JPH02121889A - Data recording medium - Google Patents

Abstract

PURPOSE:To obtain a long life data recording medium not easily generating surface roughness even under high temp. and high humidity environment by forming a recording film containing a specific alloy as well as carbon and hydrogen in an amorphous state on a substrate. CONSTITUTION:A data recording medium 18 is constituted of a substrate 3 and the recording film 14 laminated to the substrate 13. The recording film 14 contains an AgxTe100-x (2<=x<=50atomic%) as well as carbon and hydrogen to show an amorphous state and data is recorded thereon by the irradiation with laser beam. When this recording film is mounted, the data recording medium stably keeping recorded data even in a high temp. and high humidity state and excellent in recording sensitivity can be provided.

Description

Detailed Description of the Invention [Objective of the Invention] (Industrial Application Field) The present invention is directed to writing information by aggregating recording film components by irradiating the components with a laser beam, and changing the amplitude of the laser beam due to the aggregation of the components. The present invention relates to an information recording medium that reads information through changes.

(Prior Art) As a type of information recording medium, information is recorded by irradiation with laser light and the recorded information is reproduced.
A device equipped with a recording film containing Te as a main component has been developed. Furthermore, a recording film containing carbon and hydrogen in addition to the Te-based recording film has been developed and put into practical use (see Japanese Patent Laid-Open No. 58-9234).

When creating this recording film, tellurium (Te) is sputtered in an atmosphere containing hydrocarbon gas.

As a result, a recording film (hereinafter referred to as a Te-C film) having higher sensitivity and superior oxidation resistance than a film containing only Te (Te film) is obtained. This recording film is an amorphous film and is made of Te.
5 (and H), and it is known that at least C and H form a chemical bond.

This recording film cannot be formed even if it is attempted to be formed by vapor deposition using Te and hydrocarbon as sources (without using plasma), following the Te film, and can only be obtained by using plasma. This is because a film is formed by a chemical reaction between C and H after the hydrocarbon gas is once decomposed in plasma, and this is a major feature when forming an optical recording film.

(Problem to be Solved by the Invention) Comparing the recording film made of Te and hydrocarbon as described above and the recording film made of Te at a high temperature and high humidity of 65° C. and 90% (under accelerated conditions), Te film oxidizes within just one week and optical recording performance is impaired, whereas Te film
The C film remained stable without being oxidized even after one month.

However, the recording film of the Te-C film also crystallizes at high temperatures (above about 75 degrees Celsius), resulting in a rough surface that increases noise and has a greater effect on the reproduced signal. .

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, it is an object of the present invention to provide a long-life information recording medium whose surface does not easily become rough even under high temperature and high humidity environments.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention includes a substrate, and an A g * T film formed on the substrate and on which information is recorded by irradiation with a laser beam. e 100-m (2≦x≦50
%) alloy and an amorphous recording film containing carbon and hydrogen.

(Function) The optical recording film of the present invention uses an AgTe alloy, and is able to maintain a stable surface appearance even at high temperatures.

The present invention provides an information recording medium that stably maintains recorded information and has excellent recording sensitivity even under high temperature and high humidity conditions by including a recording film containing an AgTe alloy and carbon and hydrogen. It is something that can be done. Hereinafter, the recording film of the present invention will be referred to as an "AgTe-C film" for convenience.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view schematically showing the structure of the information recording medium of the present invention. The information recording medium of the present invention is composed of a substrate 13 and a recording material 111% 14 laminated on the substrate 13.

The substrate 13 is made of a material that is transparent to laser light that is irradiated onto the information recording medium for recording and reproducing information. For example, when using a laser beam having an oscillation wavelength near infrared, polycarbonate (PC), polymethyl methacrylate (PMMA), glass, polyolefin, epoxy resin, etc. are used.

The recording film 14 is made of an Ag-Te alloy containing carbon and hydrogen.

If there is a difference in the reflectance of the cluster components dispersed in the C-H matrix when they are agglomerated and when they are dispersed, for example, cluster dispersion can be made to correspond to the absence of information and aggregation to the presence of information. Can record. Aggregation of clusters can be caused by heat generation due to laser irradiation. When Te is used as a single substance, the difference in reflectance between aggregation and dispersion is not so large. However, when a component that can form an alloy with this is added, a difference may be observed. In the present invention, it has been found that this effect is significant when 2 to 50 atomic % of Ag is added.

In the information recording medium according to the present invention, information is recorded using the difference in reflectance before and after the phase change. The value of the film thickness is advantageous because the interference effect decreases as the film thickness increases and converges to a certain reflectance, and becomes large when the reflectance is close to that given. Therefore,
Considering the recording film according to the present invention and the fact that the laser power during recording increases as the film thickness increases, the thickness is set to 5000 Å or less.

Example 1 A method for forming the information recording medium shown in FIG. 1 will be described.

FIG. 2 is a schematic diagram of a sputtering apparatus for forming the recording film of the present invention. First, open the valve 2 of this sputtering device to the rotary pump 3 side and set the inside of the chamber 1 to 0.2 Torr.
Exhausted to r. Next, the valve 2 was opened to the cryopump 5 side, and the temperature was evacuated to below 1X10-5 Torr. At this time, since there was no need to control the displacement, the conductance valve 4 was left fully open.

Next, the valve 6 was opened, and 10 3 CCM of Ar gas was introduced into the chamber 1 from the Ar gas line 7 while being controlled by a mass flow controller (not shown). Next, while monitoring the pressure inside the chamber 1 with an ion gauge (not shown), the conductance valve 4
Adjusted to Torr. After confirming that this pressure does not fluctuate, a D
Sputter cleaning was performed by applying 100 W from the C power supply 10 and performing sputter discharge for 5 minutes with the shutter 11 closed.

After stopping the supply of Ar gas and the supply of DC power, the inside of the chamber 1 is temporarily pumped using the cryopump 5. X 1
It was evacuated to below 0' Torr. Then valves 6 and 17
Open the chamber 1 and introduce Ar gas and CH4 gas into the chamber 1.
105 C through gas line 7 and CH4 gas line 8 while adjusting with a mass flow controller (not shown).
We introduced commercials one by one.

Next, the pressure inside the chamber 1 was controlled to 5×10 −3 Torr using the conductance valve 4 . After confirming that there is no pressure fluctuation, apply DC to AgTe target 9.
A power of 100 W was applied from the power supply 10, and spatter was emitted for 7 cycles. After confirming stable discharge, the shutter 11 was opened, and a recording film 14 containing an AgTe alloy, carbon, and hydrogen was laminated on the PC board 13 that had been set on the rotor 12 in advance. The rotor was rotated at 60 rp@.

When the number of membranes Iν' reached 1000 people, the shutter was closed and the power supply was stopped.

Next, the conductance valve 4 is fully opened and the cryopump 5 is used to pump the inside of the chamber 1. X 10-5To
Exhausted to below rr. Next, open the valve 15 and turn on the N
By introducing N2 gas into the chamber 1 from the 2 gas line 16 and returning it to atmospheric pressure, the medium 18 is taken out.
The information recording medium shown in FIG. 1 was formed.

As a result of X-ray diffraction analysis, it was confirmed that the recording film 14 thus obtained was an amorphous film in which no diffraction peak was observed from a specific diffraction angle. Unlike a polycrystalline film, an amorphous film does not have grain boundaries, so that reproduction laser light is not modulated at the grain boundaries and does not generate grain boundary noise.

A g 33T e 67 obtained by the above method,
When the film thickness of a recording film containing C and H is 1000, as shown in Figure 3, the reflectance reaches a minimum value due to the multiple interference effect, so the film changes from amorphous (dispersed state) to crystalline state at this film thickness. When the phase changes to (agglomerated state), a significant increase in reflectance can be observed, indicating that information has been recorded.

In the above embodiments, a transparent organic resin substrate was used, but the substrate may be opaque when the writing and reproducing laser beams are incident from the recording film side without passing through the substrate.

Example 2 By the method shown in Example 1, Ag 3]T e 67
, C and H were deposited on a PC board by 250 people at a rotation speed of 1800 rpm and a recording frequency of 3.7 MHz.
Under conditions of recording pulse width 5 n5ec, linear velocity 5.5 m
When writing with a laser power of 7 mW at the location corresponding to /see, a good C/N of 30 dB (Ca
rrlcr/Nolse) ratio was obtained.

In the recording film according to the present invention having a thickness of 250 mm, when the writing laser power exceeds 10 mW, not only cluster components agglomerate but also pits are formed, causing confusion when reading information. Therefore, in order to prevent the formation of bits, a fourth
As shown in the figure, an information recording medium 21 can be obtained in which a dielectric film 20 with a thickness of 300 to 1000 layers is laminated on a recording film 14 formed on a substrate 13. As the dielectric film, 5i02.5iOSA, SiN, etc. can be used. If the dielectric film is thinner than 300 people, pinholes may occur, and if it exceeds 1000 people, the film forming time will be longer.

In such a three-layer structure, the minimum value of reflectance due to multiple interference effects changes depending on the refractive index and film thickness of each dielectric.

Further, as shown in FIG. 5, when the information recording medium 18 consisting of the substrate 13 and the recording film 14 according to the present invention is bonded to each other via the adhesive layer 19, the dielectric film 20 covers the surface of the recording film 14 with the bonding layer 18. It also serves as protection from heat.

In the present invention, since information is recorded using phase change, there is no need for air to exist on the recording film.
It is possible to directly bond two pieces of information recording media together. Furthermore, since the information recording according to the present invention is not based on the formation of bits, there is no possibility that a portion melted by irradiation with a laser beam will form a rim (bulge) due to interfacial tension at the substrate interface. That is, only a difference in reflectance occurs in the recording film, and so-called marking portions and non-marking portions are clear, so that there is no scattering of the readout laser beam by the rim, which occurs in the case of recording by bit formation. Furthermore, since no rims are formed, it is possible to narrow the bit spacing and perform high-density recording.

Example 3 In Example 1, the flow rate ratio Q (Q-rX/ (X
+Y))
A-1-R-T; R is reflectance and T is transmittance), so the laser power during recording must be increased. Therefore, if the flow rate ratio Q is 5≦Q≦50%, then C
The optical absorption rate does not decrease due to too much H and H. Furthermore, within the range of the above Q value, the degree of change in reflectance under high humidity is smaller than that of a single AgTe alloy film that does not contain C and H, and it has a longer life.

As shown in FIG. 6, the reflectance of a recording film containing A g , , Te 6□ and a film thickness of 250 deposited according to the method of Example 1 at a flow rate ratio of Q-5 and 50% is as shown in FIG. Even in an atmosphere (65° C.-90%) in which the reflectance of the single film and the single AgTe film (Q-0) is reduced by rapid oxidation, it was extremely stable with no significant change for 1000 hours. The reflectance is normalized by setting the reflectance immediately after film formation to 1.

This means that it can be formed on organic resin substrates such as PC and PMMA that are relatively permeable to oxygen and water without using a dielectric protective film. The optical recording sensitivity is better when the film is formed on an organic resin substrate with low thermal conductivity than when it is formed on a glass substrate. Therefore, according to the present invention, it is possible to obtain an information recording medium with high optical recording sensitivity.

Example 4 An information recording medium having a four-layer structure having the dielectric films described above above and below a recording film was manufactured.

FIG. 7 is a schematic diagram of a sputtering apparatus for forming the recording film of the present invention. First, the valve 52 of this sputtering device is opened to the rotary pump 53 side, and the inside of the chamber 51 is
Exhausted torr. Next, the valve 52 was opened to the cryopump 55 side, and the temperature was evacuated to below I.times.10@-5 Torr. At this time, there is no need to control the exhaust volume, so
The conductance valve 54 was left fully open.

Next, open the valve 56, and
1103 CC of gas was introduced into the chamber 51 while adjusting the gas with a mass flow controller (not shown). Next, while monitoring the pressure inside the chamber 51 with an ion gauge (not shown), the conductance valve 54
Adjusted to -3T orr. After confirming that this pressure does not fluctuate, connect the RF power supply 78 to 5i02.
300W was supplied to target 79.

Close the shutter 80 for 5 minutes and sputter clean the 5i02 surface, then open the shutter 80 and remove the 5i02 film 7.
1 on the rotor 62 in advance.
Laminated on top. The rotation speed of the rotor 62 is 60 rp during film formation.
It was kept at m.

After 1000 people formed films, the shutter 80 was closed to stop the discharge. Furthermore, the gas supply was also stopped and the cryopump 65
The inside of the chamber 51 was evacuated to 1×10 Torr or less.

Next, a recording film containing AgTe, C, and H was formed as follows.

First, open the valve 56, and then
1103 CC of gas was introduced into the chamber 51 while adjusting the gas with a mass flow controller (not shown). Next, while monitoring the pressure inside the chamber 51 with an ion gauge (not shown), the conductance valve 54
It was adjusted to ~3T orr. After confirming that this pressure does not fluctuate, five Ag-Te alloy targets (5 inch diameter; composition is Ag 45T e 55; at%
) was applied with 100 W from the DC power supply 60, and sputter cleaning was performed by performing sputter discharge for 5 minutes with the shutter 61 closed.

After stopping the supply of Ar gas and the supply of DC power, the inside of the chamber 1 is once IX1 using the cryopump 55.
The exhaust was evacuated to 0-5 Torr or less. Then valves 56 and 6
7 and put Ar gas and CH4 gas into the chamber 51.
Ar gas line 57 and CH.

IO3CCM was introduced at a time through gas line 58 while being controlled by a mass flow controller (not shown). Next, the pressure inside the chamber 51 was controlled to 5 x 10-3 Torr using the conductance valve 54. After confirming that there was no pressure fluctuation, 100 W was applied to the five AgTe targets from the DC power supply 60 to cause sputter discharge.

After confirming that stable discharge was occurring, the shutter 61 was opened, and a recording film 64 containing an AgTe alloy, carbon, and hydrogen was laminated on the previously laminated 5i02 film 71. When the film thickness reached 1,000 people, the shutter was closed and the power supply was stopped.

Next, the conductance valve 54 is fully opened, and the inside of the chamber 51 is reduced to 1×10 Torr using the cryopump 55.
Exhausted to below.

Next, in exactly the same manner as in the case of forming the SiO2 film, RF power was supplied to the 5i02 target 80 in an Ar gas atmosphere to deposit the 5i02 film 71 on the 1000 person recording film 64. After forming the film 5i02, the gas in the chamber 1 is evacuated to below I×1O−5 Torr using the cryopump 55.

Next, open the valve 65 to drain N2 from the N2 gas line 66.
After introducing the two gases into the chamber 51 and returning the pressure to atmospheric pressure,
The medium 70 was taken out.

FIG. 8 is a sectional view schematically showing the structure of the information recording medium of this example. The information recording medium 70 of this embodiment includes a substrate 63 and dielectric films 7 sequentially laminated on the substrate 63.
1. It is composed of a recording film 64 and a dielectric film 71.

The recording film of this example had a dielectric film not only at the interface with the substrate but also on the side in contact with air, so it had extremely excellent oxidation resistance. Such a structure is possible because
This is because, as mentioned earlier, a recording method that utilizes phase change was adopted.

[Effects of the Invention] As explained above, according to the present invention, it is possible to provide an information recording medium that is free from oxidation even at the interface with the substrate and has a highly sensitive recording film.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an information recording medium according to an embodiment of the present invention, and FIG. 2 is an optical recording film forming apparatus according to an embodiment of the present invention.
FIG. 3 is a diagram showing changes in reflectance due to multiple interference effects, FIG. 4 is a cross-sectional view of a dielectric film laminated on the recording film of the information recording medium of the present invention, and FIG. 5 is a diagram showing the information recording medium of the present invention. FIG. 6 is a cross-sectional view of an air sandwich type medium, FIG. 6 is a diagram showing changes in playback time and reflection level, FIG. 7 is an optical recording film forming apparatus according to an embodiment of the present invention, and FIG. 8 is a diagram showing changes in reflection level. FIG. 3 is a cross-sectional view of an information recording medium according to another embodiment of the present invention. 1...Chamber, 9...AgTe alloy target, 13...PC board, 14...
...AgTe-C film.

Claims (1)

[Claims] (1) A substrate, Ag_xTe_1_0_0_-_x(2≦x
≦50 atomic %) alloy, and an amorphous recording film containing carbon and hydrogen.