Abstract:
An inductive-coupled plasma apparatus employs a shield to reduce sputter contamination. A method for manufacturing the shield is included. An apparatus for generating a high-density plasma includes a process chamber having a dielectric window located along a plane, a coil located outside the process chamber proximate to the dielectric window and substantially parallel to the plane, and a shield located between the coil and the dielectric window. The shield has multiple openings, wherein the multiple openings of the shield are disposed at locations corresponding to areas between the turns of the coil.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0001]    The present application claims priority under 35 U.S.C. §119 to Korean Patent Application No. 99-12530 filed on Apr. 9, 1999, the entire contents of which are hereby incorporated by reference for all purposes.  
         BACKGROUND OF THE INVENTION  
         [0002]    1. Field of the Invention  
           [0003]    The present invention relates to the field of semiconductor device manufacturing and, more particularly to an inductive-coupled plasma apparatus employing a capacitive shield to reduce sputter contamination and a method for manufacturing the shield.  
           [0004]    2. Description of the Background Art  
           [0005]    The uniform and rapid processing of materials using induction generated, plasma-based processes (also referred to as inductive-coupled plasma processes ) is important in the fields of semiconductor device manufacturing, packaging, optics, and the like. Many plasma processes are extensively used for the depositing or reactive etching of layers during semiconductor device fabrication. Especially, a radio frequency (RF at about 13.56 MHz) induction plasma source is known to produce high electron density plasma, thus providing high processing rates.  
           [0006]    For example, a semiconductor substrate is disposed within an evacuated chamber coupled to a source of plasma. By appropriately biasing the substrate, the plasma is coupled to the substrate for ion bombarding the substrate, for etching patterns in the substrate, or for depositing ions on the substrate to grow layers of selected materials thereon.  
           [0007]    Hereinafter a conventional inductive-coupled plasma apparatus shown in FIG. 1 and FIG. 2 is explained in detail. The conventional inductive-coupled plasma apparatus includes a process chamber  20  and a RF housing  40  which is often called a match box. The process chamber  20  includes a supporter  22  for supporting at least one semiconductor wafer  28 , an edge ring  24  surrounding the supporter  22  and a gas injection ring  26  for injecting gas into the process chamber  20 . Also the process chamber  20  further includes a pump  30  for controlling a pressure of an inner space of the process chamber  20 .  
           [0008]    A spiral coil  44  shown in FIG. 2 is coupled to the RF housing  40 . Power is supplied from RF power supply line  48  to the spiral coil  44 . The spiral coil  44  is supported by a coil holder  46 , which is fixed to the RF housing  40  through a rod  80 . The spiral coil  44  is separated from the plasma by a planar dielectric window  42 .  
           [0009]    However, in this conventional apparatus, high potentials on the coil cause some degree of capacitive coupling. Therefore, some particular regions, especially regions located underneath the coil on the surface of the planar dielectric window, are etched more excessively than other regions. Thus the etching process is contaminated due to falling particles from the etched regions of the planar dielectric window.  
           [0010]    A technique is thus desired for maintaining high inductive coupling between the coil and the plasma, so that improved processing rates and reduction of sputtered contaminates from the dielectric window may be realized.  
         SUMMARY OF THE INVENTION  
         [0011]    The present invention is therefore directed to an inductive coupled plasma apparatus which substantially overcomes one or more of the problems due to the limitations and disadvantages of the related art.  
           [0012]    It is therefore an object of the present invention to provide an apparatus for maintaining high inductive coupling and reducing sputtered contaminates from the dielectric window.  
           [0013]    The present invention is directed to an apparatus for enhanced inductive coupling to plasma with reduced sputter contamination. The present invention eliminates sputtering of the dielectric window generated by high potentials on the adjacent spiral-like or helical coil by adding a shield between the dielectric window and the coil.  
           [0014]    The shields of the present invention are designed so that they do not interfere with the inductive coupling of the coil to the plasma, but interfere with the capacitive electric fields generated by the coil.  
           [0015]    A primary advantage of the shield of the present invention is the reduction or elimination of sputtered contaminants from the dielectric vacuum window.  
           [0016]    In order to attain the above objects, according to an aspect of the present invention, there is provided an apparatus for generating a high-density plasma, which includes a process chamber having a dielectric window located along a plane, a coil located outside the process chamber proximate the dielectric window and substantially parallel to the plane and a capacitive shield located between the coil and the dielectric window, wherein the shield has multiple openings, and wherein the multiple openings of the shield are disposed at locations corresponding to areas between the coil.  
           [0017]    In the apparatus according to the invention, the coil may be spiral-shaped and the dielectric window and the shield may be substantially flat, and each of the multiple openings of the shield may be concentric-shaped.  
           [0018]    Furthermore, the shield may further include a portion extending outwardly and the apparatus may further include a shield holder for supporting the shield by coupling the portion extending outwardly.  
           [0019]    Still further, in the apparatus, the coil may be helical-shaped, the dielectric window and the shield may be disposed concentrically within the coil, and the shield may have a number of helically extending and circumferentially spaced openings.  
           [0020]    Still further, in the apparatus, the shield may be made of an aluminum metal or a copper metal, and a surface of the shield may be coated with a silver.  
           [0021]    According to another aspect of this invention, there is provided a method of manufacturing a shield of an apparatus for generating a high-density plasma using a coil and having a dielectric window, the method including carrying out an etching process using the plasma, examining a characteristic pattern of etched portions of the surface of the dielectric window, designating first portions to be etched and second portions to be deposited, manufacturing the shield having a first portion corresponding to first portions of the dielectric window and a second portion to be opened corresponding to second portions of the dielectric window, and disposing the second portion of the shield at locations corresponding to areas between the coil.  
           [0022]    Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]    A more complete appreciation of the present invention, and many of the attendant advantages thereof, will become readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings, which are given by way of illustration only and thus are not limitative of the present invention, and in which like reference symbols indicate the same or similar components, wherein:  
         [0024]    [0024]FIG. 1 is a sectional view showing a conventional inductive-coupled plasma apparatus for etching;  
         [0025]    [0025]FIG. 2 is a plane view showing a spiral coil of the inductive-coupled plasma apparatus shown in FIG. 1;  
         [0026]    [0026]FIG. 3 is a view showing a surface of a dielectric window of the inductive-coupled plasma apparatus shown in FIG. 1 after an etching process;  
         [0027]    [0027]FIG. 4 is a diagram showing patterns copied from a characteristic of the surface of the dielectric window shown in FIG. 3;  
         [0028]    [0028]FIG. 5 is a flowchart showing a method of manufacturing a shield of the present invention;  
         [0029]    [0029]FIG. 6 is a plane view showing a shield according to a preferred embodiment of the present invention;  
         [0030]    [0030]FIG. 7 is an exploded perspective view showing a coil unit of an inductive-coupled plasma apparatus according to a preferred embodiment of the present invention;  
         [0031]    [0031]FIG. 8 is a sectional view showing an inductive-coupled plasma apparatus including the shield according to a preferred embodiment of the present invention; and  
         [0032]    [0032]FIG. 9 is an exploded perspective view showing a shield used in a helical coil according to another preferred embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0033]    It should be understood that the description of this preferred embodiment is merely illustrative and that it should not be taken in a limiting sense. In the following detailed description, several specific details are set forth in order to provide a thorough understanding of the present invention. It will be obvious, however, to one skilled in the art that the present invention may be practiced without these specific details.  
         [0034]    With reference to FIG. 3 through FIG. 8, one preferred embodiment of a inductive-coupled plasma apparatus according to the invention is described.  
         [0035]    A characteristic etching pattern shown in FIG. 3 and FIG. 4 indicates the fact that the etched portions of the surface of the dielectric window coincide with a configuration of the spiral coil. To explain the above mentioned fact in detail according to FIG. 4, portions indicated by numerals  1 ,  3 ,  4  and  6  are etched portions and portions indicated by numerals  2  and  5  are portions deposited with particles. According to the etched pattern, the etched portions are all disposed underneath the coil.  
         [0036]    The high potentials on the coil cause some degree of capacitive coupling, particularly in the vertical direction of the coil (or in an orthogonal direction between the coil and the dielectric window). This capacitive coupling collects ions, which results in etching at the particular regions of the dielectric window disposed underneath the coil. Therefore, some particular regions of the dielectric window disposed underneath the coil are etched more excessively than other regions.  
         [0037]    Therefore, the shield of a preferred embodiment of the present invention as illustrated in FIG. 6 includes two regions. The first regions indicated by  62 - 1 ,  62 - 2 ,  62 - 3  and  62 - 4  corresponding to the coil are not opened and the second regions  64 - 1 ,  64 - 2 ,  64 - 3  and  64 - 4  corresponding to areas disposed between the turns of coil are open. The first regions  62 - 1 ,  62 - 2 ,  62 - 3  and  62 - 4  are disposed underneath the coil and are added between the coil and the dielectric window to protect the surface of the dielectric window against capacitive coupling in the vertical direction. The second regions  64 - 1 ,  64 - 2 ,  64 - 3  and  64 - 4  are disposed at locations corresponding to areas between the turns of the coil and are arcuate-split or concentric split shaped.  
         [0038]    In the present invention, the shield is manufactured by the following steps according to FIG. 5. At first step S 500 , the etching process is carried out using the plasma, and in the next step S 510 , a characteristic pattern of etched portions on the surface of the dielectric window is examined. In the next step S 520 , first portions of the dielectric window that are etched and second portions that are deposited are designated, and in the next step S 530 , the shield having a first portion corresponding to the first portions of the dielectric window and a second portion to be opened corresponding to the second portions of the dielectric window is manufactured. And in final step S 540 , the shield is disposed so that the second portion is disposed at locations corresponding to areas between the coils.  
         [0039]    However, it is to be understood that the shape of the slits of the shield according to the present invention is not limited to the disclosed preferred embodiments. On the contrary, it is intended to cover various modifications and similar arrangements.  
         [0040]    With reference to FIGS.  7 - 9 , shields of preferred embodiments of the present invention are described.  
         [0041]    Shield  60  of a preferred embodiment of the present invention is added between the coil  44  and the dielectric window  42  shown in FIG. 8. The coil  44  is supplied with power by RF power supply source  48 . A coil holder  46  holds the coil  44 .  
         [0042]    The shield  60  is fixed to at least one shield holder  70 . The shield holder  70  includes a slit  72  to contain an extending portion  66  of the shield  60  and a screw hole  74  for coupling a screw  76 .  
         [0043]    In a preferred embodiment of the present invention, as most clearly seen in FIG. 7, a central portion  51  of coil  44  is open. A first portion  50 ,  52  of the coil  44  is disposed corresponding to a first cover portion  62 - 1  of the shield  60 , a second portion  54  is disposed corresponding to a second cover portion  62 - 2  of the shield  60 , a third portion  56  of the coil  44  is located corresponding to a third cover portion  62 - 3  and a fourth portion  58  of the coil  44  is located corresponding to a fourth cover portion  62 - 4 .  
         [0044]    As described above, portions of the shield  60  corresponding to locations underneath the coil are portions having no hole or slit, but portions of the shield corresponding to locations underneath gaps between the turns of coils are portions that are opened, or for example having slits or holes. Portions having no hole protect the dielectric window against capacitive coupling. Thus, particular portions of the dielectric window corresponding to locations underneath the coil are not excessively etched.  
         [0045]    Referring to FIG. 8, an inductive-coupled plasma apparatus including a shield having multiple slits is illustrated.  
         [0046]    The shield  60  is added between the coil  44  supported by the coil holder  46  and the dielectric window  42 . The shield  60  is supported by the shield holder  70 . In the slit  72  of the shield holder  70 , the extending portion  66  of the shield  60  is inserted.  
         [0047]    A shield according to another preferred embodiment of the present invention is illustrated in FIG. 9. The apparatus shown in FIG. 9 includes a helical coil  86 , a shield  84  disposed concentrically within the coil  86 , and an internal tube  82  of a low loss dielectric insulating material, e.g., of quartz.  
         [0048]    A lower end of the coil  86  is electrically connected to the shield  84  by a screw  90 . The shield  84  can be mounted on the internal tube  82  or coupled to the inner wall of a process chamber by a coupling mechanism. The coupling mechanism includes a support member  110  and an extending member  100  of the shield  84 . The support member  110  may be coupled to an extending member  100  with a screw  120 . The support member  110  can be connected with the process chamber.  
         [0049]    The shield  84  is provided with a number of helically extending and circumferentially spaced slits  88 . The shape of the slits  88  correspond to the shape of the helical coil  86 .  
         [0050]    In the present invention, the shield may be made of an aluminum metal, or a copper metal which has a good conductive property. Also, the surface of the shield can be coated with a silver, which increases conductivity and prevents corrosion.  
         [0051]    In a preferred embodiment of the present invention, the thickness of the shield may preferrably be between 0.5 mm and 2.0 mm.  
         [0052]    According to a shield of the present invention, it is possible to prevent etching on the surface of the dielectric window at locations corresponding to areas underneath coils. This prevention reduces contamination of the semiconductor wafer and improves the yield of the semiconductor process.  
         [0053]    Further, it is possible to prolong the average span of the dielectric window, which results in production cost savings.  
         [0054]    The invention has been described using exemplary embodiments. However, it is to be understood that the scope of the invention is not limited to the disclosed preferred embodiments. On the contrary, it is intended to cover various modifications and similar arrangements. Such modifications are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.