Sputtering apparatus

Abstract: A sputtering apparatus of the present invention is used for manufacturing optical discs. On loading and unloading of disc substrates to and from a vacuum chamber (2), a disc entrance and exit opening (3) provided on the vacuum chamber is closed by a tray (11) having an opening (11b) at the center thereof on which the disc substrate is placed and a push up rod (12) having a closing side closing the opening of the tray on the lower side thereof. Sealing of the disc entrance and exit opening may be made positive and the vacuum chamber is uniformly evacuated so that an excellent sputtering can be performed.

Description: Background of the Invention 1. Field of the Invention The present invention relates to a sputtering apparatus used for manufacturing optical discs, comprising a reflective film made of a metal material such as aluminum deposited upon a disc substrate and, in particular, to a sputtering apparatus which is capable of successively carrying out sputtering-treatment of a disc substrate. 2. Description of the Prior Art Optical discs which are formed for enabling given information signals such as audio or video signals to be recorded or reproduced have been proposed. The optical disc comprises a disc substrate of a material such as polycarbonate or acryl resin, having bits or grooves formed thereon which is coated with a reflective film made of metal material such as aluminum. A method of coating a disc substrate with a metal material includes vacuum deposition, ion plating and sputtering methods. The vacuum deposition and ion plating methods include the steps of heating a metal material (evaporation source) to evaporate the metal material in a vacuum chamber and exposing a disc substrate to the vapor of the metal material for depositing the metal material on the substrate. Mass production of optical discs by these methods has to rely upon a so-called batch manufacturing system in which a multiplicity of optical disc are manufactured by one time evaporation of the metal material by using a large vacuum chamber which is capable of collectively containing a plurality of optical discs. Therefore, the manufacturing system does not only become more complicated in structure and larger in size, but also the resultant products become nonuniform in quality in different positions in the vacuum chamber. In contrast to this, the sputtering method has advantages that treatment is completed in a short period of time, that successive treatments are possible and that coating of individual disc substrates can be performed on the same condition. Accordingly, adoption of this sputtering method can not only provide the substrates with uniform coating, but also well cope with mass production and multi-kind production. The sputtering treatment comprises charging a discharging gas such as argon at a low pressure into a vacuum chamber in which disc substrates and a metal material (target) such as aluminum are disposed, establishing an electric field in the vacuum chamber to ionize the discharging gas and striking atoms and molecules out of the metal material with the ionized discharging gas. That is, in the vacuum chamber, the discharging gas is ionized and collides with the metal material. The metal material is thus scattered so that the scattered metal material is deposited upon the disc substrates to form thin films thereon. A sputtering apparatus for performing this sputtering treatment has been proposed which is designed to successively perform the sputtering treatments on a plurality of disc substrates by rotating a disc-like carrying table on which the plurality of disc substrates are placed in a circumferential direction as shown in, for example, Fig. 1. The sputtering apparatus is designed so that the inner pressure is kept at a given vacuum degree and has a vacuum chamber 103 which is formed with a disc entrance and exit opening 101 through which disc substrate 100 is loaded and unloaded and a sputtering treatment portion 102 for performing sputtering treatments. The disc entrance and exit opening 101 is provided with a lid 104a for keeping an inner pressure in the vacuum chamber 103, which is supported and is moved toward and away from the vacuum chamber 103. On the other hand, the sputtering treatment portion 102 has a disc treatment opening 105 which is formed similarily to the disc entrance and exit opening 101 and a cylindrical treatment portion 106 mounted on the vacuum chamber 103 so that the portion 106 covers the upper side of the disc treatment opening 105. A metal material (target) 107 which is sputtered on the substrate 100 is disposed in the treatment portion 106 and argon gas and the like are charged therein at a low pressure. A disc-like carrying table 108 which successively carries a plurality of the disc substrates 100 between the disc entrance and exit opening 101 and the sputtering treatment portion 102 is disposed in the vacuum chamber 103. The carrying table 108 is supported on a rotary shaft 108a projecting in the vacuum chamber 103 and is driven by drive means (not shown) to rotate around the axis thereof. The carrying table 108 is formed with a circular positioning recess 108b on which the disc substrate 100 rests. A tray 109 which positions the disc substrate 100 by aligning a centering hole 100a of the disc substrate 100 with the recess 108b is adapted into the recess 108b. The tray 109 is formed into a disc having a diameter slightly larger than outer diameter of the disc substrate 100 and is provided at the substantial center thereof with a projection 109a which passes through the chucking centering hole of the disc substrate 100. A through-hole 108c through which push up rods 110 and 111 for pushing up the tray 109 pass is formed in the substantial center of the positioning recess 108b of the carrying table 108. The push up rods 110 and 111 pass through through-holes which are opposite to the disc entrance and exit opening 101 and the sputtering treatment portion 102, respectively and extend to the inside of the vacuum chamber 103, and are designed to be moved in a vertical direction by a drive apparatus (not shown). When the disc substrate 100 is carried to positions opposite to the disc entrance and exit opening 101 and the sputtering treatment portion 102, the respective push up rods 110 and 111 are moved upward for urging the trays 109 and 109 upon the peripheries of the disc entrance and exit opening 101 and the disc treatment opening 105, respectively so that the vacuum chamber 103 is sealed from the outside (atmosphere). When unloading of the disc substrate 100 from the opening 101 and sputtering treatment in the sputtering treatment portion 102 is completed, the respective push up rods 110 and 111 are moved toward the bottom of the vacuum chamber 103. In the thus formed sputtering apparatus, the plurality of disc substrates 100 supplied from the disc entrance and exit opening 101 are successively carried to the sputtering treatment portion 102 at which they are successively subjected to sputtering treatment and simultaneously with this, unloading of the sputtering-treated disc substrates 100 and loading of the untreated disc substrates 100 onto the carrying table 108 is carried out. Removal of a sputtering-treated disc substrate and supply of the untreated new disc substrate D to the carrying table 108 is achieved while the tray 109 is brought into a pressure-contact with the peripheral edge of the disc entrance and exit opening 101 by the push up rod 110. The vacuum chamber 103 is sealed by a seal member such as an O-ring provided along the peripheral edge of the tray 109 so that the atmosphere is prevented from being introduced into the vacuum chamber 103. After completion of these operation, the disc entrance and exit 101 is closed by the lid 104a and simultaneously with this, the vacuum chamber 103 is evacuated to a given vacuum pressure suitable for sputtering by operating a vacuum pump. Since the carrying table 108 is disc-like in shape and the distance between the upper side of the carrying table 108 and the vacuum chamber 103 is very short, evacuation particularly above the disc substrate cannot be sufficiently achieved, the vacuum degree in the vacuum chamber 103 cannot be made uniform. If the vacuum degree is insufficient in such a manner, residual impurities such as water or gas remained in the disc substrate D is scattered to deposit upon a sputtering electrode and the like, resulting in that an excellent film may not be formed. Due to a fact that the tray has a very heavy weight and that the pressure in the sputtering treatment portion 102 is as high as about 130 kg/m², deterioration of the O-ring (not shown) for sealing a space between the push up rod 111 for supporting the tray 109 and the vacuum chamber 103 is remarkable. Objects and Summary of the Invention A known sputtering apparatus (EP-A-0 291 690) comprises a vacuum chamber having a supply opening for a disk to be coated. Arranged in the interior of the chamber is a rotary table reciprocating the discs between the area of the opening and the sputtering area. By lifting trays disposed in recesses of the rotary table, the discs are lifted and lowered. Provided outside the vacuum chamber is a pivot arm for transporting the discs to the opening, for closing the opening from outside and for discharging the coated discs again. Due to the rotary table having a large cross-sectional area, uniform vacuum in particular in the sputtering section above the discs can hardly be obtained. A further sputtering apparatus (US-A-3,915,117) comprises a plurality of vacuum chambers, namely at least one loading chamber and one coating chamber. The discs are reciprocated between the chambers by means of a rotary arm. When loading a disc to be coated, the loading chamber is opened so that vacuum in this chamber gets lost. After loading, vacuum is produced again in this chamber. In an apparatus of this type very much energy is wasted by reproducing vacuum again and again. Another known sputtering apparatus (EP-A-0 354 297 or EP-A-0 433 049) comprises a rotary table in a vacuum chamber rotating the discs to be coated in pairs toward each a coating station. The discs are supplied to the rotary table via complex lock stations from a magazine by means of gripping pliers. In the sputtering apparatus according to EP-A-0 443 049 (falling under Article 54(3)EPC - not relevant for inventive step), the discs to be coated are supplied individually by means of a lid. The disc is fixed to the underside of the lid by means of suction cups. During coating of the disc, the lid seals off the vacuum chamber. When the lid is removed with the coated disk, the opening of the vacuum chamber is sealed by a disc support until the lid has received another disk and seals the opening again. However, in such a sputtering apparatus, automatic handling of the discs provides only a small disc throughput. It is an object of the present invention to provide a sputtering apparatus which is capable of achieving a high quality sputtering treatment upon a disc substrate. It is another object of the present invention to provide a sputtering apparatus which is capable of positively sealing between the inside of a vacuum chamber and the atmosphere and providing the inside of the vaccum chamber with a given vacuum degree by a compact vacuum pump at a moment. It is a further object of the present invention to provide a sputtering apparatus which is capable of providing an uniform vacuum degree in a vacuum chamber. It is a further object of the present invention to provide a sputtering apparatus which is capable of achieving loading and unloading of members to be sputtering-treated into and from a vacuum chamber at a moment. In order to accomplish the above object, the sputtering apparatus of the present invention comprises a vacuum chamber having a supply opening through which a member to be sputtering-treated is loaded into and unloaded from the chamber and a sputtering-treatment portion; a lid for closing said supply opening; a tray having an opening formed in substantial center thereof on which the member to be sputtering-treated is placed; push up rod vertically movable toward and away from the supply opening, having a closing side for closing the opening of the tray from the lower side of the tray; and carrying means for carrying said member between said supply opening and said sputtering treatment portion while the member to be treated is placed upon the tray, whereby the supply opening of the vacuum chamber is closed by the lid during the sputtering treatment, and the supply opening of the vacuum chamber is closed by the tray and the closing side of the push up rod which closes the opening of the tray on the lower side thereof. F. Operation The supply opening of the vacuum chamber is doubly closed by the tray and a closing side of the push up rod which closes upwardly the opening of the tray during loading and unloading of members to be treated since the sputtering apparatus of the present invention has an opening in the substantial center of the tray on which the member to be treated is placed and is provided with the push up rod having a closing side for closing the opening in an upward direction. Therefore, sealing between the inside of the vacuum chamber and the atmosphere is so positive that the introduction of the atmosphere into the vacuum chamber is prevented. When loading and unloading of the member to be treated is completed, the supply opening of the vacuum chamber is closed by the lid and simultaneously with this, the push up rod is immerged so that the tray is placed on the carrying by means and evacuation is performed by the vacuum pump. Since an opening is formed in the substantial center of the tray, evacuation above the disc substrate is performed through this opening and water and gas and the like contained in the disc substrate is evacuated together with air. Therefore, the vacuum degree becomes uniform and deposition upon the sputtering electrode due to scattering of the gas and the water is avoided so that an excellent sputtering treatment can be performed. Brief Description of the drawings: Other objects and advantages of the present invention will become more clear by reading the detailed description of the embodiments with reference to the drawings; in which Fig. 1 is a longitudinal sectional view showing an example of a prior art sputtering apparatus; Fig. 2 is a perspective view showing an embodiment of an optical disc manufacturing apparatus; Fig. 3 is a longitudinal sectional view of a vacuum chamber of the apparatus; Fig. 4 is a cross sectional view of the vacuum chamber; Fig. 5 is an enlarged longitudinal sectional view showing main components of the vacuum chamber on the side of the disc entrance and exit opening; Fig. 6 is a longitudinal sectional view of the vacuum chamber showing a condition when a disc substrate is loaded; Fig. 7 is a longitudinal sectional view of the vacuum chamber showing a condition when loading of the disc substrate is completed; Fig. 8 is a longitudinal sectional view of the vacuum chamber showing the condition when carrying of disc substrate to a sputtering treatment portion is completed; Fig. 9 is a longitudinal sectional view of the vacuum chamber showing a condition when the disc substrate is subjected to sputtering treatment; Fig. 10 is a longitudinal sectional view of the vacuum chamber showing a condition when the sputtering treatment is completed; Fig. 11 is a longitudinal sectional view of the vacuum chamber showing a condition when carrying of the disc substrate to disc entrance and exit opening is completed; Fig. 12 is a longitudinal sectional view of the vacuum chamber showing a condition when the disc substrate is unloaded; Fig. 13 in a longitudinal sectional view showing another example of a tray forming an optical disc manufacturing apparatus; Fig. 14 is a longitudinal sectional view showing a further example of a tray forming an optical disc manufacturing apparatus; (the embodiments according to figures 2 - 14 are not according to the invention) Fig. 15 is a longitudinal sectional view showing a vacuum chamber of an embodiment of an optical disc manufacturing apparatus; Fig. 16 is a cross sectional view of the vacuum chamber; Figs. 17 through 25 are longitudinal sectional views sequentially showing the sputtering process performed of the optical disc manufacturing apparatus of the present embodiment; Fig. 17 shows a condition wherein a disc entrance and exit opening is closed by a tray; Fig. 18 shows a condition when a disc substrate is loaded; Fig. 19 shows a condition when loading of the disc substrate is completed; Fig. 20 shows a condition wherein carrying of disc substrate to a sputtering treatment portion is completed; Fig. 21 shows a condition wherein the disc substrate is subjected to sputtering treatment; Fig. 22 shows a condition wherein the sputtering treatment is completed; Fig. 23 shows a condition wherein carrying of the disc substrate to disc entrance and exit opening is completed; Fig. 24 shows a condition wherein the disc substrate is unloaded; and Fig. 25 shows a condition wherein closing sides of the lid are changed; Description of the Preferred Embodiments An embodiment in which the present invention is not fully applied will now be described with reference to the drawings. In this embodiment, the sputtering apparatus is applied to an apparatus for manufacturing optical discs in which disc substrates made of a synthetic resin such as polycarbonate and acrylic resins are formed with a thin film made of a metal material such as aluminum by sputtering. The optical disc manufacturing apparatus comprises a vacuum chamber 2 housed in a rectangular housing 1 (not shown) and an evacuating system including a vacuum pump and the like disposed below the vacuum chamber 2 as shown in Fig. 2. The vacuum chamber is formed on shown in Figs. 3 and 4 so that it is evacuated by the vacuum pump so that the inner pressure is maintained at a given vacuum pressure. A disc entrance and exit opening 3 through which untreated and treated disc substrates are loaded and unloaded is juxtaposed with a sputtering treatment portion 4 in which sputtering treatments are performed to the disc substrates on the upper side of the vacuum chamber 2. The disc entrance and exit opening 3 is formed as a supply opening through which untreated and treated disc substrates are loaded and unloaded into and from the vacuum chamber 2, respectively and is formed into a substantially circular shape having a diameter larger than the outer dimension of the disc substrates depending upon the shape of the disc substrates. A lid 5 which is capable of opening and closing the disc entrance and exit opening 3 is provided thereabove. The lid 5 is supported by a support mechanism (not shown) so that it is moved toward and away from the vacuum chamber 2 in a direction of arrows A₁ and A₂ in Fig. 3. The lid 5 is moved toward the vacuum chamber 2 to pressure-contact with the peripheral edge of the disc entrance and exit opening 3 for closing the disc entrance and exit opening 3 and is moved away from the vacuum chamber 2 for opening the disc entrance and exit opening 3. The lid 5 has sucking pads 5a on the side facing to the disc entrance and exit opening 3. The disc substrate is sucked by the sucking pads 5a so that loading and unloading of the disc substrate to and from the disc entrance and exit opening is carried out. A seal member such as O-ring 5b is provided along the peripheral edge on the lower side thereof so that an air tightness inside of the vacuum chamber 2 is kept when the peripheral edge of the lid 5 is brought into a pressure-contact with the peripheral edge of the disc entrance and exit opening 3. The sputtering treatment portion 4 comprises a disc treatment opening 6 which is formed similarily to the disc entrance and exit opening 3 and a treatment portion 7 for keeping the inner pressure in the vacuum chamber 2 at an evacuated pressure which is mounted on the vacuum chamber 2 to cover the upper side of the disc treatment opening 6. The treatment portion 7 comprises a cylindrical enclosure having a closed upper end and is charged with a metal material (target) 8 used for sputtering and a low pressure discharging gas such as argon which is necessary for sputtering treatment. A given electrostatic field is established in the treatment portion 7. A swing arm 9 forming a carrying means for shifting the disc substrate between the disc entrance and exit opening 3 and the sputtering treatment portion 4 is provided in the vacuum chamber 2. The swing arm 9 is disc shaped only at the free end on which the disc substrate rests and is tapered at the base end. The swing arm 9 is bolted at the base end thereof to the tip end of the rotary shaft 10 which projects upward in the vacuum chamber 2 and is by swung around the axis thereof in directions represented by arrows L₁ and L₂ in Fig. 4 by a drive device (not shown). For example, the swing arm 9 is swung over an angle of about 90° represented by ϑ in Fig. 4 for achieving carrying of the disc substrates between a position below the disc entrance and exit opening 3 and a position below the sputtering treatment portion 4. O-rings for maintaining an airtightness in the vacuum chamber 2 are provided in a through-hole (not shown) bored in the bottom of the vacuum chamber through which the rotary shaft 10 extends to the inside of the vacuum chamber 2. A circular positioning recess 9a on which a disc substrate rests is formed on the upper side of the swing arm 9 at the free end thereof. A through-hole 9b is bored in the center of the recess 9a. Push up rods 12 and 13 which will be described hereafter extend through the hole 9b. A tray 11 on which a disc substrate rests is adapted into and placed upon the recess 9a. The tray 11 is formed into a disc having a diameter slightly larger than the outer dimension of the disc substrate and has a disc resting face 21 on an upper side thereof opposite to the disc entrance and exit opening 3 on which the disc substrate is placed. A ring-like seal member 11a such as O-ring is mounted along the outer peripheral edge of the tray 11 so that it surrounds the disc resting face 21. The seal member in adapted to maintain an airtightness in the vacuum chamber 2 when the peripheral edge of the tray 11 is in a pressure-contact with the peripheral edge of the disc entrance and exit opening 3 on the lower side of the tray 11. The tray 11 is formed in the substantial center thereof a circular opening 11b to which push up rods 12 and 13 described hereafter extend. Accordingly, the weight of the tray 11 can be reduced so that the force of the push up rod 12 for urging the tray upward may be made smaller and the durability of the O-ring provided in the through-hole 12a bored at the bottom of the vacuum chamber 2 through which the push up rod 12 extends to the inside of the vacuum chamber 2 can be enhanced. The opening 11b has such a dimension that the disc substrate placed upon the disc resting face 21 will not fall therethrough and is formed in such manner that the inner diameter gradually increases from the upper to lower side thereof. That is, the inner peripheral surface of the opening 11b is tapered so that the opening diameter is gradually increased toward the bottom of the vacuum chamber 2 from the disc resting face 21. At the bottom of the vacuum chamber 2, there are provided push up rods 12 and 13 which are vertically moved in a direction of arrows B₁ and B₂ in Fig. 3 toward and away from the disc entrance and exit 3 and the disc treatment opening 6, respectively by a drive device including control means (not shown). Among the push up rods 12 and 13, the push up rod 12 facing to the disc entrance and exit opening 3 is provided at the tip end thereof with a circular positioning portion 14 which is extended to position in the opening 11b formed in the tray 11 for positioning the tray 11 and a circular tray push up portion 15 provided under the portion 14 having a closing side 15a which closes the opening 11b of the tray 11 at the lower side thereof. The positioning portion 14 has a tapered outer peripheral surface having a diameter gradually reducing from the base end to the upper side thereof and is formed in the shape of cone corresponding to the shape of the opening of the tray 11. Since the positioning portion 14 is provided with a tapered outer peripheral surface having a reduced diameter at the tip end thereof which is on the insertion side relative to the tapered opening 11b, a insertion operation into the opening 11b is positive and easy. The positioning portion 14 is provided in the substantial center of the upper side thereof with a circular projection 14a which is inserted into the centering hole of the disc substrate resting upon the tray 11 for positioning the disc substrate. The tray push up portion 15 is formed into a disc having a diameter smaller than the inner diameter of the push up rod through-hole 9b of the swing arm 9 and larger than the inner diameter of the opening 11b of the tray 11 and is formed with the positioning portion 14 in the substantial center thereof. An annular side 15a between the outer peripheral edge of the tray push up portion 15 and the positioning portion 14 defines a closing side for closing the opening 11b of the tray 11 when the push up rod 12 is extended upward to abut on the bottom of the tray 11. A seal member 15b such as O-ring and the like is mounted on the upper side of the tray push up portion 15 along the peripheral edge thereof for keeping an airtightness in the vacuum chamber 2 when the peripheral edge of the tray push up portion 15 is brought into a pressure contact with the peripheral edge of the opening 11b of the tray 11. At a tip end of the other push up rod 13 facing to the disc treatment opening 6, there is formed a disc-like substrate push up portion 16 for pushing up a disc substrate resting upon the tray 11 toward the disc treatment opening 6. The substrate push up portion 16 is formed into a disc having a diameter smaller than the inner diameter of the opening 11b of the tray 11 and larger than the inner diameter of the centering hole of the disc substrate and has an upper side upon which the disc substrate rests. Accordingly, if the push up rod 13 extends toward the disc treatment opening 6, only the disc substrate which has rested upon the tray 11 is pushed up while it rests upon the substrate push up portion 16. A cylindrical projection 16a which is inserted into the centering hole of the disc substrate for performing the positioning thereof is provided in the substantial center of the substrate push up portion 16 so that the positioning of the disc substrate relative to the substrate push up portion 16 is performed. Seal members such as O-ring and the like (not shown) for keeping an airtightness in the vacuum chamber 2 are provided in through-holes 12a, 13a bored in the bottom of the vacuum chamber 2 through which the push up rods 12 and 13 extend into the vacuum chamber 2. The thus formed push up rods 12 and 13 are operated to extend upward when the tip end of the swing arm 9 is positioned to face to the disc entrance and exit opening 3 and the disc treatment opening 6, respectively. That is, as shown in Fig. 6, the positioning portion 14 of the push up rod 12 is extended upward into the opening 11b of the tray 11 resting upon the swing arm 9 through the push up rod through-hole 9a formed in the swing arm 9 so that the positioning of the tray 11 is carried out and the opening 11b of the tray 11 is closed by the closing side 15a provided on the tray push up portion 15 of the push up rod 12. When the push up rod 12 is further extended, the upper side of the peripheral edge of the tray 11 is brought into a pressure-contact with and is supported by the peripheral edge of the disc entrance and exit opening 3. Since the seal members 11a and 15b such as O-rings are provided along the peripheral edges of the tray 11 and the tray push up portion 15, respectively, the disc entrance and exit opening 3 is doubly closed by the tray 11 and the closing side 15b of the tray push up portion 15 which closes the opening 11b of the tray at the lower side thereof, resulting in a positive sealing between the vacuum chamber 2 and the outside thereof. On the other hand, the projection 16a provided at the tip end of the push up rod 13 is extended through the push up rod through-hole 9b of the swing arm 9 and the opening 11b of the tray 11 to adapt to the centering hole of the disc substrate resting upon the tray 11 so that the disc substrate is positioned on the substrate push up portion 16 as shown in Fig. 9. When the push up rod 13 is further extended, the disc substrate is lifted up to the vicinity of the disc treatment opening 6. Since only the disc substrate is located in the disc treatment opening 6, a spacing is formed between the disc substrate and the disc treatment opening 6. In the thus formed optical disc manufacturing apparatus, a conveying operation of the disc substrate between the disc entrance and exit opening 3 and the sputtering treatment portion 4 in performed by one swing arm 9 at a small swing angle, the vacuum chamber may be made compact in size and the vacuum chamber 2 may be made larger in volume. Therefore, a vacuum pump for evacuating the chamber may be made compact and the period of time required for the evacuation may be shortened. The optical disc are manufactured by the optical disc manufacturing apparatus as follows: The tray 11 resting upon the swing arm 9 is firstly raised upwardly by pushing the push up rod 12 facing to the disc entrance and exit opening 3 in a direction of an arrow B₁ in the drawing toward the disc entrance and exit opening 2 as shown in Fig. 6 so that the peripheral edge of the tray 11 is brought into a pressure-contact with the peripheral edge of the disc entrance and exit opening 3. At this time, the disc entrance and exit opening 3 is doubly closed by the tray 11 and the closing side 15a of the tray push up portion 15 provided on the tip end of the push up rod 12 which closes the opening 11b of the tray 11 on the lower side thereof. Since the seal members 11a and 15b are provided on the tray 11 and the tray push up portion 15, respectively, sealing between the inside of the vacuum chamber 2 and the atmosphere becomes positive so that the atmosphere is prevented from entering into the vacuum chamber 2. Since the tray 11 is provided with the opening 11b, the weight of the tray 11 is light so that a high loading will not be imposed upon the push up rod 12. Accordingly, the durability of the O-ring provided in the through-hole through which the push up rod 12 is extended into the vacuum chamber 2 is enhanced. Subsequently, the lid 5 is separated from the vacuum chamber 2 in this condition so that the upper side of the tray 11 is exposed upward through the disc entrance and exit opening 3. A disc substrate 200 to be treated is placed upon the tray 11. Since the projection 14a provided on the tip end of the push up shaft 12 projects upward from the upper side of the tray 11 at this time, the projection 14a extends through the centering hole of the disc substrate. Accordingly, the disc substrate 200 rests upon the tray 11 which it is positioned upon the tray 11. The vacuum degree which has been lost by the opening and closing operation of the disc entrance and exit opening 3 is recovered by operating the vacuum pump while the disc entrance and exit opening 3 is closed by the lid 5 by moving the lid 5 downward as shown in Fig. 7. Then the tray 11 is placed upon the recess 9a of the swing arm 9 by retrecting the push up rod 12 in the side at which the vacuum pump and the like is provided in a direction of an arrow B₂ to move the tray 11 downward. Since the tray 11 is formed with the opening 11b in the center thereof, evacuation above the disc substrate 200 carried out via the centering hole 201 of the disc substrate 200. Accordingly, the vacuum degree above the disc substrate 200 becomes uniform and water and gas contained in the disc substrate 200 is evacuated together with air. Since only one swing arm 9 is provided in the present embodiment of the vacuum chamber 2, there is no obstacle for evacuation. Accordingly, a given vacuum degree can be reached at a moment, for example, in only not longer than one second. After the tray 11 has been placed upon the tip end of the swing arm 9, the swing arm 9 is swung to the sputtering treatment portion 4 in a direction of an arrow L₁ in the drawing so that the disc substrate 200 resting upon the tray 11 is positioned below disc treatment opening 6 as shown in Fig. 7. If the positioning of the tray 11 is completed, the push up rod 13 located below the tray 11 in Fig. 8 is extended upward in a direction of an arrow B₁ to move the disc substrate 200 to the vicinity of the disc treatment opening 6 as shown in Fig. 9. Since the push up rod 13 has a substrate push up portion 16 which is formed into a disc having a diameter smaller than the inner diameter of the opening 11b of the tray 11 and larger than the inner diameter of the centering hole 201 of the disc substrate 200, the rod 13 will lift only the disc substrate 200 upward through the push up rod through-hole 9b and the opening 11b of the tray 11. Accordingly, the force for lifting the push up rod 13 upward may be made smaller and the durability of the O-ring provided in the through-hole 13a through which the push up rod 13 extends into the vacuum chamber 2 can be enhanced. Since the projection 16a provided on the tip end of the push up rod 13 is inserted into the centering hole 201 of the disc substrate 200, the disc substrate 200 is held while it is positioned by the push up rod 13. When the position of the disc substrate 200 relative to the disc treatment opening 6 has been determined, the sputtering treatment of the disc substrate 200 is commenced. Since a clearance is formed between the disc substrate and the disc treatment opening 6, water and gas and the like contained in the disc substrate 200 is migrated to the bottom of the vacuum chamber 2 through this clearance. Therefore, deposition of these gases upon the sputtering electrode due to scattering is avoided so that an excellent sputtering treatment may be achieved. After the sputtering treatment has been completed, the push up rod 13 is immersed into the side at which the vacuum pump and the like is provided in a direction of an arrow B₂ as shown in Fig. 10 so that the disc substrate 200 is placed upon the tray 11. If the disc substrate 200 is placed upon the tray 11, the swing arm 9 is swung to the disc entrance and exit opening 3 in a direction of an arrow L₂ in Fig. 3. The tray 11 on which the disc substrate 200 formed with a thin film of aluminum is positioned below the disc entrance and exit opening 3 as shown in Fig. 11. If the tray 11 is positioned below the disc entrance and exit opening 3, the push up rod 12 is extended in a direction of an arrow B₁ to move the tray 11 upward as shown in Fig. 12 so that the disc entrance and exit opening 3 is doubly closed by the tray 11 and the closing side 15a provided on the push up rod 12 which closes the opening 11b of the tray 11 on the lower side thereof. The lid 5 is then separated from the vacuum chamber 2 so that the disc substrate 200 resting on the tray 11 is removed out of the vacuum chamber 2 through the disc entrance and exit opening 3 and a new disc substrate 200 is positioned and placed upon the upper side of the tray 11. Thereafter, disc substrates are successively sputtering-treated by sequentially repeating the above mentioned steps. If optical discs are manufactured in such a manner by using the optical disc manufacturing apparatus of the present invention, excellent sputtering treatment can be achieved to provide good quality metal films containing no gases since water and gas and the like contained in the disc substrates will not be scattered upon a sputtering electrode and the like. Although positioning of a disc substrate resting on the disc resting face 21 of the tray 11 is performed by bringing the projection 14a projecting from the center of the positioning portion 14 provided on one of the push up rod 12 into an engagement with the centering hole of the disc substrate in the above-mentioned embodiment, positioning of the disc substrate may be performed so that the outer periphery of the disc substrate resting upon the tray 11 is hold. That is, disc adapting recesses 51 and 52 having dimensions corresponding to the outer diameters of the disc substrates are formed on the upper side of the tray 11 on which the disc substrate is placed as shown in Fig. 13. In this case, large and small disc adapting recesses 51 and 52 corresponding to different sizes of the disc substrates are formed at different depths so that disc substrates having different diameters are positioned therein, respectively. Forming the disc adapting recesses 51 and 52 in such a manner makes it possible to support the disc substrate resting on the tray 11 at the outer periphery thereof so that it is positioned on the disc adapting recesses 51 and 52. The disc adapting recesses 51 and 52 may be formed stepwise depending upon the various disc substrates resting upon the tray 11. Providing the disc adapting recesses 51 and 52 in such a manner eliminates the projection on the push up rod 12 which is engaged with the centering hole of the disc substrate which was necessary to achieve positioning of the disc substrate. Although the opening 11b of tray 11 which is engaged with the positioning portion 14 provided on the push up rod 12 is tapered so that the opening diameter is gradually increased from the disc resting face 21 to the lower side thereof, the opening 11b may be formed into a cylindrical shape having a constant diameter from the disc resting face 21 to the lower side thereof. In this case, the positioning portion 14 which is engaged with the opening 11b is also formed into a cylindrical shape on the outer periphery thereof corresponding to the opening 11b. Now a detailed embodiment of a sputtering apparatus of the present invention including a mechanism for loading and unloading of a member to be sputtering-treated using a lid which closes a supply opening provided on a vacuum chamber through which the member to be sputtering-treated is loaded and unloaded will be described with reference to drawings. The vacuum chamber 201 is evacuated by the vacuum pump so that the inner pressure is maintained at a given vacuum pressure and has at the substantially central part thereof a duct 201a connected with the vacuum pump as shown in Figs. 15 and 16. A disc entrance and exit opening 202 through which untreated and treated disc substrates are loaded and unloaded is juxtaposed with a sputtering treatment portion 203 in which sputtering treatments are performed to the disc substrates on the upper side of the vacuum chamber 201. The disc entrance and exit opening 202 is formed as a supply opening through which untreated and treated disc substrates are loaded and unloaded to and from the vacuum chamber 201, respectively and is formed into a substantially circular shape having a diameter larger than the outer dimension of the disc substrates depending upon the shape of the disc substrates. A lid 204 which is capable of opening and closing the disc entrance and exit opening 202 is provided thereabove. The lid 204 is formed into such a dimension that it is capable of closing the disc entrance and exit opening 202 and has at the opposite sides thereof sides 204a and 204b which closes the disc entrance and exit opening 202. The closing sides 204a and 204b are circular faces having areas sufficient to close the disc entrance and exit opening 202. The outer peripheral edge of the closing side 204a or 204b is brought into contact with the peripheral edge of the disc entrance and exit opening 202 for closing the opening 202. Seal members 205 and 206 as O-rings are provided on the closing sides 204a and 204b of the lid 204 in the vicinity of the outer peripheral edge thereof to contact with the peripheral edge of the opening 202 for keeping an airtightness in the vacuum chamber 201. Stepped circular sides 207 and 208 having such a dimension that they can be located inside of the disc entrance and exit opening 202 are formed on the closing sides 204a and 204b of the lid 204, respectively at the substantial center thereof. Holding means including sucking pads 207a and 208a for sucking the disc substrates are provided on the stepped sides 207 and 208. These stepped sides 207 and 208 are provided to reduce the distance between the sucking pads 207a and 208a and a tray 218 which will be described hereafter for positively sucking the disc substrate on the tray 18 by the sucking pads 207a and 208a. The thus formed lid 204 is mounted on the rotary shaft 210 of the drive device 209 including a motor and the like and may be reversed as is represented by an arrow X in Fig. 15. That is, the lid 204 may be rotated together with the rotary shaft 210 by the fact the lid 204 is fixed to the rotary shaft 210 by a bolt threadably engaged with the shaft 210 at the tip end thereof. The shaft 210 extends through a through-hole (not shown) of the lid 204 extending in a diametrical direction at a mid-level of the thickness of the lid 204. Accordingly, the lid 204 is driven by the operation of the drive device 209 so that the opposite closing sides 204a and 204b are rotated by 180° to be reversed. The lid 204 is supported in such a manner that it is movable in a vertical direction with respect to the disc entrance and exit opening 202. That is, the lid 204 is mounted on the tip end of a support shaft 211 of a drive device such as an air cylinder (not shown) upwardly, projecting from the bottom of the vacuum chamber 201 via a connecting member 212 so that it is movable in a vertical direction as represented by an arrow C in the drawing. The drive device is provided on the lower side of the vacuum chamber 201. The support shaft 211 of the drive shaft 211 is disposed in a through-hole extending through the vacuum chamber 201 in a height direction in the vicinity of the disc entrance and exit opening 202. Accordingly, it can be expected that the apparatus becomes more compact in size. For example, bearings 213 and the like are press-inserted into the through-hole through which the support shaft 211 extends for making the sliding of the support shaft 211 easier. The lid 204 which is supported as is mentioned above is moved toward the vacuum chamber 201 to pressure-contact with the peripheral edge of the disc entrance and outlet opening 202 for closing the disc entrance and outlet opening 202 with one of the closing sides 204a and to suck the sputtering-treated disc substrate resting upon the tray 218 by means of sucking pads 207a. The, the lid 204 is moved away from the vacuum chamber to remove the treated disc substrate out of the vacuum chamber 201 and to open the disc entrance and exit opening 202. The lid 204 is reversed while the lid 204 is elevated so that an untreated disc substrate sucked to the other closing side 204b will face to the disc entrance and exit opening 202. The sputtering treatment portion 203 comprises a disc treatment opening 201 which is formed similarily to the disc entrance and exit opening 202 and a treatment portion 215 for keeping the inner pressure in the vacuum chamber 201 at an evacuated pressure which is mounted on the vacuum chamber 201 to cover the upper side of the disc treatment opening 214. The treatment portion comprises a cylindrical enclosure having a closed upper end and is charged with a metal material (target) 216 used for sputtering and a low pressure discharging gas such as argon which is necessary for sputtering treatment. A given electrostatic field is established in the treatment portion 215. A swing arm 217 forming a carrying means for shifting the disc substrate between the disc entrance and exit opening 202 and the sputtering treatment portion 3 is provided in the vacuum chamber 201. The swing arm 217 is disc shaped only at the free end on which the disc substrate rests and is tapered at the base end. The swing arm 217 is bolted at the base end thereof to the tip end of the rotary shaft 218' which projects upward in the vacuum chamber 201 and is by swung around the axis thereof in directions represented by arrows L₃ and L₄ in Fig. 16 by a drive device (not shown). For example, the swing arm 217 is swung over an angle of about 90° represented by ϑ₁ in Fig. 16 for achieving carrying of the disc substrates between a position below the disc entrance and exit opening 202 and a position below the sputtering treatment portion 203. A circular positioning recess 217a on which a disc substrate rests is formed on the upper side of the swing arm 217 at the free end thereof. A through-hole 217b is bored in the center of the recess 217a. Push up rods 219 and 220 which will be described hereafter extend through the hole 217b. A tray 218 on which a disc substrate rests is adapted into and placed upon the recess 217a. The tray 218 is formed into a disc having a diameter slightly larger than the outer dimension of the disc substrate. A projection 218a for positioning the disc substrate by extending through a chucking centering hole of the disc substrate is provided in the center of the tray 218. Accordingly, the disc substrate is positioned with respect to the swing arm 217 while it is fixed to the tray 218 adapted to the positioning recess 217a. A seal member 218b such as O-ring is attached to the peripheral edge of the tray 218 so that an airtightness in the vacuum chamber 201 is maintained when the tray 218 upwardly pressure-contacts with the peripheral edge of the disc entrance and exit opening 202 at the peripheral edge thereof. The push up rods 219 and 220 are provided at the bottom of the vacuum chamber 201. The rods 219 and 220 are vertically movable toward and away from the disc entrance and exit opening 202 and the disc treatment opening 214 in a direction represented by arrows E and F in Fig. 15, by the drive device (not shown) provided with control means (not shown). The push rods 219 and 220 extend to the inside of the vacuum chamber 201 through through-holes (not shown) bored in the bottom of the vacuum chamber 201 and face to the disc entrance and exit opening 202 and the disc treatment opening 214, respectively. Disc-like push up members 219a and 220a for stable pushing up the tray 218 through the hole 217b bored in the swing arm 217 are secured to the tip ends of the push up rods 219 and 220. The push up rods 219 and 220 are urged upward when the tip end of the swing arm 217 faces to the disc entrance and exit opening 202 and the disc treatment opening 214, respectively. In other words, the tray 218 resting on the swing arm 217 is raised by the push up rod 219 and 220 extending through the hole 217b provided in the swing arm 217 at the disc entrance and exit opening 202 and the disc treatment opening 214 and is brought into a pressure-contact with the peripheral edge of the disc entrance and exit opening 202 and the disc treatment opening 214. Since the seal member 218b such as O-ring is provided along the peripheral edge of the tray 218, a more positive sealing relation between the vacuum chamber 201 and the atmosphere is assured. The optical discs are manufactured by the present optical disc manufacturing apparatus at follows: The tray 218 resting upon the swing arm 217 is firstly raised upwardly by pushing the push up rod 220 facing to the disc entrance and exit opening 202 in a direction of an arrow E₁ in the drawing toward the disc entrance and exit opening 202 as shown in Fig. 17 so that the peripheral edge of the tray 218 is brought into a pressure-contact with the peripheral edge of the disc entrance and exit opening 202. The disc entrance and exit opening 202 is then closed by the tray 218. Since the tray 218 is provided with a seal member 218b at the peripheral edge thereof, the inside of the vacuum chamber 201 is sealed from the atmosphere so that the atmosphere is prevented from penetrating into the inside of the vacuum chamber 201. The lid 204 is then separated from the vacuum chamber 201 by moving the support shaft 211 for vertically moving the lid 204 in a direction of an arrow C₁ so that the upper side of the tray 218 is exposed through the disc entrance and exit opening 202. Untreated disc substrates D₁ is then sucked to the pads 207a located on the lower side of the pads 207a and 208a provided on the opposite sides of the lid 204, respectively. The support shaft 211 is subsequently immersed into the bottom of the vacuum chamber 201 in a direction of an arrow C₂ in Fig. 18 to lower the lid 204 toward the disc entrance and exit opening 202 for closing the disc entrance and exit opening 202 with one of the closing sides 204a of the lid 204. As a result of this, the inside of the vacuum chamber 201 is sealed from the atmosphere. Although the drawing is exaggeratedly drawn as if sealing is achieved by only the seal member 205 provided on the lid 204, the closing side 204a is practically in a close-contact with the peripheral edge of the disc entrance and exit opening 202. The disc substrate D₁ sucked to one of the closing sides 204a of the lid 204 is placed upon the tray 218 under this condition. At this time, the disc substrate D₁ is positioned in place by means of the projection 218a provided in the substantial center of the tray 218. The vacuum degree which has been lost by the opening and closing operation of the disc entrance and exit opening 202 is recovered by operating the vacuum pump while the disc entrance and exit opening 202 is closed by the lid 204 as shown in Fig. 19. Simultaneously with this, the tray 218 is placed upon the recess 217a of the swing arm 217 by immersing the push up rod 220 in the side at which the vacuum pump and the like is provided in a direction of an arrow D₂ to move the tray 218 downwardly. Since only one swing arm 217 is provided in the present embodiment of the vacuum chamber 201, there is no obstacle for evacuation. Accordingly, a given vacuum degree can be reached at a moment, for example, in only not longer than one second. After the tray 218 has been placed upon the tip end of the swing arm 217, the swing arm 217 is swung to the sputtering treatment portion 203 in a direction of an arrow L₄ in Fig. 16 so that the disc substrate D₁ resting upon the tray 218 is positioned below the disc treatment opening 214 as shown in Fig. 20. After the positioning of the tray 218 has been completed, the push up rod 219 provided below the tray 218 is extended toward the disc treatment opening 214 in a direction of an arrow F₁ for bringing the peripheral edge of the tray 218 into a pressure-contact with the peripheral edge of the disc treatment opening 214 as shown in Fig. 21. As a result of this, the disc treatment opening 214 is closed by the tray 218. Under this condition, sputtering of the disc substrate D₁ is commenced. After the sputtering treatment has been completed, the push up rod 219 is immersed into the side at which the vacuum pump and the like is provided in a direction of an arrow F₂ so that the tray 218 on which the disc substrate D₁ is placed is placed upon the swing arm 217 (compare fig. 22). If the disc substrate D₁ is placed upon the swing arm 217, the swing arm 217 is swung to the disc entrance and exit opening 202 in a direction of an arrow L₂ in Fig. 16 so that the tray 218 on which the disc substrate D₁ formed with a thin film of aluminum is placed is positioned below the disc entrance and exit opening 202 as shown in Fig. 23. If the tray 218 is positioned in a given position, the push up rod 220 is pushed up toward the disc entrance and exit opening 202 in a direction of an arrow J as shown in Fig. 24 to move the tray 218 upwardly so that the tray 218 closes the disc entrance and exit opening 202. The sputtering-treated disc substrate D₁ is sucked by the sucking pads 207a provided on the lid 204 which has closed the disc entrance and exit opening 202. Subsequently, the support rod 211 for vertically moving the lid 204 is pushed upward in a direction of an arrow K in Fig. 25 to separate the lid 204 from the vacuum chamber 201 and the lid 204 is reversed in a direction of an arrow L while the support rod 211 is elevated to change the closing side 204b facing to the disc entrance and exit opening 202. That is, an untreated disc substrate D₂ sucked to the other sucking pad 208a is caused to face to the disc entrance and exit opening 202 and the sputtering treated disc substrate D₁ is reversed to the side opposite to the opening 202. Subsequently, as mentioned above the support rod 211 is immersed into the vacuum chamber 201 side as shown in Fig. 18 to close the disc entrance and exit opening 202 by the lid 204. After sequentially achieving the above-mentioned steps, the untreated new disc substrate D₂ is sputtering-treated. While the new disc substrate D₂ is sputtering-treated, the treated disc substrate D₁ sucked to the closing side 204a opposite to the disc entrance and exit opening 202 is removed and an untreated new disc substrate is sucked to the sucking pads 207a provided on the closing side 204a. Since this operation can be carried out during sputtering treatment, there is sufficient time. Therefore, the present apparatus is very advantageous to automate the sputtering treatment. If the optical discs are manufactured by using the optical disc manufacturing apparatus of the present embodiment in such a manner, loading and unloading of untreated and treated substrates to and from the vacuum chamber 201 can be achieved at a moment and remarkable enhancement of productivity can be expected. For example, the period of time required for manufacturing an optical disc is about 6 seconds and loading and unloading of the disc substrates to and from the vacuum chamber 201 is completed within only 0.5 second. Accordingly, remarkable shortening of the period of time can be expected and the other treatments can be carried out within a sufficient period of time, for example 5.5 seconds. Although the lid 204 for holding members to be treated is a two-sided body provided with closing sides 204a and 204b in the optical disc manufacturing apparatus in which the present invention is embodied, the lid 204 may be a polygon such as three, four and five and more sided body without being limited to two-sided body.

Claims: A sputtering apparatus, comprising: a vacuum chamber (2, 201) having a supply opening (3, 214) through which a member (D1, D2) to be sputtering-treated is loaded and unloaded and a sputtering-treatment portion (4, 203); means for closing (5, 204) said supply opening (3, 202) by any one of a plurality of closing sides (205, 206) which are provided with holding means (207a, 208a) for holding the members (D1, D2) to be sputtering-treated; a tray (11, 218) on which the member (D1, D2) to be sputtering-treated is placed; lifting means (12, 13, 219, 220) for raising and lowering said tray (11, 218) in the position of said sputtering-treatment portion (4, 203) and said supply opening (3, 202); and a swing arm (9, 217) for carrying said member (D1, D2) between said supply opening (3, 202) and said sputtering-treatment portion (4, 203) while the member (D1, D2) to be treated is placed upon the tray (11, 218) in the vacuum chamber (2, 201), whereby the supply opening (3, 202) of the vacuum chamber (2, 201) is closed by the closing means (5, 204) during the sputtering treatment, and the supply opening (3, 202) is closed by the tray (11, 218) while the member (D1, D2) to be sputtering-treated is unloaded and/or a new member (D1, D2) is loaded. A sputtering apparatus according to claim 1, wherein said lifting means (12, 13, 219, 220) includes at least a push up rod (12, 13) which is controlled to raise and lower said tray (11, 218) to close and open said supply opening (3, 202) or to bring the tray (11, 218), which carries said member (D1, D2), in the position of said sputtering-treatment portion (4, 203). A sputtering apparatus according to claim 2, wherein said push up rod is adapted to raise and lower said tray (11, 218) via said swing arm (9, 217). A sputtering apparatus according to claim 1, wherein said closing means (5, 204) is provided to be raised and lowered between a position in which it closes said supply opening (3, 202) and a position above said supply opening (3, 202). A sputtering apparatus according to claim 4, wherein said closing means (5, 204) is raised and lowered while said supply opening (3, 202) is closed by said tray (11, 218). A sputtering apparatus according to claim 1, wherein said closing means (5, 204) selectively switches to select any one of the plurality of closing sides (205, 206), which is to close said supply opening (3, 202) when a sputtering treatment of the member (D1, D2) to be sputtering-treated is performed in said sputtering-treatment portion (4, 203). A sputtering apparatus according to claim 6, wherein said closing means (5, 204) is a body in a polygon form, comprising at least two sidewalls as closing sides (205, 206) whereby the closing sides (205, 206) are provided to be rotatable with respect to said closing means (5, 204). A sputtering apparatus according to claim 1, wherein said tray (11, 218) is provided with positioning means (51, 52, 218a) for positioning the member (D1, D2) to be sputtering-treated resting upon said tray (11, 218).

Inventors: IKEDA JIRO, IKEDA, JIRO
Applicants: SONY CORP, SONY CORPORATION
Application year: 1991
Main classification: C23C14
IPC codes: C23C14, G11B7