JPH0218724A - Optical information recording medium and production thereof - Google Patents

Abstract

PURPOSE:To improve the contrast ratio of a reproduction signal by forming a recording film so as to include a 1st layer which contains carbon, hydrogen, oxygen, and further fluorine and has the specific atomic ratio of the fluorine and the carbon and a 2nd layer which is formed by dispersing fine particles of metal indium and org. matter contg. fluorine into a matrix consisting of indium oxide. CONSTITUTION:A underlying layer (1st layer) 12 is controlled to a 0-0.5 range in the value of the atomic ratio F/C of the fluorine and carbon in the thin film and the recording layer (2nd layer) 13 has the structure dispersed with the metal indium and the org. matter contg. the fluorine in the indium oxide matrix. The formation of such underlying layer 12 and the recording film 13 is executed in such a manner that the gaseous compsns. differ and particularly the discharge pressures and impressed electric powers differ. The contrast ratio of the reproduction signal is improved in this way and the simplification of the production process is attained.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to an optical information recording medium in which information is optically recorded and reproduced by laser beam irradiation. The present invention relates to an optical information recording medium capable of large-scale recording and reproduction, and a method of manufacturing the same.

(Prior Art) Optical information recording media that use various types of recording films with different recording principles are known.A typical recording principle is that holes, called holes, are formed in a thin film called a recording film. It forms part of the Also known is an optical information recording medium whose recording principle is to form a raised deformed portion of a recording film called a bubble, which was disclosed by the present inventor in Japanese Patent Application Laid-Open No. 61-107547.

Comparing these conventional optical information recording media from the viewpoint of recording and reproducing characteristics, particularly reproduction signal contrast ratio, they have the following characteristics. That is, the reproduction signal contrast ratio in a recording medium using a hole-forming type recording film is at a level of about 0.4 to 0.5, regardless of the type of recording film.

On the other hand, although the reproduced signal contrast ratio of the bubble-forming type recording medium disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 61-107547 is higher than that of the hole-forming type recording medium, it is at a level of about 0.5 to 0.6. Ta.

By the way, it is known that the following relationship holds between the reproduced signal contrast ratio and the reproduced signal SN ratio.

That is, in the above equation, Pr: reproduction beam power DR=data transfer rate Ro: amount of reflected light from the unrecorded portion R1: amount of reflected light from the recorded portion, respectively. According to this, when the reproduction signal contrast ratio is the same, increasing the data transfer speed
It can be seen from the above equation that the ratio decreases.

On the other hand, one important technical challenge for optical memory disks is to improve the data transfer speed to the same level as magnetic disks. Therefore, there has been a strong desire to develop a technique that increases the data transfer speed by some means without reducing the S/N ratio.

Furthermore, in order to keep the cost of the optical information recording medium low, this characteristic improving means must not be complicated.

(Problems to be Solved by the Invention) As mentioned above, when the reproduced signal contrast 1-ratio is the same, increasing the data transfer rate will reduce the SN ratio. on the other hand,
Improving this data transfer speed to the same level as magnetic disks is an important technical challenge for optical memory disks.

An object of the present invention is to provide a novel optical information recording medium that has a significantly high reproduced signal contrast ratio that enables the realization of a sufficiently large signal-to-noise ratio even when the data transfer speed is increased, and that also has a low cost. is to provide.

[Structure of the invention]

(Means for solving problems) The reproduction signal contrast ratio is also significantly high.

At the same time, in order to obtain an optical information recording medium that is low in cost, that is, has good cost performance, in the present invention,
Take the following measures.

The first method is to use a bubble-forming type recording film that can provide a higher reproduction signal contrast ratio than a recording medium using a normal hole-forming type recording film. Specifically, the recording film disclosed in Japanese Patent Application Laid-Open No. 61-107547 is improved and is of the same type as the recording film also disclosed by the present inventors in Japanese Patent Application No. 62-188760. Furthermore, a new recording film that has been improved upon is used.

Second, a bubble trigger layer that promotes bubble formation in the recording film is interposed between the substrate and the recording film as a base layer.
The recording film has a layered structure.

FIG. 1 shows a schematic cross-sectional view of an optical information recording medium 10 of the present invention. In FIG. 1, 11 is a substrate, 12 is a bubble trigger layer, and 13 is a recording sample.

Third, in order to reduce costs, the bubble trigger layer can be formed continuously with the recording film, unlike ordinary organic resin layer formation methods such as the spin code method, in other words, the formation of the recording film. This is done using a new plasma polymerization method using the sputtering equipment used in

(Function) The recording film disclosed in Japanese Patent Application No. 62-188760 has the following features:
The structure of the recording film formed by sputtering an indium target with a mixed gas of CH, CF, and 02 is such that metallic indium and an organic substance containing fluorine are dispersed in an indium oxide matrix.

The characteristics of a recording film using a recording film having the characteristics of this structure are listed below. The first is long life, and the second is excellent recording and reproducing characteristics.

The long-life characteristic is provided because the reaction between the metallic indium dispersed in the indium oxide matrix and atmospheric moisture, that is, the deterioration reaction of the metallic indium, is suppressed by the dispersed fluorine-containing organic substance.

Excellent recording and reproduction characteristics, especially a high reproduction signal contrast ratio, are due to the fact that when irradiated with a recording laser beam, organic substances containing fluorine in the recording film evaporate and the indium oxide matrix is deformed, in other words, bubbles are formed. This is due to the characteristic recording principle of

When a plasma-polymerized layer is interposed as an underlayer between the recording film and the substrate, the reproduction signal contrast ratio of this recording medium becomes larger. This is because the surface of the underlayer evaporates during irradiation with the writing laser beam, promoting deformation of the indium oxide matrix. That is, the base layer made of the plasma polymerized film has a bubble trigger function.

It is thought that any organic thin film has the bubble trigger function. However, in order to reduce the cost of the recording medium, it is essential to ensure consistency in the manufacturing process with the recording film. That is, unless the organic thin film can be formed by the same type of manufacturing process in the same sputtering apparatus as the recording film, it is inappropriate as the underlayer of the recording medium. As a result of various experiments, the present inventors have discovered that by changing the conditions for forming the recording film of the recording medium of the present invention within a certain range, it is possible to form an underlayer suitable for the purpose.

(Example) The plasma polymerized film used as the underlayer of the recording film of the present invention uses hydrocarbon, fluorocarbon, and oxygen as raw material gases. There is no problem as long as the indium target used for the subsequent formation of the recording film remains attached to the electrode of the sputtering device during discharge. This is because the source gas composition and discharge conditions are selected so that no polymeric film is deposited on the target surface, while a plasma polymeric film is deposited on the substrate of the recording medium.

As the hydrocarbon used for forming the underlayer, any hydrocarbon can be used as long as its molecular formula has an atomic ratio H/C of hydrogen to carbon of 1 or more and 4 or less.

Specifically, CH4・C2H6・C1H,・C41+1
Paraffinic hydrocarbons such as 0, C,114・C,H.

Olefinic hydrocarbons such as C4H, C, H1□・C
G.H.

Cyclic hydrocarbons such as

As the fluorocarbon used for forming the underlayer, it is suitable that in its molecular formula, the atomic ratio F/C between fluorine and carbon is greater than 2 and less than 4.

Specifically, CF4-C,F, -C3F, -C
, Flo, and other paraffinic hydrocarbons are preferred.

Oxygen gas is added to prevent the polymer film from adhering to the surface of the indium target, reduce radicals, etc. in the polymer film, and improve stability in the atmosphere.

These raw material gases have a gas flow rate of hydrocarbon, fluorocarbon, and oxygen of Q) 1 cmQFC-Q.

As such, it is controlled to fall within the following range.

0≦Q FC/ Q HC≦1.0 0.1≦QO/(Ql(C+QFC+QO)≦0.4 This gas composition is shown in a diagram in Figure 2. In Figure 2, the hatched trapezoidal The area.

This is the composition of the raw material gas that is effective for forming the underlayer.

The same sputtering device is also used to form the recording film. Sputtering is performed using a mixed gas consisting of hydrocarbon, fluorocarbon, and oxygen.

As the hydrocarbon used for forming the above film, any of the hydrocarbons used for forming the base layer described above can be used.

The fluorocarbon used for forming the recording film has a molecular formula with an atomic ratio F/C of fluorine and carbon of 0.5.
As mentioned above, any fluorocarbon having a number of 4 or less can be used. Specifically, CF4・C,F.

C,F,・C4F,. Paraffinic fluorocarbons such as C2F4・C,F,・C4F, etc., olefinic fluorocarbons such as C”'C4Fs' C* Fx□・
It is a cyclic fluorocarbon such as C, F, etc. However, more desirable fluorocarbons have an F/C value of 1 or more and 2.
7 or less.

The conditions for forming the underlayer and recording film will be explained below.

Generally, in the discharge in a sputtering device, there are five parameters that can be changed: gas composition, discharge pressure, applied power, discharge time, and average residence time of the gas.

In the recording medium of the present invention, the underlayer and the recording film are formed not only by the above-mentioned difference in gas composition but also by using different discharge pressures and applied powers. The shaded area in FIG. 3A, which schematically shows a diagram of the formation conditions with the recording film, is a suitable area for forming the underlayer.

The shaded area in FIG. 3B is a suitable area for forming a recording film. The region C in FIG. 2 is the region where the polymer adheres to the target surface. The thin film formed in the second region has little bubble trigger function when used as an underlayer, and has low recording sensitivity as a recording film.

When forming an underlayer, a decrease in discharge pressure requires a commensurate decrease in applied power, while when forming a recording film, an increase in discharge pressure requires a commensurate decrease in applied power. An increase in applied power is required.

Although the vertical and horizontal axes of the diagram in FIG. 3 have arbitrary scales, the principle remains the same even if the device is changed. In the case of a normal general RF magnetron sputtering device, the underlayer is formed with an applied power of 350 W or less and a discharge pressure of about 10 mT.
It is desirable to form the recording film under conditions of 450 W or more and a discharge pressure of about 10 mTo.
It is desirable to carry out the test under conditions of rr or less.

The length of the discharge time is related to the increase or decrease in film thickness. The thickness of the underlayer is not particularly limited, and is suitably about 50 to 200 nm. The thickness of the recording film is in the range of 50 to 200 nm, particularly preferably in the range of 50 to 150 nm. Furthermore, when forming the underlayer, it is advantageous to extend the average residence time of the gas in order to improve the deposition rate.

The base layer produced in this way has an atomic ratio F/C of fluorine and carbon in the thin film controlled within the range of 0 or more and 0.5 or less, and its evaporation temperature is 200°C or less. It has the following characteristics.

<Example-1> RF magnetron sputtering device (manufactured by Tokuda Seisakusho, CFS-8E-) equipped with an indium target with an outer diameter of 127 mg
An optical information recording medium was manufactured using the RF type. The substrate used was made of polycarbonate and had a thickness of 1.2 ms and an outer diameter of 130 cm.

The underlayer was formed by a plasma polymerization method using a mixed gas of C2H4.CF4.0□ as a raw material gas. The mixing ratio of raw material gas is Qcz)+4+QCF, where Q is the gas flow rate.
4 + QO2= 20 SCCM p QCF4 /
Qc2u* = L, O constant, Qoz/ (Qc
au4+ QCF4+ Qoz)=R.

R=0, 0.1, 0.2, 0.3, 0.4, 0.5 and 6
Species changed. The discharge pressure was 15mτorr, and the applied power was 300W.

The discharge time was 5 minutes.

The recording film was formed using a mixed gas of C, I+4.C2F, and .02. The mixing ratio is Qc*H+=143CCM,
QC, 2F+=6SCCM, 00226500M. Sputtering conditions are 8 mTorr discharge pressure and 80
The applied power was 0 W and the discharge time was 2 minutes.

Prior to manufacturing the recording medium, conditions for forming the underlayer were checked. That is, after the underlayer was formed, it was taken out from the sputtering apparatus without depositing a recording film, and the formation status of the underlayer and the target surface condition were observed. R=
When the base layer was formed with O, a polymer film was attached to the target surface after discharge. Furthermore, the gloss on the surface of the base layer was also lost. That is, when oxygen was not contained in the raw material gas, the underlayer was formed. Remaining 5 other than R=0
The base layer of the seeds was transparent and had a glossy surface, giving it a good appearance. Furthermore, no polymer was observed to adhere to the target surface after discharge.

The underlayer is formed with five types of gas compositions except R=O.

A recording film was formed continuously.

The recording and reproducing characteristics of the five types of optical discs manufactured in this way were measured. The measurement was performed at a rotation speed of 1110 Orpm.
, at a radius of 55III11. The wavelength of the laser beam is 830 nm, and the NA of the objective lens is 0.6.
It is. Recording was performed using a laser output of 10 mW and a pulse width of 1
It was performed at 50 nsac. For playback, laser output is 0.5m
This was done using a W continuous beam.

The value of the reproduced signal contrast ratio was 0.5 for the optical disc with R=0.5 and an underlayer formed, and the remaining four types of optical discs had a significantly large value of 0.70 to 0.80. Ta. The reproduced signal contrast ratio was defined by the formula for giving the SN ratio shown above.

When the adhesion of the underlayer to the substrate or recording film was evaluated using an adhesive tape peeling method, no peeling was observed in any of the five types of optical discs except for R=0.

Furthermore, the life characteristics of these five types of optical discs excluding R=O were evaluated by the following method. That is, 60°C, 90% R
Spectral reflectance before and after standing for 500 hours under H conditions (
This is an evaluation based on a change in wavelength (830 nm).

The spectral reflectance before being left is R6, and after being left R□, R0
The value of /no was 0.95 or more for all of the five types of optical discs, which showed good life characteristics.

<Comparative Example-1> In order to confirm the bubble trigger effect of the underlayer, an optical information recording medium having a single recording film layer was manufactured in the same manner as in Example-1 without interposing the underlayer.

The reproduced signal contrast ratio measured under the same conditions as in Example-1 was 0.5. Therefore, the bubble trigger effect of the base layer is as follows: R = 0.1-0.2-0.3 4
Regarding seeds, it was found that the reproduced signal contrast ratio was 1.4 to 1.6 times higher.

<Example-2> Only the composition of the raw material gas during the formation of the underlayer is changed.

The optical disc was manufactured in the same manner as in Example-1 except for the following.The mixing ratio of the 0M material gas was as follows.

QCF4/QC2)+4=0.51 Qczo4+
Qcp preference +Qoz=20SCCM constant, Qog
/ (QC2H+ + QCF4 +QO2)=R, R=0.1-0.2・0.3-0.4・0.5 and 5
Species changed.

The value of the reproduced signal contrast ratio obtained in the same manner as in Example 1 was 0.55 for the optical disc formed with R=0.5, and for all of the other four types of optical discs. The value was extremely large, ranging from 0.75 to 0.80.6 <Example 3> An optical disk was manufactured in the same manner as in Example 1 except that only the raw material gas composition during the formation of the underlayer was changed. I did it. The mixing ratio of raw material gas is QCF4/QCZH
4=O, Qc2u4+ QQ2=20 SCCM is constant, Qoa/(QcaH4+Qoz)=R, R
=O, l-0, 2, 0.3, 0.4, 0.5 and 5 different variations were made.

The value of the reproduced signal contrast ratio obtained in the same manner as in Example 1 was 0.55 for the optical disc formed with R=0.5, and 0.55 for the other four types of optical discs. The value was significantly large, ranging from 80 to 0.85.

<Example 4> The underlayer was formed using a plasma polymerization method using a mixed gas consisting of CH, ・C, F, ・0□ as a raw material gas, and the recording film was formed using CH4・C-C4F, ・0□. The sputtering method was performed using a mixed gas consisting of:

The raw material gas composition when forming the underlayer is Q o-/ (Q C
H−+ Q c3Fi + Q 2 ) value is kept constant at 0.4, and as Q C3Fg / Q cH4=S, s
= o -0,2-o,4-0.6-0.8-t,
o -1, 2 and 7 different variations were made. The conditions for forming the base layer are:
The applied power was 300 W, the discharge pressure was 20 m Torr, and the discharge time was 5 minutes.

The sputtering gas composition when forming the recording film was QC114.
= 14 SCCMI QC4Fll = 63CCM
+QO2=63CCM. The conditions for forming the recording film were an applied power of 800 W.

The discharge pressure was 8 mTorr and the discharge time was 2 minutes.

The substrate was a PC substrate with a thickness of 1.2 m and an outer diameter of 130 nm.Following the formation of the base layer, the recording film was formed continuously.

The recording and reproducing characteristics of the seven types of optical discs manufactured in this manner were measured in the same manner as in Example-1.

The reproduction signal contrast ratio value of the optical disc formed with S=1.2 was 0.55. Regarding the remaining six types of optical discs, the reproduced signal contrast ratio increased as the S value decreased. That is, when S=t, O, 0.60
However, when S=O, it increased to 0.75.

Next, the value of the atomic ratio F/C between fluorine and carbon in the underlayer was measured. The sample was formed on a silicon substrate under exactly the same conditions as mentioned above. The method for measuring the F/C value is X-ray photoelectron spectroscopy (XPS).

When S=1.2, the value of F/C was 0.7. As the S value decreased, the F/C value monotonically decreased. That is, S=
When 1.0, F/C=0.5. When S=0.5, F/
C=0.2. When S=O, F/C=O.

Furthermore, the evaporation temperature was measured for a thin film formed under the same conditions as this underlayer. Measurement is by thermogravimetric analysis (T
GA). The evaporation temperature of the thin film formed with S=1.2 was 220°C. Also.

The evaporation temperature decreased monotonically as the S value decreased. That is, S
When S=1.0, the evaporation temperature was 200°C, and when S=0.5, it was 180″cf. When S=O, it was 160°C.

<Example-5> The only difference is the raw material gas composition when forming the base layer.

Seven types of optical disks were manufactured in the same manner as in Example-4.

The raw material gas composition is QC1+4 + Qc3rs +
Q□z = 20SCCM + QO2/ (QCH
4+ Q (IFI, + QO2) = 0.1 constant, Q C3Fll/ Q clI4= S, S
= O-0, 2-0, 4-0, 6・0.8・1.0・1
．． 2 and 7 different types.

The value of the reproduced signal contrast ratio obtained in the same manner as in Example 1 was 0.5 for the optical disc formed with S=1.2.
It was 5. Regarding the remaining six types of optical discs, the playback contrast ratio increased as the S value decreased. That is, when S=1.0, it was 0.65, but when S=0, it increased to 0.80.

Further, the value of the atomic ratio F/C between fluorine and carbon determined in the same manner as in Example 4 was 0.6 when S=1.2. As the S value decreased, the F/C value monotonically decreased.

That is, when s=i, o, F/C=0.5°; when S=O, S, F/C=0.3. When S=O, F/C=0.

Furthermore, the evaporation temperature determined in the same manner as in Example-4 was 230°C when s = i, z, and was 200°C or less for all six types of S-1, 0 and below. Ta.

<Example 6> An optical card was manufactured using the same sputtering apparatus as used in Example 1. The board is 86 x 54
It is made of polyester resin with a diameter of 0.4 m.

The underlayer was formed from CI+, .03F, and 1-02.

The gas composition is Q(:11.=14 SCCM+ Qc,i
Fs = 3SCCM+Q ox = 65CCM. Applied power was 300 W, discharge pressure was 15 m, T
orr, the discharge time is 5 minutes.

Subsequently, a recording film was formed. The mixed gas used for sputtering was the same as that used for forming the base layer. The gas composition is QcH4:=I4 SCCM.

Qo2F,=3SCCM, and Qo2=68CCM.

The applied power was goow, the discharge pressure was 8 mTorr, and the discharge time was 5 minutes.

Next, a polycarbonate protective substrate measuring 86 x 54 x 0.4 m was adhered with UV curing resin.

The recording and reproducing characteristics of the optical card thus manufactured were investigated as follows. That is, the slow speed was 50 m/sec, and the recording laser beam was 5 mW x 50 μsec.

Laser beam wavelength is 780nm + objective lens N
A is 0.17. Reproduction was performed using a continuous beam of 0.5 mW.

The reproduced signal contrast ratio determined was an extremely good value of 0.85.

〔Effect of the invention〕

In the optical information recording medium of the present invention, the recording film deposited on the substrate is made of hydrocarbon, fluorocarbon, etc. as the first layer.
Since it has a two-layer structure of a thin film formed by sputtering with a plasma using oxygen as a raw material gas, a second layer of indium gas, and a mixed gas of hydrocarbon, fluorocarbon, and WjIi as a target, the following effects are achieved.

(2) Since the first layer acts on the second layer as a bubble trigger layer, the reproduced signal contrast ratio takes an extremely high value of approximately 0.8, which is twice that of a normal hole-forming type recording medium.

(2) As a result, signal processing with fewer errors can be performed even when the data transfer rate is increased.

(2) Since the first and second layers can be easily formed using the same sputtering device, the manufacturing process is extremely simple. As a result, productivity is high and costs can be reduced.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a cross section of the optical information recording medium of the present invention, FIG. 2 is a diagram showing the mixed gas composition necessary for manufacturing the optical information recording medium of the present invention, and FIG. 3 is a diagram showing the optical information recording medium of the present invention. FIG. 3 is a diagram for explaining discharge conditions necessary for manufacturing a medium. 10...Optical information recording medium 11...Substrate 12...Bubble trigger layer 13...Recording film 12: Bubble Tri n-layer 1llIl Factor 13: Hiroyu Fujimi Agent Patent attorney Hiroo Oo 'of>-+↑: Vot Manufacturing method 3, relationship with the person making the amendment Patent applicant (307) Toshiba Corporation 4, agent No. 4-41-11 Kamata, Ota-ku, Tokyo 144 - Telephone number 736 in the Tsunoda Building General Patent Office 3558 5. Column 6 of Detailed Description of the Invention of the Specification Subject to Amendment, Contents of Amendment (1) Line 15 of page 13 of the specification is corrected as follows. "I did. The mixing ratio is QC2H4 = 1.68SCCM, Q
C2F4 =2.65CCMJ (2) Next, correct page 17, line 20 (last line) of the specification. '+ QCaFs + qa) = o, 4 constant tosi, QC
4F8/QCH雫'' (3) Page 18, line 6 of the specification' Q C4F-=
6 SCCM J' Q C4Fs = 0, 7S
Correct to CCM J. (4) r borialate J on page 21, line 3 of the specification is “
Corrected to ``bolyarylate''. (5) Q CI Fs on page 21, line 5 of the specification
= 3 SCCM J r Q C3Fs = 0.4
Correct to SCCM J. (6) r QCJs on page 21, line 11 of the specification =
3 SCCMJ' Q C2Fs = 0, 3SC
Correct to CM J. that's all

Claims (2)

[Claims] (1) In an optical information recording medium in which a recording film is formed on a substrate for recording and reproducing information by irradiation with a laser beam, the recording film is formed on a substrate using carbon, hydrogen, oxygen, or
Furthermore, a first layer is a thin film that contains at least fluorine and has an atomic ratio F/C of fluorine and carbon within the range of 0≦F/C≦0.5, and a first layer that is laminated thereon and is made of indium oxide. 1. An optical information recording medium comprising a second layer which is a thin film formed by dispersing metallic indium fine particles and an organic substance containing fluorine in a matrix. (2) In a method of manufacturing an optical information recording medium in which information is recorded and reproduced by laser beam irradiation, a first layer is formed on a substrate using a plasma polymerization method using a mixed gas of hydrocarbon, oxygen, or even fluorocarbon. A method for manufacturing an optical information recording medium, comprising: forming a second layer on the first layer, and forming a second layer by a patterning method using a mixed gas of hydrocarbon, fluorocarbon, and oxygen using an indium target.