JPS62222893A - Optical information recording medium and its manufacture - Google Patents

Abstract

PURPOSE:To impart high film hardness and excellent solvent resistance and to enhance the sensitivity to pulse laser beam, by forming a recording layer from a polymer membrane containing 70wt% or more of a phthalocyanine compound. CONSTITUTION:The recording layer of a recording medium is formed of a polymer membrane containing 70% of more, pref. 85% or more of a phthalocyanine compound, pref., a metal phthalocyanine compound. As the phthalocyanine compound, for example, a compound represented by general formula (I) (wherein M is a divalent metal, for example, Pb, Cu and Ni etc., a tetravalent metal oxide such as VO, trivalent or tetravalent metal halide such as CrF, X is a hydrogen atom or a halogen atom and may be different or same) is designated. It is necessary to set high frequency output to 200-2,000mW/cm<2> from such a vewpoint that a desired film thickness is obtained when a polymer membrane is formed and absorption in a semiconductive laser wavelength region is enhanced. Further, it is necessary to set the internal pressure of a reaction container to 1X10<-4>-8X10<-2>Torr from such an aspect that the properties (powdery or film like article) of the polymer of the phthalocyanine compound are controlled to a film form.

Description

[Detailed description of the invention] [Field of industrial use] The present invention relates to an optical information recording medium and a method for manufacturing the same.

More specifically, the present invention relates to an optical information recording medium for recording and reproducing information using a laser, and a method for manufacturing the same.

[Prior Art] Conventionally, as a recording medium that records information using a laser, the laser irradiation part absorbs energy from the laser and is locally heated, causing state changes such as melting and evaporation, which are then formed into signal pits. There are known devices that record information. This is what is called a heat mode optical recording material.

As this type of recording material, chalcogenide thin films such as Te or metal thin films are known, but they suffer from problems such as an increase in bit errors because the difference in reflected light intensity between recorded and non-recorded areas is insufficient. However, there are still many problems in that many of them are toxic, they have poor stability against oxidation, and there are problems with thin film production technology-1.

In order to solve these problems with inorganic thin films, various methods using organic thin films have been studied. That is, the objective is to achieve high sensitivity and reduce manufacturing costs by utilizing the excellent thermal properties (low melting point, low decomposition temperature, low thermal conductivity, etc.) of organic materials.

Specifically, for example, squalium pigments (D, J, G
ravoteljn et, al,, 5PIIshi420
, 327 (+983), etc.), azulene derivatives (JP-A-58-21.4182, etc.), indanthrene derivatives (JP-A-58-224448, etc.), cyanine dyes, etc. A dye dispersed in a thermoplastic polymer as a light absorber (James W.
.

Whocler et, al., 5PIE 420.3
9 (1983), etc.) are known.

On the other hand, semiconductor lasers have recently made remarkable progress, and because they are small and inexpensive, semiconductor lasers have been used as light sources for various recording devices. The oscillation wavelengths of these semiconductor lasers are generally on the relatively long wavelength side, and currently, semiconductor lasers used as light sources for recording and reproducing devices have oscillation wavelengths in the range of 780 to 830 nm. There are many.

In order to perform sensitive recording with such a semiconductor laser, a recording layer is required that has absorption characteristics corresponding to the oscillation wavelength.

However, in general, recording layers using metal thin films or chalcogenide thin films have high reflectance in this region.
Further, in a recording layer using a normal organic dye, there is no absorption in this region. Therefore, attempts have been made to use cyanine dyes and organometallic complexes (for example, phthalocyanine compounds) that have absorption in this region as recording layers.

However, when a cyanine dye or an organometallic complex is used as a recording layer, sensitivity can be improved due to its excellent thermal properties, but there are many problems as described below.

(1) The use of dyes and organometallic complexes that efficiently absorb semiconductor laser light is constrained by the fact that they must have the same structure. The number of targets is small, which is a hindrance to selection and sensitivity. It is also very expensive, leading to increased costs.

(2) In general, organic thin films have weak mechanical strength, are easily scratched, and are troublesome to handle. Even if a protective layer is provided to prevent this drawback, organic substances (such as polymers) cannot be used. Methods such as a spin coater that use a solvent for coating are difficult to apply because the recording layer itself has poor solvent resistance.

The same can be said of a two-layer type recording layer in which a light absorption layer is provided as an underlayer and a state change layer (pit recording layer) of an organic substance is provided as an upper layer.

(3) In the wavelength range of light, especially semiconductor laser light, the difference in intensity of reflected light between recorded and non-recorded areas is not sufficient, and the problem of using an inorganic thin film has not been overcome. This difference in reflected light intensity is directly equivalent to the signal "1" and "0".
If it is not sufficient, bit errors will increase, and indirectly, the permissible range of reproduction frequencies to be used will become narrower.

The reason why the difference in the intensity of reflected light between the recording area and the non-recording area is not sufficient is that in the conventional technology, the recording area and the non-recording area are separated by ■ method of dividing by shape change ■ crystalline ← amorphous phase. One example is the use of a method of classification based on changes. In the case of ■, the reflected light intensity is 10
The change is about ~20%, and in the case of ■, it can be about 30% if you carefully examine the materials, but it is less than that for the case of 71.

"Problems to be Solved by the Invention" The present invention fully utilizes the excellent thermal properties of organic materials, and also solves the various problems mentioned above ((1) to (3).
) problem).

[Means for Solving the Problems] The present invention provides an information recording medium that performs recording and reproduction using a laser, in which 70% (by weight) of a phthalocyanine compound is used.
- An optical information recording medium having a polymeric thin film as a recording layer, in which a gas containing a sublimated phthalocyanine compound is used at a high frequency output of 200 to 2000 IIIWlcI112, and a pressure during discharge when producing the optical information recording medium. A method for manufacturing an optical information recording medium in which a polymerized thin film to be a recording layer is formed by plasma polymerization in the range of 1X10-4 to 8X10' Torr, and a thin film containing a phthalocyanine compound when manufacturing the optical information recording medium. After forming, the discharge voltage], X]0-4~8X 1O
High frequency 111 power in the range of -2 Torr 200-2000
The present invention relates to a method for producing an optical information recording medium in which a polymerized thin film serving as a recording layer is formed by plasma polymerization at IIIW/cJ.

[Embodiment] Recording and reproduction are performed on the recording medium of the present invention using a semiconductor laser such as AρGaAs5lnGaP or other laser. Further, the recording layer of the recording medium contains a phthalocyanine compound,
It is preferably formed from a polymeric thin film containing 70% or more, preferably 85% or more of a metal phthalocyanine compound.

As the phthalocyanine compound, for example, the general formula (
■): [Left below blank space] (In the formula, H represents ■ such as Pb, Cu, Ni,
valent metal, oxide of a valent metal such as vO, or halide of a valent or valent metal such as CrF, where X is a hydrogen atom or a halogen atom, and each X may be different or the same. Examples include compounds represented by

Compound represented by general formula (I) (M-Pc(X)+6)
As a specific example, for example, Cu-Pc(If)+6, Cu-Pc(C#)n (
J() (n-1 to 1B), 6-n Co-Pc(H)+6, N1-Pc(H)+6, Mg-
Pc(H)+6, CrCI-Pc(H)+g 1. Pb
-Pc(H)+6, Mn-Pc(H)+6, Zn-Pc
(II)+6, CrP-Pc(II)+6, V-Pc(
lI) +s, VO-Pc (II) +6, VC(!
-Pc(It)+6, Cr-Pc(It)+6, M C
I-Pc(II)+6, MCAI-Pc(CJ)
n (II) (n-1~1B)6-n 1nc&1-Pc(II)+6, In-Pc(CI)n
(II) (n-1~1B), 6-n Ga-Pc(II)+s, 5n-Pc(It)+6,
Pr-Pc(II)+6, Ga-Pc(C1))n
(It) (n-1 to 16), Ti-Pc(I
I) +6 6-n I can raise it somewhere.

The phthalocyanine compounds are generally thermally and chemically stable and have excellent long-term stability such as weather resistance. Also,
It is generally easy to handle because it has thermal sublimation properties.

In the present invention, H of the compound represented by general formula m is p
Preferred are phthalocyanine compounds such as b, vo, Cu or former, especially pb or Cu. When these phthalocyanine compounds are used, almost no decomposition occurs during the subsequent plasma polymerization, and powder It is not uncommon for thin films to be formed that do not absorb in the wavelength range of semiconductor lasers or semiconductor lasers. Furthermore, if M contains a metal as described above, the recorded area formed by laser irradiation tends to have a composition with a high metal content, and the difference in reflected light intensity from the non-recorded area that is not irradiated with the laser is large. A characteristic called nariyazui arises.

The proportion of the phthalocyanine compound in the polymerized thin film is 7.
If the disease becomes 0%, the difference in reflected light intensity between the recorded area and the non-recorded area, which is the effect of the present invention, cannot be obtained sufficiently, which is not preferable.

Examples of polymerized thin film forming components other than phthalocyanine compounds include saturated hydrocarbon gases such as methane, ethane, propane, and butane, unsaturated hydrocarbon gases such as ethylene and propylene, and polymers formed from them. can give.

The thickness of the polymerized thin film is preferably 100 to 1,0000, more preferably 1,500 to 5,000.

Next, the manufacturing method of the present invention will be explained.

Thin films containing phthalocyanine compounds can also be formed by methods such as vacuum evaporation, ion blasting, sputtering, and ion cluster beam methods, but these methods alone cannot produce highly crosslinked or entangled polymeric thin films. However, when these methods are combined with plasma polymerization to form a polymerized thin film, the sensitivity to laser irradiation during recording is high, and the difference in reflected light intensity between recorded and non-recorded areas during playback is reduced. It is preferable to use a polymeric thin film having characteristics such as being large and easy to change the necessary physical strength.

As a method of combining a method such as a vacuum evaporation method with a plasma polymerization method, etc., a thin film may be first formed by a method such as a vacuum evaporation method, and then a plasma polymerization method may be applied to make the thin film into a polymerized thin film. Further, when forming a thin film by a method such as a vacuum evaporation method, a method such as a plasma polymerization method may be applied at the same time to form a polymerized thin film at one time.

For example, by the resistance heating method, lXl0-5~1x10'
One or more of the phthalocyanine compounds listed below and methane, ethane, propane, etc., which are used in combination if necessary so that the phthalocyanine compound content in the polymerized thin film falls within a predetermined range. Saturated hydrocarbon gases such as butane, unsaturated hydrocarbon gases such as ethylene and propylene, halogen gases, and inert gases such as argon used as diluents or carrier agents, etc. ~2000
mW/cJ, preferably 400~1oo.

IIIW/aI, more preferably 600 to LOOOm
W/ cd, pressure during discharge IX 10' ~ 8X 1.0
-2 Torr, preferably IX 1.0' to lJx
1O-2Torr, more preferably 5X 10'~
Plasma polymerization is performed in the range of 5.times.10.about.2 Torr, and a polymerized thin film, preferably about 500 to 100,000 mm thick, is formed on a substrate made of a material such as glass, polycarbonate, polymethyl methacrylate, or aluminum.

In this case, the high frequency output should be 200 to 2000 mW/c.
It is necessary to set the pressure in the reaction vessel to I
It is necessary to set the pressure to 10-4 to 8X 10' Torr, or to control the properties of the polymerized product of the phthalocyanine compound (powder, film, etc.) into a film.

If the high frequency output is outside the range of 200 to 2000 mW/c♂, the resulting polymeric thin film may not be thick enough, or in extreme cases may not be able to be replaced at all, or the absorption in the wavelength range of semiconductor lasers, etc. may be insufficient. and the pressure inside the reaction vessel is LX 10' ~
If it is outside the range of 8X 1O-2 Torr, only polymeric thin films or powder materials that do not absorb in the wavelength range of semiconductor lasers etc. can be obtained.

In the present invention, a polymeric thin film can be formed without introducing an inert gas as long as the pressure is within the above range.

Further, under a predetermined reduced pressure, a phthalocyanine compound placed in a tantalum board or crucible is heated to 400 to 500°C and sublimated to form a vapor-deposited thin film on the substrate.
Thereafter, it may be formed into a polymerized thin film by plasma polymerization or the like under the above-mentioned predetermined conditions. At this time, only one type of phthalocyanine compound may be used, or two or more types of phthalocyanine compounds may be used in combination. Further, a compound other than the phthalocyanine compound, such as a squalium pigment, may be allowed to coexist.

In this case as well, the polymerized thin film of the phthalocyanine compound formed by plasma polymerization etc. is
Different properties can be produced depending on the discharge power, etc.

The polymerized thin film of the phthalocyanine compound obtained in this way exhibits an absorption spectrum with almost the same λmax as a vapor-deposited thin film simply formed by a vacuum evaporation method, but the surface hardness and solvent resistance are lower due to the polymerization. Greatly improved.

FIG. 1 is a graph showing a specific example of the absorption spectra of a simple vapor-deposited thin film using the same type of phthalocyanine compound and a polymerized thin film formed by plasma polymerization.

The polymer thin film thus formed has high sensitivity to semiconductor laser light and the like, and functions as a recording layer of an optical information recording medium.

Next, the recording conditions for the obtained polymeric thin film and the characteristics after recording will be described.

For recording, a semiconductor laser such as Ga#As or 1nGaP is generally used.

The polymerized thin film is irradiated with a laser pulse having an output of about 1 to 30 mW focused on a spot with a diameter of 0.6 to 1.2 mm using an optical system for an irradiation time of about 50 ns to 50 m sec.

After that, apply 1 to 5II1w to the laser irradiation part (recording part).
irradiate it with a low-power laser beam and examine the reflected light intensity.

Similarly, the same operation is performed for the non-recording portion.

When the recording medium of the present invention is used, contrary to the previously reported tendency that the reflected light intensity of the recorded area decreases compared to the value of the non-recorded area, the intensity of reflected light increases, and surprisingly, Depending on the conditions, the rate of change in the reflected light intensity between the recorded area and the non-recorded area may be as follows: Reflected light intensity in the recorded area - Reflected light intensity in the non-recorded area Reflected light intensity in the non-recorded area may be 100% or more. It has been discovered by the present inventors that this is possible. Such a large change in reflected light intensity has never been reported and is thought to be based on a completely new mechanism. In order to investigate the cause of this, the laser beam irradiated area was observed using a scanning electron microscope, and the presence of free metal was found in the laser beam irradiated area. In other words, when recording is performed using the recording medium of the present invention, the recording area has a composition containing a large amount of metal, and the non-recording area has a composition mainly composed of organic metals, which is the same as the original polymeric thin film, and the reflected light intensity of both is reduced. are significantly different,
It has become clear that this method is a new organometallic optical information recording medium that is completely different from conventional ones.

The plasma-polymerized thin film of a phthalocyanine compound according to the present invention obtained in this manner can be used even with a phthalocyanine compound, which has little absorption in the wavelength range of a semiconductor laser in a normal simple vapor-deposited thin film, and for which recording pits cannot be formed by a semiconductor laser. It has the characteristics that the formation of recording pits becomes "+J", and the reflected light intensity between the recorded area and the non-recorded area after recording is significantly different, and reproduction is easy. Therefore, various phthalocyanine compounds are used. In addition, the polymerized thin film of the present invention has significantly increased film hardness due to polymerization and is less likely to be scratched. This is easier than vapor-deposited thin films or phthalocyanine vapor-deposited thin films.

Furthermore, the polymeric thin film has excellent solvent resistance, and even when a protective layer or an organic state change layer (pit recording layer) is provided on the recording layer using a spin coater, the recording layer has good solvent resistance. It has two advantageous characteristics: , production.

Next, the recording medium of the present invention will be explained based on examples.

Example 1 and Comparative Example 1 Lead phthalocyanine (Pb-Pc(If) +6) was placed on a tantalum board and heated to 0.04T using a rotary pump.
The glass substrate was heated to sublimation at 400 to 500'C, plasma-polymerized at a high frequency output of 200III11/c[112, and cleaned.
A lead phthalocyanine polymer thin film was formed to have the thickness of a human film.

For comparison, do the same thing without applying high frequency,
A lead phthalocyanine vapor-deposited thin film was formed to a thickness of approximately 3,000 mm.

The resulting lead phthalocyanine polymerized thin film was amber and transparent, and its absorption spectrum was similar to that of a simple vapor-deposited thin film.
The peak of ax was shown. The results are shown in Figure 1.

In addition, when the film hardness and solvent resistance of the film were measured according to the following method, in the case of the polymerized thin film, no change was observed at all even after immersing it in a solvent for 911.3 days, but it was found that the film had a hardness of 911.3 days. In the case of a thin film, the hardness is 513. Solvent 1: When immersed in e, it was completely dissolved and dispersed in 1 to 2 hours.

The results are shown in Table 1.

Furthermore, the obtained lead phthalon anine polymer thin film was irradiated with M GaAS semiconductor laser light (λ-780nI!1) whose beam diameter was narrowed down to IJlm by an optical system in a 50μsec pulse with a laser power of 7mW. ,
When the surface was observed using a scanning electron microscope, it was confirmed that pits with a size of 1 mu were formed.

However, even when the lead phthalocyanine vapor-deposited thin film was irradiated with semiconductor laser light in the same manner as described above, no pits were formed.

(Membrane hardness) Measured according to JIS K 5401 to measure the maximum hardness at which scratches occur under a load of 50g.

(Solvent resistance) Using quinoline as a solvent, the test piece was immersed in a large amount of solvent, left at room temperature, and then observed.

Example 2 and Comparative Example 2 Copper phthalocyanine (Cu-Pc(H) +s) was plasma-polymerized under the same conditions as in Example 1, and a copper phthalocyanine polymer thin film with a thickness of about 3000 was formed on a cleaned glass substrate. Ta.

For comparison, do the same thing without applying high frequency,
A thin film of copper phthalocyanine was deposited to a thickness of approximately 3,000 mm.

The absorption spectrum of the obtained copper phthalocyanine polymerized thin film showed the same λmax as a simple vapor-deposited thin film. Results first
As shown in the figure.

Further, the film hardness and solvent resistance of the film measured in the same manner as in Example 1 were 11.
No change was observed after being immersed in the solvent for 3 days, but in the case of a mere vapor-deposited thin film, the hardness was 6B and it was completely dissolved and dispersed within 1 to 2 hours when immersed in the solvent. The results are shown in Table 1.

Furthermore, an MGaAs semiconductor laser beam (λ-780 nm) whose beam diameter was narrowed down to one cylinder by an optical system was applied to the obtained copper phthalocyanine polymer thin film on the film with a laser power of 7 mW and a pulse of 5 μSee. 11
When the film was irradiated with No. 1 and the surface was observed using a scanning electron microscope, it was confirmed that pits the size of one coral were formed.

However, no pits were formed even when the copper phthalocyanine vapor-deposited thin film was irradiated with semiconductor 1 nosa light in the same manner as described above.

Example 3 A mixture of lead phthalocyanine and copper phthalocyanine at a ratio of 1=1 (weight ratio) was placed on a tank board,
Plasma polymerization was carried out under the same conditions as in Example 1, and the film thickness was approximately 30 mm.
A copolymerized thin film of lead phthalocyanine and copper phthalocyanine was formed on a cleaned glass substrate.

When the film hardness and solvent resistance of the obtained thin film were measured, the OH hardness and solvent resistance were also the same as in Example 1.2. The results are shown in Table 1.

In addition, the obtained lead phthalocyanine-copper phthalocyanine polymer thin film was injected with a VGaAs semiconductor laser beam (λ = 780 nm) with a beam diameter of 111 m by an optical system at 6.7 mV and 5 μsec pulse 11. Upon irradiation, it was observed using a scanning electron microscope that clean pits of In size were formed.

[Blank below] 1 24 1 Example 4 A mixture of copper phthalocyanine and lead phthalocyanine at a ratio of 1:1 (weight ratio) was placed on a tantalum board, and the pressure was reduced to 5 x 10-2 Torr using a rotary pump, and the pressure was reduced to 400 to 500 Torr. Sublimated by heating at ℃, high frequency output 400
Copper phthalocyanine was applied to a glass substrate by plasma polymerization at mW/cJ to a film thickness of about 5000 nm.
A copper phthalocyanine composite polymer thin film was formed.

GaAl! As semiconductor laser (λ
= 830 nm) using a laser pulse (output 1.8 m
A recording portion was formed by irradiating the film for a period of time (L time 15 μsec).

After that, irradiate the non-recorded area with a weak laser of 3 mW,
Looking at the reflected light intensity during reproduction, the voltage after photoelectric conversion was 1.2 mV. On the other hand, when the recording section was similarly examined, the same voltage was 2.5 mV, and the rate of change in reflected light intensity was 1.
It was as high as 0.8%.

When this recorded portion was observed with a scanning electron microscope at a magnification of 10,000 times, the free metal was detected as being dispersed in fine particles of 0.01 μm or less.

Example 5 Putting lead phthalocyanine into tantalum board 400~5
It was heated to 00° C. and vacuum evaporated at 4×1O−5 Torr to form a deposited thin film on the glass substrate-1-.

Then, the deposited thin film was subjected to a vacuum of IX 1O-3 Torr.
3 in a plasma atmosphere with a high frequency output of 800 mW/c-
Exposure for 0 minutes. In the polymerized thin film prepared in this way,
When laser light was irradiated to form a recorded area by the method described in Example 4, the intensity of reflected light during reproduction of the non-recorded area was 2.0 mV in photoelectric conversion voltage value, but the value of the recorded area was 2.0 mV. was 3.7 mV, and the rate of change in reflected light intensity was 85.0%.

Comparative Example 3 A recording medium using an inorganic material containing 70% or more of Te.
An optical recording medium with a recording layer containing 1500 mW
/Q♂ was produced by high frequency sputtering method.

The recording layer produced had a thickness of 1,000 layers.

In the same manner as in Example 4, a laser was irradiated to form a recorded area, and the intensity of reflected light during reproduction was measured. The intensity of reflected light during reproduction of the non-recorded area was 7.1 mV in photoelectric conversion voltage value. However, the value of the recording part was [i, 2 mV, the rate of change in reflected light intensity was -12.7%, and the absolute value of the change was significantly inferior to that in Example 4.

Comparative Example 4 Te was evaporated from a tantalum board by heating, ethylene gas was introduced, and plasma polymerization was performed at a high frequency output of 10,100 O/cl at 5×10 −2 Torrs to produce a Tc-polyethylene composite thin film with a thickness of 3,500.

As in Example 4, a laser was irradiated to form a recorded area, and the reflection intensity during reproduction was measured. The reflected light intensity during reproduction of the non-recorded area was 8.0 mV, but the value of the recorded area was 8.0 mV. is 5.
4 mV, and its rate of change was -32.5%.

[Effects of the Invention] The phthalocyanine compound polymerized thin film has high film hardness (II to 911 in terms of hardness), excellent solvent resistance, high sensitivity to pulsed laser light, and a high resistance between recorded and non-recorded areas after recording. Since the difference in reflected light intensity is large, the recording medium of the present invention using this polymerized thin film also has these characteristics.

[Brief explanation of drawings]

FIG. 1 is a graph showing the absorption spectra of the plasma polymerized thin films obtained in Examples 1 and 2 and the vapor deposited thin films obtained in Comparative Examples 1 and 2. Hi

Claims (1)

[Scope of Claims] 1. An optical information recording medium that performs recording and reproduction using a laser, the recording layer being a polymeric thin film containing 70% by weight or more of a phthalocyanine compound. 2 The phthalocyanine compound has the general formula (1): ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the formula, M is a valent metal of II, a metal oxide of IV valence, or a metal oxide of valence IV
Claim 1: A compound represented by a valent or IV valent metal halide, where X is a hydrogen atom or a halogen atom, and each X may be different or the same. The optical information recording medium described above. 3 M of the phthalocyanine compound represented by general formula (1)
The optical information recording medium according to claim 2, wherein is Pb, Cu, Ni or VO. 4. When manufacturing an optical information recording medium that records and reproduces information using a laser and has a recording layer of a polymeric thin film containing 70% by weight or more of a phthalocyanine compound, a gas containing a sublimated phthalocyanine compound is used. An optical information recording medium that forms a polymerized thin film as a recording layer by plasma polymerization in the range of high frequency output of 200 to 2000 mW/cm^2 and discharge pressure of 1 x 10^-^4 to 8 x 10^-^2 Torr. Manufacturing method. 5. A thin film containing a phthalocyanine compound is formed when producing an optical information recording medium that is recorded and reproduced by laser and has a recording layer of a polymerized thin film containing 70% by weight or more of a phthalocyanine compound. Later, the voltage during discharge is 1 x 10^-^4 ~ 8 x 10^-^2T
High frequency output 200-2000mW/cm in the range of orr
^2 A method for producing an optical information recording medium by plasma polymerization to form a polymerized thin film that becomes a recording layer.