Abstract:
The present invention relates to a method for repairing a semiconductor device. The method includes cutting a fuse without creation of residue by transforming the fuse into a nonconductor of high resistance by oxidizing the fuse by irradiating the fuse with an oxygen ion beam instead of a laser in a blowing process. The method includes transforming a fuse corresponding to a defective cell among a plurality of fuses formed in an upper portion of a semiconductor substrate into an oxide film.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
   Priority to Korean patent application number 10-2008-0073933, filed on Jul. 29, 2008, the disclosure of which is incorporated by reference in its entirety, is claimed. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to a semiconductor device, and more particularly, to a method for repairing a semiconductor device. 
   Generally, as semiconductor devices become highly integrated, in case of DRAM, the size of the chip increases while memory capacity increases. 
   2. Description of Related Technology 
   If even one memory cell among numerous micro memory cells of a semiconductor device has a defect as a result of the fabrication of the semiconductor device, the whole device is regarded as being defective and is discarded, thereby reducing device yield. 
   To overcome this problem, presently, the semiconductor device is designed with redundancy cells, which are formed in advance. A defective cell may be replaced with a redundancy cell, resulting in repair of the whole memory, and thereby improving (or not reducing) yield. 
   The repair operation with a redundancy cell is performed to identify a defective memory cell through a test after wafer processing and to replace the corresponding address of the defective memory cell with an address signal of a spare cell. When an address signal corresponding to a defective line is inputted, the defective line is substituted by a redundancy line. 
     FIG. 1  is a diagram illustrating a conventional semiconductor device. View (a) is a plane diagram illustrating a semiconductor device, and view (b) is a cross-sectional diagram taken along line A-A′ of (a). 
   Referring to  FIG. 1 , a first interlayer insulating film  12  is formed on an upper portion of a semiconductor substrate  10  having a lower structure (not shown). A line type fuse  14  is formed on an upper portion of the first interlayer insulating film  12 . Here, the fuse  14  has a structure on which a barrier metal layer  14   a , a conductive layer  14   b  and an anti-reflection layer  14   c  are stacked. The barrier metal layer  14   a  and the anti-reflection layer  14   c  are preferably formed with a stacked structure of a Ti film and a TiN film, respectively. 
   The conductive layer  14   b  is preferably formed with the same material as a metal wiring of a cell region, for example, aluminum (Al). A fuse blowing target  16  indicates a target area to which a laser is irradiated in a blowing process. A second interlayer insulating film  18  is formed on the whole surface of the semiconductor substrate  10  in which the fuse  14  is formed. 
     FIG. 2  is a diagram illustrating a method of repairing of the semiconductor device illustrated in  FIG. 1 . 
   Referring to  FIG. 2 , a conventional blowing process irradiates a laser into the fuse  14  corresponding to a defective cell to cut. However, a crack can be generated in the first interlayer insulating film  12  due to a laser energy in the blowing process. 
   A residue B of the conductive layer  14   c  or the barrier metal layer  14   a  can remain in a place where the crack is generated, such that it can not be determined that the fuse  14  is cut, even in case of cutting. 
   Accordingly, there is a problem of generating device failure as a repair of the defective cell is not successfully performed. Moreover, the blowing process using a laser energy performs cutting by melting, vaporizing, or exploding the fuse  14  such that it can have an associated problem of generating device failure due to the damage of the adjacent fuse  14 . 
   BRIEF SUMMARY OF THE INVENTION 
   Various embodiments of the present invention are directed at providing a method for repair of a semiconductor device, which includes transforming at least a portion of a fuse corresponding to a defective cell, among a plurality of fuses formed over a semiconductor substrate, into an oxide film. 
   According to an embodiment of the present invention, the fuse preferably includes a barrier metal layer and a conductive layer. Preferably, the conductive layer is formed with a material selected from the group consisting of Al, W, Cu, Pt, polysilicon, WSi x , Ti, TiN and TaN. The fuse can further include an anti-reflection layer over the conductive layer. The barrier metal layer and the anti-reflection layer preferably include a stacked structure of a Ti film and a TiN film, respectively. The fuse is preferably formed with a thickness in a range of about 100 Å to about 5000 Å. 
   According to an embodiment of the present invention, transforming at least a portion of the fuse corresponding to a defective cell is performed by irradiating an oxygen ion beam on the fuse. Preferably, the oxygen ion beam is irradiated with an acceleration energy in a range of about 10 keV to about 1 MeV and optionally further preferable with a dose in a range of about 1.0E21 to about 6.0E23. The oxygen ion beam can be irradiated by sequentially varying the acceleration energy. The method can include irradiating the oxygen ion beam with a first acceleration energy and then with a second acceleration energy less than the first acceleration energy. The oxygen ion beam can be irradiated with a single acceleration energy. The oxygen ion beam is preferably irradiated through a nozzle. The oxygen ion beam is preferably irradiated one or two times. The oxygen ion beam is preferably irradiated with an inert gas. Preferably, the spot size of the oxygen ion beam is in a range of about 30 nm to about 30000 nm. 
   According to an embodiment of the present invention, a whole of the fuse can be transformed into the oxide film. Preferably, only a portion of the fuse is transformed into the oxide film. Preferably, a resistance of the fuse which is transformed into the oxide film is in a range of about 1 kΩ to about 100 kΩ. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a more complete understanding of the disclosure, reference should be made to the following detailed description and accompanying drawings. 
       FIG. 1  is a diagram illustrating a conventional semiconductor device. 
       FIG. 2  is a diagram illustrating a conventional method of repairing of the semiconductor device illustrated in  FIG. 1 . 
       FIG. 3  is a diagram illustrating a semiconductor device according to the invention. 
       FIG. 4  is a diagram illustrating a method of repairing of the semiconductor device illustrated in  FIG. 3 . 
   

   While the disclosed method is susceptible of embodiments in various forms, specific embodiments are illustrated in the drawings (and will hereafter be described), with the understanding that the disclosure is intended to be illustrative, and is not intended to limit the invention to the specific embodiments described and illustrated herein. 
   DESCRIPTION OF EMBODIMENTS 
     FIG. 3  is a diagram illustrating a semiconductor device according to the invention. View (a) is a plane diagram illustrating the semiconductor device, and view (b) is a cross-sectional diagram taken along line C-C′ of (a). 
   Referring to  FIG. 3 , a first interlayer insulating film  102  is formed over a semiconductor substrate  100  having a lower structure (not shown). A line type fuse  104  is formed over the first interlayer insulating film  102 . A second interlayer insulating film  108  is formed over the semiconductor substrate  100  in which the fuse  104  is formed. 
   In this embodiment, the fuse  104  has a structure on which a barrier metal layer  104   a , a conductive layer  104   b  and an anti-reflection layer  104   c  are stacked. In this embodiment, the barrier metal layer  104   a  and the anti-reflection layer  104   c  are formed with a stacked structure of a Ti film and a TiN film, respectively. 
   The conductive layer  104   b  is formed with a material selected from the group consisting of aluminum (Al), tungsten (W), copper (Cu), platinum (Pt), polysilicon, tungsten polysilicon (WSi x ), titanium (Ti), titanium nitride (TiN), and tantalum nitride (TaN). It is preferable that the thickness of the fuse  104  is in a range of about 100 Å to about 5000 Å. A fuse blowing part  106  indicates an area to which an oxygen ion beam is irradiated in the blowing process. A spot size of the oxygen ion beam is smaller than the spot size of the laser illustrated in  FIG. 1 . 
   In the meantime, in the embodiment of the present invention, it is exemplified that the fuse  104  has a stacked structure of the barrier metal layer  104   a , the conductive layer  104   b  and the anti-reflection layer  104   c . However, it is not limitative and the invention can be applied if the fuse  104  is formed with a plate layer of a cell region, or even if the fuse  104  is formed only with the barrier metal layer  104   a  and the conductive layer  104   b . If the fuse  104  is formed with the barrier metal layer  104   a  and the conductive layer  104   b , and without an anti-reflection layer  104   c , the fuse  104  can be formed to be exposed on the upper portion of the conductive layer without an insulating layer. 
     FIG. 4  is a diagram illustrating a method for repair of the semiconductor device illustrated in  FIG. 3 . 
   Referring to  FIG. 4 , the repairing method of the invention irradiates an oxygen ion beam  110  on the fuse  104  corresponding to a defective cell to change the fuse  104  into an oxide film  112 . For example, the conductive layer  104   b  is transformed into Al 2 O 3  or Al 3 O 5  when the conductive layer  104   b  is formed with Al. 
   If the conductive layer  104   b  is formed with tungsten (W), copper (Cu), platinum (Pt), titanium (Ti), titanium nitride (TiN), or tantalum nitride (TaN), then, the layer is transformed into WSiO x , CuO 2 , PtO, TiO x , TiON, or TaON, respectively. Similarly, the barrier metal layer  104   a  and the anti-reflection layer  104   c  (if present) are transformed into corresponding portions of the oxide film  112 . 
   Here, the oxygen ion beam  110  can obtain an oxygen ion by injecting O 2 , O 3 , or a gas including an oxygen ion with an inert gas into a chamber, and plasma discharging to separate the oxygen ion and electrons. The inert gas preferably includes a gas such as helium (He) or argon (Ar). A gas which does not react to O 2  or O 3  gas can be applied in the invention without a limitation. 
   It is preferable that the acceleration energy is in a range of from 10 keV to 1 MeV and optionally further preferable that the dose is in a range of about 1.0E21 to about 6.0E23 in the irradiating of the oxygen ion beam  110 . The acceleration energy of the oxygen ion beam  110  can be controlled according to the thickness or material of the fuse  104 . For example, the thicker the thickness of the fuse  104  becomes, the more the acceleration energy has to be increased. Further, the higher specific densities of the materials serving as the fuse  104  are, the more the acceleration energy has to be increased. The frequency of the irradiating oxygen ion beam  110  can be one or two times. 
   In one embodiment, the irradiating process of the oxygen ion beam  110 , the acceleration energy is sequentially varied in a range of about 10 keV to about 1 MeV such that a whole thickness of the fuse  104  can be changed into the oxide film  112 . For example, the oxygen ion is irradiated to a lower portion of the fuse  104  when the acceleration energy is relatively high at first. Thereafter, when the acceleration energy is gradually lowered, the oxygen ion is irradiated while going up from the lower portion to a middle portion, and up to an upper portion. 
   Then, the whole thickness of the fuse  104  can be oxidized. In another embodiment, the oxygen ion beam  110  can be irradiated with a single energy such that the whole thickness of the fuse  104  can be changed into the oxide film  112 . It is preferable that the oxygen ion beam  110  is irradiated through a nozzle in order that the oxygen ion is concentrated. The fuse  104  can be sputtered by using the oxygen ion beam  110 . If an inert gas is added to the oxygen ion beam  110 , the etch rate of the fuse  104  can be increased. The inert gas preferably includes a gas such as He or Ar. A gas which does not react to O 2  or O 3  gas can be applied in the invention without a limitation. In this case, the thickness of the fuse  104  is decreased while being transformed into the oxide film  112 . Therefore, the conversion rate can be increased. 
   Moreover, the fuse blowing part  106  can be a middle portion of the fuse  104  like conventional technology (See  FIGS. 1(   a ) and  3 ( a )). However, it is not limitative and thus it can be an edge part of the fuse  104  (e.g., upper or lower portion of the fuse as illustrated in  FIG. 3(   a )) or the whole of the fuse  104 . In addition, the location of the fuse blowing target  106  can be arbitrarily selected. 
   Accordingly, it is not necessary that the length of the fuse  104  in a major axis direction has a long length. The spot size of the oxygen ion beam  110  can be as small as about 1/10 in comparison with the laser spot size used in the prior method such that the length of the fuse  104  in a minor axis direction can be reduced, thus, the method is advantageous for highly integrated devices. 
   In this way, if a part or a whole of the fuse  104  is changed into the oxide film  112 , then, the resistance of the fuse  104  is enhanced to a value in a range of about 0.25Ω to about 100 k Ω. That is, the fuse  104  has a high resistance, which is physically equivalent to a state of cutting. Therefore, the fuse  104  is cut without changing the form. There remains no residue, or there is no damage on the adjacent fuse  104  such that a device failure can be prevented. 
   The above embodiments of the present invention are illustrative and not limitative. Various alternatives and equivalents are possible. The invention is not limited by the type of deposition, etching polishing, and patterning steps described herein. Nor is the invention limited to any specific type of semiconductor device. For example, the present invention may be implemented in a dynamic random access memory (DRAM) device or non volatile memory device. While the present invention has been described with respect to the specific embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the following claims.