Patent Application
20080251376
The present invention relates to a vacuum processing device depositing continuously a multilayer film on a substrate of such as an optical disk or an optical component, and a method of fabricating optical disks.
Optical disks such as the compact disk (CD) or the digital versatile disk (DVD) have been diversified recently, and therefore availability thereof has been still growing from an information medium of reading-only to an optical information medium capable of writing. Synthetic resin, typically polycarbonate, having a low mold shrinkage ratio or a low expansion coefficient is used for materials of the disk substrate. Information is recorded on the surface of the substrate as a pit row in the case of the read-only disk, and a guide groove to become a track for laser is formed on the surface of the substrate in the case of the disk capable of writing. A multilayer film containing a writing layer is deposited on the surface in order to constitute the disk.
In
The multilayer film is constituted of a dielectric material layer, a writing layer and a reflection layer, which are deposited by sputtering. However, the dielectric material layer takes longer to obtain the same thickness as the metallic layer because film-depositing efficiency thereof by sputtering is low compared to the metal. The multilayer film is deposited continuously by passing sequentially in order through a plurality of film-depositing chambers which sputter respective layers, so that multilayer film-depositing tact is limited by a film-depositing chamber that takes the longest time for film-depositing.
In the case of continuous film-depositing in a vacuum like this, temperature rising due to the heat of plasma discharge at the film-depositing process cannot be effectively diminished by cooling the substrate, so that temperature of the substrate rises each time it passes through every film-depositing chamber. For instance, the temperature of a substrate in 25 degrees Celsius rises to 100 degrees Celsius after film-depositing. It has been hitherto proposed that the disk substrate awaits during a certain time in the load lock chamber after film-depositing so as to be slowly cooled (e.g. Patent Document 1). When awaiting in the vacuum processing device like the above, i.e. cooling the substrate during this process is tried by means of stopping any one of the film-depositing chambers, e.g. the third film-depositing chamber 124, the temperature of the substrate must be sharply changed before and after the stopped film-depositing chamber for the post-processes in order to cool it sufficiently by one tact time. If the multilayer film is deposited on the condition that the temperature of the substrate is largely different, stress-strain is generated in the multilayer film. Therefore, the stress-strain gives a strain to the multilayer film-deposited substrate taken out from the main chamber, and results in generating a warp of the substrate called ‘tilt’. An internal strain of the polycarbonate substrate itself molded by a stamper is further added thereto. Because extent of ‘the tilt’ is not uniform for every substrate and deformation occurs, the problem is to decrease these factors. For example, permissible ranges of the tilt for the optical head utilizing a laser having the wavelength of 640 nm are to be within 0.8 degree for radial tilt and within 0.3 degree for tangential tilt, so that even a warp of μm unit of the disk may be a cause of some trouble.
Moreover, quickening the tact time is required to improve the efficiency of mass-production. Aiming at shortening the time of sputtering process in each film-depositing chamber requires increment of electric power for sputtering. As a result, rising of temperature of the substrate in each process becomes more remarkable, and results in increasing the cause of the tilt. Patent Document 1: Japanese Patent Laid-Open No. 2003-303452
The present invention is intended to suppress rise of the temperature of a processed object due to the heat generated by continuous sputtering in a vacuum, and to obtain a vacuum processing device diminishing generation of the tilt or deformation in the processed object. The present invention is further intended to obtain an optical disk having a tilt or deformation being minor.
An aspect of the present invention is as follows.
(1) A vacuum processing device comprises:
a main chamber capable of being evacuated in a vacuum state;
a load lock mechanism carrying a processed object into and out of the main chamber while holding the vacuum state of the main chamber;
a rotary carrying table disposed in the main chamber, and forming a carrying route for the processed object;
a plurality of film-depositing chambers for depositing a film in a multilayer-shape on the processed object, disposed in the main chamber along a circumference about the rotating shaft; and
cooling mechanisms disposed between respective film-depositing chambers, and cooling the processed object.
(2) The cooling mechanism is disposed between the load lock mechanism and the film-depositing chamber.
(3) When the carrying route is a trace of the center of the processed object to be carried, the carrying route by rotation of the horizontal rotary carrying table traces a certain circle, and the load lock mechanism, the film-depositing chamber and the cooling mechanism are disposed at an interval of a certain angular distance about the rotating shaft along the circle.
(4) The film-depositing chambers are disposed on a first circumference with a central portion thereof at the rotating shaft of the rotary carrying table, and the cooling mechanisms are disposed on a second circumference, wherein the second circumference is different from the first circumference with respect to radii thereof.
(5) A susceptor carrying the processed object is disposed on the rotary carrying table, and the susceptor is movable between the first circumference and the second circumference on the rotary carrying table in a radial direction thereof.
(6) The cooling mechanism contains a cooling chamber.
(7) In the main chamber, an area occupied by one of the cooling chambers is smaller than an area occupied by one of the film-depositing chamber.
(8) The cooling mechanism is provided with a cooling chamber, and capable of isolating hermetically from a space of the main chamber.
(9) A susceptor carrying the processed object is disposed on the rotary carrying table, and the susceptor is lifted by a susceptor-pusher and pressed on an opening wall of the cooling chamber so as to come to be hermetically sealed.
(10) The cooling mechanism includes an inlet portion introducing a gas into the cooling chamber and acting as a heat conducting member from the processed object.
(11) A cooling member having a cooling surface is provided in the cooling chamber.
(12) Each of the cooling chambers is capable of setting a temperature individually.
(13) The processed object on which a film is deposited by the film-depositing chamber is a disk-like processed object having a substrate of synthetic resin.
(14) The present invention is characterized by a manufacturing method of an optical disk, wherein a multilayer film is obtained by depositing continuously sputter-deposited films on a disk substrate of synthetic resin upon executing a plurality of sputtering processes in an evacuated atmosphere, characterized in that a cooling process is inserted between all the sputtering processes in order to maintain a temperature of the substrate to be 50 degrees Celsius maximum.
A vacuum processing device capable of suppressing the tilt or deformation of the processed object carried out of the device can be realized upon suppressing rise of the temperature of the processed object due to reservation of heat thereby caused by the heat generated by continuous sputtering in a vacuum and depositing a sputtered film on the processed object always maintained at a predetermined low temperature.
In the present invention, ‘vacuum’ means a state that is depressurized to a pressure lower than the atmospheric pressure, and ‘vacuum processing’ means carrying out film-depositing by sputtering and cooling processing at a reduced pressure.
The present invention is to maintain the temperature for film-depositing on the processed object within a predetermined range by disposing a cooling mechanism between respective film-depositing chambers in a main chamber having a plurality of film-depositing chambers. Starting of film-depositing in each chamber can be controlled at the optimum temperature. Referring to the drawings, embodiments of the present invention will be explained hereinafter.
In the main chamber, a horizontal rotary carrying table 50 whose axis 51 is positioned at the center of the chamber is disposed in order to carry a disk substrate on which a multilayer film is deposited, from the load lock mechanism to each film-depositing chamber and cooling mechanism. An exhausting path 53 is deposited in a rotating shaft 52 horizontally rotating intermittently in the direction of the arrow and connected with a rotation driver portion 54 and an exhaust system 55.
As shown in
As shown in
Further explanation about the cooling mechanism and the susceptor will be executed next. In
The susceptor 57 placed on the carrying table base member 56 is positioned above the opening 50a of the base member, and held movable vertically at the periphery of the opening through a guide pin 59. The susceptor 57 is constituted of a susceptor base 60 fixed to the base member 56 and a dish-like disk substrate holder 62 supported by a pillar portion 61 provided at the center of the top surface of the stand, and a stopper 63 to fix the disk substrate is formed at the periphery of the holder 62. The seal portion 64 of O-ring is provided at the top periphery of the susceptor base 60.
The pusher 11 is attached to the bottom portion 13 of the main chamber corresponding to the cooling chamber 41 so as to move vertically along the wall of the chamber with a hermetically evacuated state. When the pusher 11 rises in the direction of the arrow as shown in
The pusher 11 descends in the direction of the arrow as shown in
Referring to
The load lock chamber 21 of the load lock mechanism 20, which carries the disk substrate 101 in and out of the main chamber 10, is formed by the space divided hermetically in a vacuum state with the hollowed inner wall 12b of the thick top plate 12, the lock opening lid member 22 opening and closing the outer side thereof, and the susceptor 57 at the inner side thereof. A pair of lock opening lid members 22 are mounted on both ends of the rotatable disk-carrying arm 23 respectively, and hermetically fitted to the load lock chamber 21 with flexibly removable mode by rotating the arm. As shown in
Under the condition that the load lock chamber 21 is open to the atmosphere side, the boundary thereof to the space of the main chamber 10 is sealed by the susceptor 57 pressed by the pusher 11 to prevent air from flowing in the main chamber. The lock opening lid member 22 delivers the disk substrate 101 to the susceptor 57 and the load lock chamber is hermetically sealed. Then, the load lock chamber 21 is evacuated by an exhaust system (not shown), and has a pressure equal to the atmosphere of the main chamber 10. In this condition, the pusher 11 is retracted, and the susceptor 57 is disconnected from the load lock chamber and returns to the predetermined position of the carrying table 50.
The pushers 11 corresponding to the film-depositing chamber 30 and the cooling chamber 40 move up and down in synchronization with the vertical movement of the pusher of the load lock mechanism, so that all pushers rise and descend simultaneously. That is to say, because the susceptors 57 have the load lock chamber 21, the film-depositing chamber 30 and the cooling chamber 40 sealed off hermetically from the space of the main chamber while the pushers 11 are raised, carrying in and out the disk substrate 101, depositing each one layer and cooling the disk substrate are carried out in the load lock mechanism, in the film-depositing chamber 30 and in the cooling chamber 40 respectively.
After one tact time has finished, the susceptors 57 are separated from each chamber and return to the carrying table, then the carrying table 50 rotates to carry each disk substrate to the next chamber. For example, a disk substrate carried in the load lock chamber 21 is transported to the cooling chamber 40a, and a disk substrate cooled in the cooling chamber 40a is transported to the film-depositing chamber 30a. A disk substrate on which one layer film is deposited in the film-depositing chamber 30a is transported to the next cooling chamber 40b. Thereafter, film-depositing and cooling are repeated sequentially. The disk substrate carried again in the load lock chamber 21 is carried out of the main chamber by the load lock mechanism 20 in the condition that the inside of the chamber 21 sealed by the susceptor returns to the atmosphere, and carried to the next UV-cured overcoat layer-coating process.
As has been explained above, this embodiment is provided with a cooling chamber located between a load lock mechanism and a film-depositing chamber so that the processed object can be cooled in the cooling chamber while the object moves to the next processing stage. The action thereof will be explained hereinafter.
As shown in Table 1, influence on the tilt of the disk substrate is deterioration of the rate of acceptable products due to generation of irreversible distortion in the substrate at a temperature above 70 degrees Celsius. Distortion is reversible at 70 degrees Celsius or less, and the tilt becomes hard to be generated at an ordinary temperature. Because there is no possibility of distortion remaining in the substrate at 50 degrees Celsius or less, width of temperature rising can have some margin. In consequence, sputtering time can be shortened by increasing the sputtering input power. Thereby, the tact time can be shortened.
When the disk substrate carried to the load lock mechanism is a polycarbonate synthetic resin substrate shortly after molded by a stamper machine of the preceding process, the substrate itself is in the condition heated up to a temperature higher than the room temperature. Therefore, if the substrate in the condition of a high temperature is transported to the first film-depositing chamber 30a, the temperature thereof further rises during sputtering and the condition of film-depositing is deteriorated.
Upon disposing the first cooling chamber 40a between the load lock mechanism 20 and the first film-depositing chamber 30a in this embodiment, an appropriate film can be obtained by controlling and decreasing once the temperature of the substrate. If the temperature of the substrate is sufficiently controlled before load lock, the cooling chamber can be blank or omitted.
The cooling chambers 40b to 40d interposed between respective film-depositing chambers decrease the temperature of the substrate heated up due to each film-depositing to 50 degrees Celsius or less, and diminish the stress generated between the substrate and the multilayer film, so that generation of the tilt after fabrication is suppressed.
The cooling chamber 40e between the final film-depositing chamber 30d and the load lock chamber 20 is to prevent any distortion in the substrate from being generated due to rapid cooling caused by coming into contact with the atmosphere and to buffer lowering of the temperature of the substrate when the substrate heated up in the film-depositing chamber 30d is carried out in the atmosphere via the load lock mechanism. When the temperature of the substrate is sufficiently controlled after the substrate has been carried out from the load lock just as the substrate is carried in the load lock, this cooling chamber can be blank or omitted.
In accordance with this embodiment as mentioned above, the temperature of the processed substrate can be maintained to be 50 degrees Celsius or less, so that the tilt or deformation required for an optical disk having a multilayer film can be sufficiently suppressed. Furthermore, this embodiment can be applied to not only the optical disk but also optical components such as the optical interference filter composed of a multilayer film.
The diameter of the second circumference c2 is smaller than that of the first circumference c1 in the case of
In a vacuum processing device comprised of a load lock chamber and four film-depositing chambers, a vacuum processing device having a structure in which cooling mechanisms are disposed between respective film-depositing chambers has been described in the embodiments mentioned heretofore. However the present invention is not restricted to a device having four film-depositing chambers, but applicable to a device having a plurality of processing chambers.
Moreover, a film-depositing chamber having an evaporating source by an electron beam not a discharge sputtering source can be included in a part of the film-depositing chamber.
Though explanation for a mask of a disk-like processed object has been omitted, the present invention can be applied to all processed objects regardless of the presence or absence of the mask.
In addition, the present invention can be also applied to an optical component having a multilayer film deposited on a thin glass substrate whose distortion is affected by depositing of the multilayer film as the processed object, as well as a multilayer-deposited synthetic resin substrate like an optical disk.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-146416 | May 2004 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2005/008881 | 5/16/2005 | WO | 00 | 11/8/2006 |
