Abstract:
A substrate holder configured for holding a substrate, the substrate having a peripheral side surface. The substrate holder includes a base configured for supporting the substrate thereon and at least one block provided on the base. The at least one block is structured and arranged for covering a predetermined area of the peripheral side surface of the substrate.

Description:
TECHNICAL FIELD  
       [0001]     The present invention relates to a substrate holder for use in a sputtering apparatus and a sputtering apparatus having the substrate holder.  
       DESCRIPTION OF RELATED ART  
       [0002]     Amorphous carbon (a-C) and hydrogenated amorphous carbon (a-C:H) films have attractive properties such as high hardness, low friction, electrical insulation, chemical inertness, optical transparency, biological compatibility, selective photon absorption, smoothness etc. For a number of years, these economically and technologically attractive properties have drawn almost unparalleled interest. Carbon films with very high hardness, high resistivity, and dielectric optical properties are now described as diamond-like carbon (DLC).  
         [0003]     Several methods have been developed for producing DLC films such as: primary ion beam deposition of carbon ions (IBD); sputtering deposition of carbon with or without bombardment by an intense flux of ions (physical vapor deposition or PVD); deposition from an RF plasma, sustained in hydrocarbon gases, onto substrates negatively biased (plasma assisted chemical vapor deposition or PACVD).  
         [0004]     A common feature of the aforementioned methods for producing DLC films is that the DLC film is deposited in tiny particles, for example, carbon ions or plasma that is composed of a variety of ions. Typically a plate is used for holding a substrate to be sputtered during the deposition of a DLC film from such particles in a manner such that the DLC film covers the whole surface of the substrate except those parts in contact with the plate. Referring to  FIG. 9 , a DLC film  82  is formed on a substrate  80 . The DLC film  82  includes a wrap structure  822  at the corner of the substrate. The wrap structure  822  has greater inner stress than that of a plain DLC film, so the DLC film  82  often peels at the corners of the substrate  80 .  
         [0005]     Therefore there is a desire to develop a substrate holder for holding a substrate to be sputtered a DLC film thereon and a sputtering apparatus having the same, the substrate holder can prevent wrap structure being formed at a corner of a substrate.  
       SUMMARY  
       [0006]     In one embodiment, a substrate holder configured for holding a substrate, the substrate having a peripheral side surface. The substrate holder includes a base configured for supporting the substrate thereon and at least one block provided on the base. The at least one block is configured (i.e., structured and arranged) for covering a predetermined area of the peripheral side surface of the substrate.  
         [0007]     In another embodiment, A sputtering apparatus for depositing material onto a substrate includes a vacuum chamber; a target holder; and a substrate holder. The target holder and the substrate holder are disposed in the vacuum chamber and face towards each other. The substrate holder is configured for holding the substrate, which includes a base configured for supporting the substrate thereon and at least one block provided on the base. The at least one block is structured and arranged for covering a predetermined area of the peripheral side surface of the substrate.  
         [0008]     This and other features and advantages of the present invention as well as the preferred embodiments thereof and a substrate holder configured for holding a substrate and a sputtering apparatus having the same in accordance with the invention will become apparent from the following detailed description and the descriptions of the drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0009]     Many aspects of the present invention can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present invention.  
         [0010]      FIG. 1  is a cross sectional schematic view of a substrate holder in accordance with a first embodiment;  
         [0011]      FIG. 2  is a cross sectional schematic view of a substrate holder in accordance with a second embodiment;  
         [0012]      FIG. 3  is a cross sectional schematic view of a substrate holder in accordance with a third embodiment;  
         [0013]      FIG. 4  is a schematic view of a baffle plate of the substrate holder in accordance with a fourth embodiment;  
         [0014]      FIG. 5  is a sputtering apparatus in accordance with a fifth embodiment;  
         [0015]      FIG. 6  is similar with  FIG.1 , but showing a substrate held in the substrate holder of  FIG. 1 ;  
         [0016]      FIG. 7  is similar with  FIG. 6  but showing a DLC film deposited on the substrate;  
         [0017]      FIG. 8  is a cross sectional schematic view of the DLC film deposited on the substrate, which has no wrap structure at the corner of the substrate after the substrate holder of  FIG. 7  is removed; and  
         [0018]      FIG. 9  is a cross sectional schematic view of a conventional DLC film deposited on a substrate.  
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0019]     Referring to  FIG. 1 , a substrate holder  100  used in a sputtering apparatus in accordance with a first embodiment includes a base member  10  and at least a block, e.g. a baffle plate  12 . The baffle plate  12  can be fixed on the base member  10  or integrally formed on the base member  10 . The baffle plate  12  and the base member  12  co-orperatively define an open-ended chamber  14  configured for receiving a substrate to be sputtered therein. The baffle plate  12  includes an inner side surface  122  that is configured for tightly contacting with a peripheral side surface of the substrate. The baffle plate  12  has a height higher than that of the substrate. Preferably, the baffle plate  12  is higher than he substrate by a distance from about 1 micrometer to 10 micrometers. In the preferred embodiment, the baffle plate  12  covers the entire peripheral surface of the substrate, alternatively, the baffle plate can cover just the top corner of the substrate.  
         [0020]     Referring to  FIG. 2 , a substrate holder  200  in accordance with a second embodiment is similar to that of the first embodiment, but also includes at least two springs  24 . Each of the springs includes a first end  242  and a second end  244 . The first end  242  is fixed on the base member  20  and the second end  244  is connected with a corresponding baffle plate  22 . Each of the springs  24  is configured for pressing a corresponding baffle plate  22  against a substrate disposed on the base member  20 . Preferably, at least two protrusions  26  are formed on the base member  20 . The first end  232  is connected with a corresponding protrusion  26 .  
         [0021]     Referring to  FIG. 3 , a substrate holder  300  in accordance with a third embodiment is similar to that of the second embodiment except that the at least two springs are replaced by at least two screws  34 . Each of the screws  34  is threadedly engaged with a corresponding protrusion  302  formed on the base member  30 . Each of the screws  34  includes a first end  344 . The first end  344  is configured for pressing a corresponding baffle plate  32  tightly against a substrate to be sputtered.  
         [0022]     Referring to  FIG. 4 , a substrate holder in accordance with a fourth embodiment is similar to that of the first embodiment except that the baffle plate  42  includes a first plate  422  and a second plated  424  slidably connected with the first plate  422 . The second plate  424  is configured for pressing against a substrate to be sputtered disposed on the base member  40 . In the preferred embodiment, the first plate  422  and the second plate  424  both include a slit  4222  thereon. A screw  426  is used for fixing the second plate  424  and the first plate  422 . The relative position of the first plate  422  and the second plate  424  can be adjusted using the slit and the screw  426 . The adjustable height of the baffle plate  422  enables the substrate holder  400  to have better adaptability in processing a variety of substrates having varying thicknesses.  
         [0023]     Referring to  FIG. 5 , a sputtering apparatus  500  having the substrate holder  100  in accordance with a fifth embodiment includes a reactor  50 . The reactor  50  defines a discharge chamber  52  therein. A target holder  54  and the substrate holder  100  are disposed in the discharge chamber  52  face to each other. The target holder  54  is configured for holding a target material such as carbon or graphite thereon. The substrate holder  100  is spaced away from the target material  54  thereby defining an interspace region therebetween. The reactor  50  further defines an inlet  502  and an outlet  504 . A vacuum pump  58  is configured for vacuumizing the discharge chamber  52  through the outlet  504 .  
         [0024]     Referring to  FIG. 6 , a method for sputtering a DLC film with the sputtering apparatus  500  is described below in detail. A substrate  16  to be sputtered is positioned in the open-ended chamber  14  defined by the baffle plate  12  and base member  10 . The substrate  16  includes a top surface  162  and peripheral side surface  164 . The inner side surface  122  tightly contacts with the peripheral side surface  164 . A discharge gas is input into the discharge chamber  52  after the discharge chamber  52  is vacuumized to  10 - 2  Pa or less using the vacuum pump  58 . The discharge gas can be inert gas such as argon, neon etc. Then a voltage is applied between the target material  54  and the substrate  16  for ionizing the discharge gas to form a plasma, the plasma bombards the target material  54  and forms DLC-forming particles. Such particles deposit on the substrate and form a DLC film  18  thereon.  
         [0025]     Referring to  FIG. 7  the DLC film  18  covers both the inner side surface  122  and the top surface  162 , but only a few particles can reach the area near to the corner of the substrate therefore the DLC film formed in that area is very loose and can easily be peeled off. Referring to  FIG. 8 , a DLC film  18  without wrap structure at the corners of the substrate  16  is formed after the substrate holder  100  is removed. Such a DLC film has better peel resistance at the corners of the substrate  16 .  
         [0026]     In the preferred embodiment, we take sputtering as an example to describe the method for depositing a DLC film, however, the substrate holder can also used in other methods for depositing DLC film such as IBD, PVD and chemical vapor deposition (CVD). In other words, we can surround the substrate with a baffle plate in the deposition of a DLC film on a substrate to obtain a DLC film without wrap structure at the corner of the substrate, so that the DLC film has a better peel resistance at the corners of the substrate.  
         [0027]     It is to be understood that the above-described embodiments are intended to illustrate rather than limit the invention. Variations may be made to the embodiments without departing from the spirit of the invention as claimed. The above-described embodiments illustrate the scope of the invention but do not restrict the scope of the invention.