording techniques. Ru. Further recording techniques used to manufacture the data storage medium of the present invention include: It contains a record of the harmonic fringes formed by the diffraction grating. The diffraction grating itself is circular, It has a spiral or linear scale and is illuminated by collimated light. This results in , images are formed in the form of harmonic fringes of the grating at a set of various distances from the grating, and these images The photoresist is exposed.

Step 4) Another first step is the one commonly used in making a replica of a graduated spectroscopic grating. Using advanced techniques, for example, first a very thin coating of a mold release agent such as mannitol is applied. By providing a master mold and casting a layer of thermoset plastic onto it, The first step is to make a negative copy. This technique allows the original to undergo minimal damage. You can get a large number of copies made in the first place.

Step 7) Duplicate products can be cast, injection molded, compression molded or embossed. formed from metal appliances by one of a number of processes including: The last of these techniques The two methods are well-known technologies in the field of gramphone records or video discs. Uses details.

Use a resist that is exposed and developed to form the desired surface texture pattern. Mechanical or optical cutting steps can be used instead of steps 1) to 3) above. Directly apply the desired surface texture pattern onto the plastic or metal substrate using a Can be formed in contact. Mechanical cutting is performed using a piezoelectrically driven needle. optics The cutting may be carried out using a U laser and suitable optical or multi-spot techniques. I can. By modulating the laser beam with this technique, You can also create a grid. Cutting may be performed directly using an electron beam.

Materials suitable for use as magneto-optic layers include transition elements, rare earth elements, at least also an alloy of one rare earth element and at least one transition element, and at least one of a transition element and at least one metalloid. works satisfactorily Examples of materials that can be used include iron, cobalt, nickel, terbium-iron, and cadrinium. - Contains cobalt, and manganese-bismuth. One particular preferred material is It is an amorphous or misaligned alloy of rubium-enamel, which is in a favorable state. When processed below, it can have magnetization characteristics perpendicular to the film plane.

The dielectric constant of at least one of the magneto-optical material and the optical reflective material is preferably It must have a negative real part and a small imaginary part at the frequency of the radiation. do not have.

In the particular example of this first embodiment shown in FIG. 1, the substrate 1 is formed of a dielectric material; It has a textured structure on its upper surface. The morphology of this surface is a sine wave, and the pinch is 580 nm, and the height from peak to valley is 33 nm. 20nm thick aluminum N 2 is deposited on the substrate. A terbium-iron layer 3 with a thickness of 25 nm is applied to this aluminum layer. um layer. TbFeF is deposited by any of the known methods. , an amorphous layer, or a layer that becomes amorphous through subsequent heat treatment. form a gap. Vacuum sputtering with residual oxygen pressure below 100 nanoTorr I found it appropriate to do a ring.

In a similar example using readout radiation at a wavelength of 633 nm, the pinch of grain 612 nm and a depth of 110 nm (peak-to-valley). Wavelength W=820 In yet another example using nm readout radiation, the grain pitch is set to 794 nm. and the depth is set to 115 nm. The dimensions of layers 2- and 3 are shown in Figure 1. It was given in connection with.

In a variant of the embodiment shown in FIG. 1, the metal mirror layer 2 is omitted. others , the structure and dimensions are the same. Two examples of this deformed structure are both magneto-optical A layer of TbFe is present as a material, and the thickness of this layer is 25 nm. first An example is used with a readout wavelength of W = 633 nm, and its texture is pitch-perfect. The peak-to-valley depth (P) is 612 nm, and the peak-to-valley depth D) is 110 nm.

The second example is used at a readout wavelength W = 820 nm, and the parameter P-7 94 nm, D=115 nm.

The shallow-grained structure of this first embodiment of the invention allows the radiation to When the electric vector E is linearly polarized parallel to the plane of incidence, the readout Increase credibility. This is referred to as the polarization of the plane of incidence. The surface texture is in the form of a lattice. When taking the configuration, the polarization of the readout beam is preferably strictly perpendicular to the grating lines. Must. (This means that the texture is... two lattices that intersect at right angles. It is not necessary when it takes the form of ) Improved the textured surface of the above shallow grid. The governing physical laws have not yet been completely elucidated. As known to the applicant Where the surface is textured, the interaction between the radiation and the magnetic layer is reduced. Increased. This is caused by plasma or magnetic plasma excitation, and this excitation reduces the reflection of the unchanged component and increases the intensity of the Kerr component. It will be enlarged. A film with a thickness in the range of 10 nm to 120 nm is used, and the substrate If it is desired to use a magnetization characteristic that is oriented almost naturally perpendicular to Amorphous alloys of TbFe have been found to be particularly suitable.

Reads small recording bits, typically 400nm to 5000nm in linear dimension In the case of and is therefore made to hit the surface from a wide angle. This radiation is The intensity changes smoothly over the range.

The radiation reflected from a surface also emerges within an angular range of The intensity changes mainly smoothly, but over a small part of this angular range it changes significantly. A significant decrease in strength is observed. This is left in Figure 3(a), middle) and (CL). There is. At the angular position of this intensity drop (via an appropriately oriented analyzer) The observing photodetector observes a significant increase in the intensity of the magneto-optic component that carries the information. do. This photodetector also detects a radiation component polarized parallel to the incident radiation (31 We also observe a significant decrease in the intensity of the reflected component. As a result, the readout contrast and , both the signal-to-noise ratio of the readout and the signal-to-noise ratio are significantly improved. Therefore, the present invention A method for reading data stored on a data storage medium, the method comprising: reading data stored on a data storage medium; The corner where the reflectance sharply decreases (drapes) when observed or scanned with readout radiation. A method is also provided for monitoring the strength of magneto-optic signals within a range of degrees.

Figure 4 shows the intensity of the information-retaining component at and around this drooping point of the surface reflectance. It is a graph measured by way of example. In Figure 4, curve A is shallow as in Figure 1. This shows the case where the magneto-optic layer is provided on the lattice plane, and curve B is similar to this. This structure shows the case where a silver layer is provided on the magneto-optic layer, and Curve C is for a flat substrate.

If the reflectance droop of the surface is very sharp - this means that there is a highly reflective layer on the textured edges of the surface. Occurs when a metal layer or magnetic metal layer is provided - when the magnetization direction of the magnetic layer is reversed The position of the reflectance drooping point changes significantly. Therefore, another readout method is −reflectance It is to measure the angular position of droop. The deviation is achieved using circularly polarized readout radiation. It is convenient to do so. Therefore, the present invention provides a method for storing data stored on a data storage medium. A second method of reading is when the surface of the medium is observed or scanned with readout radiation. to monitor the angular position where the reflectance from the medium clearly decreases (sags). We also provide methods. This method provides a high readout signal-to-noise ratio. It is not known whether it is as useful as the first method.

The occurrence of reflectance droop is caused by the collective electron movement (surface polariton or plasma) within the magnetic film. This is due to the fact that rasmons) are excited by the incident radiation, and the surface The grain structure allows the incoming radiation to effectively couple with this collective electron motion. Make it.

This shallow surface of the first embodiment provides strong absorption over a narrow range of angles. and slightly improves writing sensitivity.

When reading out from a shallow surface using 633 nm radiation, It has a sinusoidal shape with a wavelength of 25 to 40 nm, and its period is the wavelength of the readout radiation. The best results were obtained when the size was slightly smaller. Magnetic films found to be suitable include e.g. For example, the thickness of is in the range of 5 nm to 50 nm. Under these conditions, the magneto-optic component The intensity of the normal reflected component was increased by a factor of 7.5 and the intensity of the normal reflected component was reduced by 2.

In the case of actual erasable data storage and retrieval media, magnetization refers to This is because the density can be maximized. In this configuration, the preferred material for the magnetic layer is M nB1. TbFe, GclTbFe, and other rare earth elements-transition elements It is an alloy.

According to a second embodiment of the invention, a deeper-textured surface matches the texture of the surface. A data storage medium is provided comprising a substrate coated with a thin magnetic film. This kimegumi The fabric preferably has an average spatial dimension smaller than the wavelength of the readout radiation, and The depth is preferably at least 1/10 of the wavelength of the readout radiation, more preferably or at least 1/6. Let W be the wavelength of writing or reading radiation. A grating depth of 0.25W to 0.5W has been found to be particularly effective. surface is exposed In the case of area relief gratings, the average spatial dimension is the grating pitch. The surface relief is , may take the form of a single grid, or two or more grids may be arranged at an angle to each other. It may take any other form. If there are two grids, they are placed at right angles to each other. Ru. A single grid has been found to be particularly effective. A thin magnetic film is placed on a textured surface. It may be continuous or intermittent. An example of this structure is Shown in Figure 5 (al, (bl and (C)). This figure and all subsequent figures In , 11 is a magnetic layer with a texture similar in depth, period, and outline to that of the magnetic layer. A data storage medium is provided comprising a substrate having a surface. This textured surface is coated with a thin metal film, which is then coated with a thin magnetic film, and both film layers are It matches the texture of the surface. One or both of these membrane layers Continuous or intermittent. Examples of this structure include one with a cap-shaped top and one with a sine wave top. The shape of the contour is shown in FIG. 6, fat to tel. The top is hat-shaped Conveniently, the average electromagnetism between the Mira layer and the underlying magneto-optic film = 18- or the optical path length (including the phase change that occurs at the interface of two optically different media) mirror is approximately an odd multiple of the quarter wavelength of the read or write radiation. Layers are placed. In the particular example shown in FIG. 6(c), the texture pitch is 30 0 nm, the depth (peak-to-valley) is 400 nm, and the shape is a sinusoidal wave. Temptation The electronic body is first coated with a 30 nm aluminum layer, followed by a 35 nm layer of aluminum. Rubium-iron coated.

According to a fourth embodiment of the invention, a thin film of metal is deposited on a flat substrate, and A textured material similar in depth, period and contour to that described in the second embodiment of the invention. A dielectric layer presenting a surface is coated on the thin film of the metal. This dielectric layer is then coated with A thin magnetic film is coated. One or both of the above membrane layers may be continuous or intermittent. It is. An example of this structure is shown in Figure 7 (a) for a structure with a hat-shaped upper part. ) and (bl).

According to a fifth embodiment of the invention, a thin magnetic film is deposited on a flat substrate, and A textured material similar in depth, period and contour to that described in the second embodiment of the invention. A dielectric layer presenting a surface is coated on the magnetic film. This dielectric layer is then coated with a thin A metal film is coated. Either or both of the above membrane layers may be continuous or intermittent. Ru. This embodiment of the invention is shown in No. 71 FFC+ and fdl.

According to the sixth embodiment, the structure of any one of the first to fifth embodiments is defined in A dielectric material is coated over the structure. The presence of the dielectric layer protects the magnetic and optical layers It is advantageous above. However, in the case of shallow grating structures, the coherence of the magneto-optical signal can be further improved. The layer thickness can be adjusted to increase. In the case of deep lattice structures, By having a dielectric layer on top, the surface reflectance increases as shown in Figure 3(c). The angle at which acute IJ' droop occurs is widened, typically ranging from about 1 degree to about 3 degrees. increased to a degree. In such a structure, at least the lower surface of the coating of the dielectric layer, If the top and bottom surfaces are both textured and magneto-optic, /or matched to a metal film. FIG. 8 shows an example of such a structure. core In the example, the substrate 1 is a dielectric material (e.g. polymethyl methacrylate) having a thickness of about IN. G), and on top of that, a single layer 12 of silver or aluminum with a thickness of about 50 nm. be coated. This is also an intermediate dielectric layer formed of polymethyl methacrylate. 13 is formed on top of the mirror layer 12 and as shown by known techniques. It is shaped to have a sinusoidal surface texture. The maximum depth of layer 13 is approximately 800 It is nm. Zones 11 of the magneto-optical material are arranged at the peaks and valleys of the sinusoidal texture. The maximum depth of the magnetic material (amorphous TbFe) is 20 nm. this Above these zones is a further dielectric layer 14 made of aluminum nitride. attached. This layer 14 matches the texture and the readings measured within the dielectric layer 14. If the wavelength of the emitted radiation is W, then the thickness is preferably approximately W/4 nm. Therefore , the value of W is 633 nm (in air), and the refractive index of the dielectric layer 14 is 2゛, 2 In this case, the thickness of layer 14 is approximately 70 nm. In this example, the texture (deep peaks and valleys) are close to the pinch, the former at 220 nm and the latter at 300 nm. Ru.

The structure shown in FIG. 9 consists of a base 1 having a sinusoidal surface texture. Zones of magnetic and optical material are applied to the peaks and valleys. Above these zones are Additional layers of aluminum nitride or silicon dioxide to match the surface texture. A dielectric layer 14 is formed. The thickness of this layer 14 is determined by the readout measured within the dielectric material. A is the value of the wavelength W of the radiation. This value is calculated by dividing the wavelength in vacuum by the refractive index of the dielectric material. This is the value. 220-1 of the medium according to this embodiment of the invention An example is given below. The first is used for readout radiation with a wavelength of W-633 nm. Pinch (P) - 612 parts m, depth from peak to valley D) - 80 nm. The second one is used for readout radiation with wavelength W=820 nm, and P=79 4 nm and D=85'nm. In these two examples, the magneto-optic material is amorphous. Fass terbium-iron with an average zone thickness of 20 nm. Similarly, Layer 14 is aluminum nitride and has an average thickness of about 70 nm.

In all embodiments of the invention, mechanical damage is prevented and the functional layer of the media is A top coat layer is applied on top of the other layers to prevent dirt and dust from sticking. this Such a layer is conveniently made of a plastic material, for example polymethyl methacrylate, or It is made of polycarbonate, and its thickness is, for example, from 10 microns to about 2 mm. Anything up to that point is fine. Apart from having a protective layer as part of the structure of the medium itself During use of the medium, a protective cover, e.g. a plastic membrane, is suspended close to the surface of the medium. It will be ensured that

In each of the second, third, fourth, fifth and sixth embodiments of the present invention, Does the target tissue have a cap-shaped (square wave) contour at the top or a cross-hatched contour? or a sinusoidal surface relief grating or this is most conveniently a crossed contour. However, other contours, such as triangular or serrated contours, are also included within the scope of the invention. shall be In each case, either writing or reading data (or (both), the depth of the grating is 0.25 of the wavelength of the write or read radiation. It has been found that a specific effect can be obtained when the amount is within the range of 0.5 times to 0.5 times. write In this case, the effect is achieved either in a crossed grid or in a single grid configuration.

For readout, a single grating configuration is preferred.

When writing to a single grating feature, the light is linearly polarized perpendicular to the grating lines. It has been shown that for very low reflectances, complete absorption occurs in the case of Ru. This significant absorption occurs over a wide angle of incidence and tightly focuses the radiation into a cone. Even in the case of very small recording spots that need to be bundled, The incident radiant energy of the area is used for thermomagnetic recording, giving extremely high writing sensitivity. can be done.

Even when writing to a cross-lattice topology, the incident radiation For any polarization state...complete absorption occurs, resulting in very high writing sensitivity. degree is obtained.

When reading out from a single grating configuration, the polarized light perpendicular to the grating lines is The readout radiation causes the intensity of the "normal" reflected acid to be very low. Furthermore, the author Due to the new energy absorption, the strength of the magneto-optic component is significantly increased. These are Together, the angle of polarization rotation of the reflected readout radiation is increased considerably. which case Also, a flat surface mounted on a flat (untextured) substrate surface over a wide angle of incidence An increase in rotation angle of 4 or 5 times is observed over the rotation angle obtained from the magneto-optic film. one In general, for readout from this structure, the contrast and signal-to-noise ratio Both are increased considerably.

In deeper lattice structures, the phase of the radiant energy collapses upon reflection from the structure. This absorption is mainly caused by low reflectance and high absorption. It is thought that this phenomenon occurs in the magneto-optical layer, and the recording sensitivity can be increased. Also, this machine The structure increases the electric field within the magneto-optic layer, which increases the magneto-optic interaction. is increased.

The surface texture structures are shown in Figures 6 (bl, (C1, fdl and (el) and Figure 7 (a). In the structure shown in l~(d+, the writing polarized in the plane of incidence perpendicular to the grid lines Excellent performance was obtained when using input and readout radiation.

For a sinusoidal structure, if the write speed and read radiation wavelength is 633 nm, The preferred pinch depth is 150-400 nm, and the top is cap-shaped. For the structure of , it is 120 to 300 nm. One layer of thin metal mirror is opaque It must be thick enough to This mirror must not be made of aluminum as a single layer. In some cases, a thickness of 15 to 50 nm is suitable. A metal layer is attached to the top of the structure. (thus, this layer extends intermittently across the surface), its thickness is typically typically in the range of 10-50 nm, and the material is of the texture of the first example. Any of the rare earth element-transition element alloys described above for shallow surfaces.

Other structures mentioned above can greatly improve read performance, but currently, Limitations regarding the structures in FIGS. 6(b), (d), (B) and FIGS. 7(a)-(d) No such improvement has been observed.

The sinusoidal structure and the cap-shaped structure have two additional manufacturing reasons. preferable. First of all, the magnetic layer provided on the image-forming structure is substantially planar. Therefore, the magnetization direction of the recording bit is well defined with respect to the read radiation, and the maximum A magneto-optic signal is provided. Second, these types of structures are either by photolithographic techniques 1, mechanical scoring, or reproduction from an existing surface. It can be formed as follows. In particular, in the case of the structures shown in FIGS. 5 and 6, for example “Mapping” of grid-form media by interference field photolithography and electroplating techniques "star" can be formed, and embossing, casting, injection molding and compression molding Multiple copies can be made by such techniques. This allows for high yields. Reliable and reproducible manufacturing can be easily performed.

The magneto-optic layer consists of a controlled amount of magneto-optic material at a controlled deposition angle. , formed (at low pressure) by spackling or vapor deposition on a textured surface You can also.

Materials found suitable as dielectric (e.g., substrate) layers include polycarbonate, Photoresist, polymethyl methacrylate, high temperature resistant nylon and polyester including. These materials can be added to existing markings by known means such as embossing or casting. Child surface contours can be easily duplicated. By these means, you can achieve “master” status. A child surface can be duplicated any number of times. Therefore, for each memory structure There is no need to form a conductor grid profile. This ease of forming lattice contours makes it possible to This contrasts with the case of manufacturing a solid body; in this latter case, the required fine tolerances are In addition to being difficult to achieve, such tolerances must be reproduced during the manufacturing of each manufactured body. Must be. In the structure according to the invention, fine tolerances are applied to the master grid. must be satisfied. However, once this is achieved, Reproducibility of the grid within these tolerances is easily achieved. The master lattice is e.g. nickel electroplating on grids formed by photolithographic techniques, mechanical cutting or other means. It is a form with a lucky charm. Also - the materials mentioned above as examples are currently considered preferred. Necessary for recording information on and erasing information from magneto-optical materials It can withstand high temperatures without damage. like this Other induction materials that can withstand temperatures include glass, which is generally It is not easy to duplicate the grid shape of the master grid.

Materials found suitable for the high reflectance metal layer of the structure include silver, gold, copper and aluminum. Including minium. Other metals are effective as well.

Gosen of the Bureau of Foreign Affairs 0J-■　g　3　N Cao　You　＄　F　＆　（You 8%　・＼ X I o,’ country °　I　Gloss enemy ψ　) 09゜ °１〉〉　 Procedural amendment (formality) 1. Incident display PCT/GB8410 O1472, title of invention data storage and Improvements to Records 3, Persons Making Amendments.

Relationship to the case: Applicant 5. Date of amendment order: June 25, 1985 International search report ImmonalAppHemonNo, PCT/GB 84100147ANN EX To THr: INTERNATIONAL 5EARCHREPOR TQm INTERNAT 0NAL APPLICATION No, PCT /GB 84100147 (SA 7100) DE-A-223557412 107/73 NoneFR-A-21911970N102/74 DE-A -230352010101/74US-A-359406420107/71 None

Claims (1)

[Claims] 1. Used in optical read/write systems using optical read radiation of wavelength W an optical data storage medium having regular raised and depressed areas; having or comprising regions having a surface texture arranged in an array; The period (pitch) measured in the transverse direction with respect to the average surface level is less than or equal to the wavelength W. and the depth (peak-trough) is 10 to 1,000 nanometers. In the body, (a) a base; (b) It is arranged at least in the peaks and valleys of the above surface texture structure and conforms to these. and a regular array of zones of magneto-optic material. . 2. Claim 1 further comprising a regular array of layers or zones of light reflective material. Media described in. 3. Claim 2, wherein the light reflective material is placed below the magneto-optic material. medium. 4. Claim 2, wherein the light-reflecting material is disposed on a magneto-optic material. medium. 5. A thin metal film constituting a light reflecting material is deposited on the magneto-optical film. The medium described in box 4. 6. The thin metal film is made of silver, gold, copper or aluminum. The medium described in Section 5. 7. The thickness of the thin metal film is 5 to 30 nanometers. The medium described in item 6. 8. The pitch of the above surface texture structure is approximately equal to its depth (from peak to valley). The medium according to any one of the above items in the range. 9. The pitch (P) and depth (D) (from peak to valley) of the surface texture structure are 0. The medium according to any one of the above claims in the relationship 5D<P<8D. 10. The medium further comprises an overcoat dielectric layer. Media listed in 11. The top dielectric layer is adapted to the textured surface according to claim 10. medium. 12. The overlying dielectric layer is silicon monoxide, silicon dioxide or aluminum nitride. 12. The medium according to claim 10 or 11, formed of: 13. The thickness of the magneto-optic film is in the range of 5 to 150 nanometers. Media listed in any of the sections. 14. The surface texture should be in the form of alternating substantially parallel grooves and overhangs. The medium according to any of the above items within the scope of the request. 15. Claim: The groove and the overhang are uniformly spaced apart and have a uniform depth and shape. The medium according to paragraph 14. 16. The grooves and overhangs may be in the form of concentric rings or concentric spirals. The medium according to item 14 of the scope of demand. 17. The surface texture is such that two series of straight grooves and overhangs are at an angle to each other. 16. A medium according to claim 14 or claim 15, which comprises a medium arranged in parallel. 18. As set forth in claim 17, the two series of grooves and overhangs are perpendicular to each other. Media 19. The above magneto-optic layer is made of iron, cobalt, nickel, terbium-iron, quadrium Any of the above items of the claims which is um-cobalt or manganese-bismuth. Media described in. 20. In each of the preceding claims, the textured surface has a sinusoidal contour. Media listed in 21. The depth of the surface texture (from peak to valley) is in the range of 10 to 200 nanometers. A medium according to any one of the preceding claims. 22. The textured surface has an average spatial dimension smaller than W and less depth. The medium according to any one of claims 1 to 20, wherein both are 1/10 of W. body. 23. In any of the preceding claims, the textured surface is in the form of a lattice. Media described. 24. 24. The medium of claim 23, wherein said grating has a substantially square wave profile. body. 24. 24. The medium of claim 23, wherein said grating has a substantially sinusoidal profile. body. 26. 24. The medium of claim 23, wherein the grating has a substantially serrated profile. body. 27. The raised surface portions of the lattice (islands) and the depressed surface portions of the lattice (indentations) ), on which a magneto-optic zone is formed. Media on which it is published. 28. The magneto-optic zone is formed only on the raised surface part (island part) of the grating. The medium according to claim 24 or 25. 29. The magneto-optic zone is formed only on the concave surface parts (indentations) of the grating. The medium according to claim 24 or 25. 30. The magneto-optic layer is formed on top of the metal mirror layer, and the metal mirror layer is placed in the recesses of the grating. The medium according to claims 2 and 29, which is also on the surface portion (indentation) . 31. A thin metal film is formed on a flat substrate, and this film has the above-mentioned textured surface. A dielectric layer is deposited, which can be a continuous or discontinuous thin film. Claims 22, 23, 24, or The medium according to paragraph 25. 32. A magneto-optic layer is formed on the flat substrate, and this layer includes the above-mentioned textured surface. A dielectric layer having a surface is deposited, and the surface of the dielectric layer has a continuous or discontinuous surface. Claims 22, 23, 24, or 25 coated with a metal thin film Media described. 33. The textured surface has a sinusoidal contour, the pitch and depth of which are When the wavelength W of the readout radiation is 633 nanometers, the wavelength W of 150 to 400 nanometers is 24. The medium according to any one of claims 22 to 23, which is within the range. 34. The textured surface has a sinusoidal contour whose pitch and depth are readable. When the wavelength W of the extended radiation is 820 nanometers, the range of 200 to 550 nanometers is 33. The medium according to any one of claims 22 to 32. 35. The textured surface has a square wave profile, the pitch and depth of which are: When the wavelength W of the readout radiation is 633 nanometers, the wavelength W of 180 to 300 nanometers is 33. The medium according to any one of claims 22 to 32, which is a range. 36. The textured surface has a rectangular wavy profile, the pitch and depth of which are When the wavelength W of the readout radiation is 820 nanometers, the wavelength W of 240 to 400 nanometers is 33. The medium according to any one of claims 22 to 32, which is a range. 37. The thickness of the metal mirror layer is in the range of 15 to 50 nanometers. The medium according to item 30 or item 31. 38. stored on the optical data recording medium according to any of the above claims. In a method of reading data, the surface of a medium is observed or scanned with readout radiation. monitor the angular position where there is a sharp decrease (doop) in the reflection from the medium when A method characterized by: 39. Optical data recording medium according to any one of claims 1 to 36 In a method of reading data stored in a medium, the surface of the medium is observed by reading radiation. or magneto-optical signals within an angular range that causes a sharp decrease (doop) in reflectance when scanned. A method characterized by monitoring the strength of.