JPS58161161A - Recording member - Google Patents

Abstract

PURPOSE:To obtain an optical disk having high stability and high sensitivity, by using that which contains one among S, Se, Sb, C, Si, etc., and Te, as a recording film, and changing the composition in the film thickness direction of the recording layer. CONSTITUTION:Two disks 24, 26 are opposed with its recording films 23, 25 inside, and are made to adhere to the inside circumference and the outside circumference by placing spacers 21, 22 between, by which an enclosed structure is obtained. In order to obtain stable ones as these recording films 23, 25, those which contain one element selected from S, Se, Sb, C, Si, Ge and Sn, and Te are used. Also, the composition is changed in the film thickness direction of this recording layer, and on at least one of the substrate side of the recording layer or the vicinity of the end part of the surface side, an area which contains more oxygen than its mean content is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention applies to a recording thin film provided on a predetermined substrate using a recording beam such as a laser beam, which is FM-modulated with an analog signal such as video or audio, or an electronic computer. The present invention relates to a recording member that allows digital information such as data and facsimile signals to be recorded in real time, and a method for manufacturing the same.

In recent years, an information recording method that writes information on a metal thin film provided on a substrate using a laser beam or the like has attracted attention.This type of recording method uses the thermal energy of a recording beam such as a laser beam to This is a book that records by forming holes or depressions in a thin metal film and causing changes in the atomic arrangement such as crystallization. There are many practical advantages to forming holes rather than recesses.

The main points of the method for recording information onto a disc-shaped recording member using light will be explained below.

As shown in Fig. 1, a recording member (optical disc 1) is rotated at high speed around a rotating shaft 2, and the distance between the recording head 3 and the recording film of the disc is kept constant to correspond to the information to be recorded. A laser beam 4 (an electron beam or the like may also be used) modulated into pulses is focused and irradiated onto the recording film. In the case of recording by hole formation, as shown in FIG. 2, the irradiated portion of the recording film 5 is melted on the substrate 6, deformed by thermal movement, and a portion is evaporated. When a part of the substrate is exposed in the irradiated area due to deformation and evaporation, the hole expands due to surface tension, and a bulge is formed around the hole.

Conventionally, materials with practical sensitivity that can be used for the above-mentioned recording thin film include Bi and 'l'e.

Cd, chalcogen glass, crystalline chalcogenide.

Many materials are known, including low oxides such as To.

However, thin films of these materials generally do not have sufficient stability in humid air, and transmittance increases easily due to oxidation. Regarding A s -'r e -Se type thin films, Japanese Patent Application Laid-Open No. 53-31108 and Journal of Ap
plied physics volume 50 page 6881 (
1979) and Japanese Patent Application Laid-Open No. 56-3443, the stability is quite high, but it cannot be said that the stability is still sufficient. To obtain sufficient stability, changes in recording sensitivity must also be suppressed.

The present invention provides an extremely stable recording member.

The recording film of the recording member of the present invention has the following percentage characteristics.

The recording film contains at least a portion selected from the group consisting of S, Se, Sb, C, Si, Ge, and Sn, and Te. Then, the composition is varied in the thickness direction of this recording layer. Near the edge of the recording layer on the substrate side or the surface side (in other words, near the interface between the recording layer and the substrate, or when a reflective film etc. is formed on the substrate and the recording layer is formed on this) It means near the interface between the reflective film or a film adjacent to the reflective film and the recording film, or near the interface between the recording film and the protective film when a protective film is formed on the recording film.

In this specification, the upper and lower surfaces of the recording layer in the film thickness direction are also referred to as the upper and lower surfaces of the recording layer, even when six layers are provided on the upper and lower surfaces of the recording film as a modification or improvement plan other than the above-mentioned specific example. The semiconductor device is characterized in that at least one of the ends (also referred to as the end portion on the substrate side) has a region containing more oxygen than its average content.

Although it is preferable to have the basic configuration at both ends, many effects can be obtained even if it is provided only at one end.

/ The recording film itself may be crystalline, amorphous, or a mixture of both states.

The composition ratio of each part of the recording film is configured as follows.

First, a preferable average composition over the entire recording film will be described.

The content of Te is preferably in the range of 39% or more and 98% or less, particularly preferably 50% or more and 96% or less, in terms of atomic percent. Oxygen content 1ifi atomic number percent - 0113 or more 60
A range of % or less is preferred. In the case of recording by hole formation, a range of 0.2% or more and 25% or less is particularly preferable. If the content is too large, the recording sensitivity will decrease and, in the case of pore formation, the pore shape will be disordered.

Contained elements other than the above are Sj SeI SJ C#3i
, Qe, and 3n, and the content thereof is preferably in the range of 1% or more and 35% or less, and particularly preferably in the range of 2% or more and 20% or less in terms of atomic percent. . Among these elements, Se is most preferable because it has a remarkable effect of preventing changes over time, has a small decrease in sensitivity due to its addition, and is less likely to cause disturbance in the pore shape in the case of recording by forming pores. The next most preferred is Sb, which has a great effect on preventing changes over time, but slightly lowers the recording sensitivity.

Additional elements other than those mentioned above include In and pb.

Possible materials include 13i, Tt, Zn, and Cd. These reduce grain size when added. Alternatively, it has the effect of preventing the occurrence of cracks. Among these, in, pb, and Bi are excellent. The amount added is preferably 1% or more and 30% or more in terms of atomic percent.
m has the effect of making the film amorphous; there are other elements that can be added without any particular effect, but may be added. For example, At and Ga.

Hg, Cu, Ag, Au, Pd, Pta Rh.

These are Ir, Ni, Co, Ti, Cr, Mo, W, and Ta.

The distribution of each element in the film thickness direction is configured as follows.

The most important thing is how to contain oxygen. As described above, a region containing more oxygen than the average content of the entire layer is provided on at least one of the substrate side and surface side near the edge of the recording film. Oxygen may have a certain distribution within this region, but the maximum value is preferably 2° atomic % or more. The maximum content of oxygen can be about 90 atomic percent.

The thickness of this region containing a large amount of oxygen should be 1 Å or more expressed as the half-width of the distribution curve and 115 or less of the film thickness (if there are multiple oxygen-rich regions, the thickness of the region with the highest peak should be conditions).

The more preferable range varies depending on the recording method.

When holes or recesses are formed in the recording layer, the thickness is preferably 160 Å or less. In the case of a recording method using a change in atomic arrangement such as a phase change, the thickness is preferably 600 Å or less, particularly 60 Å or less.

Of course, oxygen may also be contained only in this region.

Next, when adding elements such as S, Se, Sb, C, Si, Ge, and 3n, they may be distributed uniformly throughout the layer, but they may overlap with the region containing a large amount of oxygen. It is preferable that the content of these elements in this region and slightly inside the film is higher than the average content of the entire layer.
Even when this region overlaps with a region containing a large amount of oxygen, it is preferable to arrange the region so that it exists slightly inside the film, and the maximum content of the element is 40 atomic percent or more. good. The thickness of the region is preferably 2 Å or more, particularly preferably 10 Å or more, expressed as the half width of the element distribution curve. The upper limit of the thickness of this region is half width, which is 1/1/2 of the total film thickness.
It is preferably 6 or less (if there are multiple high concentration regions of the element, the condition is for the one with the highest peak concentration).

If this region is too thick, the recording sensitivity decreases and recording by a semiconductor laser becomes difficult.

Note that the maximum distance between the peak of the distribution of certain elements such as Se in the film thickness direction and the peak of the distribution of oxygen in the film thickness direction is about 1/6 of the film thickness of the recording film. Also good.

It is preferable that the composition change in the film thickness direction as described above is not formed discontinuously.

The preferred thickness of the entire recording film varies depending on the recording method.

30 in the case of a method that records by forming holes or recesses in the recording film.
The range is preferably from 100 to 800 people, particularly preferably from 100 to 400 people.

On the other hand, in the case of a method that performs recording by changing the atomic arrangement such as a phase change, the range of 30 to 3000 is preferable; if the film is too thick, the recording sensitivity will decrease and recording with a semiconductor laser will become difficult, also decreases. On the other hand, if it is too thin, the stability of the film will deteriorate and the shape of the pores will be disordered when they are formed. However, regardless of the recording method, the lifetime of the recording film can be extended by configuring the composition distribution described above.

Since the recording film of the present invention itself has a compositional change in the film thickness direction, recording can be performed by taking advantage of this, or by creating a compositional change especially near the center of the film to cause reactions and mutual diffusion between regions with different compositions. By adjusting the recording laser power, it is also possible to carry out reading using the resulting change in optical properties or volume change of the film.

The protective film formed on the recording film is preferably an organic material, and an ultraviolet curable or thermosetting resin or a solvent-soluble resin is used. In addition, oxides, sulfides, or composite films (including multilayer films) of these and organic materials may also be used.

Vacuum deposition is a simple method for forming a recording film, but
When forming a film by other methods such as sputtering, glow discharge (plasma polymerization), or vapor deposition in a gas, when changing the composition in the film thickness direction, simultaneous multi-source rotation as described in the embodiments of the present invention may be used. Vapor deposition is suitable. As a treatment for forming an oxygen-containing layer on the film surface, it is preferable to raise the temperature in oxygen or air, and it is effective to raise the temperature to 30C or more and 150C or less. It is recommended that the relative humidity be 80% or more.In addition, treatment in plasma, treatment with ultraviolet rays in an oxygen-containing atmosphere, treatment with organic or inorganic acids may be performed, and the treatment time depends on the treatment conditions. Although the details vary, treatment for 5 minutes or more is preferable.

metal thin films, oxides, chalcogenides, organic thin films,
A substance that increases light absorption, such as a dye or an organic layer containing a dye, is used.

The present invention will be explained in detail below using examples.

Example 1 A substrate 7 having a replica of a tracking groove formed with an ultraviolet curable resin on the surface of a donut plate-shaped chemically strengthened glass having a diameter of 30 cr and a thickness of 1.1 cm has an internal structure as shown in a plan view in FIG. 3. was placed in a vacuum evaporation apparatus. Three vapor deposition boats 8, 9, and 10 are arranged in the vapor deposition apparatus. The center positions of these boats are located below the portion on which information is to be recorded on the disk, and approximately on the circumference of the disk whose center is the same as the central axis 11 of rotation of the disk.

All of these boats are designed to prevent droplets or blobs of the deposition material from flying off and adhering to the substrate.
The structure is such that the vapor deposition raw material cannot be directly seen from the place where the vapor deposition film is deposited. On two of the three boats, each
Te and 5e were added. Masks 12, 13, 14 having fan-shaped slits and shutters 15° 16, 17 are arranged between the boat and the substrate. The opening angle of the slit layer was approximately 12 degrees. The substrate was rotated at 12 rpm, and a current was applied to each boat to evaporate the evaporation raw material in each boat.The amount of evaporation from each boat was detected using a crystal oscillator type film thickness monitor. , control the current flowing through the boat so that the evaporation rate is constant &, Te
The ratio of the evaporation amount of 3e and 3e is 80:
The shutters of both boats were fully opened at the same time so that there were 20 people, and they were closed at the same time when the thickness reached about 300 people. The vapor deposited film thus formed was wetted at #30.
The surface was oxidized by leaving it in a 95% environment for about 24 hours.

This deposited film has a component distribution as shown in FIG. Near the edges of the recording film on the substrate side and the front side, there are regions containing more oxygen than the average content of the entire layer. or,
Also near the ends of the substrate side and the surface side, there are regions containing more selenium than the average content of the entire layer.

Recording on the film formed as described above was performed as follows. The disk on which the recording film is deposited is rotated at 24 rpm, and the light from the semiconductor laser (wavelength: 8,300 nm) is kept at a level that does not allow recording, and the lens in the recording head focuses the light and irradiates it from the substrate side onto the disk, causing reflection. By detecting light, the head was driven so that the center of the tracking groove always coincided with the center of the light spot. While tracking in this way, recording is performed by performing automatic focusing so that the focus is on the recording film, and returning the laser power to the original level that was strengthened according to the information signal. Recordings were made by jumping to other grooves as necessary. Recording was performed by forming holes in the recording film with a diameter of approximately α8 μm that reached the substrate.

Reading was performed as follows. 24 or disc
pm, and while performing tracking and automatic focusing in the same way as during recording, the strength of the reflected light was detected using a laser power that would not be recorded, and the information was reproduced.

The recording film of this example, which had been stored in a normal room for about one year, was stored for one month at 25C relative humidity of 50% and 60C relative humidity of 9%.
Even when stored at 5% for 2 weeks, the light transmittance hardly changed, and even after additional recording, both the pore shape and sensitivity remained unchanged from the initial state.

On the other hand, a film formed in the same manner was heated at 25°C for 1 month at about 50% humidity, then at 60°C at 95% humidity.
%, an increase in transmittance of about 3% occurred as a result of storage for 2 weeks. The effect of the heat treatment mentioned above, ie, the effect of the region where oxygen is introduced with a peak, is clearly visible.

By the heat treatment, a relatively stable oxide layer with a peak oxygen concentration of 20% or more is formed. Furthermore, it is presumed that the formation of a 9e high concentration region with a thickness of about 2 Å or more at half width just inside this oxide layer further suppresses oxidation inside the film9. S
If the oxidation is performed so that the thickness of the e-high concentration region becomes approximately 10λ or more in half width, the life can be particularly extended.

When the average Se content of the recording film was changed, after oxidation at 30C relative humidity of 95% for 24 hours, 25C relative humidity of about 50
The increase in transmittance when stored in a clean environment for 3 months showed a tendency to saturation, and the increase was as follows.

When the transmittance increases by 3%, residue is generated inside the pores,
Recording sensitivity decreased by about 10%.

If the average Se content of the recording film is increased (in terms of atomic percent) of 35% or more, it becomes difficult to record with a semiconductor laser, and if it exceeds 70%, many defects will occur in the film within a few days, making it unusable. becomes.

Part or all of 3e as s, sb, c, si.

Similar results can be obtained by replacing Qe and Sn, but there are some phenomena that occur when the addition amount is increased, which is different from the case of #ise. For fc, for example, Si and Qe, the recording sensitivity decreases and the hole shape becomes easily disordered, making it difficult to obtain a high S/N ratio and error rate, which limits the use of the fc. S causes the surface condition of the film to deteriorate. C is usually introduced in the form of an organic substance or by decomposing or polymerizing an organic substance, but it deteriorates the surface condition of the resin film. In the case of sb, there are few drawbacks other than a decrease in sensitivity, but the crystal grains of the film become larger and the noise becomes slightly higher.

However, the preferred range of content is 3
5 at, -% or less.

If the surface oxidation layer (thickness and half-width) is not 160 Å or less, the recording sensitivity will decrease, reflectance and transmittance will change, and in the case of recording by hole formation, the hole shape will be easily disturbed. Particularly good results can be obtained with a thickness of 80 Å or less. The average thickness of this layer is 1 Å
It needs to be more than that.

Adding at least one element of In, Pb, and Bi to the above recording film has the effect of reducing crystal grains, suppressing noise, and preventing the occurrence of cracks, which is preferable.TL, 7. Adding at least one element of n and Cd has some effects such as making crystal grains smaller. The addition t is particularly preferably in the range of 1% or more and 30% or less in terms of atomic percent.

Example 2 Using the same substrate as in Example 1, a recording film was deposited using the same vapor deposition apparatus as in Example 1. By adjusting the opening angle of the shutter on each boat during vapor deposition, a region with a high 3e content was formed on the surface of the film and near the interface with the substrate, as shown in FIG. The difference from Example 1 is that there is a region with a high Se content near the interface of the recording film immediately after vapor deposition. After being left in an atmosphere of 30C and 95% humidity for 24 hours after vapor deposition, an oxide layer was formed on the surface as shown in FIG.

When the recording film of this example was kept in a clean environment of 25R humidity of 50% for one month and then in a 60C humidity of 95% for two weeks, almost no increase in transmittance was observed. It is effective when the thickness of the portion with a high Se content is 2 Å or more, and a significant effect is obtained when the thickness is 10 Å or more. If a whole (Se-free region) is provided on the surface and this part is made into an oxide layer, the thickness of this layer is 60 mm.
When the hole was crossed by a person, the sensitivity decreased by more than 20% and the shape of the hole became disordered.

As shown in FIG. 7, the optical disc of this embodiment is made by placing two identical discs 24 and 26 facing each other with their recording films 23 and 25 inside, and bonding them with spacers 21 and 22 sandwiched between the inner and outer peripheries. used.

Even if the disc is sealed and filled with dry air, moisture from the outside air will enter the disc through the adhesive, and the average temperature of the outside air will become equal to the average humidity inside the disc after about a year. Therefore, oxidation resistance of the recording film is required. When an acrylic resin (PMMA) plate is used instead of a chemically strengthened glass plate for the substrate, moisture permeates even more quickly, but the recording film of this example maintains sufficient stability.

When the thickness of the portion with a high Se content (evaluated by the half-width of the concentration distribution) was increased, sensitivity decreased and noise and errors increased. Therefore, unless the thickness (half width) of this portion is set to about 1/6 or less of the film thickness, that is, about 130 Å or less in this case, the application will be limited. In a recording film that performs recording by phase change, the film thickness can be increased by about 3,000 mm, so the thickness of the portion with a high Se content is about 500 mm. Although a value of A or less is permissible, in this case as well, a value of 100λ or less is preferable from the viewpoint of sensitivity.

In this embodiment, recording is performed by forming holes in the same manner as in Embodiment 1.

The formation of the Te1l oxide layer on the surface or the interface with the substrate forms a dense and stable Se-rich layer immediately inside it that cannot be formed by controlling the atomic ratio during vapor deposition, and this layer forms a layer with a high concentration of Se, which is difficult to form inside the oxidation layer. By helping prevent the progression to
Stabilize the membrane.

Table 1 shows examples of recording members using additive elements other than Fise. In these recording members, oxide layers are provided at the upper and lower ends of the recording film, as in the example shown in FIG. 6. The peak value of the oxygen content in the oxidized layer is about 45 to 55 at.%, and the width of this region is about 10 to 60 at.% as the half width of the concentration distribution curve.

In Table 1, the peak value of additive elements such as Sn other than u and se does not exceed 50%, which is preferable since there is no disturbance in the pore shape.

Even in these examples, there was almost no change in light transmittance even when stored in an atmosphere of 60R humidity f95%. Even in actual recording, completely normal recording was possible.

In the case of the recording film No. 13 in Table 1, in which the surface of the film made of Te only is oxidized, the stability is slightly higher than that without a forced oxidation layer, but the bond between Te and oxygen is not so strong, and the film Since there is nothing to prevent the progress of oxidation to the inside, stability sufficient for practical use cannot be obtained.

Example 3 A substrate similar to that of Example 1 was placed in a vacuum deposition apparatus similar to that of Example 1. Each of the three deposition boats has a 'l'
e Ox, T es and Se were added.

The vapor deposition raw material was evaporated from each boat to form a vapor deposited film in which the atomic ratio of Te and oxygen was approximately 1:1, and the average content of Se was approximately 5% in atomic percent. Film thickness is approximately 150
There were 0 people. This film is approximately 3%
An acrylic resin layer was applied as a protective layer to a thickness of about 0.5 μm on the primary recording film, which had been oxidized in the vicinity of its surface.

The recording film of this example also showed almost no increase in transmittance even after being placed in a clean environment of 50% 25ri degree for about one month and then placed in an environment of 60Cg&#95% for two weeks.

Recording is performed on the recording film of this example in the same manner as in Example 1, but in this example, no holes are formed in the recording film, and changes in reflectance and transmittance occur, which are thought to be due to changes in atomic arrangement. .

As detailed above, the recording member of the present invention has extremely high stability and can be made at a low price, so the benefits obtained are extremely large.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an outline of a method for recording on the recording member of the present invention, FIG. 2 is a diagram showing a state in which recording is performed by forming holes in the recording member of the present invention, and FIG. FIG. 4 is a diagram showing the structure inside the vapor deposition apparatus for vacuum vapor depositing the recording member of the present invention.
The figure shows the film structure of the recording film after surface oxidation of the recording film shown in FIG. 1, which is an embodiment of the present invention, and FIG. 2 is a diagram showing the cross-sectional structure of the recording member of the present invention. DESCRIPTION OF SYMBOLS 1... Recording member, 2... Rotating shaft, 3... Recording head, 4... Laser light, 5... Recording film (thin film), 6
... Substrate, 7... Substrate on which a replica of the tracking groove was formed, 8,9.10... Vapor deposition boat, 11
... Central axis, 12.13.14 ... Mask, 15,
16,17...shutter, 18,19.20...
Film thickness monitor, 21.22...Spacer, 23.2
5...Recording film, 31 ¥J 1 Figure ¥J z Figure ¥J 3 Figure ¥Jα 'f), sth item 6 Figure 1: JZ226 Procedural amendment/indication of 11 cases Patent Application No. 42764 of 1982 Nari, the 1st son of the company, used to supplement recording materials 1 + 1... Yahi Patent applicant and 1 1 + 1 □ 51st / 41st ceremony? t:
i)] Supplementary Personnel 1 ■ Addition to the "Detailed Description of the Invention" column of the subject specification of Mi. Correct "more than" to "less than or equal to 1". 2. Add "ga" after "more than" on page 9, line 20. 3. Delete the "-" on page 18, line 5 of the same name. 4. Correct "temperature" in line 5 of page 20 to "humidity". 5. Add the following sentence after line 11 on page 24. [Example 4] A substrate similar to that in Example 1 was placed in a vacuum evaporation apparatus similar to that in Example 1. Te%S was added to each of the three evaporation ports.
e, and Sn were added. The vapor deposition raw material was evaporated from each boat, and the atomic ratio was Sn 20 Te 7o Se 10
A recording film with a film thickness of about 600 mm was formed with the composition.

Claims (1)

[Claims] 1. A recording member having at least a substrate and a recording film formed on the substrate, wherein the recording film is made of S, Se, or Sb.
, C, Si, Ge, and 9n, and contains at least Te selected from the group consisting of A recording member characterized in that at least one of its neighboring regions contains oxygen and has nine regions. 2. The recording member according to claim 1, wherein the maximum value of the oxygen concentration distribution in the oxygen-containing region is from 20 atomic % to 90 atomic %. 3. The thickness of the oxygen-containing region is 11 times the thickness of the recording film when expressed as the half-width in the oxygen distribution curve.
5 or less, the recording member according to claim 1 or 2, wherein: 4, the above S, Se, Sb, C, S'', Ge and 9n,
The predetermined element is present in at least one of the substrate side and the surface side near the edge of the recording film in the composition distribution in one direction of the film thickness of the recording film, among the regions selected from the details of 9 and containing at least the name. A recording member according to claim 1, 2 or 3, characterized in that the recording member has a region having a content of the predetermined element that is larger than the average content of the predetermined element. 5. The recording member according to claim 4, wherein the maximum value in the distribution of the content of the predetermined element in the film thickness direction is 40 atomic % or more. 6. The position of the maximum value in the distribution of the content of the predetermined element in the film thickness direction is located inside the recording film from the position of the maximum value in the distribution of the oxygen content in the film thickness direction. A recording member according to claim 4 or 5. 7. The thickness of the region having the maximum value in the distribution of the content of the predetermined element in the film thickness direction is 1/6 of the film thickness of the recording film when expressed as the half width of the distribution curve of the predetermined element.
Claims 4 and 5 are characterized by the following:
The recording member according to item 6 or item 6. A recording member.