JPS6050642A - Production of optical information recording medium - Google Patents

Abstract

PURPOSE:To obtain a homogeneous recording medium excellent in flatness, by accommodating the product of electric power density to be applied to a specific metallic target and the average stay time of dissociation gas for including H (hydrogen) in an optical information recording film as a constituent in a discharge space within a specific range. CONSTITUTION:One of Te, Sb and Ag is fitted to the lower surface of a power applying terminal 5 in a vacuum case 1 as a target 4 and a substrate consisting of glass or transparent plastic is set up on an opposed holder 6. Air in the case is exhausted from an exhaust port 2 and hydrocarbon such as CH4 or gas such as NH3 which can dissociate H by plasma sputtering is fed from a gas guiding port 3 with about 10<-3>-10<-2>Torr. Inert gas such as Ar and N2 is fed together with the dissociation gas so that the partial pressure of the dissociation gas is higher than that of the inert gas. The process is controlled so that the recording film is formed in the range setting up the product of the electric power density to be applied to the target metal and the average stay time of the dissociation gas in the discharge space to 0.05Wsec/cm<2>-0.5Wsec/cm<2>. Thus, the recording medium comparatively high and uniform in stacking speed and superior in recording and reproducing characteristics is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to a method of manufacturing an optical information recording medium in which information is recorded by causing an optical change by irradiation with a laser beam.

[Technical background and problems of the invention]

Information recording using a laser beam has a uniformly high recording density (
It has q′+ features such as being able to record real time.

Research and development has been carried out in recent years. Light extinction + l? Conventionally, recording media have been used in which a chalcogenide thin film such as Te, a dye thin film, etc. are formed on a transparent resin substrate. However, such information recording media have a serious problem in that they deteriorate during storage due to the influence of oxygen, moisture, or ultraviolet rays in the air, causing problems in recording and reproducing information.

JP-A-57-165292 proposes a recording medium in which Te is mixed with carbon in order to eliminate the drawbacks of the prior art. One method for manufacturing a recording film containing Te and carbon is to sputter a Te target with hydrocarbon gas plasma. However, sputtering has conventionally been used as a method for sputtering a metal target with plasma of a rare gas such as Ar to form a thin film of the metal. Sputtering using combinations with a high possibility of reaction between the target and plasma gas, or using dissociative gases such as hydrocarbons, has rarely been put to practical use. Therefore, when performing such sputtering on an industrial scale, The detailed film formation conditions are often unknown. For example, when using a Wl-dissociating gas, the dissociation process changes depending on the applied power, the pressure during film formation, the flow rate of the introduced gas, etc., and the characteristics of the formed film change.

Moreover, the condition values of the above items to be set during film formation vary depending on the sputtering apparatus. Therefore, there is an inconvenience in that the optimum film forming conditions must be determined by conducting numerous experiments for each individual device.

[Purpose of the invention]

An object of the present invention is to eliminate the drawbacks of the prior art and to provide a method for manufacturing an optical information recording medium in which a well-controlled recording film is formed by sputtering using a dissociative gas.

[Summary of the invention]

In the method for manufacturing the original information recording medium of the present invention, in the process of forming a recording film on a substrate by sputtering a metal target with plasma of a dissociative gas, the power density applied to the target and the discharge space of the dissociative gas are controlled. The average stay time within the area is 0. O05W sec/c
m'' and smaller than 0.5 Wsec/C1l+''.

Here, the power density is the power applied to the target per unit area. In addition, the average residence time can be calculated using the following formula.

〔Effect of the invention〕

According to the present invention, film forming conditions applicable to any sputtering apparatus can be set in advance. Therefore,
The advantages of applying sputtering using a dissociative gas at an industrial level are extremely large.

[Example of invention]

Hereinafter, the present invention will be explained in detail based on examples.

FIG. 1 shows an example of a sputtering apparatus for implementing the present invention. In the figure, 1 is a vacuum container, 2 is an exhaust port connected to a vacuum pump (not shown), 3 is a gas outlet containing a dissociable gas, 4 is a metal target, 5 is a terminal for applying power,
6 is a grounded counter electrode which also serves as a substrate holder.

When manufacturing an optical information recording medium, a substrate made of transparent organic resin or glass is placed on the substrate holder 6, and the vacuum container 1 is heated to about 1" Torr from the gas inlet. Introducing a gas that detects dissociative gases,
A gas flow rate so that the inside of the empty container 1 reaches a predetermined pressure of 1.4",
And it is preferable to prepare the exhaust rat to a vacuum pump. 10
If it is less than "I", orr level, it is difficult to obtain stable discharge. Further, when the IQ-' Torr is higher than that, stable sputtering is difficult. After the vacuum container 1 reaches a predetermined pressure, power is applied between the target 4 and the counter electrode 67 via the power terminal 5 to cause discharge. A recording film is formed on the substrate by sputtering the target 3 using plasma containing a dissociative gas that generates PP in the discharge.

The dissociable gas is dissociated by electric discharge. Solution: Various active r′Jj4 generated by light, those involved in sputtering, those that interact with the target, Jti on the plate:
There are various things such as 1't. Therefore, activity 1
The weight, number, and energy η of 111 have a huge influence on the self-recording and reproducing characteristics of 611, and the rate of deposition onto the substrate.

The most important factors that do not affect the dissociation process are the average residence time of the dissociative gas in the nitrogen chamber and the applied power of 1 B degree. The longer the average residence time and the higher the applied power density, the more the dissociative reaction is promoted.

In other words, the target area usually takes a constant value for each subactor device, but even if the discharge pressure, interelectrode distance, and applied power density are fixed, if the flow rate of the dissociative gas changes, the average residence time of the M dissociative gas will change. changes, and therefore the progress of the dissociation reaction changes and the formation process of the recording film changes. This is the main reason why the formation of a recording film by sputtering containing a dissociable gas is complicated.

The applicants conducted various experiments to control the product of the applied power density and the average residence time of the M-separating gas within a predetermined range.
We have found that it is possible to form a recording film in a controlled manner regardless of the sputtering device.

FIG. 2 is a diagram for forming a recording film by sputtering containing a dissociative gas. In the figure, 11
is the upper limit of the applied power density independent of the device 1''X to prevent the substrate from being damaged by heating due to discharge.The value is approximately 2W/cm2.j2 is the upper limit of the applied power density for stable discharge to connect. This is the lower limit that does not depend on the equipment. (For direct measurement, it is 0.01 W/cm. This is the lower limit. 1m for 1st shift
5ec is 1 pressure early. 14 is the upper limit of the average 'AiI residence time determined from the discharge pressure ζ. The price is 1
It is about 00 msec.

In FIG. 2, the area (1) surrounded by the diagonally shaded straight line 12, i3 and the curve 15 is the area () where the residence time of the σl!1·ff gas is short, the applied power density is This is a region in which the 71J'r?:11 reaction does not proceed sufficiently because of the small value of 71J'r?:11.Therefore, the deposition rate of the recording film in the 1-vertical region If is extremely slow <1. This is an inappropriate area.

In Fig. 2, direct, fS 11, J 4 and curve 10
The shaded area surrounded by is the solution fiit I'
This is a region where the average residence time of l' gas is long (and the applied power density is high), and the dissociation reaction progresses excessively.If a recording film is formed in region 111, the deposition rate of the film is high, but , the reaction between the deposited recording film and the active species due to dissociation progresses gracefully, and the flatness of the recording film is impaired.When the flatness is impaired, the reflectance of the recording film decreases.Reflectance varies depending on the refractive index of the recording film, etc.
40 coefficient 8 degrees or more is preferable.

When the androlytic gas is a hydrocarbon-based gas, the polymerization reaction of the hydrocarbon progresses significantly in region 12, so that a recording film is not formed and a powdery polymer may even be deposited on the picture plate.

Lines 11, 12, 13, 14 and ti
If a recording film is formed within the region 11 surrounded by the B lines 15 and 16, it is possible to manufacture a medium with excellent recording and reproducing characteristics, and at the same time, there is an industrial necessity that the film formation speed is high. can also be satisfied.

Implementation 1 - 1 In an RF bipolar detection sputtering device equipped with a circular target made of I'e with a diameter of 20 cm, the distance between the electrodes was set to 7 cm, and CH4 gas was used as the hydrocarbon at 2×10
-2Torr was installed. 21 in FIG. 3 shows the relationship between the film deposition rate when sputtering is performed with various CH flow rates and applied power densities and the product of the applied power density and the half-uniform night time of CH.

It can be seen that the deposition rate decreases significantly in the region where the product of the applied power density and the average residence time is smaller than o:o05. 0
．． A medium consisting of a recording film formed in an area larger than 005 could be recorded by irradiation with a semiconductor laser beam of 5 cm W x 200 n5 ec, and exhibited excellent recording and reproducing characteristics with a modulation degree of the reproduced signal of 60%.

Example-2 A circular target made of sb with a diameter of 12 cm was used.
fi L/ fCD In the C fuller magnetron Subanota jij i&, the distance between the electrodes is 12 cm, and the C
The gases f(, and NH) were introduced at 5×10 ” Torr so that the partial pressure ratio of CH4 and NHs was 5/1.

Film deposition rate, applied power density, and CI (4°N) when CH4, NH, flow rate and applied power density K are varied.
The relationship between the product of Hs and the average residence time is shown at 22 in FIG. A medium made of a recording film formed under conditions where the value of the above product was greater than 0005 exhibited good recording and reproducing characteristics.

Example 3 In an RF planar magnetron sputtering apparatus equipped with a circular target consisting of eight nines with a diameter of 15 cm, the distance between the electrodes was set to 8 cm, and CH4 and Ar gas were introduced at a pressure of 6 x 10' Torr. CH,
The partial pressure ratio between Ar and Ar is 4/1.

CH4, Film deposition rate, applied power density and CH, when the Ar flow rate and the applied power density are varied.

The relationship between the product and the average residence time of Ar gas is shown in 23 in Figure 3.
Shown below. A medium consisting of 11 recordings made by Tohki Co., Ltd. and having the above-mentioned performance value of greater than 0.005 exhibited good recording and reproducing characteristics.

Example-4 In a 7% F bipolar sputtering device equipped with a circular target made of Te with a diameter of 20 cm, the distance between the electrodes was 5 cm, and CH4 gas was
It was introduced to make it r. Film formation was performed by sputtering while varying the CH4 current and applied power density. The substrate is a 5 mm thick acrylic plate, and the film thickness is 600A.
It is. 31 in FIG. 4 shows the results of measuring the reflectance of a semiconductor laser (wavelength: 8300 A) for media with different products of force density and average residence time during application 'r. The surface of the medium recording film formed in a region where the applied force and the average residence time were greater than 0.5 lost its flatness, and the reflectance decreased to 40% or less.

In the vicinity of the first injection described above, a powdery -11i compound was deposited on the substrate.

Practical Example 1 - 5 In an RF planar magnetron sputtering system equipped with a circular target of 15 cm (7) SF) in diameter, the distance between the 4 poles was 7 cm, and the CH< and Ar gas was 5 X 10-' Torr. It was introduced to become CH4
The partial pressure ratio on and Ar is 2/1. Film formation was performed by varying the CH4, Ar flow rate and applied power density. The substrate is an acrylic plate with a thickness of 1.5 mm, and the film thickness is 500A. Applied power density and average! 32 in FIG. 4 shows the results of inhibiting the reflectance in the same manner as in Example 4 for media with different night time characteristics. The value of the above result is 0
．． The surface of the medium recording film formed in an area smaller than 5 had extremely good flatness, exhibited a reflectance of 40 inches or more, and exhibited good recording and reproducing characteristics.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of an apparatus for implementing the manufacturing method of the present invention, FIG. 2 is an explanatory diagram regarding the manufacturing method of the present invention, and FIG. 3 is a deposition of a recording film of a recording medium manufactured by the present invention. A diagram showing the relationship between speed, applied power density, and average residence time, and FIG. It is a figure showing a relationship. DESCRIPTION OF SYMBOLS 1... Vacuum container, 2... Exhaust port, 3... Gas inlet, 4... Target, 5... Power application terminal, 6...
・Substrate holder. Representative patent attorney Noriyuki Chika (and 1 other person) Figure 1 Figure 2 Average return time direction Figure 3

Claims (1)

[Claims] (1) A recording film containing a small amount of metal and hydrogen is formed by sputtering a metal target with a plasma of a gas containing a dissociative gas in which hydrogen is one of the host components. In the method of / cm 2 A manufacturing method for a former information recording medium characterized by forming a recording film in an area smaller than L. (2) Few gold 1/J1 targets (both Te and Sl)
, Ag. (4) The dissociable gas is CH, (5
) A method in which plasma is generated from a mixture of dissociative and 10 gases. (6) The dissociable gas is hydrocarbon and nitrogen or ammonia.