Abstract:
An electrostatic discharge (ESD) circuitry bus within closed ring is disclosed. The closed ring comprises a plurality of metal layer. A metal layer can conduct electricity to another metal layer by conductive plugs. An oxide region can separate the closed ring into two closed ring regions by payout. Each closed ring region does not conduct electricity to each other by an oxide region. One closed ring section is Vdd bus. Therefore, the closed ring of the present invention can be sued by Vss bus and Vdd bus at the same time.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a closed ring structure of electrostatic discharge circuitry, and more particularly relates to a closed ring structure for being used by the Vss bus and Vdd bus at the same time.  
         [0003]     2. Description of the Prior Art  
         [0004]     There are some electrostatic discharge circuitries (ESD) in most applications of the integrated circuit. The circuitry can be used to absorb and release the static electricity with high voltage, which can damage circuit. One of the electrostatic discharge circuitry is an input/output (I/O) unit. The functions of the I/O unit are: the signal can be used in the core of the circuit region from the I/O pad, and the I/O unit is also used to amplify and activate the signal, which is from the internal of the core circuit to the external of the IO pad. And the I/O pad can be connected to the wire of the packaging component.  
         [0005]     Generally, the static electricity controlled and moved by the human is about 2000 voltages (just like the current with 1.3A flowing through 1500(ohm)) and most of the electrostatic discharge circuitry can release and absorb enough static electricity, which can cause the static electricity discharge.  
         [0006]     The prior art is related to the present invention, referring to U.S. Pat. No. 6,078,068, and the patent provides an integrated circuit with electrostatic discharge protect structure. Referring to  FIG. 1  is a vertical view of the semiconductor die, the die of the integrated circuit is included a core logic region with a plurality of transistors. The transistors are connected to each other and formed a specific integrated circuit. A plurality of input/output cells  106  are limited in the surrounding area of the die of the integrated circuit. The prior art is provided a ESD bus die edge seal  120 , which: is disposed in the outside of a plurality of input/output cells  106 . The input/output cells  106  are closely connected to the outside the die of the integrated circuit. The external part of the input/output cell  106  is included a plurality of Vss power cells. A plurality of ESD cross-coupled diodes  110  are connected between a plurality of Vss power cells and ESD bus die edge seal. And a sealed structure is provided in the united closed ring structure of the ESD circuitry of the die.  
         [0007]     The semiconductor die described above is included a bonding pad  108  and ESD bus die edge seal  120 . The ESD bus die edge seal  120  is coupled to the chosen input/output cell  106  by the ESD cross coupled diode  110 . The outside of the ESD bus die edge seal  120  is the oxidized surface  104   a  of the first circle. The inside of the ESD bus die edge seal  120  is the oxidized surface  104   b  of the second circle. In order to provide an efficient electric depletion path to prevent causing a high voltage ESD in the production, packaging, or the components in shipping, all the Vss cells are connected to the ESD bus die edge seal  120 .  
         [0008]      FIG. 2  is a cross-sectional view of the semiconductor die seal in the prior art. And comparing to  FIG. 1 , the ESD bus die edge seal  120  comprises a first metal layer  21 , the second metal layer  22 , the third metal layer  23 , the forth metal layer  24 , the fifth metal layer  25  and the sixth metal layer  26 . The oxidized layer used to be the obstruction and the seal structure in the surrounding area of the semiconductor die is filled between each metal layer. There is a P-substrate in the bottom of the semiconductor die. And the P-substrate comprises a doped region, which is a P+ substrate contact.  
         [0009]     The first metal layer  21  is electrically connected to the P+ substrate contact by the conductive contact  21   a  and the conductive contact  21   b . The first metal layer  21  is electrically connected to the second metal layer  22  by the conductive plug  22   a  and the conductive plug  22   b . The second metal layer  22  is electrically connected to the third metal layer  23  by the conductive plug  23   a  and the conductive plug  23   b . The third metal layer  23  is electrically connected to the forth metal layer  24  by the conductive plug  24   a  and the conductive plug  24   b . The forth metal layer  24  is electrically connected to the fifth metal layer  25  by the conductive plug  25   a , and the conductive plug  25   b . The fifth metal layer  25  is electrically connected to the sixth metal layer  26  by the conductive plug  26   a  and the conductive plug  26   b . The metal layers of the ESD bus die edge cell can be electrically connected to each other by the conductive plugs. The electric charge moving from the die edge  204  can be attracted by the Vss power supply, which is provided by the ESD cross coupled diode  210 . And the width W 2  of the ESD bus die edge seal  120  is about 4 μm˜40 μm. For the 0.35 mm conduction, the width W 2  of the seal is about 6 μm˜30 μm.  
         [0010]     Because the seal of the prior art can only be used to be the ESD Vss electrostatic discharge bus, it is not a good way to use the seal structure to decrease the size of the die and the cost of the production.  
       SUMMARY OF THE INVENTION  
       [0011]     The purpose of the present invention is to overcome the drawbacks described above, and a new structure provided to let the seal be used by the Vss bus and the Vdd bus at the same time. Therefore, the size of the die can be decreased.  
         [0012]     The present invention provides a new structure to let the seal be used by the Vss bus and Vdd bus at the same time and then the cost can be reduced.  
         [0013]     The present invent provides a new electrostatic discharge (ESD) circuitry bus within the closed ring structure. The closed ring includes a plurality of metal layers. The oxidized layer is used to divide each of the metal layers. The metal layers can be electrically connected to each other by the conductive plug. By the layout, the oxidized layer can be used to divide the closed ring into two closed ring regions, which are not electrically connected to each other. One of the two closed ring regions is the Vss electrostatic discharge bus, and the other is the Vdd electrostatic discharge bus. Therefore, the closed ring structure of the present invention can be used by the Vss bus and the Vdd bus at the same time. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]     The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:  
         [0015]      FIG. 1  is vertical view of the semiconductor die.  
         [0016]      FIG. 2  is a cross-sectional view of the closed ring structure in the semiconductor of the prior art.  
         [0017]      FIG. 3  is a cross-sectional view of the closed ring structure according to the first embodiment of the present invention.  
         [0018]      FIG. 4  is a cross-sectional view of the closed ring structure according to the second embodiment of the present invention.  
         [0019]      FIG. 5  is a cross-sectional view of the closed ring structure according to the third embodiment of the present invention.  
         [0020]      FIG. 6  is a cross-sectional view of the closed ring structure according to the forth embodiment of the present invention.  
         [0021]      FIG. 7A  is a vertical view of the third metal layer according to the fifth embodiment of the present invention.  
         [0022]      FIG. 7B  is the first cross-sectional view of the closed ring structure according the fifth embodiment of the present invention.  
         [0023]      FIG. 7C  is the second cross-sectional view of the closed ring structure according to the fifth embodiment of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0024]     The detailed description of the present invention will be discussed in the following embodiments, which are not intended to limit the scope of the present invention, but can be adapted for other applications. While drawings are illustrated in details, it is appreciated that the quantity of the disclosed components may be greater or less than that disclosed, except expressly restricting the amount of the components.  
         [0025]      FIG. 3  is the vertical view of the closed ring structure in the first embodiment of the present invention. And comparing with the  FIG. 1A  and  FIG. 3 , the closed ring  120  includes a first metal layer  31 , a second metal layer  32 , a third metal layer  33 , a forth metal layer  34 , a fifth metal layer  35 , a sixth metal layer  36  and all the metal layers are isolated by the oxidized layer. The right side of the sixth metal layer  36  is the oxidized layer surface  104   a  of the first circle and the right side of which is the oxidized layer surface  104   b  of the second circle. The bottom of the closed ring  120  is a P substrate. And the P substrate is included a doped region, which is the P+ substrate contact.  
         [0026]     The conductive contact  31   a  and the conductive contact  31   b  are used to connect between the first metal layer  61  and the P+ substrate contact. The conductive plug  32   a  and the conductive plug  32   b  are used to connect between the first metal layer  31  and the second metal layer  33 . The oxidized is used to electrically isolate the region between the third metal layer  33  and the forth metal layer  34 . The conductive plug  35   a  and the conductive plug  35   b  are used to connect between the forth metal layer  34  and the fifth metal layer  35  the conductive plug  36   a  and the conductive plug  36   b  are sued to connect between the fifth metal layer  35  and the sixth metal layer  36 .  
         [0027]     According to  FIG. 3 , there are no conductive plugs can be used to electrically connect between the third metal layer  33  and the forth metal layer  34 . The region below the third metal layer  33  is the Vss electrostatic discharge bus and the Vss electrostatic discharge bus is connected to the Vss power source bus. The region above the forth metal layer  34  is not electrically connected to the bottom portion of the closed ring structure, so the region can be the Vdd electrostatic discharge bus. The Vdd electrostatic discharge bus is connected to the Vdd power source bus. All the metal layers, which are formed between the Vss electrostatic discharge bus and the Vdd electrostatic discharge bus, are disposed in the different layers. The Vss electrostatic discharge bus and the Vdd electrostatic discharge bus is electrically isolated to each other. Therefore, the structure of the present embodiment can be used by the Vss electrostatic discharge bus and the Vdd electrostatic discharge bus at the same time.  
         [0028]      FIG. 4  is the closed ring structure according to the second embodiment of the present invention. Comparing  FIG. 4  with  FIG. 1A , the closed ring  120  includes a metal region  411  and a metal region  412  of the first metal layer, a metal region  421  and a metal region  422  of the second metal layer, a metal region  431  and a metal region  432  of the third metal layer, a metal region  441  and a metal region  442  of the forth metal layer, a metal region  451  and a metal region  452  of the fifth metal layer, a metal region  461  and a metal region  462  of the sixth metal layer. And all the metal layers are isolated to each other by the oxidized layer. The right side of the metal region  462  is the oxidized surface  104   a  of the first circle, and the left side of which is the oxidized surface  104   b  of the second circle. The bottom of the closed ring  120  is the P substrate. The P substrate includes two doped regions. The left side of the doped region is the P+ substrate, and the right side of the doped region is the N well and the N+ substrate contact. The conductive properties of these two doped regions are different.  
         [0029]     The metal region  411  of the first metal layer is electrically connected to the P+ substrate contact by the conductive contact  41   a . The metal region  411  of the first metal layer is electrically connected to the metal region  421  of the second metal layer by the conductive plug  42   a . The metal region  421  of the second metal layer is electrically connected to the metal region  431  of the third metal layer by the conductive plug  43   a . The metal region  431  of the third metal layer is electrically connected to the metal region  441  of the forth metal layer by the conductive plug  44   a . The metal region  441  of the forth metal layer is electrically connected to the metal region  451  of the fifth metal layer by the conductive plug  45   a . The metal region  451  of the fifth metal layer is electrically connected to the metal region  461  of the sixth metal layer by the conductive plug  46   a.    
         [0030]     The metal region  412  of the first metal layer is electrically connected to the N+ substrate contact by the conductive contact  41   b . The metal region  412  of the first metal layer is electrically connected to the metal region  422  of the second metal layer by the conductive plug  42   b . The metal region  422  of the second metal layer is electrically connected to the metal region  432  of the third metal layer by the conductive plug  43   b . The metal region  432  of the third metal layer is electrically connected to the metal region  442  of the forth metal layer by the conductive plug  44   b . The metal region  442  of the forth metal layer is electrically connected to the metal region  452  of the fifth metal layer by the conductive plug  45   b . The metal region  452  of the fifth metal layer is electrically connected to the metal region  462  of the sixth metal layer by the conductive plug  46   b.    
         [0031]     To compare  FIG. 4  with  FIG. 2 , the structure of  FIG. 4  is that the structure of  FIG. 2  is divided into two closed ring region by the oxidized layer. The width W 41  of the left side of the closed ring region or the width W 42  of the right side of the closed ring region is about haft of the width of the closed ring region in  FIG. 2 . The left structure of the closed ring region is not electrically connected to the right structure of the closed ring region. Therefore, the left side of the closed ring structure is Vss electrostatic discharge bus. The Vss electrostatic discharge bus is electrically connected to the Vss power source bus. The right side of the closed ring structure is the Vdd electrostatic discharge bus and the slide line is drawn in the Vdd electrostatic discharge bus region. The Vdd electrostatic discharge bus is electrically connected to Vdd power source bus. The Vdd electrostatic discharge bus is disposed near the Vss electrostatic discharge bus and is electrically isolated to each other. Therefore, the structure of the present embodiment can be used by the Vss electrostatic discharge bus and the Vdd electrostatic discharge bus at the same time.  
         [0032]      FIG. 5  is the cross-sectional view according to the closed ring structure of the third embodiment of the present invention. And comparing  FIG. 5 ′ with  FIG. 1A , the closed ring  120  includes a first metal layer  51 , a metal region  521  and a metal region  522  of the second metal layer, a metal region  531  and a metal region  532  of the third metal layer, a metal region  541  and a metal region  542  of the forth metal layer, a fifth metal layer  55  and a sixth metal layer  56 . The right side of the sixth metal layer is the oxidized surface  104   a  of the first circle and the left side of which is the oxidized surface of the second circle  104   b . The bottom of the closed ring is a P substrate. The P substrate includes a doped region, which is a P+ substrate contact.  
         [0033]     The first metal layer  51  is electrically connected to P+ substrate contact by the conductive contact  51   a  and the conductive contact  51   b . The first metal layer  51  is electrically connected to the metal region  521  of the second metal layer by the conductive plug  52   a  and the conductive plug  52   b . The metal region  521  of the second metal layer is electrically connected to the metal region  531  of the third metal layer by the conductive plug  53   a  and the conductive plug  53   b . The metal region  531  of the third metal layer is electrically connected to the metal region  541  of the forth metal layer by the conductive plug  54   a . The metal region  522  of the second metal layer is electrically connected to the metal region  532  of the third metal layer by the conductive plug  53   c . The metal region  532  of the third metal layer is electrically connected to the metal region  542  of the forth metal layer by the conductive plug  54   b  and  54   c . The metal region  542  of the forth metal layer is electrically connected to the fifth metal layer  55  by the conductive plug  54   b . The forth metal layer  54  is electrically connected to the fifth metal layer  55  by the conductive plug  55   a  and  55   b . The fifth metal layer  55  is electrically connected to the sixth metal layer  56  by the conductive plug  56   a  and  56   b.    
         [0034]     To compare the closed ring in  FIG. 3  and  FIG. 5 , the structure in  FIG. 5  is that the closed ring is divided into the bottom left portion and top right portion. This structure is more complicated than the structure in  FIG. 3  and  FIG. 4 . The bottom left portion of the closed ring structure is not electrically connected to the top right portion of the closed ring structure. Therefore, the bottom left portion of the closed ring structure is the Vss electrostatic discharge bus and the top right portion of the closed ring structure is the Vdd electrostatic discharge bus. The Vdd electrostatic discharge bus is electrically connected to the Vdd power source bus. Therefore, the structure of the present embodiment can be used by the Vss electrostatic discharge bus and the Vdd electrostatic discharge bus at the same time. And comparing to the  FIG. 3 , the oxidized layer divided from the closed ring  120  is irregular in the present embodiment. The Vss electrostatic discharge bus and the Vdd electrostatic discharge bus are formed in the step shape by the cross-sectional view. The positions of these two step shapes are complementary to each other and the mechanism strength can be enhanced in the parallel and vertical direction of the die. So the structure of the present embodiment is harder than the structure in  FIG. 3 .  
         [0035]      FIG. 6  is the cross-sectional view according to the closed ring structure of the forth embodiment in the present invention. The closed ring  120  includes a first metal layer  61 , a second metal layer  62 , a metal-region  631 , a metal region  632  and a metal region  633  of the third metal layer, a forth metal layer  64 , a fifth metal layer  64 , and a sixth metal layer  66 . All the metal layers are isolated to each other by the oxidized layer. The right side of the sixth metal layer  66  is the oxidized layer  104   a  of the first circle and the left side of which is the oxidized layer  104   b  of the second circle. The bottom of the closed ring is a P substrate. The P substrate includes a doped region, which is a P+ substrate contact.  
         [0036]     The first metal layer  61  is electrically connected to the P+ substrate by the conductive contact  61   a  and conductive contact  61   b . The first metal layer  61  is electrically connected to the second metal layer  62  by the conductive plug  62   a  and the conductive plug  62   b . The second metal layer  62  is electrically connected to the metal region  632  of the third metal layer by the conductive plug  63   a . The metal region  631  of the third metal layer is electrically connected to the forth metal layer  64  by the conductive plug  64   a . The metal region  633  of the third metal layer is electrically connected to the metal layer  64  by the conductive plug  64   b . The forth metal layer  64  is electrically connected to the fifth metal layer  65  by the conductive plug  65   a  and the conductive plug  65   b . The fifth metal layer  65  is electrically connected to the sixth metal layer  66  by the conductive plug  66   a  and the conductive plug  66   b.    
         [0037]     By comparing  FIG. 6  with  FIG. 3 , the structure of  FIG. 6  is the closed ring divided into the top portion and the bottom portion by the oxidized layer. The top portion of the closed ring region is not electrically connected to the bottom portion of the closed ring region. But the structure of the present embodiment is more complicated than the structure in  FIG. 3 . The bottom portion of the closed ring structure is the Vss electrostatic discharge bus and the Vss electrostatic discharge bus is electrically connected to the Vss power source bus. The top portion of the closed ring structure is the Vdd electrostatic discharge bus and the Vdd electrostatic discharge bus is drawn by the slide line. The Vdd electrostatic discharge bus is electrically connected to the Vdd power source bus. Therefore, the structure of the present embodiment can be used by the Vss electrostatic discharge bus and the Vdd electrostatic discharge bus at the same time. By comparing to  FIG. 3 , the closed ring structure is isolated by the oxidized layer and the shape of the oxidized layer is irregular. So the structure of the present embodiment is harder than the structure in  FIG. 3 .  
         [0038]      FIG. 7A  is the cross-sectional view according to the third metal layer of the fifth embodiment in the present invention. The third metal layer is divided by the oxidized layer into two metal regions  731  and  732 , which are not electrically connected to each other. And the metal region  731  and the metal region  732  are like a concave connected to a protruding. There are three conductive plugs  73   b ,  74   a  and  74   b .  FIG. 7A  is divided into  FIG. 7B  and  FIG. 7C  by the cross-sectional line  7 B and  7 C.  FIG. 7B  is the first cross-sectional view according to the closed ring structure of the fifth embodiment in the present invention. By comparing  FIG. 7B  with  FIG. 1A , the closed ring  120  includes a first metal layer  71 , a second metal layer  72 , a metal region  731  and a metal region  732  of the third metal layer, a metal region  741  and a metal region  742  of the forth metal layer, a fifth metal layer  74  and a sixth metal layer  76 . All the metal layers are isolated to each other by the oxidized layer. The right side of the sixth metal layer  76  is the oxidized surface  104   a  of the first circle and the left side of which is the oxidized surface  104   b  of the second circle. The bottom of the closed ring  120  is a P substrate, which includes a P+ substrate contact.  
         [0039]     The first metal layer  71  is electrically connected to the P+ substrate contact by the conductive contact  71   a  and the conductive contact  71   b . The first metal layer  71  is electrically connected to the second metal layer  72  by the conductive plug  72   a  and the conductive plug  72   b . The second metal layer  72  is electrically connected to the metal region  732  of the third metal layer by the conductive plug  73   b . The metal region  732  of the third metal layer is electrically connected to the metal region  741  of the forth metal layer by the conductive plug  74   a . The metal region  742  of the forth metal layer is electrically connected to the fifth metal layer  75  by the conductive plug  75   b  and the conductive plug  75   c . The fifth metal layer  75  is electrically connected to the sixth metal layer  76  by the conductive plug  76   a  and the conductive plug  76   b.    
         [0040]     By comparing  FIG. 7B  with  FIG. 3 ,  FIG. 4 ,  FIG. 5 ,  FIG. 6 , the closed ring structure of  FIG. 7B  is divided by the oxidized layer into the top portion and the bottom portion. The top portion and the bottom portion of the closed ring structure are isolated to each other. Therefore, the bottom portion of the closed ring structure can be used by a Vss electrostatic discharge bus and the Vss electrostatic discharge bus is electrically connected to the Vss power source bus. The top portion of the closed ring structure can be used by a Vdd electrostatic discharge bus and the Vdd electrostatic discharge bus is drawn by the slide line. The Vdd electrostatic discharge bus is electrically connected to the Vdd power source bus. Therefore, the structure of the present embodiment can be used by the Vss electrostatic discharge bus and the Vdd electrostatic discharge bus at the same time.  
         [0041]      FIG. 7C  is the second cross-sectional view according to the closed ring structure of the fifth embodiment in the present invention. By comparing to  FIG. 1A , the closed ring  120  includes a first metal layer  71 , a second metal layer  72 , a metal region  731  and a metal region  732  of the third metal layer, a metal region  741  and a metal region  742  of the forth metal layer, a fifth metal layer  75 , and a sixth metal layer  76 . All the metal layers are isolated to each other by the oxidized layer. The right side of the sixth metal layer  76  is the oxidized surface  104   a  of the first circle and the left side of which is the oxidized surface  104   b  of the second circle. The bottom of the closed ring  120  is a P substrate. The P substrate includes a doped region, which is a P+ substrate contact.  
         [0042]     The first metal layer  71  is electrically connected to the P+ substrate by the conductive contact  71   a  and conductive contact  71   b . The first metal layer  71  is electrically connected to the second metal layer  72  by the conductive plug  72 A and the conductive plug  72   b . The second metal layer  72  is electrically connected to the metal region  731  of the third metal layer by the conductive plug  73   b . The metal region  731  of the third metal layer is electrically connected to the metal region  741  of the forth metal layer by the conductive plug  74 B. The metal region  742  of the forth metal layer is electrically connected to the fifth metal layer  75  by the conductive plug  75   b  and the conductive plug  75   c . The fifth metal layer  75  is electrically connected to the sixth metal layer  76  by the conductive plug  76 A and the conductive plug  76   b.    
         [0043]     By comparing  FIG. 7C  with  FIG. 3 ,  FIG. 4 ,  FIG. 5 , and  FIG. 6 , the closed ring structure in  FIG. 7A  is divided into the top portion and the bottom portion by the oxidized layer. The top portion and the bottom portion of the closed ring structure are not electrically connected to each other. Therefore, the bottom portion of the closed ring structure is used to be the Vss electrostatic discharge bus. The Vss electrostatic discharge bus is electrically connected to Vss power source bus. The top portion of the closed ring structure is used to be the Vdd electrostatic discharge bus and the Vdd electrostatic discharge bus is electrically connected to the Vdd power source bus. Therefore, the structure in the present embodiment can be used by the Vss electrostatic discharge bus and the Vdd electrostatic discharge bus. But the structures in  FIG. 7A ,  FIG. 7B  and  FIG. 7C  are more complicated than the structure in  FIG. 3 ,  FIG. 4 ,  FIG. 5  and  FIG. 6 . The structure of the oxidized layer electrically isolates these two closed ring structures in the present embodiment is more irregular than the structure in  FIG. 3 ,  FIG. 4 ,  FIG. 5  and  FIG. 6 . The conductive plugs are crossly disposed, so the strength of the 3 dimension can be enhanced. The structures of the embodiments in  FIG. 7A ,  FIG. 7B , and  FIG. 7C  is harder than the structures in  FIG. 3 ,  FIG. 4 ,  FIG. 5  and  FIG. 6 .  
         [0044]     It should be noted that the closed ring structure of the present invention is not always like the sealed ring structure in  FIG. 1A . The closed ring structure of the present invention can be a non-sealed ring structure or the structure can be used to form an electrostatic discharge bus shown in the present invention.  
         [0045]     Although specific embodiments have been illustrated and described, it will be appreciated by those skilled in the art that various modifications may be made without departing from the scope of the present invention, which is intended to be limited solely by the appended claims.