Abstract:
The present invention discloses a fuse of a semiconductor device and manufacturing method thereof. The fuse of a semiconductor device of the present invention includes a first conductive pattern; and a second conductive pattern which is separated from the first conductive pattern with a given gap, wherein the first conductive pattern and the second conductive pattern are melted in a laser irradiation to be connected. Accordingly, the present invention prevents the damage of the adjacent fuse in the repair process, enabling to improve the reliability of device and accomplish the high integration.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The priority of Korean patent application No. 10-2008-0133216 filed on Dec. 24, 2008, the disclosure of which is hereby incorporated in its entirety by reference, is claimed. 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to a method of manufacturing a semiconductor device, more particularly, to a method of manufacturing a fuse of a semiconductor device for improving the repair yield. 
         [0003]    If any one of numerous cells in a semiconductor memory device fails, the device may not be able to properly perform the function as a memory, and thus it is treated as defective goods. However, it is not efficient in terms of yield to discard the semiconductor memory device as defective goods even though a fail was generated in a part of the cells in the semiconductor memory device. 
         [0004]    Therefore, recently, redundancy cells are being placed in the semiconductor memory device. When a bad cell is generated, the bad cell is replaced with a redundancy cell. That is, the redundancy cell is provided in the semiconductor memory device in advance, so that the semiconductor memory device would not have to be discarded for a few defective cells. The process of replacing the bad cell with a redundancy cell is called a repair process. 
         [0005]    In order to perform the repair process, the semiconductor memory device includes a fuse unit which stores address information of the bad cell according to the connection state of fuse. 
         [0006]      FIG. 1   a  is a plan view illustrating a conventional fuse unit of a semiconductor device, and  FIG. 1   b  is a cross-sectional view taken along Y-Y′ of  FIG. 1   a.    
         [0007]    As shown in  FIGS. 1   a  and  1   b , a plurality of fuses  101  are formed on a substrate  100  in which a certain substructure is equipped. At this time, the fuse  101  can be formed together with a plate electrode or metal line of a capacitor. 
         [0008]    An insulating layer  102  covering the fuse  101  is formed in the upper portion of the fuse  101 , and the insulating layer  102  includes a fuse box  103 . At this time, a certain thickness T of the insulating layer  102  remains in the upper portion of the fuse  101  of the fuse box  103 . 
         [0009]    Conventionally, after forming the above described fuse unit, a repair was performed by using a fuse blowing method of cutting a corresponding fuse  101  by irradiating a laser to a selected fuse  101  through the fuse box  103 . However, the fuse blowing method has a following problem. 
         [0010]    Firstly, the thickness T of the insulating layer  102  which remains in the upper portion of the fuse  101  has to be uniform so as to reliably perform the fuse cutting. However, in the entire substrate  100 , it is very difficult to uniformly form the thickness T of the insulating layer  102  remaining in the upper portion of the fuse  101 . Thus, in some cases, the fuse cutting is not normally generated. Accordingly, there is a problem where the repair yield is reduced. 
         [0011]    Moreover, the adjacent fuse  101  may be damaged by the explosion power generated in the fuse cutting. Moreover, a conductive by-product may be generated by the explosion power generated in the fuse cutting and the adjacent fuse  101  may be damaged due to the generated conductive by-product, or an electrical short is generated between the adjacent fuses  101 . 
         [0012]    Moreover, due to the problem resulting from the above-described explosion power and the conductive by-product, the length L of the fuse  101  and the gap W between the adjacent fuses  101  need to be increased to secure a process margin. Hence, there is a problem in that the integration density of semiconductor devices including the fuse unit is lowered. 
       BRIEF SUMMARY OF THE INVENTION 
       [0013]    Various embodiments of the invention are directed to perform a repair without cutting the fuse by improving the structure of a fuse unit such that the repair can be performed with a more simple logic and a problem resulted from the fuse cutting can be solved. 
         [0014]    According to an embodiment of the present invention, a fuse of a semiconductor device comprises: a first conductive pattern; and a second conductive pattern which is separated from the first conductive pattern with a given gap, wherein the first conductive pattern and the second conductive pattern are melted in a laser irradiation to be connected. 
         [0015]    Preferably, the first conductive pattern and the second conductive pattern are formed in the same plane. 
         [0016]    Preferably, a fuse of a semiconductor device further comprises an insulating layer which is formed on an upper portion of the first conductive pattern and the second conductive pattern and an upper portion of a space where the first conductive pattern and the second conductive pattern are separated. 
         [0017]    Preferably, the given gap is smaller than ⅓ to 1/2.5 of the height of the first conductive pattern and the second conductive pattern. 
         [0018]    Preferably, the end portion of the first conductive pattern is formed with a convexly protruded form, and the end portion of the second conductive pattern is formed with a concave form receiving the end portion of the first conductive pattern. 
         [0019]    Preferably, the end portion of the first conductive pattern and the end portion of the second conductive pattern are symmetrically formed each other with           shaped feature. 
         [0020]    Preferably, the first conductive pattern and the second conductive pattern are formed with one of the tungsten W, the aluminium Al, the titanium Ti, the copper Cu, the titanium nitride TiN, the Iridium Oxide IrO2, the tungsten silicide WSi and the titanium silicide TiSi. 
         [0021]    According to an embodiment of the present invention, a method of manufacturing a fuse of a semiconductor device comprises: forming a plurality of fuses on a substrate including a substructure; and forming an insulating layer in an upper portion of the fuse, wherein, in forming a plurality of fuses, each fuse is formed with a first conductive pattern and a second conductive pattern which are separated with a given gap. 
         [0022]    Preferably, in forming an insulating layer, a void is formed in a lower portion of a space in which the first conductive pattern and the second conductive pattern are separated. 
         [0023]    Preferably, the first conductive pattern and the second conductive pattern are formed to be separated with a gap which is smaller than ⅓ to 1/2.5 of the height of the pattern. 
         [0024]    The present invention prevents the damage of the adjacent fuse in the repair process by forming the fuse in such a manner that the repair process is made by a melting method not by a blowing method, thereby, enabling to improve the reliability of device and accomplish the high integration. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0025]      FIG. 1   a  is a plan view illustrating a conventional fuse unit of a semiconductor device, 
           [0026]      FIG. 1   b  is a cross-sectional view taken along Y-Y′ of  FIG. 1   a.    
           [0027]      FIG. 2  is a plan view illustrating a structure of fuse according to a first preferred embodiment of the present invention. 
           [0028]      FIG. 3   a  is a cross-sectional diagram taken along A-A′ of  FIG. 2 . 
           [0029]      FIG. 3   b  is a cross-sectional diagram taken along B-B′ of  FIG. 2 . 
           [0030]      FIG. 4  is a diagram illustrating a fuse contact unit according to the present invention, which is melted to be connected. 
           [0031]      FIG. 5  is a plan view illustrating a structure of fuse according to a second preferred embodiment of the present invention. 
           [0032]      FIGS. 6   a  to  6   c  are process cross-sectional diagrams illustrating a method of manufacturing a fuse having the structure of  FIG. 3 . 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0033]    Embodiments of the present invention are described in detail with reference to the accompanying drawings. The same reference numbers are used throughout the drawings to refer to the same or like parts. 
         [0034]    Firstly, the technical principle of the present invention is briefly illustrated. 
         [0035]    In the present invention, the initial state of each fuse is separated into a conductive pattern of two parts. Thereafter, the fuse of a fuse contact unit is melted by irradiating a laser onto the separated part (hereinafter, ‘fuse contact unit’) so that the separated conductive pattern is electrically connected. That is, in the present invention, the repair process is performed by using a fuse melting method not by a fuse blowing method. At this time, in the present invention, two conductive patterns can be simultaneously formed with one patterning process by forming the separated two fuses on the same plane. 
         [0036]    Moreover, in the present invention, an overhang of an insulating layer is used in order to secure a space (i.e., void) in which the melted fuse can be connected while the conductive pattern is not exposed to an external environment. The overhang of an insulating layer is caused in the formation of the insulating layer in the upper portion of a fuse so that a void is formed in the lower portion of fuse contact unit. 
         [0037]      FIG. 2  is a plan view illustrating a structure of fuse according to a first embodiment of the present invention.  FIG. 3   a  is a cross-sectional diagram taken along A-A′ of  FIG. 2 .  FIG. 3   b  is a cross-sectional diagram taken along B-B′ of  FIG. 2 . 
         [0038]    A plurality of line fuses  201  are formed on a substrate  200  in which a certain substructure is equipped. 
         [0039]    An insulating layer  202  covering a fuse  201  is formed in the upper portion of the fuse  201 . At this time, in the fuse box  203  region to which a laser is irradiated, the insulating layer  202  is formed with a given thickness T in such a manner that the energy of an irradiated laser can be sufficiently delivered to the fuse  201 . The height H of a fuse is formed to be 8000 or more. 
         [0040]    Particularly, each fuse  201  of the present invention includes a fuse contact unit  204  which electrically separates the fuse  201  of line-shape into two parts  201   a ,  201   b  in the fuse box  203 . The fuse contact unit  204  is a region to which laser is irradiated in the repair process, and electrically connects the fuse  201  when the fuse contact unit  204  is melted by the laser. 
         [0041]    That is, in an initial state, (i.e., before a repair process is performed), each fuse  201  of the present invention is not connected as one continuous line, but formed in such a manner that two conductive patterns  201   a ,  201   b  are electrically separated with a constant gap D. If a laser is irradiated to the fuse contact unit  204  in the repair process, the first conductive pattern  201   a  and the second conductive pattern  201   b  are melted and electrically connected. 
         [0042]    At this time, in the fuse contact unit  204 , the gap D between the first conductive pattern  201   a  and the second conductive pattern  201   b  are formed in the upper portion of the fuse  201  in such a manner that an inter metal dielectric (IMD) does not gap fill the space between the first conductive pattern  201   a  and the second conductive pattern  201   b  and a void (refer to dotted circles in  FIG. 3 ) is formed to be approximately 50% of the height of the fuse  201  (4000 Å˜5000 Å). 
         [0043]    Generally, if the fuse  201  is formed in such a manner that the aspect ratio D:H of the gap D between the first conductive pattern  201   a  and the second conductive pattern  201   b  to the fuse height H becomes 1:2.5˜1:3 or more, an overhang phenomenon is generated during the formation of the insulating layer  202 . The overhang is generated in the upper portion of the fuse  201  such that the insulator is not gap filled in the lower portion of the fuse contact unit  204  and a void is generated in the lower portion. 
         [0044]    In the present invention, in the formation of the insulating layer  202  on the upper portion of the fuse  201 , a void is intentionally formed in the lower portion of the fuse contact unit  204 . The first conductive pattern  201   a  and the second conductive pattern  201   b  are then connected to each other by a laser in a repair process. The laser is irradiated locally at the fuse contact unit  204  such that the conductive patterns  201   a  and  201   b  are melted and flow into the void (see  FIG. 4 ). This is done while maintaining the integrity of the insulating layer  202 , which prevents the fuse  201  from being exposed to the external environment. 
         [0045]    As described above, the present invention does not use the fuse blowing method but uses a fuse melting method such that the explosion phenomenon, for example, the explosion in the fuse cutting is not generated, thereby, does not affect the adjacent fuses. Moreover, the present invention can prevent damage to the insulating layer due to the explosion phenomenon so that the fuse is not exposed to the external environment, thereby, the reliability of fuse can be increased. 
         [0046]    Moreover, the present invention can form the fuse with one conventional patterning process by forming two conductive patterns  201   a ,  201   b . The exposed surface area (i.e., in the void) where the first conductive pattern  201   a  and the second conductive pattern  201   b  face each other in the fuse contact unit  204  may be formed as large as possible so that two conductive patterns  201   a ,  201   b  can be more reliably connected during the fuse melting. 
         [0047]    Therefore, in the present invention, when separating the fuse  201  into the first conductive pattern  201   a  and the second conductive pattern  201   b , the minor axis of the fuse  201  is not separated in a straight line but is separated in a zig zag or other pattern to increase the length of the break line. 
         [0048]    For example, as shown in  FIG. 2 , the end portion of the first conductive pattern  201   a  is convexly protruded with a scoop shape while the end portion of the second conductive pattern  201   b  adjacent to it is formed with a concave shape which receives the end portion of the first conductive pattern  201   a . Another example, as shown in  FIG. 5 , the end portion of the first conductive pattern  201   a  and the end portion of the second conductive pattern  201   b  can be formed to be symmetrical with an           shaped feature. 
         [0049]    The shape of  FIGS. 2 and 5  are just two embodiments of the present invention and various modifications are possible. 
         [0050]      FIGS. 6   a  to  6   c  are cross-sectional diagrams illustrating a method of manufacturing a fuse having the structure of  FIG. 3 . 
         [0051]    Referring to  FIG. 6   a , a plurality of fuses  201  (in  FIG. 5 , only one fuse is shown) are patterned in the upper portion of the fuse region of the substrate  200  in which a certain substructure (not shown) has already been formed. 
         [0052]    At this time, the two fuse regions  201   a ,  201   b  are separated with a constant gap D as shown in  FIG. 2  or  FIG. 5  to form one fuse  201 . That is, in the present invention, each fuse  201  is formed with an initial state which is electrically separated. At this time, the aspect ratio D:H of the gap D between the first conductive pattern  201   a  and the second conductive pattern  201   b  to the height H of the fuse  201  is set to be 1:2.5˜1:3 or more. 
         [0053]    The fuse  201  can be formed with one of a metal layer, a conductive metal nitride layer, a conductive metal oxide layer, a metal silicide layer or a stacked combination of those materials. For example, tungsten W, aluminium Al, titanium Ti, copper Cu and so on can be used as a metal layer. The titanium nitride TiN layer can be used as a conductive metal nitride layer. The Iridium Oxide IrO2 layer can be used as a conductive metal oxide layer. The tungsten silicide WSi, the titanium silicide TiSi can be used as a metal silicide layer. Moreover, such a fuse pattern  201  is not formed not by additionally depositing the metal material layer but can be patterned together when the plate electrode or metal line of a capacitor is formed. 
         [0054]    Referring to  FIG. 6   b , an insulating layer  202  is formed on the upper portion of the substrate  200  and fuse  201 . The insulating layer  202  can be formed with an oxide layer. Silicon oxide film (SiO2), Boron Phosphorus Silicate Glass (BPSG), Phosphorus Silicate Glass (PSG), Tetra Ethyle Ortho Silicate (TEOS), Un-doped Silicate Glass (USG), Spin On Glass (SOG), High Density Plasma (HDP), Spin On Dielectric (SOD) and so on can be used as an oxide layer. 
         [0055]    As described, in the formation of the insulating layer  202  in the upper portion of the fuse  201 , the aspect ratio D:H of the gap D between the first conductive pattern  201   a  and the second conductive pattern  201   b  to the height H of the fuse  201  may be made 1:2.5˜1:3 or more. This generates an overhang of the insulating layer in the upper portion of the separated space due to the step coverage of the insulating layer such that the insulating layer does not gap fill the lower portion but creates a void. 
         [0056]    That is, in the present invention, the separated space between the first conductive pattern  201   a  and the second conductive pattern  201   b  is not gap filled by the insulating layer  202 , so that the void is intentionally formed. Accordingly, it is advantageous for the void formation to form the fuse  201  with the thickness of the metal line as large as possible when forming the fuse  201  with the metal line. 
         [0057]    Referring to  FIG. 6   c , the insulating layer of the fuse box  203  region to which a laser is irradiated is etched to a certain depth, so that only an insulating layer of a given thickness above the fuse  201  remains in the fuse box  203  region. This allows the heat energy of the irradiated laser to be sufficiently delivered to the fuse  201 . 
         [0058]    In the above-described embodiment, it was explained that the insulating layer  202  is formed in the upper portion of the fuse  201  so that the fuse  201  is not exposed to the external environment in the fuse contact unit  204 . However, the fuse  201  can also be formed without the insulating layer  202 . 
         [0059]    In that case, the fuse  201  is exposed to the external environment, but the process margin for the height H of the fuse  201  and the gap D between the first conductive pattern  201   a  and the second conductive pattern  201   b  can be better secured in the formation of the fuse  201 . 
         [0060]    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 describe 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. Other additions, subtractions, or modifications are obvious in view of the present disclosure and are intended to fall within the scope of the appended claims.