Abstract:
A semiconductor device is made up of a first insulating layer having a through hole; a first interconnection which comprises a first conductive layer, a first barrier layer, and a first main interconnection, and a second interconnection connected to one of the first conductive layer and the first barrier layer. Accordingly, the semiconductor device can avoid a problem so that the Cu of the first main interconnection transfers from a portion connected to the second interconnection due to cause electromigration, the connected portion becomes a void, and the first interconnection is disconnected to the second interconnection.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the invention  
           [0002]    The present invention generally relates to a semiconductor substrate, and more particularly, the present invention relates to a damascene interconnection structure.  
           [0003]    This application is a counterpart of Japanese application Serial Number 163304/1998, filed Jun. 11, 1998, the subject matter of which is incorporated herein by reference.  
           [0004]    2. Description of the Related Art  
           [0005]    In general, it is difficult to form a pattern by etching a Copper (Cu) interconnection. In a formation of the Cu interconnection, an insulating layer such as a SiO2 or a BPSG is formed on a semiconductor substrate. Then, a recess is formed in the insulating layer so as to shape the Cu interconnection. Then, a Cu is buried in the recess. As a result, the Cu interconnection buried in the recess so-called a damascene interconnection, which is formed on the semiconductor substrate.  
           [0006]    Such the damascene interconnection is formed as shown in FIG. 1A-FIG. 1D. FIGS.  1 A-FIG. 1D are cross sectional views showing a damascene interconnection structure of a conventional art.  
           [0007]    A first interconnection pattern recess is formed using photolithography technique and etching technique in a first SiO2 film  12  having a thickness of 1 μm on the semiconductor substrate  10 . Then, a barrier layer  16  such as a TiN is formed on the first SiO2 film  12  in the first interconnection pattern recess. After then, a Cu is formed on the entire surface and the Cu is polished with alkaline solution having a colloidal-silica, so-called CMP (chemical mechanical polishing) method. As a result, a first interconnection including a main interconnection  19  which is made up of the Cu, as shown in FIG. 1A. A second SiO2 film  22  having a thickness of 1 μm is formed on the first SiO2 film  12  where the first interconnection  18  was formed. Then, a through hole  55  is formed in the second SiO2 film  22  so that a center portion of an upper surface of the first interconnection  18  is exposed, as shown in FIG. 1B.  
           [0008]    A second interconnection pattern recess  24  is formed so that a predetermined portion of the through hole  55  is remained. Then, a barrier layer  26  such as TiN is formed in the remained through hole  55  and the second interconnection pattern recess  24 , as shown in FIG. 1C.  
           [0009]    Then, a Cu is formed on the entire surface using sputtering technique, and the Cu is polished using the CMP method. As a result, a second interconnection  28  including a main interconnection  29  which is made up of the Cu, as shown in FIG. 1D.  
           [0010]    In the conventional art of the method for forming the interconnections, it is desirable to avoid a problem so that the Cu transfers from a portion connected to the second interconnection due to cause electromigration, the connected portion becomes a void, and the first interconnection is disconnected to the second interconnection.  
         SUMMARY OF THE INVENTION  
         [0011]    An object of the present invention is to provide a semiconductor device that can avoid a problem  
           [0012]    so that the Cu transfers from a portion connected to the second interconnection due to cause electromigration, the connected portion becomes a void, and the first interconnection is disconnected to the second interconnection.  
           [0013]    According to one aspect of the present invention, for achieving the above object, there is provided a semiconductor device comprising: a first insulating layer having a through hole; a first interconnection comprised a first conductive layer, a first barrier layer, and a first main interconnection; the first conductive layer formed on the first insulating layer in the first through hole; the first barrier layer formed on the first conductive layer; the first main interconnection formed on the first barrier layer so as to bury the through hole; and a second interconnection connected to one of the first conductive layer and the first barrier layer.  
           [0014]    According to another aspect of the present invention, for achieving the above object, there is provided a semiconductor device comprising: a first insulating layer having a through hole; a first interconnection comprised a first conductive layer, a first barrier layer, and a first main interconnection; the first conductive layer formed on the first insulating layer in the first through hole; the first barrier layer formed on the first conductive layer; the first main interconnection formed on the first barrier layer so as to bury the through hole; and a second interconnection connected to one of an edge portion of the first conductive layer exposed from an upper surface of the first insulating layer and an edge portion of the first barrier layer exposed from an upper surface of the first insulating layer. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    While the specification concludes claims particularly pointing out and distinctly claiming the subject matter that is regarded as the invention, the invention, along with the objects, features, and advantages thereof, will be better understood from the following description taken in connection with the accompanying drawings, in which:  
         [0016]    [0016]FIG. 1A-FIG. 1D are cross-sectional views showing a damascene interconnection structure of a conventional art.  
         [0017]    [0017]FIG. 2 is a plan-view showing a damascene interconnection structure according to a first preferred embodiment of a present invention.  
         [0018]    [0018]FIG. 3 is a cross-sectional view showing damascene interconnection structure according to the first preferred embodiment of the present invention.  
         [0019]    FIGS.  4 A- 4 F are cross-sectional views showing a method for forming damascene interconnections structure according to the first preferred embodiment of the present invention.  
         [0020]    FIGS.  5 A- 5 F are cross-sectional views showing a method for forming damascene interconnections structure according to the second preferred embodiment of the present invention.  
         [0021]    [0021]FIG. 6 is a plan-view showing a damascene interconnection structure according to a third preferred embodiment of the invention.  
         [0022]    [0022]FIG. 7 is a cross-sectional view showing a damascene interconnection structure according to a third preferred embodiment of the invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]    A storage device and an alternate processing method for defective sectors of a storage device according to first and second preferred embodiments of the present invention will hereinafter be described in detail with reference to the accompanying drawings.  
         [0024]    [0024]FIG. 2 is a plane-view showing a damascene interconnection structure according to a first preferred embodiment of a present invention. FIG. 3 is a cross-sectional view showing damascene interconnection structure according to the first preferred embodiment of the present invention.  
         [0025]    As shown in FIG. 2 and FIG. 3, a first damascene interconnection structure is preferably made up of a first  
         [0026]    insulating layer, as a first SiO2  12 , having a first through hole, and a first interconnection  18  that is buried in the first through hole. The first interconnection  18  is preferably made up of a first conductive layer such as a first TiN film  16   a , a first barrier layer such as a first Ti film  17   a , and a first main interconnection  19 . The first TiN film  16   a  is formed on the first SiO2  12  in the first through hole. The first T film  17   a  is formed on the first TiN film  16   a . The first main interconnection is formed on the Ti film  17   a  so as to bury the first through hole. The first through hole has a first extending direction and a second extending direction which is longer than the first extending direction, and forms so that the second extending direction corresponds to the flow of electron in the first interconnection  18  which is formed in the first through hole.  
         [0027]    A second damascene interconnection structure is preferably made up of a second insulating layer, as a second SiO2  22 , having a second through hole, and a second interconnection  28  which is buried in the second through hole. The second interconnection  28  is preferably made up of a second conductive layer such as a second TiN film  26 , a second barrier layer such as a second Ti film  27 , and a second main interconnection  29 . The second TiN film  26  is formed on the second SiO2  22  in the second through hole. The second Ti film  27  is formed on the second TiN film  26 . The second main interconnection  29  is formed on the second Ti film  27  so as to bury the second through hole. The second interconnection  28  is connected to one of the second TiN film  26  and the second Ti film  27  of the first interconnection  18 . The second interconnection  28  is connected to one of the second TiN film  16   a  and the second Ti film  17   a . The second interconnection  28  has a protrusion portion where the second interconnection  28  is connected to the first interconnection  18 .  
         [0028]    The protrusion portion of the second interconnection  28  is connected to the first interconnection  18  via the first through hole.  
         [0029]    In the structure mentioned above, when a voltage so as to become a high voltage is applied to the first interconnection  18  and a voltage so as to become a low voltage is applied to the second interconnection  28 , electrons flows from the second interconnection  28  to the first interconnection  18 . The Cu atoms in the first main interconnection  19  of the first interconnection  18  move to opposite direction of electron flow because of electromigration. As a result, voids are formed in the first main interconnection  19  of the first interconnection  18 . However, since the second interconnection is connected to the first Ti  17   a , the first Ti  17   a  can maintain electrically connecting between the first and second interconnections.  
         [0030]    FIGS.  4 A- 4 F are cross-sectional views showing a method for forming damascene interconnections structure according to the first preferred embodiment of the present invention.  
         [0031]    As shown in FIG. 4A, a first SiO2 film  12  as a first insulating film, a thickness of 1 μm, is formed on a semiconductor substrate  10 . First interconnections recesses  14 , a depth of 500 nm, are formed in regions which first interconnections are formed, using photolithography technique and plasma etching with a mixed gas of C2F8 and O2.  
         [0032]    As shown in FIG. 4B, TiN films  16 ,  16   a , a thickness of 30 nm is selectively formed on the first SiO2 film  12  in the first interconnection recesses  14 . Ti films  17 ,  17   a , a thickness of 5 nm, are formed on the TiN films  16 ,  16   a . CVD (Chemical Vapor Deposition) method and CMP (Chemical Mechanical Polishing) method are used for forming the TN films  16 ,  16   a  and the Ti films  17 ,  17   a . Then, a Cu is buried in the first interconnection recesses  14  and then is polished until the first SiO2 film  12  exposes, using the CMP method. As a result, a first main interconnection  19  is formed in the first interconnection recesses  14 . Therefore, a first interconnection  18  which is made up of the TiN films  16 ,  16   a , the Ti films  17 ,  17   a , and the first main interconnection  19 , are formed in the first interconnections recesses  14 .  
         [0033]    As shown in FIG. 4C, a second SiO2 film as a second insulating film, a thickness of 1 μm , is formed on the entire surface. A first through hole  50  is formed so as to expose the first SiO2 film  12   a  surface, a portion of the TiN films  16   a , and a portion of the Ti films  17   a  in the second SiO2 film. A portion of the first SiO2 film  12   a  is removed from. As a result, a portion of the TiN films  16   a  sidewalls is exposed. Here, an etching depth is about the half thickness of the first main interconnection  19 .  
         [0034]    As shown in FIG. 4D, a second interconnection recess  24 , a thickness of 500 nm, is formed in the second SiO2 film  22  using plasma etching with C2F8 gas and O2 gas.  
         [0035]    As shown in FIG. 4E, a second TiN film  26  and a second Ti film  27  are successively formed on the second SiO2 film in the second interconnection recess  24  using the same manner of the forming steps for the first interconnection  18 .  
         [0036]    As shown in FIG. 4F, a Cu is buried in the second interconnection recess  24  using sputtering method or CVD method. After then, the Cu is polished until the second SiO2 film  22  surface is exposed,  
         [0037]    A second interconnection  28  which is made up of the Cu as a second main interconnection, the second TiN film  26 , and the second Ti film  27 , are formed in the second interconnection recess  24 . Thus, the second interconnection  28  is connected to the first TiN film  16   a  and the first Ti film  17   a.    
         [0038]    FIGS.  5 A- 5 F are cross-sectional views showing a method for forming damascene interconnection structure according to the second preferred embodiment of the present invention.  
         [0039]    As shown in FIG. 5A, a first insulating film  12  is preferably made up of a SiO2 film  34 , a SiN film  32 , and a SiO2 film  30 . The SiO2 film  34 , thickness of 500 nm, is formed on a semiconductor substrate  10 . The SiN film  32  as etching stop layer, thickness of 50 nm, is formed on the SiO2 film  34 . The SiO2 film  30 , thickness of 500 nm, is formed on the SiN film  32 .  
         [0040]    Then, the SiO2 film  30  is etched using photolithography technique and plasma etching with C2F8 gas and O2 gas. In this time, SiN film  32  serves as the etching stop layer against the SiO2 film  30 . As a result, the SiO2 film patterns  12   a ,  30  and a first interconnection recess  14  are formed, respectively.  
         [0041]    As shown in FIG. 5B, TiN films  16 ,  16   a , Ti films  17 ,  17   a , and first main interconnections  19  are respectively formed in the first interconnection recess  14  using the same manner for forming steps of the first preferred embodiment. Here, a first interconnection  18  is made up of the TiN films  16 ,  16   a , the Ti films  17 ,  17   a , and the first main interconnections  19 .  
         [0042]    As shown in FIG. 5C, a second insulating film  22  is preferably made up of a SiO2 film  44 , a SiN film  42 , and a SiO2 film  40 . The SiO2 film  44 , thickness of 500 nm, is formed on the entire surface. The SiN film  42  as etching stop layer, thickness of 50 nm, is formed on the SiO2 film  44 . The SiO2 film  40 , thickness of 500 nm, is formed on the SiN film  42 .  
         [0043]    The SiO2 film  40  is etched using photolithography technique and plasma etching with C2F8 gas and O2 gas until the SiN film  42  exposes. Then, the SiN film  42  is etched using plasma etching with SF6 gas and O2 gas. Then, the SiO2 films  12 ,  44  are etched using photolithography technique and plasma etching with C2F8 gas and O2 gas until the SiN film  32  exposes. As a result, a through hole  50  is formed, and a sidewall of the TiN film  66   a , edge of the Ti films  17   a , and a part of the first main interconnections  19  are exposed in the through hole  50 .  
         [0044]    As shown in FIG. 5D, a second interconnection recess  24  which is wider than the through hole  50 , is formed by etched the SiO2 film  40  using photolithography technique and plasma etching with C2F8 gas and O2 gas.  
         [0045]    As shown in FIG. 5E, a second TiN film  26  and a second Ti film  27  are successively formed in the second interconnection recess  24  and the through hole  50  using the same manner of the forming steps for the first interconnection  18 . Here, before forming the second Ti film  26  and the second Ti film  27 , another Ti film may be formed in the second interconnection recess  24  and the through hole  50 . The first main interconnections  19  subjects to a NH3 using for forming the second TiN film  26 . As a result, the first main interconnections  19  nitrides, and it is difficult to electrically connected between the first interconnection  18  and the second interconnection  28 .  
         [0046]    As shown in FIG. 5F, a Cu is buried in the second interconnection recess  24  using sputtering method or CVD method. After then, the Cu is polished until the second SiO2 film  22  surface exposes,  
         [0047]    A second interconnection  28  which is made up of the Cu as a second main interconnection, the second TiN film  26 , and the second Ti film  27 , are formed in the second interconnection recess  24 . Thus, the second interconnection  28  is connected to the first TiN film  16   a  and the first Ti film  17   a.    
         [0048]    [0048]FIG. 6 is a plan-view showing a damascene interconnection structure according to a third preferred embodiment of the invention. FIG. 7 is a cross-sectional view showing a damascene interconnection structure according to a third preferred embodiment of the invention.  
         [0049]    As shown in FIG. 6 and FIG. 7, a first interconnection  38  is preferably made up of a TiN film  16  as a barrier layer a Ti film  17  as a conductive layer, and a first main interconnection  19  comprising a Cu. The first interconnection  38  is formed in a first SiO2 film  12 . A second interconnection  48  is preferably made up of a TiN film  26  as a barrier layer, a Ti film  27  as a conductive layer, and a first main interconnection  29  comprising a Cu.  
         [0050]    The second interconnection  48  is formed so as to cover an upper surface of and a sidewall of the first interconnection  38 .  
         [0051]    Since a connecting area is wider than the conventional art, a contact resistance is low and a current flow is easy. Therefore, it can avoid the electromigration.  
         [0052]    In the structure mentioned above, when a voltage so as to become a high voltage is applied to the first interconnection  38  and a voltage so as to become a low voltage is applied to the second interconnection  48 , electrons flows from the second interconnection  48  to the first interconnection  18 . The Cu atoms in the first main interconnection  19  of the first interconnection  38  move to opposite direction of electron flow because of electromigration. As a result, voids are formed in the first main interconnection  19  of the first interconnection  38 . However, since the second interconnection  48  is connected to the first Ti  17   a , the first Ti  17   a  can maintain electrically connecting between the first and second interconnections.  
         [0053]    While the present invention has been described with reference to the illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications of the illustrative embodiments, as well as other embodiments of the invention, will be apparent to those skilled in the art on reference to this description. It is therefore contemplated that the appended claims will cover any such modifications or embodiments as fall within the true scope of the invention.