Abstract:
In a method of cleaning a master disk according to the present invention, a self-adhesive surface sticking/peeling operation is performed on dust on the master disk by reciprocatingly oscillating the self-adhesive member while applying external forces in a plurality of directions. Dust on the master disk can be effectively removed by moving the self-adhesive member in this way and by using the adhesion of the self-adhesive member. Since the cleaning method according to the present invention is a removal method using a physical force, it has both the effect of removing organic materials and the effect of removing inorganic materials. Further, according to the present invention, the master disk to be cleaned can be cleaned in a state of being mounted on a disk holding member such as a holder. Therefore an apparatus of a comparatively simple construction can be applied in on-line form according to the cleaning method.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method and apparatus for cleaning a master disk and, more particularly, to a cleaning technique suitable for removing dust attached to a master disk for transfer of magnetic information such as format information to a magnetic recording medium used in a hard disk unit or the like or a master disk used for nanoimprinting. 
     2. Description of the Related Art 
     In recent years, it has been a common practice to write format information and address information to a magnetic disk (hard disk) for use in rapidly-widespread hard disk drives before the magnetic disk is incorporated in a drive after being supplied from a magnetic disk maker to a drive maker. This writing may be performed with a magnetic head. However, a method of (magnetically) transferring such format information and address information at a time from a master disk on which the information is written is effective and preferable. 
     In this kind of magnetic transfer technique or nanoimprinting technique, there is a need to maintain a master disk (transfer original disk) and a slave disk (transfer-destination medium) in closely-contacted state. If the degree of cleanness in the transfer environment is low, there is a problem that fine particles, dust or the like cause transfer failure or scratches or the like on the surface of the master disk. 
     As cleaning techniques, CO 2  cleaning, tape varnishing, a method of moving a foreign material by bringing a master disk into close contact with a substrate with NiP plating (dummy disk) (Japanese Patent Application Laid-Open No. 2001-176065), air blowing, plasma cleaning, scrub cleaning, ultrasonic cleaning, jet cleaning, a method using a cleaning roller (self-adhesive tape) (Japanese Patent Application Laid-Open No. 48-35771, Japanese Patent No. 3346660) and other techniques are known. 
     SUMMARY OF THE INVENTION 
     Each of the conventional techniques, however, has a drawback. That is, CO 2  cleaning is effective in removing inorganic materials but has substantially no effect in removing organic materials and leaves a watermark after cleaning. Tape varnishing entails the generation of dust with a tape. If hard dust is generated, it is dragged on the disk surface after removal to cause a scratch on the surface. 
     The method of using a dummy disk (Japanese Patent Application Laid-Open No. 2001-176065) has a low cleaning effect on a master made of a material having a low surface hardness with respect to the dummy disk. The dust removal effect of air blowing is low. Plasma cleaning has no metal removal effect and has a drawback in that the master surface is oxidized and the removal speed is low. Each of scrub cleaning, ultrasonic cleaning and jet cleaning tends to damage the master surface. Each of these cleaning methods requires removing the disk from the unit to enable cleaning and has low adaptability to a manufacturing line (on-line adaptability). Further, the dust removal effect of the method of using a conventional cleaning roller described in Japanese Patent Application Laid-Open No. 48-35771 is low. 
     Dust attached to a master disk by adhesion and transfer in magnetic transfer or nanoimprinting is dust collapsed by high-pressure pressing and attached to the disk. The attachment of this dust is based on adhesion or biting in the master. Thus, it is difficult to remove a strongly attached foreign material by any of the conventional cleaning techniques, and foreign materials are attached in different forms. It is, therefore, difficult to remove all foreign materials by one method. It has been experimentally confirmed that a removal method using a physical force is most effective in increasing both the effect of removing organic materials and the effect of removing inorganic materials. 
     In view of the above-described circumstances, an object of the present invention is to provide a master disk cleaning method and apparatus capable of effectively removing both organic and inorganic materials and introducible into a manufacturing line (applicable in on-line form). 
     To achieve the above-described object, according to an aspect of the present invention, there is provided a method of cleaning a master disk by removing dust attached on the master disk, including bringing a part of a curved portion of a self-adhesive member formed so as to have a curved self-adhesive surface facing outward into contact with the master disk, and reciprocatingly oscillating the self-adhesive member along a disk plane direction of the master disk while maintaining the part of the curved portion in a state of being pressed against the master disk. 
     According to the aspect, a self-adhesive surface sticking/peeling operation is performed on dust on the master disk by reciprocatingly oscillating the self-adhesive member while applying external forces in a plurality of directions. Dust on the master disk can be effectively removed by moving the self-adhesive member in this way and by using the adhesion of the self-adhesive member. Since the cleaning method according to the present invention is a removal method using a physical force, it has both the effect of removing organic materials and the effect of removing inorganic materials. Further, according to the present invention, the master disk to be cleaned can be cleaned in a state of being mounted on a disk holding member such as a holder. Therefore an apparatus of a comparatively simple construction can be applied in on-line form according to the cleaning method. 
     In another aspect of the present invention, a master disk cleaning method is provided in which if a width in a direction of the reciprocating oscillation of an area of landing of the self-adhesive member maintained in contact with the master disk while being in the pressed state is a; and a peak-to-peak amplitude of the reciprocating oscillation is b, a≧b is satisfied. 
     According to the aspect, the self-adhesive member is not relatively rubbed on the master disk during reciprocating oscillation. Therefore, the disk surface is not scratched by removed dust. 
     In another aspect of the present invention, a self-adhesive sheet is used as the self-adhesive member to form a looped shape of the self-adhesive sheet so that a self-adhesive surface of the self-adhesive sheet faces outward, and the reciprocating oscillation is performed while pressing a part of the looped shape against the master disk. 
     According to the aspect, the removal ability can be maintained by only changing the self-adhesive sheet. Only the self-adhesive sheet exists as an essential consumable, so that the running cost can be limited. 
     In still another aspect of the present invention, the part of the curved portion in contact with the master disk is separated from the master disk while a peeling angle is formed along a lengthwise direction of the self-adhesive member. 
     According to the aspect, no self-adhesive material remains on the master disk, because the part of the curved portion in contact with the master disk is separated from the master disk while a peeling angle is formed along the lengthwise direction of the self-adhesive member. 
     In a further aspect of the present invention, the peeling angle is formed by inclining the self-adhesive member along the lengthwise direction of the self-adhesive member with respect to the master disk. 
     According to the aspect, the peeling angle can be controlled on the side of an apparatus for implementation of the cleaning method. Therefore, the peeling angle can be controlled with improved accuracy when the part of the curved portion in contact with the master disk is separated from the master disk. 
     In still a further aspect of the present invention, the peeling angle is formed by forming the part of the curved portion so that the self-adhesive member is inclined along the lengthwise direction of the self-adhesive member with respect to the master disk when the self-adhesive member and the master disk are disposed by being opposed to each other. 
     According to the aspect, there is no need to provide a mechanism for controlling the peeling angle on the side of an apparatus for implementation of the cleaning method. Therefore the construction of the apparatus can be simplified. 
     The present invention also provides an apparatus for achieving the above-described object. That is, the present invention provides an apparatus for cleaning a master disk by removing dust attached on the master disk, comprising: a disk holding device which holds the master disk, a cleaning head on which a self-adhesive member formed so as to have a curved self-adhesive surface facing outward is held, a head drive device which moves the cleaning head along a direction perpendicular to a disk surface of the master disk held by the disk holding device and along a disk plane direction parallel to the disk surface, and a control device which controls the head drive device to bring a part of a curved portion of the self-adhesive member into contact with the master disk and to reciprocatingly oscillate the self-adhesive member along the disk plane direction of the master disk while maintaining the part of the curved portion in a state of being pressed against the master disk. 
     According to the present invention, the dust removal effect can be improved to enable removal of dust with high efficiency in comparison with the conventional method of simply performing sticking and peeling based on the adhesion of a self-adhesive material only. The present invention therefore enables effectively removing even dust firmly attached on the disk surface by pressing at a high pressure. Also, the present invention ensures high removal ability with respect to either of organic and inorganic materials, because it is a dust removal method using a physical external force. Further, the present invention enables cleaning without detaching the master disk from the apparatus and therefore enables application in on-line form. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view of the construction of a cleaning apparatus according to an embodiment of the present invention; 
         FIG. 2  is a side view seen in the direction of arrow A in  FIG. 1 ; 
         FIG. 3  is a side view seen in the direction of arrow B in  FIG. 1 ; 
         FIG. 4  is a diagram showing the construction of a cleaning head; 
         FIG. 5  is a diagram showing a state when cleaning is performed; 
         FIG. 6  is a side view seen in the direction of arrow C in  FIG. 5 ; 
         FIG. 7  is an enlarged side view seen in the direction of arrow D in  FIG. 5 ; 
         FIG. 8  is a graph showing the results of an experiment in which the relationship between the number of times sticking/peeling was performed and the rate of the dust removal effect; 
         FIG. 9  is a diagram showing translation of the cleaning head; 
         FIG. 10  is a flowchart showing a cleaning sequence in the cleaning apparatus according to the embodiment; 
         FIG. 11  is a diagram showing an example of the construction of a multiple-column head having a plurality of self-adhesive sheet loops in multiple-column form; 
         FIG. 12  is a side view seen in the direction arrow E in  FIG. 11 ; 
         FIGS. 13A to 13C  are diagrams showing the peeling angle formed between the loop of the self-adhesive sheet and the master disk when the loop of the self-adhesive sheet is separated from the disk surface of the master disk; 
         FIG. 14  is an enlarged side view seen in the direction of arrow F in  FIG. 13B ; 
         FIG. 15  is a perspective view corresponding to  FIG. 13B ; and 
         FIGS. 16A and 16B  are diagrams showing examples of expansions of the self-adhesive sheet changing gradually along the lengthwise direction of the self-adhesive sheet. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. 
     First Embodiment 
     [Example of Configuration of Cleaning Apparatus] 
       FIG. 1  is a plan view of a cleaning apparatus according to an embodiment of the present invention.  FIG. 2  is a side view seen in the direction of arrow A in  FIG. 1 .  FIG. 3  is a side view seen in the direction of arrow B in  FIG. 1 . 
     As shown in these figures, the cleaning apparatus  10  has, as its main components, holder units  16  and  18  on which master disks  12  and  14  are held, a drive unit  22  having a device for driving a cleaning head  20 , and a base plate  30 . 
     The holder units  16  and  18  have disk holding surfaces  16 A and  18 A on which the master disks  12  and  14  are held in a vertically upright attitude (such that the disk surface is parallel to a vertical line). The disk holding surfaces  16 A and  18 A of the holder units  16  and  18  face each other while being spaced apart from each other by a predetermined distance. The holder units  16  and  18  are positioned and fixed on the base plate  30 . 
     The drive unit  22  has a first-axis drive mechanism  26  which moves the cleaning head  20  attached to an end of an arm  24  in a direction perpendicular to the disk surface (the first axis: X-axis in  FIG. 1 ) and a second-axis drive mechanism  28  which moves the cleaning head  20  in a direction parallel to the disk surface (the second axis: Y-axis in  FIG. 1 ). The drive unit  22  is positioned and fixed on the base plate  30 . 
     The arm  24  may have a turning function to enable the cleaning head  20  to have its lengthwise direction at any angle from the disk holding surface  16 A or  18 A, as described below. 
     The first-axis and second-axis drive mechanisms  26  and  28  are respectively constituted by linear rails  32  and  34  disposed along their axes, ball screws  36  and  38 , motors  40  and  42  and slider tables  44  and  46 . The first-axis and second-axis drive mechanisms  26  and  28  form an XY stage, which is two-axis motor controlled. 
     The cleaning head  20  is pressed against the disk surface and moved apart from the disk surface by the first-axis drive mechanism  26 . An operation to oscillate the cleaning head  20  and lateral translation of the cleaning head  20  are performed by the second-axis drive mechanism  28 . Each of the motors  40  and  42  is connected to a controller  48  and controlled in accordance with a sequence described below. 
     The base plate  30  is a base member for setting (positioning) and fixing the holder units  16  and  18  and the drive unit  22  in a specified relative positional relationship. It is preferable that the holder units  16  and  18  and the drive unit  22  be constructed so as to be detachably attached to the base plate  30 . 
     A self-adhesive sheet  50  having a width larger than the external shape (diameter) of the master disks  12  and  14  is fixed on the cleaning head  20 , forming a loop so that its adhesive surface faces outward (forms an external surface). The portion of the adhesive sheet  50  forming such a loop will be referred to simply as “loop”. In the present embodiment, a two-head structure is adopted in which two cleaning heads  20  are disposed back to back in correspondence with two holder units  16  and  18 . However, an apparatus construction using one head capable of facing each of two holder units  16  and  18  may alternatively be adopted. Such a construction may be implemented by providing a rotating (inverting) mechanism on a head portion while removing the head on one side. 
       FIG. 4  shows the construction of the cleaning head  20 . As self-adhesive sheet  50 , a rectangular sheet of a predetermined size cut out from a roll is used. This rectangular self-adhesive sheet is roundly bent into a looped shape by turning its one end, with the self-adhesive surface facing outward. The turned end and the other end are superposed on each other and pinched in a head jig (block) as illustrated, thus attaching the adhesive sheet  50 . In this way, a loop  52  in tear drop form is obtained. The held form of the self-adhesive sheet  50  is not limited to the example shown in  FIG. 4 . The self-adhesive sheet  50  may be held in any other form in which the self-adhesive sheet is formed into a curved shape with the self-adhesive facing outward. 
     For example, BT-150E-KL (trade name), a product from NITTO DENKO CORPORATION, may be used as the self-adhesive sheet  50 . Good reseparability is required as a performance characteristic of the self-adhesive sheet to be used. If the reseparability is low, the self-adhesive material is attached to the master disk to contaminate the same. 
       FIG. 5  is a diagram showing a state where cleaning is performed.  FIG. 6  is a side view seen in the direction of arrow C in  FIG. 5 .  FIG. 7  is an enlarged side view seen in the direction of arrow D in  FIG. 5 . Hatched portions in  FIGS. 5 and 6  represent the self-adhesive sheet  50 . 
     As shown in these figures, when cleaning is performed, the loop  52  of the self-adhesive sheet  50  is brought into contact with the master disk  12  (or  14 ) and pressed against the master disk  12  (or  14 ) to such a degree that the loop  52  is not completely collapsed. In this pressed state, the cleaning head  20  (i.e., the loop  52 ) is reciprocated (swung) in a direction along the disk surface. 
     In oscillating the loop  52  without dragging (rubbing) on the disk surface, it is preferable that if the width of the contact area of the loop  52  in the oscillating direction formed by pressing is a; and the peak-to-peak amplitude of oscillation is b (the zero-to-peak amplitude is b/2), a≧b is satisfied (see  FIG. 7 ). For example, in the case of cleaning of a master disk having a diameter of about 65 mm, it is preferable that the width a of the contact area when the self-adhesive sheet  50  is pressed and collapsed be within the range from 1 to 5 mm. For example, the peak-to-peak amplitude b is set to 2.5 mm when the width a of the contact area is 3 mm. 
     Thus, the self-adhesive sheet  50  is made to move on the master disk  12  ( 14 ) so that adhesion and peeling on a small scale are repeated. In particular, it is desirable to peel off the self-adhesive sheet  50  by applying an external force in a direction parallel to the master disk surface while the self-adhesive sheet  50  in contact with the master disk  12  ( 14 ) is being pressed against dust as effectively as possible. 
     The shape of the loop  52  in the pressed state (the degree of flatness during pressing and collapsing) and the contact area (corresponding to “landing area”) vary depending on the rigidity (elasticity) of the self-adhesive sheet  50 , the force by which the loop  52  is pressed against the disk surface and the like. From the viewpoint of dust removal performance, the optimum conditions (such as conditions in terms of contact area and oscillation amplitude, conditions in terms of oscillation (reciprocating) period and the number of oscillations and a condition in terms of pressing force) are experimentally determined in advance on the basis of the characteristics of the self-adhesive sheet  50  to be used (such as the rigidity, elasticity and adhesion of the sheet). 
     For example, in an experiment made to examine the relationship between the number of sticking/peeling oscillations and the rate of removal of dust attached to a master with respect to a standard powder (polypropylene, SUS) collapsed at a disk adhesion pressure of 0.4 MPa in a case where BT-150E-KL (trade name), a product from NITTO DENKO CORPORATION, was used as the self-adhesive sheet, experimental results such as shown in  FIG. 8  were obtained when the contact width was set to 3 mm, the oscillation amplitude to 2.5 mm, the reciprocating time to 1 second/reciprocation, and the head translation pitch to 1 mm. According to the experimental results shown in  FIG. 8 , a dust removal rate of 80% was achieved with respect to polypropylene when the number of sticking/peeling oscillations was 10 or more; a dust removal rate of 70% was achieved with respect to SUS (stainless steel) when the number of sticking/peeling oscillations was 20 or more; and a removal rate of 80% was achieved with respect to SUS when the number of sticking/peeling oscillations was 30 or more. 
     From these results and the results of other experiments in which different conditions were set, it is known that making sticking/peeling oscillations 30 to 40 times suffices for achieving a dust removal rate of 70% or more regardless of the kind of dust. 
     On the basis of this knowledge, the amount of pressing of the loop  52  (contact area), the oscillation amplitude, the oscillation period, the number of oscillations and other conditions are controlled. Cleaning based on the above-described oscillating operation is performed at each of different positions (cleaning positions on the disk) to which the cleaning head  20  is fed with a predetermined pitch, as shown in  FIG. 9 . 
     That is, cleaning based on the above-described oscillating operation is repeatedly performed through a stroke range corresponding to the entire area of the disk while changing the position (the cleaning position on the disk) of the cleaning head  20  with a predetermined translation pitch. It is preferable that the head translation pitch be equal to or smaller than the width a of the contact area. In particular, it is preferable to set the head translation pitch equal to or smaller than the zero-to-peak amplitude (b/2) of oscillation. That is, if head translation pitch≦b/2 is satisfied, the sticking/peeling oscillating operation can be performed at least two times in two directions on one batch of dust. For example, if the translation pitch is set to 1 mm in condition setting when a=3 mm and b=2.5 mm, sticking/peeling can be performed in two directions on one batch of dust. 
     [Description of Cleaning Sequence] 
       FIG. 10  is a flowchart showing a cleaning sequence in the cleaning apparatus according to the present embodiment. 
     When the operation of the apparatus is started (step S 110 ), the cleaning head  20  is first moved to a starting origin position (step S 112 ). For example, in a case where cleaning is performed by moving from the left end of the disk to the right as viewed in  FIG. 9 , the leftmost cleaning position corresponds to the starting origin position. 
     Next, the head is moved to the position for the set amount of pressing (step S 114 ). This movement is caused in the direction of bringing the loop  52  into contact with the master disk  12  ( 14 ) (X-axis direction in  FIG. 1 ). Cleaning is performed by reciprocating the head with the peak-to-peak amplitude b (zero-to-peak amplitude b/2) in the Y-axis direction under the condition for realizing the predetermined contact area (width a) (step S 116 ). Sticking/peeling cleaning by this small amount of oscillation is executed for a predetermined time (or until a predetermined number of reciprocating oscillations is reached). The cleaning head  20  is thereafter moved away from the disk (step S 118 ) to separate the loop  52  from the disk surface. 
     The head is then translated by the distance corresponding to the translation pitch set in advance (step S 120 ). Determination is made as to whether or not the movement of the head through the translation stroke set in advance has been completed by this head translation (step S 122 ). 
     If the result of this determination is that the amount of movement corresponding to the predetermined translation stroke has not been reached, the process returns to step S 114  and the above-described operation (steps S 114  to S 122 ) is repeated. Cleaning on the entire area of the disk is executed by performing the cleaning operation at each position while translating the head with the predetermined pitch. When the cleaning on the entire area of the disk is finished by completing the movement through the predetermined translation stroke, the result of determination in step S 122  is Yes, that is, it is determined that the movement through the predetermined translation stroke has been completed. 
     In this case, the head is moved to the origin position (step S 124 ) and the operation of the apparatus is stopped (step S 126 ). 
     In the case of the construction provided with the two holder units  16  and  18  shown in  FIG. 1 , the above-described processing flow (steps S 110  to S 126 ) is executed for the holder units  16  and  18  one from another. That is, when the processing flow shown in  FIG. 10  is completed with respect to the disk held on one holder unit (on one side) (e.g., the one indicated by  16 ), the head is moved to the (other) holder unit on the opposite side (e.g., the one indicated by  18  in this case), followed by the same processing. 
     The controller  48  shown in  FIG. 1  includes a storage device storing a program for controlling the drive unit  22  of the cleaning apparatus  10  by the sequence as shown in  FIG. 10 , and a computer which executes the program. 
     (Modified Example) 
     While one-column cleaning head  20  is used in the apparatus shown in  FIG. 1 , a multiple-column head  21  having loops  52  arranged at certain intervals (arrangement pitch δ) in multiple column form, as shown in  FIGS. 11 and 12 , may be used, whereby the number of times pitch translation is performed can be reduced to improve the cleaning efficiency. 
     The arrangement using the multiple-column head  21  having an array of a plurality of columns as shown in  FIGS. 11 and 12  enables increasing the area of cleaning performed one time and enables the entire disk surface to be cleaned by pitch translation with a pitch equal to about half the arrangement pitch δ of the self-adhesive loops, thus improving the cleaning efficiency. 
     Second Embodiment 
     A second embodiment of the present invention has a feature relating to step S 118  in the flowchart representing the cleaning sequence shown in  FIG. 10 . More specifically, the feature relates to the operation to separate the loop  52  of the self-adhesive sheet  50  from the disk surface  12 A ( 14 A) of the master disk  12  ( 14 ) by moving the cleaning head  20  away from the master disk  12  ( 14 ). In other respects, the sequence of the second embodiment is the same or similar to the example described in the description of the first embodiment. The description of the same or similar details of the sequence will not be repeated. 
     With respect to step S 118  shown in  FIG. 10 , a method of separating the loop  52  from the disk surface  12 A ( 14 A) by moving the cleaning head  20  away from the disk surface  12 A ( 14 A) directly in the direction perpendicular to the disk surface  12 A ( 14 A) is conceivable. 
     In the second embodiment, however, a method of separating the loop  52  from the disk surface  12 A ( 14 A) while forming a peeling angle between the loop  52  and the disk surface  12 A ( 14 A) is proposed. 
     This method will be described below in detail.  FIGS. 13A to 13C  are diagrams showing separation of the loop  52  from the disk surface  12 A ( 14 A) in the second embodiment. 
       FIG. 13A  is a side view ( FIG. 6 ) seen in the direction of arrow C in  FIG. 5 , showing a state in which the loop  52  is brought into contact with the disk surface  12 A ( 14 A) with the contact width a by being pressed against the disk surface  12 A ( 14 A) by the cleaning head  20 . 
     From the state shown in  FIG. 13A , the cleaning head  20  is moved away from the disk surface  12 A ( 14 A) in the direction perpendicular to the disk surface (an upward direction as viewed in the figure), as shown in  FIG. 13B . The amount of pressing of the loop  52  against the disk surface  12 A ( 14 A) is thereby reduced, so that the loop  52  and the disk surface  12 A ( 14 A) are made to contact each other with a contact width a′. The relationship between the contact widths a and a′ is a&gt;a′. The area of contact between the loop  52  and the disk surface  12 A ( 14 A) is smaller in the state shown in  FIG. 13B  than in the state shown in  FIG. 13A . 
     The state shown in  FIG. 13B  corresponds to a state such as seen in  FIG. 14  along the lengthwise direction of the cleaning head  20 .  FIG. 14  is an enlarged side view seen in the direction of arrow F in  FIG. 13B .  FIG. 15  shows a corresponding perspective view. 
     Next, from the state shown in  FIG. 13B , the loop  52  is separated from the disk surface  12 A ( 14 A) while forming a peeling angle θ therebetween along the lengthwise direction of the self-adhesive sheet  50 , as shown in  FIG. 13C . The reason for forming the peeling angle θ along the lengthwise direction of the self-adhesive sheet  50  in this way is as described below. 
     From the state shown in  FIG. 13A  to the state shown in  FIG. 13B , the loop  52  is separated while being taken off in a state of having an arbitrary peeling angle from the disk surface  12 A ( 14 A). However, a stripping phenomenon occurs at the time of separation of the loop  52  from the disk surface  12 A ( 14 A) from the state shown in  FIG. 13B , such that an extremely large peeling force is produced. 
     Then, the loop  52  is separated from the disk surface  12 A ( 14 A) while forming the peeling angle θ along the lengthwise direction of the self-adhesive sheet  50 , as shown in  FIG. 13C . The occurrence of the stripping phenomenon is prevented in this way. Therefore the interface adhesion between the disk surface  12 A ( 14 A) and the self-adhesive material does not prevail over the cohesion of the loop  52 . As a result, the effect of preventing the occurrence of cohesion breakdown of the self-adhesive material that allows the self-adhesive material to remain on the disk surface  12 A ( 14 A) can be obtained. 
     The loop  52  may be separated from the disk surface  12 A ( 14 A) from the state shown in  FIG. 13A  to the state shown in  FIG. 13B  while forming the peeling angle θ along the lengthwise direction of the self-adhesive sheet  50  as shown in  FIG. 13C  without reducing the area of contact between the loop  52  and the disk surface  12 A ( 14 A). 
     The operation to separate the loop  52  from the disk surface  12 A ( 14 A) while forming the peeling angle θ along the lengthwise direction of the self-adhesive sheet  50  will be described in more detail. An operation to turn the cleaning head  20  for forming the peeling angle θ along to the lengthwise direction of the self-adhesive sheet  50  will be described with respect to cases relating to points on which the cleaning head  20  is turned to form the peeling angle θ along the lengthwise direction of the self-adhesive sheet  50 . 
     A case where the arm  24  shown in  FIGS. 1 and 2  has such a turning function as to turn the cleaning head  20  on an axis corresponding to a center of the cleaning head  20  in the lengthwise direction will first be considered. 
     In this case, the cleaning head  20  is turned through the predetermined angle θ on an axis corresponding to a center of the cleaning head  20  in the lengthwise direction so as to be moved away from the disk surface  12 A ( 14 A) at one end A (see  FIG. 13 ) side and brought closer to the disk surface  12 A ( 14 A) at the other end B (see  FIG. 13 ) side. 
     Then, the portion of the loop  52  from the end A side to the center in the lengthwise direction is gradually separated from the disk surface  12 A ( 14 A) while forming the peeling angle θ and is thereafter separated completely from the disk surface  12 A ( 14 A). On the other hand, the amount of pressing on the portion of the loop  52  from the center to the end B side in the lengthwise direction is increased to bend the loop  52 . 
     Thereafter, the turning operation of the cleaning head  20  is stopped and the cleaning head  20  is gradually moved away from the disk surface  12 A ( 14 A) in the direction perpendicular to the disk surface  12 A ( 14 A) by the first-axis drive mechanism  26 . The amount of pressing is then reduced in the region from the center of the loop  52  to the end B side in the lengthwise direction to reduce the amount of bending of the loop  52 . Also, the loop  52  and the disk surface  12 A ( 14 A) are gradually separated from each other while forming the peeling angle θ. At this time, the area of contact between the loop  52  and the disk surface  12 A ( 14 A) is gradually reduced along the lengthwise direction of the self-adhesive sheet  50 . When the cleaning head  20  is moved away to a predetermined distance from the disk surface  12 A ( 14 A), the loop  52  and the disk surface  12 A ( 14 A) are completely separated from each other. The loop  52  and the disk surface  12 A ( 14 A) can be separated from each other in the above-described way. 
     The loop  52  and the disk surface  12 A ( 14 A) can also be separated from each other in a similar way by turning the cleaning head  20  through the predetermined angle θ on an axis corresponding to the center of the cleaning head  20  in the lengthwise direction so that the loop  52  is separated from the disk surface  12 A ( 14 A) at the end B side and is brought closer to the disk surface  12 A ( 14 A) at the end A side. 
     A case where the cleaning head  20  is turned on an axis at the end A side in the lengthwise direction of the cleaning head  20  will next be considered. In this case, the cleaning head  20  is turned through the predetermined angle θ on an axis at the end A side in the lengthwise direction of the cleaning head  20  so as to be lightly pressed against the disk  12  ( 14 ) at the end B side. While being maintained in this state, the cleaning head  20  is gradually moved away from the master disk  12  ( 14 ) in the direction perpendicular to the disk surface  12 A ( 14 A). 
     The loop  52  and the disk surface  12 A ( 14 A) are then separated gradually from each other from the end A side in the lengthwise direction of the cleaning head  20  while forming the peeling angle θ along the lengthwise direction of the self-adhesive sheet  50 . At this time, the area of contact between the loop  52  and the disk surface  12 A ( 14 A) is gradually reduced along the lengthwise direction of the self-adhesive sheet  50 . When the cleaning head  20  is moved away by a predetermined distance, the loop  52  and the disk surface  12 A ( 14 A) are completely separated from each other. The loop  52  and the disk surface  12 A ( 14 A) can be separated from each other in the above-described way. 
     The loop  52  and the disk surface  12 A ( 14 A) can also be separated from each other in a similar way by gradually separating the loop  52  and the disk surface  12 A ( 14 A) from the end B side in a case where an axis on which the cleaning head  20  is turned is set at the end B side in the longitudinal direction. 
     A case where the cleaning head  20  is turned on an axis at the end B side in the lengthwise direction of the cleaning head  20  will next be considered. In this case, the angle of turning of the cleaning head  20  on an axis at the end B side in the lengthwise direction of the cleaning head  20  is gradually increased so that the cleaning head  20  is moved away from the master disk  12  ( 14 ) at the end A side. 
     The loop  52  and the disk surface  12 A ( 14 A) are then separated gradually from each other from the end A side in the lengthwise direction of the cleaning head  20  while forming the peeling angle θ along the lengthwise direction of the self-adhesive sheet  50 . At this time, the area of contact between the loop  52  and the disk surface  12 A ( 14 A) is gradually reduced along the lengthwise direction of the self-adhesive sheet  50 . 
     When the angle of turning of the cleaning head  20  reaches a predetermined angle, the loop  52  and the disk surface  12 A ( 14 A) are completely separated from each other. The loop  52  and the disk surface  12 A ( 14 A) can be separated from each other in the above-described way. 
     The loop  52  and the disk surface  12 A ( 14 A) can also be separated from each other in a similar way by gradually separating the loop  52  and the disk surface  12 A ( 14 A) from the end B side in a case where an axis on which the cleaning head  20  is turned is set at the end A side in the longitudinal direction. 
     As described above, a mechanism for turning the cleaning head  20 , e.g., a mechanism on the arm  24  is provided to control the peeling angle on the cleaning apparatus  10  side, thereby enabling more accurate peeling angle control at the time of separation between the loop  52  and the disk surface  12 A ( 14 A). 
     The arrangement may alternatively be such that the self-adhesive sheet  50  is attached to the cleaning head  20  in a slant position in advance as shown in  FIG. 16A , or a self-adhesive sheet  50 ′ formed into a trapezoidal shape as shown in  FIG. 16B  is attached to the cleaning head  20 . In this way, the loop  52  can be set in a state of slanting slightly with respect to the disk surface  12 A ( 14 A) along the lengthwise direction of the self-adhesive sheet  50  when the loop  52  is opposed to the disk surface  12 A ( 14 A). Since there is no need to provide a mechanism for controlling the peeling angle on the cleaning apparatus  10  side, the construction of the cleaning apparatus  10  can be simplified. 
     More specifically, in expansions H 1  and H 2  of the loop  52  of the self-adhesive sheet  50  out of the cleaning head  20 , the expansion H 1  on one side along the lengthwise direction of the self-adhesive sheet  50  and the expansion H 2  on the opposite side are set different from each other (H 1 &gt;H 2  in  FIGS. 16A and 16B ), and the expansion of the self-adhesive sheet  50  changes gradually along the lengthwise direction of the cleaning head  20 . The expansion H 2  is set at the side at which the loop  52  is first separated from the disk surface  12 A ( 14 A), while the expansion H 1  is set at the side of at which the loop  52  is finally separated from the disk surface  12 A ( 14 A). 
     As a result, separation of the loop  52  from the disk surface  12 A ( 14 A) forming the peeling angle θ along the lengthwise direction of the self-adhesive sheet  50  can be achieved by only moving the cleaning head  20  in the direction perpendicular to the disk surface  12 A ( 14 A). 
     The controller  48  shown in  FIG. 1  also includes a storage device storing a program for controlling the operation according to the second embodiment and a computer which executes the program. 
     The present invention can be suitably applied as a technique to clean a master disk for magnetic transfer used in manufacture of a magnetic recording medium. However, the range of application of the present invention is not limited to this. The present invention is applicable to any transfer apparatuses for transferring magnetic information, shape information or the like by bringing a transfer original and a transfer-destination medium into close contact with each other. That is, the present invention can be suitably applied to transfer techniques using magnetic transfer, nanoimprinting, patterned media, etc.