JPH0413253A - Magneto-optical memory element and production thereof - Google Patents

Abstract

PURPOSE:To decrease crosstalks intruded with the information of adjacent tracks by laminating thin-film layers including magnetic layers having a high thermal conductivity on a substrate including guide grooves, then removing the thin-film layers laminated in the inclined side walls of the guide grooves by dry etching. CONSTITUTION:The guide grooves 50 having the inclined side walls 39, 40, 41, 42 of the shape flaring toward upper apertures are formed on the polycarbon ate substrate 1 and the thin-film layers 2 are formed on the bottom walls of the guide grooves 50 in the regions (p), (q) and the substrate surface in the regions (l), (m), (n). There are no metallic thin-film layers having the large thermal conductivity in the regions (e), (f), (g), (h) when the regions (l), (m), (n) are subjected to recording in this case and, therefore, the information recorded in the regions (l), (m), (n) is prevented from being recorded in the regions (p), (q). The crosstalks are drastically decreased even if the diameter of a laser beam is larger than the region (m) at the time of reading the informa tion of the region (m) in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application This invention relates to a magneto-optical memory element and a method for manufacturing the same.
More specifically, the present invention relates to a large-capacity memory in which a magnetic recording layer is laminated on a substrate having a guide groove, and in which information can be recorded, reproduced, and erased using light such as a laser beam, and information can be rewritten.

(B) Prior art As shown in FIG. 9, a conventional magneto-optical memory element of this type basically consists of a thin film layer 22 including a recording layer formed on a substrate 21 on which a guide groove 20 is formed. After that, a back coat layer 23 made of resin is formed.

Generally, the recording layer has magnetic properties as shown in the coercive force Hc-temperature line curve shown in Figure 8. During recording, the temperature of the recording layer is raised to near the Curie point (Tc) using a laser tip, and an external magnetic field is applied. This is done by aligning the magnetization of the part whose temperature has been raised by applying it to the direction of the external magnetic field.

In FIG. 9, the information is in the thin film, region l of 122.

The first recording part 2'4.25.26 of mn seems to be area p,
This is done in the second recording section 27, 28 of q. In addition, thin film layer 2
Side surfaces (side walls) 29, 30, 31, and 32 of the guide groove 20 are located in the regions e, I', g, and h of 2, and when forming the guide groove 20 on the substrate 21, the side surfaces 29 to 32 are Guide groove 20
It is difficult to form it perpendicularly to the bottom surface 20+L of the bottom surface 20+L, so that it has an inclination. This tendency is more pronounced when polycarbonate is used as the substrate 21 than when glass is used.

Therefore, a thin film layer 22 is formed on the substrate 21 on which the guide groove 20 is formed.
When forming the guide groove, the thin film layer 22 is also formed on the guide groove side surfaces 29 to 32. For example, as shown in FIG. 7, this thin film layer 1 has a structure consisting of dielectric layers 33a and 33b, a magnetic layer 34 which is a recording layer, and a reflective layer 35 as the uppermost layer. Among these, especially the recording layer 34 and the reflective layer 35 have higher thermal conductivity than the dielectric layers 33a and 33b.
When recording information by irradiating laser light 2, a wide range is heated to near the Curie point via the thin films @29 to 32 on the side surfaces of the guide groove.

That is, in FIG. 9, area 1. 1st record FW of m, n
24.25.2.6, areas e, f,
g, h! 17) The second recording layer 27 in the area p has areas 1. m first recording layer 24.
On the other hand, part of the information on the 132nd recording layer 25 and 26 of the areas m and n is recorded on the second recording layer 28 of the area q.

(c) Problems to be Solved by the Invention By the way, if a laser beam is irradiated onto a track in area ff; in order to destroy the information written in area m, then the diameter of the laser beam or the maximum width of the track in area m Since it is larger than M, information written in areas p and q will also be read. As mentioned above, the region p and territory region include region 1. Since the information written in area n and the f information are recorded, there is a possibility that the information written in the tracks in area l and area n may be superimposed on the information in area m.

That is, there was a problem in that crosstalk caused by the mixing of information from adjacent tracks becomes large.

(d) Means and operation for solving the problem This invention includes:
A magneto-optical memory that has a thin film layer containing a magnetic layer with substantially high thermal conductivity on a substrate with multiple guide grooves, and information is recorded, reproduced, and erased by irradiating the magnetic layer with light. In the element, a guide groove having a substantially wide sloped sidewall from the bottom surface toward the upper opening, and a thin film layer laminated on the substrate including the guide groove and over the entire surface of the guide groove except for the sloped sidewall. The method for manufacturing the magneto-optical memory element is to form a C thin film layer containing a magnetic layer with substantially high thermal conductivity on a substrate having a plurality of guide grooves, and to emit light from the W&magnetic layer. When producing a magneto-optical memory element that records, reproduces, and erases information by irradiation, (1) a guide groove is formed on a substrate, and (11) a guide groove is formed on the entire surface of the substrate, including the guide groove. A magneto-optical device characterized in that a thin film layer including a magnetic layer with substantially high thermal conductivity is laminated, and then the thin film layer laminated on the inclined side wall of the guide groove is removed by dry etching. A method for manufacturing a memory element is provided.

That is, the present invention uses a substrate having guide grooves or inclined sidewalls formed obliquely with respect to the substrate surface; and in a magneto-optical memory element, information recording and reproducing is performed using a magnetic layer on the inclined sidewalls. In addition, in order to prevent the formation of a thin film layer for erasing, the thin film layer is formed on the entire surface of the substrate including the guide groove, and then the thin film layer on the sloped side wall is removed by a dry etching method such as ion etching. , thereby making the thermal conductivity of the area where the sloped sidewall is located smaller than that of the bottom wall of the guide groove where the thin film remains or the area on the substrate between the guide grooves, and forming a thermal conductivity on the bottom wall of the guide groove. Lostalk can be reduced by making it difficult for the information recorded in each area of the thin film layer on the substrate between the guide grooves to be recorded on the thin film layer through the inclined sidewalls.

In this invention, the substrate τ' is made of carbonate, glass, or amorphous polyolefin (APO).
) are mentioned as preferred materials. These guide grooves placed on the board can be opened from the bottom of the groove.
It has sloping side walls that are substantially wider towards it.

In the second invention, the expression 6 that the guide groove has a substantially wide inclined side wall means that the longitudinal section of the groove is set to have a substantially inverted trapezoidal shape. The guide grooves are formed using a well-known method such as dry etching using glass or after spin-coding an ultraviolet curable resin on a glass substrate.
A method of pressing this onto a stun I with a guide groove, irradiating it with ultraviolet rays to harden the resin, and transferring the guide groove, the so-called 2P method (phcto pclymer method)
, an injection molding method using resin, a 2P method, or the like.

The guide groove according to the present invention has an opening diameter K of 0.1 to 10 μm [see Figure 1 3].

In this invention, the thin film layer includes: (1) a magnetic layer as a recording layer with high thermal conductivity, a second protective layer, and a reflective layer with high thermal conductivity on the entire surface of the first protective layer; A four-layer structure film (see Figure 7) in which the film is sequentially laminated or (11) a three-layer structure film in which a magnetic layer and a second protective layer are sequentially laminated over the entire surface on the first protective layer is preferable. It is mentioned as.

The thickness of the magnetic layer (thickness in the stacking direction) (see GII 7th Reference) is preferably 0.01 to 0.28 m, and the thickness H0 of the thin film layer (see Figure 1) is 0.02 to 0.3 μm. preferably 0.03 μm or more preferably -).

In this invention, first, on a substrate in which a thin film layer includes a guide groove,
After being laminated over the entire surface, the thin film layers deposited 11 on the sloped sidewalls are subjected to dry etching.

A known method is used for this dry etching method, such as a dry etching method using Ar' ions. In addition, dry etching methods using N2 and CF4 are also preferred.

A removal method using Ar'' ions will be explained.

In FIG. 2, a thin film layer formed on a substrate (indicated by reference numeral 14) is attached to a substrate holder 13 which can be rotated in the direction of the arrow shown by FR in the figure, and while rotating the holder 13,
The substrate is irradiated with accelerated Ar' ions in an oblique direction (direction indicated by A in the figure).
``Ion irradiation is done at the irradiation part indicated by reference numeral 18.19. x, y, z are orthogonal coordinates, and the substrate and substrate holder 13 are in the x-y plane and are irradiated with Ar' ions. The direction is within the X-Z plane.The irradiated parts 18 and 19 are on the X axis at the beginning of the irradiation, and at the beginning of the irradiation, as shown in FIG. The facing side is effectively etched and the thin film layers 29, 31 [see 3 in FIG. 1] in areas e and H are removed. In FIG. 4, the arrow direction indicated by B indicates the center direction of the substrate l, and the arrow direction indicated by C indicates the outer circumferential direction.

Thereafter, the substrate holder 13 rotates half a turn, and initially marks 18.
When the part that was at position 19 comes to position, it will become A from now on.
Since the ion irradiation is performed from the outer circumferential direction of the substrate, a thin film layer 30.32 is formed in the regions f and h as shown in FIG.
1' (see FIG. 9) are efficiently etched and removed. By rotating the substrate in this manner, the layer 4 formed on the side surface of the guide groove is removed over the entire area of the substrate.

In the second invention, a magnetic layer having substantially high thermal conductivity means, for example, that during recording, the temperature of the magnetic layer is raised to near the Curie point by a laser beam with a diameter of 0.065 μm, and then a desired external magnetic field is applied. The temperature is raised and the magnetization of the r: portion becomes external magnetism iA.
0.1 to 1, OJ/aIIl/deg.
A material having a thermal conductivity of /see is preferable.

(e) Examples The present invention will be described in detail below based on examples shown in the drawings. Note that this invention is not limited by this.

In FIG. 1, the magneto-optical memory element has a guide groove 50 formed on a polycarbonate substrate l, which has sloped side walls 39, 40, 41, and 42 that become wider toward the upper opening, and a thin film layer 2 in a region p. .

q and on the bottom wall of the guide groove 50 in area 1.q. m.

It is formed on the upper surface of the substrate at point n.

Since this example has the above configuration, area 1. m
, n, areas e and f.

Area 1 because there is no metal thin film layer with high thermal conductivity in g and h.
．． Information recorded in areas m and n is never recorded in areas p and q.

As a result, when reading information in area m, crosstalk is greatly reduced even if the diameter of the laser beam is larger than area m, and the quality of the reproduced signal can be improved.

A polycarbonate substrate with guide grooves formed by injection molding was used as the substrate, a protective layer of AIN, a recording layer of DyFeCo, and a reflective layer of At were formed by RF sputtering, and an epoxy acrylate resin was formed as a back coat layer 3. A magneto-optical disk having the structure shown in FIG. 1 was prepared and compared with a conventional medium having the structure shown in FIG. 9 using the same material.

That is, the disc rotation speed was 3600 rpm, the laser power was 7 mV during recording, and the laser power was 1.5 during playback.
Recording was performed by magnetic field modulation at mV, laser beam wavelength of 780no+, and NA≦0.55.

Figure 6 is a view of the guide groove viewed from above.
．． After recording a bit length of 2.37 μm on track 2.26, track 2.25 is read and mixed into the reproduced signal.
Evaluated with signal magnitudes of 24 and 2.26 r. Table 1
is the result.

From Table 1, it can be seen that the crosstalk is 4 dB.
It can be seen that it is decreasing. That is, the quality of the reproduced signal is improved and the probability of read errors is reduced.

(F) Effects of the Invention As described above, the magneto-optical memory element and the method for manufacturing the same according to the present invention reduce the area where heat conduction occurs during recording by removing the thin film layer formed on the side surface of the guide groove. Only on the track to be recorded. As a result, crosstalk caused by signals from adjacent tracks being mixed into the reproduced signal can be significantly reduced, and this has the effect of increasing the quality of the reproduced signal and the reliability of the device.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the main part configuration of a magneto-optical memory element according to an embodiment of the present invention, FIGS. 2 to 5 are illustrations of manufacturing steps in the above embodiment, and FIG. 6 is an illustration of the operation of the above embodiment. FIG. 7 is an explanatory diagram of the main part configuration in the above embodiment and conventional example, FIG. 8 is a characteristic diagram showing the temperature dependence of the coercive force of the recording layer, and FIG. 9 is a main part configuration showing the conventional example. It is an explanatory diagram. ■---Substrate, 2---Thin film layer, 39.40
．． 41.42... Slanted side wall of guide groove, 50...
-Guide groove, 1, m, n...Track area, p, q-...Guide groove area, e, f, g, h......Incline side wall area of the guide groove.

Claims (1)

[Claims] 1. A thin film layer including a magnetic layer with substantially high thermal conductivity is provided on a substrate having a plurality of guide grooves, and information is recorded and reproduced by irradiating the magnetic layer with light. In addition, in a magneto-optical memory element in which erasing is performed, a guide groove having a substantially wide inclined side wall from the bottom surface toward the upper opening, and a substrate including the guide groove and the entire surface of the guide groove excluding the inclined side wall. A magneto-optical memory element consisting of a thin film layer laminated on a. 2. Magneto-optical technology, in which a thin film layer containing a magnetic layer with substantially high thermal conductivity is formed on a substrate with multiple guide grooves, and information is recorded, reproduced, and erased by irradiating the magnetic layer with light. When manufacturing a memory element, (i) a guide groove is formed on a substrate, and (ii) a thin film layer including a magnetic layer with substantially high thermal conductivity is laminated over the entire surface of the substrate including the guide groove. (iii) A method for manufacturing a magneto-optical memory element, comprising: thereafter removing the thin film layer laminated on the inclined sidewalls of the guide groove by dry etching.