JPH11144338A - Thin film forming apparatus to disk-shaped optical recording medium material and thin-film forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lessen the occurrence of differences in film thickness at various parts in the formation of thin films when the revolution number of magnets is small and due to the differences in the position of the magnets in an initial period of sputtering, and the nonuniformity in the erosion of a target the thin film in a device for forming a thin film to a disk-shaped optical recording medium material. SOLUTION: This apparatus has a rotating means 8 which is mounted at a magnetic field generating means 6 and rotates the magnetic field generating means 6, number of revolution detecting means 9, 10, 11 which are mounted at the revolving shaft of the rotating means 8 and a control means 12 which controls the rotation of the rotating means 8 in such a manner that the number of revolutions at the time necessary for one time of thin film formation is a natural number and controls the rotation start angle of the magnetic field generating means 6 at every starting time of the sputtering so as deviate the angle by a prescribed angle from the start angle of the previous time. The rotation is so controlled that the number of revolutions of the rotating means 8 at the time necessary for one time of thin film formation attains the natural number.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a disc-shaped optical recording medium, and more particularly, to a method for producing a disc-shaped optical recording medium by sputtering a thin film on a surface of a substrate or the like of the disc-shaped optical recording medium as a reflective layer. It relates to a method of forming.

[0002]

2. Description of the Related Art In order to manufacture a disk-shaped optical recording medium, it is necessary to form a laser light reflecting layer on the surface of a substrate or the like. For this purpose, for example, a CD (Compact) is required.
Disk), about 100 μm of aluminum is deposited. However, for example, a recordable CD-R
In the case of (CD-Recordable), since the recording layer uses an organic dye such as a cyanine dye, a phthalocyanine dye, or an azo dye, the reflection layer formed thereon is compounded with an organic dye. Gold is used as a material, and a thin film of about 100 μm is formed by sputtering instead of vapor deposition because of its high melting point. Here, the structure of the CD-R will be briefly described. A thin film of an organic dye of about 100 μm formed on one surface of a transparent and high-strength polymer material such as polycarbonate on a disc of about 1.2 mm is recorded. There is a layer, a gold thin film of about 100 μm formed by sputtering is provided thereon as a reflective layer, and a protective layer of about 5 μm is formed thereon. Therefore, recording and reading to and from the CD-R are performed by a laser beam or the like that has passed through a transparent polymer material from the side where the above-mentioned recording layer and reflective layer are not formed. By the way, sputtering is a technique in which a thin film can be formed by attaching a target material of a positive electrode to the surface of a substrate of a negative electrode or the like by ions or the like ejected by discharge, and applying a magnetic field to the sputtering chamber to form a target material. It is known that the rate of attachment to the negative electrode can be increased. Magnets are used in magnetron sputtering apparatuses that apply such a magnetic field, but the magnetic field of the fixed magnet limits the range of movement of electrons and the like, and the thickness of the sputtering thin film of the target material attached to the substrate Is different at each part on the substrate, and the uniformity of the film thickness distribution tends to be problematic. If the uniformity of the film thickness distribution of the thin film on the substrate is poor,
In order to obtain a predetermined reflection characteristic over the entire substrate, it is necessary to form a thin film so that the thinnest portion satisfies the predetermined film thickness, and the average thickness of the entire film increases. Time increases and production efficiency decreases. In addition, a large amount of sputtering target material is required, so that the cost of expensive gold material increases. Further, even if the production process is set so as to obtain a film pressure higher than a predetermined value due to poor uniformity, a defect that the thin film partially does not reach the predetermined film thickness easily occurs, which also lowers the production efficiency. Will be. In order to improve the uniformity of the film thickness distribution, the magnet can be rotated and the magnet is rotated during sputtering, so that the influence of the magnetic field is not biased to a specific area within the substrate and sputtering is performed. Began to take place.

[0003]

However, in recent years, it has been desired to reduce the time for forming a thin film from the viewpoint of production efficiency, and from the viewpoint of production cost, it is necessary to further improve the uniformity of the film thickness of the thin film. There has been a demand for improved performance and reduced manufacturing costs, and it is becoming difficult to achieve further improvements by simply rotating the magnet. Specifically, for example, the number of rotations of the magnet in one sputtering is reduced because the time required for forming the thin film is reduced, or the means for rotating the magnet (such as a motor) can be reduced in size and an inexpensive motor can be used. It is desired that the thickness of the thin film be further reduced to the required minimum and uniform in order to reduce the amount of gold used in the thin film material. An example will be described to explain the problem of the film thickness caused by reducing the number of rotations of the magnet. For example, a case where the magnet can be rotated by 99 turns and a half in one sputtering,
Considering the case where only half a turn can rotate the magnet,
In the former case of 99 rotations and a half, there is a portion where the magnet is rotated and sputtered for only 99 rotations on the substrate and a half where the magnet is rotated and the sputtering is performed for 100 rotations half each. Become. On the other hand, when the magnet can be rotated only one and a half rotations, the part where the magnet is rotated and the sputtering is performed only one rotation on the substrate and the part where the magnet is rotated and the sputtering is performed two rotations are half. Will be present one by one. On the substrate, there is a 1% difference on one substrate between the portion where the magnet was rotated and sputtered 99 times and the portion where the magnet was rotated and sputtered 100 times. However, there is a 50% difference on one substrate between the part where the magnet is rotated for one time and the sputtering is performed and the part where the magnet is rotated and the sputtering for two times is performed. become. In other words, when the number of rotations of the magnet decreases, the difference in film thickness between the portion swept by the rotation of the magnet and the portion not swept due to the formation of the thin film greatly increases, and the influence on the film thickness distribution increases. Further, when the number of rotations of the magnet used for one sputtering is reduced as described above, the influence of the magnetic field due to the position of the magnet at the start of sputtering when forming a thin film with a uniform film thickness increases. Further, when forming a thin film with a uniform film thickness, it is difficult to stably control the discharge voltage of sputtering, and it tends to increase particularly in the initial stage of discharge, and the surface state of the substrate to which gold or the like is attached by sputtering. In some cases, the voltage at the beginning of discharge is considerably higher than the normal discharge voltage, and increases by the amount of reduction of gold or the like at the target where the magnet is located at the beginning of discharge, causing non-uniform erosion of the target. . The present invention reduces the difference in film thickness generated in each part in the formation of a thin film when the number of rotations of the magnet is small,
It is an object of the present invention to reduce the occurrence of a difference in film thickness when a thin film is formed and the occurrence of non-uniform erosion of a target depending on the position of a magnet in an early stage of sputtering.

[0004]

In order to achieve the above object, the present invention provides a thin film forming apparatus for forming a thin film using magnetron sputtering in which a magnetic field is generated on the surface of a disc-shaped optical recording medium material to perform sputtering. A rotating means attached to the magnetic field generating means for rotating the magnetic field generating means, and a control means for controlling the rotation so that the number of rotations of the rotating means in a time required for one thin film formation becomes a natural number. It is characterized by having. As the control by the control means, the rotation speed is controlled such that the product of the rotation number of the rotation means and the time required for one thin film formation is a natural number. Further, in a thin film forming apparatus for forming a thin film using magnetron sputtering for generating a magnetic field on the surface of a disc-shaped optical recording medium material and performing sputtering, a rotating means attached to the magnetic field generating means for rotating the magnetic field generating means And control means for controlling the rotation start angle of the magnetic field generation means at each start of sputtering to be shifted from the previous start angle by a predetermined angle. By controlling the rotation speed of the magnet in sputtering and the position of the magnet at the beginning of sputtering as described above, the difference in film thickness is reduced even at a small number of rotations, and the bias of the target adhesion at the start of sputtering is also reduced. Can be formed.

[0005]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a magnetron sputtering apparatus according to one embodiment of the apparatus for forming a thin film on a disc-shaped optical recording medium material of the present invention. FIG.
Here, the main parts related to the present invention are mainly shown, and parts that are important for the operation of the thin film forming apparatus but are not so relevant to the present invention are partially omitted in the drawings. The sputter chamber 1 is a space (chamber) for forming a thin film by causing a discharge in sputtering and attaching a target described below to the substrate. The target 2 is a material serving as a base of a thin film in sputtering. Electrons and positrons generated by electric discharge collide with the material of the target and are repelled to the space of the sputtering chamber 1 to fly out. Adheres to a thin film. The substrate 3 is a disc-shaped optical recording medium material on which a thin film of a target material is formed. The inner mask 4 is a masking material for masking a central portion on the substrate 3 where a thin film is not formed by sputtering.
The outer mask 5 is a masking material for masking a peripheral portion on the substrate 3 where a thin film is not formed by sputtering. The magnet 6 is for applying a magnetic field to the sputtering chamber 1 to increase the attachment speed of the target material.

The magnet rotating shaft 7 is for rotating the magnet, and the magnet 6 is attached in a braided manner. The motor 8 is a motor connected to the magnet rotating shaft 7 for rotating the magnet, and is a motor capable of controlling a predetermined angle like a stepping motor, for example. The encoder 9 is attached to the magnet rotating shaft 7 and outputs a pulse formed by passing and blocking light of a semiconductor laser 10 described later to know the rotation angle and the rotation speed of the motor 8. The semiconductor laser 10 is a light source of a laser signal that is converted into a pulse signal by the encoder 9 and supplied to the light receiving unit 11 described below. The light receiving unit 11 receives a pulse signal converted into a signal by the rotation of the motor 8 by the encoder 9. The encoder signal processing and rotation speed control device 12 detects the position and rotation speed of the magnet from the output signal of the encoder 9 and outputs a signal for controlling the position and rotation speed of the motor 8. The motor drive device 13 supplies a drive signal and power for the motor 8 based on the encoder signal processing and the control signal from the rotation speed control device 12. Sputter condition management equipment 14
Determines the time from the start to the end of the sputtering based on the encoder signal processing and the signal of the magnet position and the rotation speed from the rotation speed control device 12 together with other conditions.

In the above configuration, the signal received by the light receiving section 11 from the light source of the semiconductor laser 10 pulsed by the encoder 9 becomes a signal of the position and the number of rotations of the magnet by the encoder signal processing and rotation number control device 12. The data is input to the motor driving device 13 and the sputtering condition management device 14. The position of the magnet is shifted by a preset angle in accordance with a signal input to the sputtering condition management device 14. A signal for this is returned to the encoder signal processing and rotation speed control device 12 by feedback, and the motor 8 is driven by the motor driving device 13 to move the magnet 6. Since the amount of shifting the position of the magnet is to prevent uneven erosion of the target, stepping of the motor 8, resolution of the encoder 9, encoder signal processing, and a motor 8 that can be processed by the rotation speed control device 12 are performed. It is possible to prevent biased target erosion by randomly selecting the sputtering start position from the controllable angle by using, for example, a random number table provided in the encoder signal processing and the rotation speed control device 12. . Further, as another method, the start angle of sputtering is determined by encoder signal processing and rotation speed control equipment 1.
2 or stored in a non-volatile storage means connected externally, and subjected to statistical processing by the encoder signal processing and the rotation speed control device 12 to select an angle with the smallest start record of sputtering. Erosion can be prevented. Furthermore, the erosion of a biased target can be prevented by combining the above two methods.

On the other hand, the encoder signal processing input to the motor driving device 13 and the rotation speed signal from the rotation speed control device 12 indicate that the rotation speed of the magnet is r [rpm] and the time required for one sputtering is t [ sec], r
Feedback control is performed so as to satisfy the expression of / 60 × t = N (N is a natural number). In this formula, since r indicates the number of rotations per minute, r / 60 indicates the number of rotations per second, and the total number of rotations at t seconds required for one sputtering is N (N is a natural number) That is, it means that the control is performed such that the sputtering is completed at a natural number of revolutions having the same start angle and end angle in one sputtering. The control method here is also performed in the same configuration as the control of the starting position of the magnet described above. Further, in this configuration, the signal received by the light receiving unit 11 of the light source of the semiconductor laser 10 pulsed by the encoder 9 becomes a signal of the position and the number of rotations of the magnet by the encoder signal processing and rotation number control device 12, Up to the point of input to the device 13 and the sputtering condition management device 14, the control of the starting position of the magnet is substantially the same as that described above. The signal input to the sputtering condition management device 14 is processed together with a preset time necessary for sputtering,
A signal for controlling the rotation speed to end at a natural number is fed back to the motor driving device 13 via the encoder signal processing and the rotation speed control device 12, so that the rotation of the motor 8 is drive-controlled. Since the drive of the motor 8 is controlled,
As a result, the rotation angle of the magnet 6 connected to the motor 8 is also controlled to the controlled angle of the motor 8 so that the angle of the magnet at the start of sputtering and the angle at the end thereof are the same, and the rotation number is a natural number (positive number). (Positive number).

FIG. 2 shows the case where the rotation of the present invention is controlled,
FIG. 7 is a diagram showing a difference in film thickness of a thin film at each angle on a sputtered substrate when a conventional rotation control is not performed. The horizontal axis in FIG. 2A shows the angle from the center of the substrate to be sputtered, and the vertical axis shows the thickness of the sputtered thin film at each angle. FIG.
In (a), the dotted line indicates the film thickness not controlled by the conventional rotation, and the solid line indicates the film pressure controlled by the rotation of the present invention.
And 270 °, there is a large angle at which the film thickness decreases, and conversely, near 360 °, there is an angle at which the film thickness increases. This conventional change in film thickness is mostly due to the position of the magnet at the start and end of sputtering, and FIG. 2 (a) when the position of the magnet is controlled according to the present invention.
In the solid line, there is no large change in the film thickness as in the prior art. FIG. 2B is a diagram illustrating an angle θ from the center of the sputtered substrate and a measurement position of the thin film thickness in FIG. 2A. In FIG. 2B, the angle θ is set to 0.
Starting from °, the thickness of the thin film at the measurement position (circumferential portion close to the outer periphery) is measured at each controllable angle of the motor 8,
FIG. 2A shows a series of the results.

FIG. 3 is a diagram showing the difference in film thickness between the present invention and the conventional thin film shown in FIG. 2, and is a diagram showing measurement positions for obtaining a film thickness difference between an inner peripheral portion and an outer peripheral portion. On the substrate of the disc-shaped optical recording medium, six measurement lines are set as measurement lines 1 to 6 every 0 ° to 60 °, and an inner peripheral portion, a middle peripheral portion, and an outer peripheral portion are set for each line. Set three measurement points. By setting the measurement points in this way, it is possible to determine whether or not there is a difference in the film thickness between the inner peripheral portion, the middle peripheral portion, and the outer peripheral portion. Table 1 shows the results of evaluating whether or not the film pressure has reached a predetermined film thickness by measuring the groove reflectance at each measurement point in FIG. Table 1
Among them, the case where a predetermined standard value of the groove reflectance was satisfied was indicated by ○, and the case where the standard value was not reached was indicated by ×.

[0011]

[Table 1] It can be determined that the thickness of the measurement line 1 is insufficient at the middle and outer circumferences of the substrate on which conventional rotation control is not performed, and that the thickness of the measurement line 2 is insufficient at the outer circumference. This lacking portion corresponds to the portion where the conventional film thickness falls in FIG. 2A. On the other hand, in the substrate on which the rotation control of the present invention has been performed, it can be determined that the film thickness has reached the initial position in all the lines. As described above, by using the apparatus for forming a thin film on a disc-shaped optical recording medium material of the present invention, the film thickness on the substrate can be made uniform. In the present embodiment, the encoder and the optical detecting means are used for detecting the rotation angle of the motor. However, the present invention is not limited to this, and mechanical detection or magnetic detecting means may be used. Implementation of the present invention is possible.

[0012]

As described above, in the apparatus for forming a thin film on a disc-shaped optical recording medium material according to the present invention, the number of rotations of the magnet is controlled by controlling the rotation speed of the magnet in sputtering and the position of the magnet at the beginning of sputtering. In the case of thin film formation, the difference in film thickness that occurs in each part due to the formation of the thin film is reduced, and the bias of the attachment of the target at the start of sputtering due to the position of the magnet in the early stage of sputtering is also reduced. In addition, non-uniformity of target erosion can be reduced. Therefore, even when a high-speed thin film is formed by sputtering, the distribution of the film thickness can be made uniform, and a disk-shaped optical recording medium that satisfies desired characteristics can be obtained with a minimum necessary target material.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a magnetron sputtering apparatus of one embodiment of a thin film forming apparatus for a disc-shaped optical recording medium material according to the present invention.

FIGS. 2 (a) and (b) show the case where the rotation is controlled according to the present invention and the case where the conventional rotation control is not performed. It is a figure showing a difference.

3 is a diagram showing a difference in film thickness between a thin film of the present invention and a conventional thin film in FIG. 2, and further shows a measurement position for obtaining a film thickness difference between an inner peripheral portion and an outer peripheral portion.

[Explanation of symbols]

1 ... sputter chamber, 2 ... target, 3 ...
・ Substrate, 4 ・ ・ ・ Inner mask, 5 ・ ・ ・ Outer mask, 6 ・ ・ ・ Magnet, 7 ・ ・ ・ Magnet rotating shaft, 8 ・ ・ ・ Motor, 9 ・ ・ ・ Encoder,
10: semiconductor laser, 11: light receiving unit, 1
2 ... Encoder signal processing and rotation speed control device
13 ... motor drive equipment, 14 ... sputter condition management equipment

Claims (12)

[Claims] 1. A thin film forming apparatus for forming a thin film on the surface of a disc-shaped optical recording medium material by using magnetron sputtering for generating a magnetic field and performing sputtering, the thin film forming apparatus being attached to a magnetic field generating means and rotating the magnetic field generating means. A rotating means, and a control means for controlling the rotation so that the number of rotations of the rotating means in a time required for one thin film formation becomes a natural number. Thin film forming equipment. 2. The control means sets the time required for one thin film formation to t [rotational speed] of the magnet as r [rpm].
2. The disk-shaped optical recording medium according to claim 1, wherein when [sec] is set, a formula r / 60 × t of the product of the number of rotations per second and the time t is controlled to be a natural number N. Equipment for forming thin films on materials. 3. The apparatus according to claim 1, further comprising a rotation angle detecting means provided on a rotating shaft of said rotating means, wherein said control means obtains and controls the number of rotations based on a detection signal of said detecting means. 3. The apparatus for forming a thin film on a disc-shaped optical recording medium material according to item 2. 4. The apparatus according to claim 2, wherein said control means determines and controls the rotation speed of said magnetic field generating means by setting a time required for said one thin film formation. An apparatus for forming thin films on disc-shaped optical recording medium materials. 5. A thin film forming apparatus for forming a thin film on the surface of a disc-shaped optical recording medium material by using magnetron sputtering for generating a magnetic field and performing sputtering, the thin film forming apparatus being attached to a magnetic field generating means and rotating the magnetic field generating means. And a control means for controlling the rotation start angle of the magnetic field generating means at each start of sputtering to be shifted by a predetermined angle from the previous start angle, and a disk-shaped optical recording characterized by comprising: Equipment for forming thin films on media materials. 6. A rotating shaft portion of said rotating means has a rotating angle detecting means, and said control means determines a rotation starting angle of said magnetic field generating means at each time of starting of sputtering by a detection signal of said detecting means at a previous time. The apparatus for forming a thin film on a disc-shaped optical recording medium material according to claim 5, wherein the apparatus is controlled so as to start at a predetermined angle from the start angle of the optical recording medium. 7. The control unit sets a rotation start angle of the magnetic field generation unit at each start of sputtering to a standby time between the first sputtering and the second sputtering,
The apparatus for forming a thin film on a disc-shaped optical recording medium material according to claim 5, wherein the apparatus is controlled so as to be shifted by a predetermined angle from a previous start angle. 8. The predetermined angle shifted by the control means,
The apparatus for forming a thin film on a disc-shaped optical recording medium material according to claim 7, wherein the apparatus is randomly selected from rotation angles that can be controlled by the rotation means. 9. The predetermined angle shifted by the control means,
8. The disc-shaped optical recording medium material according to claim 7, wherein an angle having the least performance obtained by statistically processing a start angle used in sputtering is selected from a rotation angle controllable by the rotating means. Thin film forming equipment. 10. A method of forming a thin film on a disc-shaped optical recording medium material by magnetron sputtering by rotating a magnetic field generating means, wherein a rotation angle of the magnetic field generating means is detected, and each rotation angle in one thin film formation is used. A method for forming a thin film on a disc-shaped optical recording medium material, wherein the integrated value of the magnetic field strength is calculated so as to be uniform at all rotation angles, and the rotation of the magnetic field generating means is controlled according to the calculation result. 11. A method for forming a thin film on a disc-shaped optical recording medium material by rotating a magnetic field generating means to perform magnetron sputtering, comprising detecting a rotation angle of the magnetic field generating means, and detecting a change in the detected rotation angle and time. The rotational speed is determined, and the rotational speed and the rotational angle are calculated such that the integral value of the passage time of the magnetic field generating means at the angular rotational angle in one thin film formation is uniform at all the detected rotational angles. And controlling the rotation of said magnetic field generating means according to the following. 12. A rotating means attached to the magnetic field generating means for rotating the magnetic field generating means, and a rotating speed such that the product of the number of rotations of the rotating means and the time required for one thin film formation becomes a natural number. A disk-shaped optical recording medium manufactured by a thin film forming apparatus that forms a thin film using magnetron sputtering that generates a magnetic field on the surface of a disk-shaped optical recording medium material and performs sputtering.