Abstract:
Embodiments consistent with the present invention provide a semiconductor device having a photo aligning key and a method for manufacturing the same. The semiconductor device includes a pattern photo aligning key formed on a scribe line of a semiconductor substrate, and a plurality of dummy pattern keys formed around the pattern photo aligning key, the dummy pattern keys having a width smaller than that of the pattern photo aligning key.

Description:
RELATED APPLICATION 
       [0001]    This application claims the benefit of priority to Korean patent application no. 10-2007-0050897, filed on May 25, 2007, the entire contents of which are incorporated herein by reference. 
         [0002]    1. Technical Field 
         [0003]    Embodiments consistent with the present invention relate to a semiconductor device and a method for manufacturing the semiconductor device, and more particularly, to a semiconductor device having a photo aligning key and a method for manufacturing the semiconductor device. 
         [0004]    2. Background 
         [0005]    In general, a contact-to-silicon (CS) layer of a semiconductor device is formed by filling a contact metal, such as tungsten (W), in a contact hole and polishing the contact metal using a chemical mechanical polishing (CMP) process. Normally, device elements having a greater area, or wide patterns, have a polishing rate greater than those having a smaller area. For example, a photo aligning key positioned in a scribe lane can be considered as a wide pattern with respect to the contact hole. Specifically, the photo aligning key usually has a width of about 1 μm to about 6 μm, and the contact hole usually has a diameter of about 1 nm to about 150 nm. Accordingly, the polishing rate of the photo aligning key is much greater than that of the contact hole. Therefore, after polishing the contact hole, the photo aligning key is eroded, which causes a problem in reading the photo aligning key in a photo process of a metal layer process. 
         [0006]    Therefore, when a copper (Cu) damascene process is used for the upper part of the contact hole, a dielectric layer is deposited after performing the CMP process on W. If the dielectric layer is transparent to a light ray and the light ray reflected from the photo aligning key can be used to distinguish the photo aligning key, then there is no problem reading the photo aligning key. 
         [0007]    However, when aluminum (Al) is formed after performing the CMP on W, as shown in  FIG. 1 , the photo aligning key can be read only if a step difference is formed in the key pattern. 
         [0008]    Specifically, referring to  FIG. 2A , in the case of a Cu based metal layer, since a metal photo process is performed after forming a dielectric layer  200 , it is possible to read the photo aligning key by using a visible light ray transparent to dielectric layer  200 , because the reflectance of tungsten  202  is different from that of a pre-metal dielectric (PMD) layer  204 . However, as illustrated in  FIG. 2B , in the case of an Al based metal layer  210 , since a visible light ray is totally reflected by metal layer  210 , it is not possible to read the photo aligning key without the step difference. 
         [0009]    In order to solve this problem, the thickness of PMD layer  204  is optimized so as to enlarge a polishing margin. However, since one must change the vertical topology of the semiconductor device if the thickness of PMD layer  204  is to be optimized, the operation characteristic of the semiconductor device may be deteriorated. Accordingly, it is not possible to secure the reliability of the semiconductor device. 
       SUMMARY 
       [0010]    Embodiments consistent with the present invention provide a semiconductor device having a photo aligning key and a method for manufacturing the same. 
         [0011]    In one embodiment consistent with the present invention, the semiconductor device includes a wide pattern photo aligning key formed on a scribe line of a semiconductor substrate, and a plurality of dummy pattern keys formed around the wide pattern photo aligning key, the dummy pattern keys having a width smaller than that of the wide pattern photo aligning key. 
         [0012]    In another embodiment consistent with the present invention, the method includes forming a wide pattern photo aligning key on a scribe line of a semiconductor substrate, forming a plurality of holes in an insulating layer formed on the semiconductor substrate and around the photo aligning key, the holes having a width smaller than that of the wide pattern photo aligning key, and forming a plurality of dummy pattern keys by filling a metal material in the holes formed in the insulating layer. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0013]      FIG. 1  illustrates a scanning electron microscope (SEM) photograph of a conventional photo aligning key. 
           [0014]      FIG. 2  is a sectional view illustrating a conventional dense photo key formed in a damascene process. 
           [0015]      FIGS. 3A to 3C  are sectional views illustrating a wide pattern photo aligning key of a semiconductor device according to an embodiment consistent with the present invention. 
           [0016]      FIGS. 4A to 4C  are sectional views illustrating an eroded wide pattern photo aligning key of a semiconductor device. 
           [0017]      FIGS. 5A to 5C  are plane views illustrating a wide pattern photo aligning key of a semiconductor device according to embodiments consistent with the present invention. 
       
    
    
     DETAILED DESCRIPTION  
       [0018]    Hereinafter, embodiments consistent with the present invention will be described in detail with reference to the accompanying drawings so that they can be readily implemented by those skilled in the art. 
         [0019]      FIGS. 3A to 3C  are sectional views illustrating a photo aligning key and a photo process capable of producing a readable photo aligning key, according to an embodiment consistent with the present invention. Hereinafter, the readable photo aligning key will be described in comparison with an unreadable photo aligning key illustrated in  FIGS. 4A to 4C . 
         [0020]    Referring to  FIG. 4A , a photo aligning key  400 , which may be a wide pattern, is eroded by a chemical mechanical polishing (CMP) process performed on a contact metal  401 , such as W, so that a step difference is removed. Referring to  FIG. 4B , when a metal layer  402  is deposited on photo aligning key  400 , a step difference is not formed in metal layer  402 . Therefore, referring to  FIG. 4C , after depositing a photoresist layer  404  on metal layer  402  in a metal photo process for etching metal layer  402 , it may be impossible to read photo aligning key  400 . 
         [0021]    Therefore, in order to prevent photo aligning key  400  from being eroded in the CMP process for contact metal  401 , one or more dummy pattern keys may be formed in a dense hole or a dense space around photo aligning key  400  to protect photo aligning key  400 . 
         [0022]    Referring to  FIG. 3A , dense holes or dense spaces, in which a dummy pattern key  302  is to be formed, are formed in an insulating layer  305  and around a wide pattern photo aligning key  300 . Dummy pattern key  302  formed in the dense holes or the dense spaces may prevent photo aligning key  300  from being eroded in the CMP process for a contact metal  301 . 
         [0023]    In one embodiment, dummy pattern keys  302  may be formed after forming wide pattern photo aligning key  300  for interlayer alignment of a semiconductor device. To form dummy pattern key  302 , a photoresist mask (not shown) may be formed on insulating layer  305 , and insulating layer  305  may be patterned using the photoresist mask as an etching mask. As a result, a plurality of dummy patterns is formed in insulating layer  305  and around photo aligning key  300 . In one embodiment, the dummy patterns may include holes having a width of about 100 nm to about 200 nm, which is smaller than the width (for example, 1 μm) of photo aligning key  300 . Then, after the dummy patterns around photo aligning key  300  are formed, a metal material may be gap filled in the dummy patterns to form dummy pattern key  302 . In one embodiment, a ratio of the width of photo aligning key  300  to that of dummy pattern key  302  may be from about 10:1 to about 20:1. As discussed above, dummy pattern key  302  may prevent photo aligning key  300  from being eroded. 
         [0024]      FIG. 5A  is a plane view illustrating photo aligning key  500  formed on a semiconductor substrate consistent with the present invention. In one embodiment, photo aligning key  500  may have a width of about 1 μm. 
         [0025]    As illustrated in  FIG. 5B , dense holes  502  are formed around photo aligning key  500 . In one embodiment, dense holes  502  may have a square shape with a width of about 100 nm to about 200 nm. In one embodiment, dense holes  502  may be filled with a metal material so as to form a dummy pattern key, which may prevent pattern photo aligning key  500  from being eroded. 
         [0026]    As illustrated in  FIG. 5C , dense spaces  504  are formed around photo aligning key  500 . In one embodiment, dense spaces  504  may have a rectangular shape and may be filled with a metal material so as to form a dummy pattern key, which may have a width of about 100 nm to about 200 nm. The dummy pattern key formed in dense spaces  504  may prevent photo aligning key  500  from being eroded. 
         [0027]    Referring back to  FIG. 3B , a metal layer  304  is deposited on wide pattern photo aligning key  300 , which is not eroded when the CMP process is performed on contact metal  301  due to the presence of dummy pattern key  302  formed of the above-described dense holes or dense spaces. As a result, metal layer  304  forms a step difference on photo aligning key  300 , because photo aligning key  300  is not eroded. 
         [0028]    Therefore, as illustrated in  FIG. 3C , after depositing a photoresist layer  306  on metal layer  304  in a metal photo process for etching metal layer  304 , it is possible to read photo aligning key  300  due to the step difference formed in metal layer  304 . 
         [0029]    While embodiments consistent with the present invention have been shown and described, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the appended claims.