Abstract:
In an embodiment, a spinning apparatus includes a spin table on which an object to be etched is placed, a rotation unit rotating the spin table, and a nozzle unit including a center nozzle, disposed on the central portion of the spin table, and at least one side nozzle, disposed on an edge of the spin table. Etching uniformity is improved over the conventional art because an etching chemical is distributed more evenly by the nozzle unit as the object to be etched is rotated. An embodiment may also include an exhaust to remove excess etching chemical.

Description:
This application claims the benefit of Korean Patent Application No. 10-2004-0083584, filed on Oct. 19, 2004, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. 
   BACKGROUND OF THE INVENTION  
   1. Field of the Invention 
   The present invention relates to a spinning apparatus, and more particularly, to a spinning apparatus for wet-etching a wafer. 
   2. Description of the Related Art 
   Generally, wet etching can be performed using wet benches, which are used to wet etch a plurality of wafers at the same time, or single water processors, which are used to wet etch one wafer at a time. Wet benches or batch wafer cleaners can process a large quantity of wafers, but, unfortunately, they occupy large areas. Also, when problems occur in the etching process, it is very likely that an entire batch of the wafers will have defects. 
   On the other hand, while single wafer processors require a long time to etch many wafers, they occupy a small area. Also, even when problems occur in the etching process, only one wafer is affected. Therefore, single wafer processors have become more prevalent than wet benches. 
   The most common form of the single wafer processor is a spinning apparatus. 
     FIG. 1  is a perspective view of a conventional spinning apparatus, and  FIG. 2  is a plan view of the spinning apparatus of  FIG. 1 . 
   Referring to  FIGS. 1 and 2 , the conventional spinning apparatus includes a spin table  1  on which a wafer is placed, and a rotation unit  3  used to rotate the spin table  1 . A back nozzle  5  to spray an etching chemical into a backside of the wafer is disposed in the center of the spin table  1 . A plurality of fixing pins  2  are disposed on an edge of the spin table  1  to fix the wafer. 
   The rotation unit  3  includes a motor (not shown) used as a driving source, and a rotation shaft  4  providing a torque produced by the motor to the spin table  1 . 
   In the conventional spinning apparatus, the amount of etching chemical sprayed to the backside of the wafer varies from region to region on the wafer. This causes a problem of a non-uniformly etched wafer backside. 
   In addition, the entire spin table  1  of the conventional spinning apparatus rotates, making it difficult to apply an etching chemical to a bevel of the wafer. Thus the bevel of the wafer cannot be easily etched. 
   SUMMARY OF THE INVENTION 
   The present invention provides a spinning apparatus that can etch a backside of a wafer uniformly. 
   The present invention also provides a spinning apparatus that can easily etch a bevel of a wafer. 
   According to an embodiment of the present invention, a spinning apparatus includes a spin table on which an object to be etched, such as a wafer, is placed. A rotation unit rotates the spin table. A nozzle unit dispenses an etching chemical to a lower surface of the object. The nozzle unit includes a center nozzle disposed at a central portion of the spin table, and at least one side nozzle disposed at an edge of the spin table. 
   A vacuum chuck unit may be disposed on the spin table so that the object to be etched is held by a vacuum. 
   The spin table may include a fixed table having an annular opening and a rotation table having the vacuum chuck unit formed inside the annular opening. A nozzle unit may be disposed on the fixed table. The rotation table may rotate with respect to the fixed table. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which: 
       FIG. 1  is a perspective view of a conventional spinning apparatus; 
       FIG. 2  is a plan view of the spinning apparatus of  FIG. 1 ; 
       FIG. 3  is a perspective view of a spinning apparatus according to an exemplary embodiment of the present invention; 
       FIG. 4  is a plan view of the spinning apparatus of  FIG. 3 ; and 
       FIG. 5  is a cross-sectional view showing a geometric relation between a side nozzle and a wafer for the spinning apparatus of  FIG. 3 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The present invention will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. In the drawings, the thicknesses of layers and regions are exaggerated for clarity. Like reference numerals in the drawings denote like elements, and thus their description will not be repeated. 
   An embodiment of the present invention is shown in  FIGS. 3 through 5 . In this embodiment a spinning apparatus includes a spin table  10  on which an object to be etched, such as the wafer W, is placed. A rotation unit  30  rotates the spin table  10 . A nozzle unit  20  dispenses an etching chemical onto a backside of the wafer W. 
   The spin table  10  includes a fixed table  11  and a rotation table  12 . The fixed table  11  further includes an inner portion  11   a  and an outer portion  11   b.  Both the inner and outer portions  11   a  and  11   b  are circular areas, and the inner portion  11   a  is concentrically within the outer portion  11   b.  The rotation table  12  is concentrically disposed between the inner portion  11   a  and the outer portion  11   b  of the fixed table  11 . The rotation table  12  can rotate with respect to both the inner and outer portions  11   a  and  11   b.  The rotation table  12  is connected to the rotation unit  30  and torque is transferred from the rotation unit  30  to the rotation table  12 . 
   The rotation unit  30  includes a driving source (not shown) and a rotation shaft (not shown) conveying the torque of the driving source to the rotation table  12 . The driving source may be a motor, a cylinder, a gear structure, or the like. 
   The nozzle unit  20  includes a center nozzle  21  and two side nozzles  22  and  23 . Another embodiment may also include one or more than two side nozzles. The center nozzle  21  and the side nozzles  22  and  23  are connected to an etching chemical container (not shown). The center nozzle  21  is disposed in the central portion of the fixed table  11  and dispenses the etching chemical onto a central portion of the backside of the wafer W. 
   The side nozzles  22  and  23  are disposed at an edge of the fixed table  11  and dispense the etching chemical onto an edge of the backside of the wafer W. In this embodiment, the angle between the side nozzles  22  and  23  around the fixed table is about 180°. In another embodiment, this angle may vary with the number of side nozzles. As is shown in  FIG. 5 , the side nozzles  22  and  23  are sloped so that they make predetermined acute angles with an axis perpendicular to a surface of the wafer W. The axes of the side nozzles  22  and  23 , that is, the direction in which the etching chemical is sprayed may make an angle αof 20° to 40° with the axis perpendicular to the surface of the wafer W. In an embodiment with three side nozzles, The side nozzles are disposed at about 120° intervals. In an embodiment with four side nozzles, the side nozzles are disposed at about 90° intervals. That is, the side nozzles are disposed at regular intervals. 
   A vacuum chuck unit  40  is disposed on the rotation table  12 . The vacuum chuck unit  40  forms a vacuum below the wafer W, thus fixing the wafer W to an upper surface of the rotation table  12 . The vacuum chuck unit  40  is connected to a vacuum source (not shown), such as a vacuum pump. The vacuum chuck unit  40  is composed of vacuum chucks  41 ,  42 , and  43 . The vacuum chucks  41 ,  42 , and  43  are disposed at about 120° intervals. In another embodiment there may be any number of vacuum chucks. In particular, when there is more than one vacuum chuck, the vacuum chucks are preferably disposed at regular intervals. 
   An exhaust port  50  may be formed in the fixed table  11  to exhaust the residual etching chemical. The exhaust port  50  may be formed in the central portion of the fixed table  11 . In particular, the exhaust port  50  may surround the center nozzle  21 . In other words, the center nozzle  21  may be positioned inside the exhaust port  50 . 
   In the present embodiment, a wafer is used as an object to be etched. However, other objects, such as a glass substrate used for LCD devices, can also be used as the object to be etched. 
   An etching process performed on a backside of a wafer using the spinning apparatus will now be described. 
   When a wafer W is placed on a spin table  10 , a vacuum source forms a vacuum below the wafer W through a vacuum chuck unit  40 . Therefore, the wafer W is fixed to the rotation table  12 . 
   The rotation table  12  is rotated by the rotation unit  30  and the wafer W rotates with the rotation table  12 . In this embodiment the rotation table  12  preferably rotates at about 3,000 rpm. 
   An etching chemical is dispensed from the center nozzle  21  and the side nozzles  22  and  23  onto the backside of the rotating wafer W. The etching chemical dispensed from the center nozzle  21  reaches a central portion of the backside of the wafer W. The etching chemical dispensed from the side nozzles  22  and  23  reaches an edge of the backside of the wafer W. The etching chemical dispensed from the center nozzle  21  and the side nozzles  22  and  23  can reach the entire backside of the wafer W uniformly because the dispensing is performed as the wafer W rotates. In particular, since the side nozzles  22  and  23  are slanted with respect to the backside of the wafer W, the etching chemical dispensed from the side nozzles  22  and  23  is sprayed from the edge of the backside of the wafer W to the central portion of the backside of the wafer W. 
   Therefore, since the etching chemical is uniformly dispensed onto the entire backside of the wafer W, the backside of the wafer is uniformly etched. In addition, since the wafer W is fixed by a vacuum, there are no barriers, such as edge clamps, retaining clips, or the like, to prevent the etching chemical from reaching a bevel of the wafer. A sufficient supply of the etching chemical to the bevel of the wafer W results in a simplification of the etching of the bevel of the wafer W. 
   After the backside of the wafer W is etched, the residual etching chemical is exhausted to the outside of the spinning apparatus through the exhaust port  50 . 
   According to the present invention, as described above, a nozzle unit is composed of a center nozzle and side nozzles so that an etching chemical is sufficiently provided to a backside of the wafer. Therefore, the backside of the wafer can be uniformly etched. 
   In addition, since the wafer is fixed by a vacuum, the etching chemical is sufficiently provided to a bevel of the wafer. Therefore, the bevel of the wafer can be easily etched. 
   While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.