JPH11213466A - Manufacturing method and device for optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the manufacturing method and manufacturing device of an optical disk capable of stably writing even a recording mark sufficiently smaller than a beam spot and reproducing the written small recording mark while stably holding it without performing the strict control of recording power. SOLUTION: At the time of arranging a target 15 and the substrate 61 of the optical disk inside a film deposition chamber 11 so as to face each other and forming one function film for contributing to the recording and reproduction of information on the substrate 61 by sputtering, one function film is formed while changing a gas pressure inside the chamber 11 and/or applied power to the target 15 and/or the rotation number of the substrate 61. Thus, the function film is turned to a layer structure for which the plural alloy layers of different composition and/or magnetic characteristics are laminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for manufacturing an optical disk capable of rewriting information.

[0002]

2. Description of the Related Art An optical disk has been attracting attention mainly as a recording medium for audio and computers since information can be rewritten, and it is desired to increase its capacity and increase the speed of information rewriting. Here, such a rewritable optical disk is roughly classified into a magneto-optical disk and a phase-change disk depending on the material of a functional film (such as a memory film) contributing to recording and reproduction of information and the recording / reproducing method.

Hereinafter, a description will be given of a magneto-optical disk as an example.
Conventionally, in a magneto-optical disk, in order to rewrite already recorded information with new information, it has been necessary to temporarily erase the recorded information (erasing operation) and then write new information. However, in recent years, a magneto-optical disk of a light modulation direct overwrite recording method (hereinafter, referred to as a “LIMDOW recording method”) that does not require the above erasing operation has been proposed.

In this magneto-optical disk of the LIMDOW recording system, the recording beam power is simply modulated (high level / low level) according to the information to be recorded, and the already recorded information is erased and new information is written. Can be performed almost simultaneously. Therefore, the operation time for rewriting with new information can be shortened and the speed can be increased by the amount that the time required for the erasing operation is not required by the LIMDOW recording method.

On the other hand, in order to respond to the demand for increasing the capacity of a magneto-optical disk, the size of each of a plurality of recording marks constituting information is reduced and the distance between adjacent recording marks is reduced. It is necessary to record information at a high density, and its development has been advanced in recent years. Here, one recording mark (a magnetic domain in a magnetization direction opposite to the surroundings) on the magneto-optical disk uses an optical modulation recording method, and is temporarily heated to a predetermined temperature or higher by a recording beam irradiation (heating area). Formed.

Therefore, in order to form a small recording mark, the heating region may be formed only in a small region in the beam spot by utilizing the temperature distribution generated in the beam spot by the irradiation of the recording beam. in this way,
A method of forming a small recording mark by making the heating area smaller than the beam spot is called a pen tip recording method.

Therefore, if this pen tip recording method is used,
Recording marks smaller than the beam spot can be successively formed on the magneto-optical disk, and information can be recorded at a high density. By the way, in general, a functional film (memory film or the like) constituting a magneto-optical disk of the above-described LIMDOW recording method or writing tip recording method is formed by discharging a single alloy target using a single-wafer sputtering apparatus.
Alternatively, it is formed while simultaneously discharging a plurality of targets using a simultaneous sputtering apparatus. Note that the film forming conditions (gas pressure in the film forming chamber, electric power applied to the target, and number of rotations of the substrate) at this time are usually kept constant.

[0008]

In writing one recording mark smaller than the beam spot by the above-described pen tip recording method, usually, the smaller the size of the recording mark, the longer the irradiation time of the recording beam. Must be shorter. This is because the shorter the recording beam irradiation time, the smaller the heating area can be.

However, on the other hand, when the irradiation time of the recording beam is shortened, the temporal fluctuation (noise) of the power of the recording beam greatly influences, and the size of the small heating region varies. Become. As described above, the memory film on which the recording mark is written is formed while keeping the film forming conditions constant. For this reason, the memory film has one composition such as an alloy film in which a rare earth metal and a transition metal are uniformly mixed, and an alloy film in which a layer of a rare earth metal and a layer of a transition metal are stacked at a constant period. It is composed of an alloy film.

Therefore, the recording power margin when writing a recording mark smaller than the beam spot on the memory film using the pen tip recording method becomes narrower as the irradiation time of the recording beam becomes shorter (as the recording mark becomes smaller).
For this reason, the variation in the size of the heating area is directly reflected as the variation in the size of the recording marks, and the size of the small recording marks formed one after another on the magneto-optical disk tends to be non-uniform.

Here, in order to form only small recording marks of a desired size one after another on the magneto-optical disk in a stable manner, it is necessary to control recording power extremely strictly. In this case, the control circuit of the power of the recording beam becomes very complicated. In addition, the small recording mark formed by the above-described pen tip recording method is reduced not only in the direction along the track but also in the track width direction, and has a very small area.

Therefore, even if a small recording mark can be formed on the memory film by the pen tip recording method, the coercive force is low in the memory film composed of an alloy film of one composition, and the magnetization direction of the recording mark is reversed. It may disappear due to the influence of the surroundings, which is the magnetization direction, or may be in an unstable state where it cannot be reliably reproduced even if it does not disappear. In particular, L
In the magneto-optical disk of the IMDOW recording method, the magnetic coupling force is transmitted from a recording film whose magnetization direction is aligned in one direction to a memory film on which a recording mark is written. It tends to be unstable.

An object of the present invention is to stably write even a recording mark sufficiently smaller than a beam spot without strictly controlling the recording power, and to stably hold the written small recording mark. It is an object of the present invention to provide a method and an apparatus for manufacturing an optical disk which can be reproduced while reproducing.

[0014]

According to a first aspect of the present invention, there is provided a manufacturing method wherein a target and an optical disk substrate are arranged in a film forming chamber so as to face each other, and one function contributing to recording and reproduction of information on the substrate. In forming a film by sputtering, one functional film is formed while changing the gas pressure in the film forming chamber and / or the power applied to the target and / or the number of rotations of the substrate.

Therefore, according to the first aspect of the present invention, alloy layers having different compositions and / or magnetic properties are sequentially stacked according to changes in gas pressure and / or applied power and / or rotation speed. Then, one functional film is formed in a layer structure. According to a second aspect of the present invention, in the method for manufacturing an optical disk according to the first aspect, the gas pressure and / or the applied power and / or the number of revolutions are changed periodically.

Therefore, according to the second aspect of the present invention, alloy layers having different compositions and / or magnetic properties are periodically laminated according to changes in gas pressure and / or applied power and / or rotation speed. Then, one functional film is formed in a layer structure. The invention described in claim 3 is:
3. The method for manufacturing an optical disk according to claim 2, wherein the gas pressure and / or the applied power and / or the number of rotations are set to:
Two different values are alternately and repeatedly changed.

Therefore, according to the third aspect of the present invention, two alloy layers having different compositions and / or magnetic properties are alternately repeated according to changes in gas pressure and / or applied power and / or rotation speed. Laminated, 1
One functional film is formed in a layer structure. According to a fourth aspect of the present invention, in the optical disk manufacturing method according to any one of the first to third aspects, sputtering is performed by discharging one alloy target or simultaneously discharging a plurality of targets. Things.

Therefore, according to the fourth aspect of the present invention, alloy layers having different compositions and / or magnetic properties are sequentially laminated according to changes in gas pressure and / or applied power and / or rotation speed. Then, one functional film is formed in a layer structure. Further, the manufacturing apparatus according to claim 5, a substrate holder for holding a substrate of an optical disk, and a film forming chamber in which a target holder for holding a sputtering target installed facing the substrate is disposed, A gas supply unit that supplies a sputtering gas into the film formation chamber, an exhaust unit that exhausts the inside of the film formation chamber, a power application unit that applies power to a target held in a target holder, and a device that records and reproduces information on a substrate. During the formation of one contributing functional film, the supply amount of the sputtering gas into the film formation chamber by the gas supply means, and / or the exhaust amount from the film formation chamber by the exhaust means, and / or the application to the target by the power application means. Control means for changing the power.

Therefore, according to the fifth aspect of the invention, the alloy layers having different compositions and / or magnetic properties are sequentially formed in accordance with the change in the supply amount and / or the exhaust amount of the sputtering gas and / or the applied power. Layered,
One functional film is formed in a layer structure. According to a sixth aspect of the present invention, in the optical disk manufacturing apparatus according to the fifth aspect, the control means controls the supply amount of the sputtering gas and / or the exhaust amount and / or the amount of forming the one functional film.
Alternatively, the configuration is such that the applied power is changed with a period.

Therefore, according to the invention, the alloy layers having different compositions and / or magnetic properties are periodically formed in accordance with the change in the supply amount and / or the exhaust amount of the sputtering gas and / or the applied power. As a result, one functional film is formed in a layer structure. According to a seventh aspect of the present invention, in the optical disk manufacturing apparatus according to the sixth aspect, the control means controls the sputtering gas supply amount and / or the exhaust amount and / or the applied power while forming one functional film. Are alternately changed to two different values.

Therefore, according to the present invention, two alloy layers having different compositions and / or magnetic properties are alternately formed in accordance with a change in the supply amount and / or the exhaust amount of the sputtering gas and / or the applied power. And one functional film is formed in a layered structure. Further, the manufacturing apparatus according to claim 8, a substrate holder for holding a substrate of an optical disk, and a film forming chamber in which a target holder for holding a sputtering target installed facing the substrate is disposed, A gas supply unit that supplies a sputtering gas into the film formation chamber, an exhaust unit that exhausts the inside of the film formation chamber, a power application unit that applies power to a target held by the target holder, and a substrate that is rotated by the substrate holder. Substrate rotating means for causing
While forming one functional film that contributes to the recording and reproduction of information,
Rotation speed control means for changing the rotation speed of the substrate by the substrate rotation means.

Therefore, according to the invention of claim 8, alloy layers having different compositions and / or magnetic properties are sequentially laminated according to the change in the number of rotations, so that one functional film has a layer structure. Formed. According to a ninth aspect of the present invention, in the optical disk manufacturing apparatus according to the eighth aspect,
The rotation number control means is configured to change the rotation number of the substrate periodically while forming one functional film.

Therefore, according to the ninth aspect of the present invention, alloy layers having different compositions and / or magnetic properties are periodically laminated according to a change in the number of rotations, so that one functional film has a layer structure. Formed. According to a tenth aspect of the present invention, in the optical disk manufacturing apparatus according to the ninth aspect, the rotational speed control means alternately changes the rotational speed of the substrate to two different values while forming one functional film. It is configured to change to.

Therefore, according to the tenth aspect of the present invention, two alloy layers having different compositions and / or magnetic properties are alternately and repeatedly laminated according to a change in the number of rotations, so that one functional film is formed. It is formed in a layer structure.

[0025]

Embodiments of the present invention will be described below with reference to the drawings.

This embodiment corresponds to claims 1 to 7. The single-wafer sputtering apparatus 10 of the present embodiment includes:
This is for forming a memory film which is one of the functional films contributing to recording and reproduction of information when manufacturing a magneto-optical disk of the LIMDOW recording method. As shown in FIG. 1, the single-wafer sputtering apparatus 10 according to the present embodiment includes a vacuum chamber 11 (a film forming chamber), a substrate holder 12 and a target holder 13 which are opposed to each other inside the vacuum chamber 11. It comprises a gas supply system 2 (21 to 23) and an exhaust system 3 (31 to 33) attached to the side wall of the vacuum chamber 11, and a control circuit 4 (41 to 43).

The target holder 13 includes a target 15 made of a TbFeCo alloy for a memory film.
(6 inches). This target 1
The specific composition of No. 5 is Tb of 20 when expressed in atomic percentage.
Atomic%, Fe is 64 atomic%, Co is 16 atomic%,
It has a compensating composition at room temperature Tr (20 ° C. to 30 ° C.) (hereinafter, the atomic percentage of the composition is expressed as Tb20Fe64Co16).

A sputtering power supply 14 is connected to the target holder 13. The sputtering power supply 14 applies a predetermined power to the target 15 held by the target holder 13. The substrate holder 12 holds a substrate 61 (diameter 86 mm) made of transparent polycarbonate. A guide groove is formed in a spiral shape on one surface of the substrate 61 (the surface facing the target 15).

On the other hand, the gas supply system 2 comprises a vacuum chamber 1
1, a gas supply pipe 22 having one end attached to a side wall, an Ar gas cylinder 21 as a sputtering gas source connected to the other end of the gas supply pipe 22, and a mass flow controller 23 provided in the middle of the gas supply pipe 22. And supplies Ar gas into the vacuum chamber 11. Here, from the gas supply system 2 to the vacuum chamber 11
The flow rate of Ar gas supplied into the inside is adjusted by the mass flow controller 23.

The exhaust system 3 includes an exhaust pipe 32 having one end attached to a side wall of the vacuum chamber 11, a vacuum pump 31 connected to the other end of the exhaust pipe 32, and an exhaust pipe 32.
And an orifice 33 provided in the middle of the vacuum chamber 11 to exhaust the inside of the vacuum chamber 11. Here, the amount of exhaust from the vacuum chamber 11 by the exhaust system 3 is adjusted by the orifice 33.

The control circuit 4 includes a CPU 41 connected to the sputtering power source 14, the mass flow controller 23, and the orifice 33, and a memory 42.
And a timer 43, and the memory 42 and the timer 43 are also connected to the CPU 41.
When forming the memory film, the control circuit 4 controls the control program stored in the CPU 41 and the various film forming conditions (power applied to the target 15, Ar gas flow rate into the vacuum chamber 11, The sputtering power supply 14, the mass flow controller 23, and the orifice 33 are individually controlled based on the amount of exhaust from the chamber 11) and the elapsed time counted by the timer 43.

More specifically, the control circuit 4 controls the sputtering power supply 14, and as shown in FIG. 2B, a period from the time ts when the formation of the memory film is started to the time te when the formation is completed. Over a period of time, the power applied to the target 15 is maintained at a predetermined value (600 W). Further, the control circuit 4 (FIG. 1) controls the orifice 33, and similarly to the above-described applied power, during the period from the time ts when the formation of the memory film is started to the time te when the formation of the memory film is finished,
The exhaust amount from the vacuum chamber 11 is kept at a predetermined value X.

On the other hand, the control circuit 4 controls the mass flow controller 23 (MFC), and as shown in FIG. 2A, a period from the time ts when the formation of the memory film is started to the time te when the formation of the memory film is completed. , The Ar gas flow rate into the vacuum chamber 11 was set to two different values (50 SCCM,
200 SCCM). Here, this A
The change in the r gas flow rate is a change having a cycle, and this cycle T
Is 12 seconds. In one cycle T, 50 SCCM
Is 1: 1 (duty ratio is 50%).

The predetermined value X of the amount of exhaust from the vacuum chamber 11 is such that when the Ar gas flow rate is 50 SCCM, the gas pressure in the vacuum chamber 11 is 2 × 10 ⁻³ Torr.
The value is determined to be r (FIG. 2A). For this reason,
When the Ar gas flow rate is 200 SCCM, the gas pressure in the vacuum chamber 11 becomes 8 × 10 ⁻³ Torr.

Therefore, the above-described vacuum chamber 11
The gas pressure in the vacuum chamber 11 also changes to two different values (2 × 10 ⁻³ Torr, 8 × 10 ⁻³ Torr) with the periodic change of the Ar gas flow rate into the inside (FIG. 2A). They are changed alternately (the period T is 12 seconds and the duty ratio is 50%). Next, an operation of forming a memory film while periodically changing the gas pressure in the vacuum chamber 11 using the single-wafer sputtering apparatus 10 (FIG. 1) configured as described above will be described.

The single-wafer sputtering apparatus 10
The operation of forming the memory film in the LI shown in FIG.
This is performed after the lower protective film 62 and the reproducing film 51 are formed on the substrate 61 of the MDOW recording type magneto-optical disk 50 (the formation of the lower protective film 62 and the reproducing film 51 will be described later). Therefore, in forming the memory film 52, the single-wafer sputtering apparatus 10 (FIG. 1)
The substrate 61 on which the lower protective film 62 and the regenerating film 51 are already formed is held by the substrate holder 12.

As shown in FIG. 2A, the memory film 5
In the period A from the time ts when the formation of the second 2 starts to the time t1 after 6 seconds, the flow rate of the Ar gas into the vacuum chamber 11 is maintained at 50 SCCM, and the gas pressure in the vacuum chamber 11 is 2 × 10 ⁻³ Torr. Is kept. Thus, the low gas pressure (2 × 10 ^{−3) is} maintained in the vacuum chamber 11.
When the target 15 made of a TbFeCo alloy (Tb20Fe64Co16) having a compensating composition is sputtered while maintaining the same at Torr, as shown in FIG. ) 52A are formed on the reproduction film 51. This period A (6 seconds from time ts to time t1)
Inside, the TM-rich alloy layer 52 formed on the reproducing film 51
The thickness D1 of A is 3 nm.

Next, in a period B from time t1 to time t2 after 6 seconds, the Ar gas flow rate into the vacuum chamber 11 is maintained at 200 SCCM, and the vacuum chamber 1
The gas pressure in 1 is kept at 8 × 10 ⁻³ Torr. Thus, the high gas pressure (8 × 1
0 ^-3 Torr) while maintaining the compensation composition of TbFeCo.
When the sputtering of the target 15 made of an alloy (Tb20Fe64Co16) is performed, as shown in FIG. 4, the alloy layer 52B in which the sub-lattice magnetization of the rare earth metal is dominant (hereinafter referred to as "RE rich alloy layer") 52B becomes TM rich as described above. It is formed on the alloy layer 52A. Note that the thickness D2 of the RE-rich alloy layer 52B formed during this period B (6 seconds from time t1 to time t2) is 3 nm.

As described above, even when the target 15 made of the same TbFeCo alloy is used, an alloy layer having a different composition due to the gas pressure in the vacuum chamber 11 is formed only when the gas pressure changes. Tb
This is because the sputtering rate of the elements constituting the FeCo alloy changes. Further, in the next period A (6 seconds from time t2 to time t3), similarly to the above-described period A (6 seconds from time ts to time t1), the vacuum chamber 11
The gas pressure inside is kept at 2 × 10 ⁻³ Torr, and the TM-rich alloy layer 52A (thickness: 3 nm) is formed on the above-mentioned RE-rich alloy layer 52B (FIG. 4).

Further, in the next period B (from time t3 to time t)
4 for 6 seconds), the period B (time t
Vacuum chamber 1 in the same manner for 6 seconds from 1 to time t2).
The gas pressure in 1 is maintained at 8 × 10 ⁻³ Torr, and the RE-rich alloy layer 52B (thickness: 3 nm) is formed on the above-described TM-rich alloy layer 52A (FIG. 4). Such a T
Formation of M-rich alloy layer 52A (thickness 3 nm) and R
The formation of the E-rich alloy layer 52B (thickness: 3 nm) is alternately repeated until a time te at which the film thickness D52 of the entire memory film 52 becomes approximately 30 nm (a time at which the formation of the memory film 52 ends).

As a result, the TM rich alloy layer 52A (thickness 3 nm) and the RE rich alloy layer 52
B (thickness: 3 nm) is alternately repeated to form a layered memory film 52. The TM-rich alloy layer 52A and the RE-rich alloy layer 52B
The memory film 52 having a layer structure in which is laminated is a perpendicular magnetization film in which the magnetization is oriented perpendicular to the film surface (vertical direction in FIGS. 4 and 3).

As described above, the memory film 5 having a layer structure
After the film 2 is formed on the reproducing film 51, an intermediate film 53, a recording film 54, a switching film 55, an initialization film 56, and an upper protective film 63 are formed on the upper surface of the memory film 52, as shown in FIG. The magneto-optical disks 50 of the LIMDOW recording method are sequentially formed to complete the recording. Here, functional films other than the memory film 52 having a layer structure constituting the magneto-optical disk 50 (lower protective film 62, reproducing film 51, intermediate film 53, recording film 54, switching film 55, initialization film 56, upper protective film) 63) will be briefly described.

These seven functional films 51, 53 to 56, 6
Each of the substrates 2 and 63 is formed using a single-wafer sputtering apparatus having substantially the same configuration as the single-wafer sputtering apparatus 10 for forming the memory film 52 described above. However,
In forming these seven functional films 51, 53 to 56, 62, and 63, the gas pressure (Ar gas flow rate, exhaust amount) in the vacuum chamber and the power applied to the target are:
It is kept constant over the period from the formation start time to the formation end time.

Therefore, the seven functional films 51, 53 to 5
6, 62, and 63 all have a uniform alloy film of one composition.
Become. Seven functional membranes 51, 53 to 56, 62, 63
In the lower protective film 62, a silicon target is disposed.
In a single wafer sputtering system (gas pressure is 1 × 10 ^-6
After reducing the pressure to Torr or less, a mixed gas of argon and nitrogen
Introduce 5 × 10^-3Torr) and the well-known R
It is formed by F magnetron sputtering. This
The lower protective film 62 formed as described above is made of silicon nitride.
And the film thickness D62 is 70 nm.

The reproducing film 51 is made of a GdFeCo alloy target (specific composition is Gd25Fe60Co1).
5) is formed in a single-wafer sputtering apparatus (gas pressure is 5 × 10 ⁻³ Torr). The reproducing film 51 thus formed has a composition of Gd25Fe60Co15.
(Compensation composition at room temperature Tr) and a film thickness D51
Is 30 nm.

The intermediate film 53 is made of a target made of a GdFeCo alloy (specific composition is Gd24Fe64Co1).
It is formed in a single-wafer sputtering apparatus in which 2) is arranged (gas pressure is 5 × 10 ⁻³ Torr). The intermediate film 53 thus formed has a composition of Gd24Fe64Co12.
And the film thickness D53 is 10 nm. The recording film 54 is formed in a single-wafer sputtering apparatus in which a target made of a DyFeCo alloy (specific composition is Dy26Fe50Co24) (gas pressure is 5 × 10 ⁻³ Torr).
r). Recording film 5 thus formed
4 is a perpendicular magnetization film having a composition of Dy26Fe50Co24,
The film thickness D54 is 20 nm.

The switching film 55 is made of TbFeC
o alloy target (specific composition is Tb16Fe
70Co14) is formed in a single-wafer sputtering apparatus (gas pressure is 5 × 10 ⁻³ Torr). The switching film 55 thus formed has a composition of T
b16 Fe70 Co14 magnetic film with a thickness D55 of 12 nm
It is.

The initialization film 56 is formed of a TbFeCo alloy target (specific composition is Tb20Fe16Co).
64) is formed in a single-wafer sputtering apparatus (gas pressure is 5 × 10 ⁻³ Torr). The initialization film 56 thus formed has a composition of Tb20Fe16Co.
64 perpendicular magnetization films, each having a thickness D56 of 30 nm.

Similarly to the lower protective film 62, the upper protective film 63 is formed in a single-wafer sputtering apparatus on which a silicon target is disposed (gas pressure is 5 × 10 ⁻³ Torr).
r). The upper protective film 63 thus formed is also made of silicon nitride, and has a thickness D63 of 70 nm. As described above, according to the present embodiment, the LI
In forming the memory film 52 among the functional films constituting the MDOW recording type magneto-optical disk 50 (FIG. 3), the film-forming conditions (in the vacuum chamber 11) were determined using the single-wafer sputtering apparatus 10 (FIG. 1). Gas pressure) different 2
Since the sputtering was performed while alternately changing two values (2 × 10 ⁻³ Torr, 8 × 10 ⁻³ Torr) (FIG. 2A), two alloy layers 52A and 52B having different compositions were alternately laminated. The memory film 52 having a layer structure can be formed (FIG. 4).

As described above, the memory film 52 has a layer structure of two alloy layers 52A and 52B having different compositions.
In the magneto-optical disk 50 of the IMDOW recording method, the recording power margin of the memory film 52 is larger than that of the memory film composed of an alloy film having one composition. Therefore, the following effects can be obtained when information is overwritten.

As is well known, in the overwrite recording of information, the power is modulated (high level / high level) on the magneto-optical disk 50 of the LIMDOW recording system in accordance with the information to be recorded.
This is performed by irradiating the recording beam while keeping the level low. When a high level recording beam is irradiated, the recording film 5
4, a recording mark (a magnetic domain whose magnetization direction is opposite to that of the surroundings) is formed in a region whose temperature has increased to near the Curie temperature Tcw (hereinafter, referred to as a “heating region”).

Here, in order to make the size of the recording mark smaller than the beam spot, in order to make the size of the above-mentioned heated area (the area where the temperature rises to near Tcw) smaller than the beam spot, a high level The method of shortening the irradiation time of the recording beam is adopted (a pen tip recording method).

As described above, when the pen tip recording method is used, variation in the size of the heating area smaller than the beam spot tends to occur due to the time fluctuation (noise) of the high level recording power. However, in the magneto-optical disk 50 of the present embodiment, the memory film 52 is not an alloy film of one composition, but two alloy layers 52A and 52B having different compositions.
Are laminated, and the recording power margin is expanded.

Therefore, the beam spot (for example, 1.
It is possible to stably overwrite a small recording mark of a certain size (for example, 0.3 μm) on the memory film 52 having a layered structure, even if the size of the heating area smaller than 1 μm varies. it can. When a low level recording beam is irradiated, the recording mark is erased. Therefore, by irradiating the magneto-optical disk 50 with a recording beam while modulating the power (high level / low level) according to the information to be recorded, the beam spot is irrespective of the recording marks already recorded. Smaller recording marks can be stably overwritten on the memory film 52 having a layered structure one after another, and high-density information can be reliably recorded.

In this case, it is not necessary to control the power of the recording beam very strictly. Note that even when the magnetic field modulation recording method is used, high-density information can be reliably recorded on the memory film 52 having a layered structure, similarly to the case where the above-described pen tip recording method is used. Further, in the magneto-optical disk 50 of the LIMDOW recording system in which the memory film 52 has a layer structure of two alloy layers 52A and 52B having different compositions, the coercive force of the memory film 52 is increased in a wide temperature range (from room temperature Tr to memory film 52 (a range up to the vicinity of the Curie temperature Tcm of 52), which is sufficiently raised to hold information.

Therefore, a recording mark (a magnetic domain whose magnetization direction is opposite to that of the surroundings) formed in the memory film 52 having a layer structure.
Is stable, as recorded, without being affected by the surrounding, which is the opposite magnetization direction, even if the size is sufficiently smaller than the beam spot and the area is very small and high density. Will be held. For this reason, even when a reproduction beam is irradiated at the time of reproducing information, the recording marks (information) formed on the memory film 52 having a layered structure are stable as they were recorded in all the areas in the beam spot. And can be reproduced accurately.

Further, since the memory film 52 having a layered structure composed of the two alloy layers 52A and 52B having different compositions has a high coercive force, it is magnetically coupled with the recording film 54 whose magnetization direction is aligned in one direction. Even when the force is transmitted via the intermediate film 53, the recording marks (information) formed on the memory film 52 having the layer structure are always stably held. Therefore, according to the magneto-optical disk 50 of the LIMOW recording method of the present embodiment, it is possible to obtain a high-density magneto-optical disk suitable for recording and reproducing information including a plurality of small recording marks.

Further, according to the magneto-optical disk 50 of the LIMOW recording system of the present embodiment, the recording has already been performed only by modulating (high level / low level) the power of the recording beam in accordance with the information to be recorded. Since a recording mark can be erased or a new recording mark can be written, the speed of the information recording operation can be increased. In manufacturing the magneto-optical disk 50 of such a high-quality LIMDOW recording system, eight functional films 51 to 56, 62, 63 constituting the magneto-optical disk 50 are used.
Can be formed by a single-wafer, single-chamber, single-wafer sputtering apparatus, so that the entire apparatus can be reduced in size and simplified, and the manufacturing cost can be reduced.

In the above-described embodiment, the gas pressure in the vacuum chamber 11 is periodically changed by periodically changing the flow rate of the Ar gas (FIG. 2A) and keeping the exhaust amount constant. While the example in which the memory film 52 is formed has been described, the gas pressure in the vacuum chamber 11 can be similarly periodically changed even when the Ar gas flow rate is kept constant and the exhaust amount is periodically changed. The memory film 52 having a layer structure can be formed.

Further, in the above-described embodiment, when changing the gas pressure in the vacuum chamber 11 to two different values, a period of a low gas pressure (A in FIG. 2) and a period of a high gas pressure (A in FIG. 2) (B) is 1: 1 (duty ratio is 50%), but the duty ratio is not limited to 50%. By changing the duty ratio, it is possible to change the thickness ratio of the two alloy layers 52A and 52B constituting the memory film 52 having a layer structure, that is, to change the magnetic characteristics of the memory film.

In the above-described embodiment, the example in which the memory film 52 is formed while changing the gas pressure in the vacuum chamber 11 at a cycle of 12 seconds has been described.
Not just seconds. By changing the period T, the sum of the thicknesses of the two alloy layers 52A and 52B constituting the memory film 52 having a layer structure can be changed, that is, the magnetic characteristics of the memory film can be changed.

Further, in the above embodiment, in the memory film 52 of the magneto-optical disk 50, the thickness D of the RE-rich alloy layer 52B and the thickness D of the TM-rich alloy layer 52A.
1 were both 3 nm, but their thickness D
1, D2 can be set to an arbitrary value within a range thicker than 0.5 nm and thinner than 50 nm. in this case,
The thicknesses D1, D2 of the alloy layers 52B, 52A may be different. Incidentally, the thickness D of each alloy layer 52B, 52A
1, the minimum value (0.5 nm) of D2 is determined for each alloy layer 52A,
It corresponds to the thickness of one atom constituting 52B. The thickness of each alloy layer 52A, 52B can be adjusted by the cycle of gas pressure change in the vacuum chamber 11 and the duty ratio.

In the above-described embodiment, the memory film 52 of the magneto-optical disk 50 is replaced with the RE-rich alloy layer 52B.
An example (FIG. 4) in which a layer structure in which the memory film 5A and the TM-rich alloy layer 52A are repeatedly laminated has been described.
2 is the RE rich alloy layer 52B and the TM rich alloy layer 52
A and a two-layer structure. Such a two-layered memory film can be formed by changing the gas pressure in the vacuum chamber 11 once at a predetermined timing.

Further, in the above-described embodiment, the example of the binary change in which the gas pressure in the vacuum chamber 11 is changed to two different values has been described.
It may be a multi-value change such as a value. Further, the change in the gas pressure in the vacuum chamber 11 is not limited to a stepwise change, and may be a continuous change. In the above-described embodiment, the example in which the memory film 52 is formed while periodically changing the gas pressure in the vacuum chamber 11 has been described. However, the change in the gas pressure in the vacuum chamber 11 is not limited to a periodic manner. For example, a change in which the gas pressure is increased or decreased at a predetermined rate or a random change between the formation start time and the formation end time of the memory film 52 may be used.

Further, in the above-described embodiment, an example has been described in which a target made of a TbFeCo alloy having a compensation composition at room temperature Tr is used to form the memory film 52 of the magneto-optical disk 50 in a layered structure. A target composed of an alloy having a predominant lattice magnetization or a target composed of an alloy having a predominant sublattice magnetization of a transition metal can also be used.

In the above-described embodiment, an example has been described in which, of the eight functional films formed on the magneto-optical disk 50, only the memory film 52 has a layer structure including a plurality of alloy layers having different compositions. A reproducing film 51 involved in an operation of reproducing information recorded in the memory film 52, an intermediate film 53 involved in an overwrite recording operation of information in the memory film 52,
The recording film 54, the switching film 55, the initialization film 56, the lower protective film 62, and the upper protective film 63 may have a layered structure.

Further, in the above-described embodiment, the eight functional films (lower protective film 62, reproducing film 51, memory film 52, intermediate film 53, recording film 54, switching film 55, initialization film, An example in which the memory film 52 is formed in a layer structure in the LIMOW recording type magneto-optical disk 50 in which the film 56 and the upper protective film 63) are formed on the substrate 61 has been described. In a magnetic disk, a memory film and other functional films can be formed in a layer structure.

In the above-described embodiment, a magneto-optical disk has been described as an example, but each functional film constituting the phase change disk may have a layered structure. (Modification of this embodiment) Next, a modification of the above-described embodiment will be described. In this modification, when a memory film having a layer structure is formed using a single-wafer sputtering apparatus having the same configuration as the above-described embodiment, the power applied to the target is periodically changed.

More specifically, the control circuit constituting the single-wafer sputtering apparatus controls a sputtering power supply connected to a target holder for holding a target.
As shown in (b), during the period from the time ts when the formation of the memory film was started to the time te when the formation of the memory film was completed, the power applied to the target was changed to two different values (600 W,
200W). Here, the change in the applied power is a change having a cycle, and the cycle T is 24 seconds. Note that, in one cycle T, a period A of 600 W and 20
The ratio of 0W to the period B is 1: 3.

The control circuit of this modification controls the mass flow controller of the gas supply system, and as shown in FIG. 5A, the time from when the formation of the memory film is started to the time when the formation of the memory film is completed. over the period until te
The Ar gas flow rate into the vacuum chamber is set to a predetermined value (50 S
CCM). Further, the control circuit of this modification controls the exhaust system orifice similarly to the control circuit of the above-described embodiment, and terminates the formation of the memory film from the time ts when the formation of the memory film is started, similarly to the Ar gas flow rate described above. The exhaust amount from the vacuum chamber is kept at a predetermined value X over a period up to the time te. The predetermined value X
Is determined so that the gas pressure in the vacuum chamber becomes 2 × 10 ⁻³ Torr when the Ar gas flow rate is 50 SCCM (FIG. 5A).

Here, an operation of forming a memory film using a single-wafer sputtering apparatus while periodically changing the power applied to the target will be described. In this case, the target held by the target holder in the single-wafer sputtering apparatus is the same as the target 15 of the above-described embodiment. As shown in FIG. 5B, the power applied to the target is maintained at 600 W in a period A from time ts when the formation of the memory film is started to time t1 six seconds later.

As described above, while applying a high power (600 W), a TbFeCo alloy (Tb20Fe64) having a compensating composition is applied.
When sputtering is performed on a target made of Co16), a TM-rich alloy layer in which the sublattice magnetization of the transition metal is dominant is formed. This period A (from time ts to time t1)
The thickness of the TM-rich alloy layer formed within 6 seconds is 3 nm.

Next, at time t2 18 seconds after time t1
In the period B up to, the power applied to the target is 20
It is kept at 0W. Thus, low power (200 W)
While applying a TbFeCo alloy (Tb20
When sputtering of a target made of Fe64Co16) is performed, a RE-rich alloy layer in which the sublattice magnetization of the rare earth metal is dominant is formed on the above-described TM-rich alloy layer.
The thickness of the RE-rich alloy layer formed during this period B (18 seconds from time t1 to time t2) is 3 nm.
It is.

As described above, even when a target made of the same TbFeCo alloy is used, an alloy layer having a different composition depending on the applied power is formed because the linearity between the applied power and the sputtering rate is different from the TbFeCo of the target. This is because it differs depending on the elements constituting the alloy.

Further, in the next period A (from time t2 to time t
3 for 6 seconds), the period A (time t
As in the case of (6 seconds from s to time t1), the applied power is 60
At 0 W, a TM-rich alloy layer (thickness 3 nm) is formed on the RE-rich alloy layer described above. Further, in the next period B (18 seconds from time t3 to time t4), similarly to the above-described period B (18 seconds from time t1 to time t2), the applied power is maintained at 200 W, and the RE rich alloy layer ( 3 nm) is formed on the above-described TM-rich alloy layer.

Such a TM-rich alloy layer (thickness: 3 n
The formation of m) and the formation of the RE-rich alloy layer (thickness: 3 nm) are alternately repeated until the time when the thickness of the entire memory film becomes approximately 30 nm (time when the formation of the memory film is completed) te. . As a result, a memory film having a layered structure in which the TM-rich alloy layer (thickness: 3 nm) and the RE-rich alloy layer (thickness: 3 nm) are alternately and repeatedly laminated is formed.

The memory film having the layer structure in which the TM-rich alloy layer and the RE-rich alloy layer are stacked as described above is also a perpendicular magnetization film whose magnetization is oriented perpendicular to the film surface. As described above, according to this modification, the LIM
In forming the memory film, among the functional films constituting the DOW recording type magneto-optical disk, two values (600 W, 200 W) having different film forming conditions (electric power applied to the target) using a single wafer sputtering apparatus. (FIG. 5B), a memory film having a layered structure in which two alloy layers having different compositions are alternately laminated can be formed (see FIG. 4).

As described above, the memory film has the different composition.
In the LIMDOW recording type magneto-optical disk having a layer structure of two alloy layers, the recording power margin of the memory film is larger than that of the memory film composed of one alloy film, as in the above-described embodiment. Have been.

Therefore, at the time of information overwrite recording, due to the time fluctuation (noise) of the high-level recording power, the heating area (the area where the temperature has risen to near Tcw) smaller than the beam spot (for example, 1.1 μm). Even if the size varies, a certain size (for example,
A small recording mark (0.3 μm) can be stably overwritten on a memory film having a layer structure.

As a result, the power is modulated (high level / low level) on the magneto-optical disk according to the information to be recorded.
By irradiating the recording beam while the recording is being performed, recording marks smaller than the beam spot can be stably overwritten on the memory film having a layer structure one after another regardless of the recording marks that have already been recorded. Information can be reliably recorded.

Further, in the LIMDOW recording type magneto-optical disk in which the memory film has a layer structure of two alloy layers having different compositions, the coercive force of the memory film can be controlled in a wide temperature range (from room temperature Tr to the Curie temperature of the memory film). (A range up to around Tcm), which is sufficiently increased to hold information. Therefore, the size of the recording mark (the magnetic domain whose magnetization direction is opposite to that of the surroundings) formed on the memory film having the layered structure is sufficiently smaller than the beam spot and has a very small area and a high density. Is also stably maintained as recorded without being affected by the surroundings having the opposite magnetization direction.

For this reason, even when a reproduction beam is irradiated at the time of reproducing information, the recording marks (information) formed on the memory film having the layered structure remain as they were recorded in all the areas in the beam spot. It is kept stable and can be reproduced accurately. Therefore, according to the magneto-optical disk of the LIMDOW recording method in which the memory film of the modified example is formed, it is possible to obtain a high-density magneto-optical disk suitable for recording and reproducing information including a plurality of small recording marks. Can be.

In the above-described modified example, when changing the power applied to the target to two different values,
The period of high power (A in FIG. 5) and the period of low power (FIG.
Although an example in which the ratio to B) in the above is set to 1: 3 has been described, this ratio is not limited to 1: 3. By changing this ratio, it is possible to change the ratio of the thicknesses of the two alloy layers constituting the memory film having the layer structure, that is, to change the magnetic characteristics of the memory film.

In the above-described modification, the applied power is set to 2
Although the example in which the memory film is formed while changing at a period of 4 seconds has been described, the period T is not limited to 24 seconds. By changing the period T, it is possible to change the sum of the thicknesses of the two alloy layers constituting the layered memory film, that is, to change the magnetic characteristics of the memory film. Further, in the above-described modification,
The example in which the thicknesses of the RE-rich alloy layer and the TM-rich alloy layer constituting the memory film are both 3 nm has been described. However, as in the above-described embodiment, these thicknesses are larger than 0.5 nm and larger than 50 nm. It can be set to any value within a thin range. In this case, the thickness of each alloy layer may be different. The thickness of each alloy layer can be adjusted by the value of the applied power, the period of its change, and the duty ratio.

Further, in the above-described modified example, an example in which the memory film has a layer structure in which the RE-rich alloy layer and the TM-rich alloy layer are repeatedly laminated has been described. May have a two-layer structure of an RE-rich alloy layer and a TM-rich alloy layer. Further, in the above-described modified example, the example of the binary change in which the applied power is changed to two different values has been described. .
Further, the change in the applied power is not limited to a stepwise change, and may be a continuous change.

Further, in the above-described modified example, the example in which the memory film is formed while periodically changing the applied power has been described. However, the change in the applied power is not limited to the period. For example, the change may be a change in which the applied power is increased or decreased at a predetermined rate from the memory film formation start time to the formation end time, or may be a random change. Further, in the above-described modification, an example in which a target made of a TbFeCo alloy having a compensation composition at room temperature Tr is used to form a memory film into a layered structure has been described. However, similar to the above-described embodiment, the sublattice magnetization of a rare earth metal is used. May be used. Alternatively, a target composed of an alloy having a predominant or a transition metal having a predominant sublattice magnetization may be used.

In the above embodiments and modifications, the function film having a layer structure is formed while changing only the gas pressure in the vacuum chamber, and the function of the layer structure is changed while changing only the power applied to the target. Although an example in which a film is formed has been described, even when both the gas pressure in the vacuum chamber and the power applied to the target are changed, the recording power margin is similarly increased and the coercive force is increased over a wide temperature range. Thus, a functional film having a layered structure can be formed.

Further, in the above-described embodiments and modified examples, an example in which a functional film having a layered structure is formed by performing sputtering without rotating the substrate has been described. However, in the single-wafer sputtering apparatus 70 shown in FIG. When the rotation motor 71 is connected to the substrate holder 12 as described above, a functional film having a layered structure can be similarly formed by performing sputtering while rotating the substrate 61 held by the substrate holder 12. .

In this case, the rotation motor 71 is connected to the control circuit 72
To change the rotation speed of the substrate 61 at a predetermined timing (for example, two different values (5 rpm,
30 rpm) to form a functional film having a layered structure in which a plurality of alloy layers having different magnetic properties are laminated, the recording power margin is increased, and the coercive force is increased over a wide temperature range. Yes (claim 8-
Claim 10). This is probably because the plasma state at the time of sputtering changes due to the difference in the number of rotations of the substrate 61.

In forming a functional film having a layered structure while changing the rotation speed of the substrate 61, the recording power margin can be changed even if the gas pressure in the vacuum chamber and / or the power applied to the target are changed in combination. It is possible to form a functional film having a layer structure in which the coercive force is enlarged and increased over a wide temperature range. Further, in the above-described embodiment and modified examples, in forming a functional film having a layered structure in which a plurality of alloy layers having different compositions and / or magnetic properties are stacked, a single-wafer sputtering apparatus in which one alloy target is arranged is used. Although the use example has been described, a simultaneous sputtering apparatus in which a plurality of targets are arranged can also be used.

As described above, even when the functional film is formed while simultaneously discharging a plurality of targets, the gas pressure in the vacuum chamber and / or the power applied to the target and / or the number of rotations of the substrate are similarly changed. This makes it possible to obtain a functional film having a layered structure in which a plurality of alloy layers having different compositions and / or different magnetic properties are stacked.
The resulting functional film having a layer structure has an increased recording power margin and an increased coercive force over a wide temperature range.

[0092]

As described above, claims 1 to 1 are provided.
According to the invention described in Item No. 0, the functional film is formed while changing the gas pressure in the vacuum chamber and / or the power applied to the target and / or the number of rotations of the substrate, so that the functional film has a composition and / or A layer structure in which a plurality of alloy layers having different magnetic properties are stacked can be employed.

As described above, 1 contributes to recording and reproduction of information.
In an optical disk in which one functional film has a layer structure in which a plurality of alloy layers are stacked, a recording mark sufficiently smaller than the beam spot is stably and reliably written without extremely strictly controlling the power of the recording beam. In addition to this, it is possible to reproduce while maintaining such a small recording mark stably, so that the density of information is increased and the reliability in recording and reproducing high-density information is improved.

Further, since there is no need to complicate the control circuit for the power of the recording beam, a high-performance recording / reproducing apparatus can be obtained at low cost.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a configuration of a single-wafer sputtering apparatus 10 according to an embodiment.

FIG. 2 is a diagram illustrating an example of a change in film forming conditions in a single-wafer sputtering apparatus 10.

FIG. 3 is a sectional view showing a configuration of a magneto-optical disk 50.

FIG. 4 is a cross-sectional view illustrating a configuration of a memory film 52 formed by the single-wafer sputtering apparatus 10.

FIG. 5 is a diagram illustrating another example of a change in film forming conditions in the single-wafer sputtering apparatus 10.

FIG. 6 is an explanatory view showing a configuration of a single-wafer sputtering apparatus 70.

[Explanation of symbols]

 10, 70 single-wafer sputtering apparatus 11 vacuum chamber 12 substrate holder 13 target holder 14 sputtering power supply 15 target 21 Ar gas cylinder 22 gas supply pipe 23 mass flow controller 31 vacuum pump 32 exhaust pipe 33 orifice 41 CPU 42 memory 43 timer 50 magneto-optical disk Reference Signs List 51 reproduction film 52 memory film 53 intermediate film 54 recording film 55 switching film 56 initialization film 61 substrate 62, 63 protective film 71 rotation motor 4, 72 control circuit

Claims (10)

[Claims] 1. A target and an optical disk substrate are arranged in a film formation chamber so as to face each other, and when one functional film contributing to recording and reproduction of information is formed on the substrate by sputtering, A method for manufacturing an optical disk, wherein the one functional film is formed while changing a gas pressure and / or an electric power applied to the target and / or a rotation speed of the substrate. 2. The method of manufacturing an optical disk according to claim 1, wherein the change in the gas pressure and / or the applied power and / or the number of revolutions is a change having a period. Method. 3. The method for manufacturing an optical disk according to claim 2, wherein the change in the gas pressure and / or the applied power and / or the rotation speed is a change in which two different values are alternately repeated. Manufacturing method of an optical disk. 4. The method for manufacturing an optical disk according to claim 1, wherein the sputtering includes discharging one alloy target,
Alternatively, the method is performed by simultaneously discharging a plurality of targets. 5. A film forming chamber in which a substrate holder for holding a substrate of an optical disc, and a target holder for holding a sputtering target placed opposite to the substrate are arranged; Gas supply means for supplying gas; exhaust means for exhausting the film forming chamber; power application means for applying electric power to a target held by the target holder; and contribution to recording and reproduction of information on the substrate. During the formation of one functional film, the supply amount of the sputtering gas into the film formation chamber by the gas supply unit, and / or the exhaust amount from the film formation chamber by the exhaust unit, and / or the target by the power application unit. An optical disk manufacturing apparatus, comprising: a control unit that changes power applied to the optical disk. 6. The optical disk manufacturing apparatus according to claim 5, wherein the control unit controls the sputtering gas supply amount and / or the exhaust amount and / or the applied power while forming the one functional film. An optical disk manufacturing apparatus characterized in that the optical disk is changed with a period. 7. The optical disk manufacturing apparatus according to claim 6, wherein the control unit controls the sputtering gas supply amount and / or the exhaust amount and / or the applied power while forming the one functional film. An optical disc manufacturing apparatus characterized by alternately changing two different values. 8. A film forming chamber in which a substrate holder for holding a substrate of an optical disc, and a target holder for holding a sputtering target placed opposite to the substrate are arranged. Gas supply means for supplying a gas; exhaust means for exhausting the film forming chamber; power application means for applying electric power to a target held by the target holder; and a substrate for rotating the substrate held by the substrate holder. Rotating means, and rotating speed control means for changing the rotating speed of the substrate by the substrate rotating means while forming one functional film contributing to recording and reproduction of information on the substrate. Optical disk manufacturing equipment. 9. The optical disc manufacturing apparatus according to claim 8, wherein the rotation speed control unit controls the rotation speed of the substrate while forming the one functional film.
An optical disc manufacturing apparatus characterized by being changed periodically. 10. The optical disk manufacturing apparatus according to claim 9, wherein the rotation speed control means controls the rotation speed of the substrate while forming the one functional film.
An optical disc manufacturing apparatus characterized in that the value is alternately changed to two different values.