Semiconductor interconnect formed over an insulation and having moisture resistant material

Abstract

A plurality of metal wires are formed on an underlying interlayer insulating film. Areas among the metal wires are filled with a buried insulating film of a silicon oxide film with a small dielectric constant (i.e., a first dielectric film), and thus, a parasitic capacitance of the metal wires can be decreased. On the buried insulating film, a passivation film of a silicon nitride film with high moisture absorption resistance (i.e., a second dielectric film) is formed, and thus, a coverage defect can be avoided. A bonding pad is buried in an opening formed in a part of a surface protecting film including the buried insulating film and the passivation film, so as not to expose the buried insulating film within the opening. Thus, moisture absorption through the opening can be prevented. In this manner, the invention provides a semiconductor device which has a small parasitic capacitance in an area with a small pitch between the metal wires and is free from a coverage defect as well as the moisture absorption through the opening for the bonding pad, and a method of manufacturing the semiconductor device.

1. A semiconductor device comprising:
 a semiconductor substrate bearing semiconductor elements;  
 an interlayer insulating film formed on said semiconductor substrate;  
 a metal wire layer including plural metal wires formed on said interlayer insulating film;  
 a surface protecting film including a first dielectric film with a small dielectric constant for filling  forming at least a part of areas among said metal wires in said metal wire layer and a second dielectric film with a higher moisture absorption preventing function than said first dielectric film for covering said metal wire layer and said first dielectric film, said second dielectric film having a function of suppressing moisture absorption of said first dielectric film;  
 an opening for a bonding pad formed in said surface protecting film; and  
 a bonding pad forming in said opening for obtaining external electrical connection,  
 wherein said bonding pad and said second dielectric film of said surface protecting film completely cover said first dielectric film within said opening so as not to expose said first dielectric film, and  
   wherein said entire upper surface of said first dielectric film is substantially flat .  
 
     
     
       2. The semiconductor device of  claim 1 ,
 wherein said first dielectric film is buried, among said areas among said metal wires, at least in an area having a minimum pitch between said metal wires.  
 
     
     
       3. The semiconductor device of  claim 1 ,
 wherein said first dielectric film is formed on said interlayer insulating film and said metal wires, and said second dielectric film is formed over said first dielectric film,  
 said opening is formed through said first and second dielectric films, with exposing a part of at least one of said metal wires of said metal wire layer, and  
 said bonding pad is buried in said opening so as to cover a side face of said first dielectric film within said opening and is connected with said at least one of said metal wires.  
 
     
     
       4. The semiconductor device of  claim 3 ,
 wherein said bonding pad extends above a top surface of said second dielectric film.  
 
     
     
       5. The semiconductor device of  claim 4 ,
 wherein said bonding pad has an area larger than a connecting portion with said at least one of said metal wires, and extends above a top surface of said second dielectric film to reach a portion above said semiconductor elements on said semiconductor substrate.  
 
     
     
       6. The semiconductor device of  claim 3 ,
 wherein said bonding pad is buried in said opening with a top surface thereof placed at a level equal to or lower than a top surface of said second dielectric film.  
 
     
     
       7. The semiconductor device of  claim 3 ,
 wherein a third dielectric film for preventing moisture absorption is disposed between said first dielectric film and any of said interlayer insulating film and said metal wires.  
 
     
     
       8. The semiconductor device of  claim 7 ,
 wherein said third dielectric film is made from a silicon nitride film.  
 
     
     
       9. The semiconductor device of  claim 1 ,
 wherein said first dielectric film is formed merely in said areas among said metal wires,  
 said second dielectric film is formed to be in contact with a top surface of said first dielectric film and top surfaces of said metal wires of said metal wire layer,  
 said opening is formed through merely said second dielectric film, and  
 a part of at least one of said metal wires functions as said bonding pad.  
 
     
     
       10. The semiconductor device of  claim 9 ,
 wherein a thin etching stopper film with high etching selectivity against said interlayer insulating film is disposed between said first dielectric film and said interlayer insulating film.  
 
     
     
       11. The semiconductor device of  claim 9 ,
 wherein a third dielectric film for preventing moisture absorption is disposed between said first dielectric film and any of said interlayer insulating film, said metal wires and said second dielectric film.  
 
     
     
       12. The semiconductor device of  claim 1 ,
 wherein said first and second dielectric films are formed merely in said areas among said metal wires, and  
 a part of at least one of said metal wires of said metal wire layer functions as said bonding pad.  
 
     
     
       13. The semiconductor device of  claim 1 ,
 wherein said first dielectric film is made from at least one oxide film selected from the group consisting of a silicon oxide film, a silicon oxide film doped with fluorine and a porous silicon oxide film, or a composite film including an organic insulating film and at least one oxide film selected from the group consisting of a silicon oxide film, a silicon oxide film doped with fluorine and a porous silicon oxide film.  
 
     
     
       14. The semiconductor device of  claim 1 ,
 wherein said first dielectric film has a dielectric constant of 3.9 or less.  
 
     
     
       15. The semiconductor device of  claim 1 ,
 wherein said second dielectric film is made from a silicon nitride film.  
 
     
     
       16. The semiconductor device of  claim 1 , wherein said bonding pad directly contacts one of said plural metal wires formed on said interlayer insulating film. 
     
     
       17. The semiconductor device of  claim 1 , wherein said bonding pad directly contacts said surface protecting film. 
     
     
       18. A semiconductor device comprising:
   a semiconductor substrate;        an interlayer insulating film formed on said semiconductor substrate;        a first dielectric film with a small dielectric constant and metal wires formed on said interlayer insulating film; said first dielectric layer disposed between said metal wires;        a second dielectric film, which has a higher moisture absorption preventing function than said first dielectric film, formed on a surface of said first dielectric film and on a surface of each metal wire, said second dielectric film having a function of suppressing moisture absorption by said first dielectric film; and        an opening formed in said second dielectric film so as to expose at least one of said metal wires,        wherein the surface of said first dielectric film and the surface of said metal wires are flat, and        wherein said metal wires under said opening and said second dielectric film completely cover said first dielectric film within said opening so as not to expose said first dielectric film.      
     
     
       19. The semiconductor device of  claim 18 , wherein said first dielectric film is at least formed in an area having a minimum pitch between the metal wires.  
     
     
       20. The semiconductor device of  claim 18 , wherein said first dielectric film is made from an oxide film or a composite film consisting at least one of a TEOS film, a silicon oxide film doped with fluorine and a porous silicon oxide film, or a composite film including an organic insulating film and at least one of a TEOS film, a silicon oxide film doped with fluorine and a porous silicon oxide film.  
     
     
       21. The semiconductor device of  claim 18 , wherein said first dielectric film has a dielectric constant of  3 . 9  or less.  
     
     
       22. The semiconductor device of  claim 18 , wherein said second dielectric film is made from a silicon nitride film.  
     
     
       23. The semiconductor device of  claim 18 , wherein the second dielectric film is in contact with said at least one metal wire exposed in said opening.  
     
     
       24. A semiconductor device comprising:
   a semiconductor substrate;        an interlayer insulating film formed on said semiconductor substrate;        a metal wire layer including plural metal wires formed on said interlayer insulating film;        a first dielectric film with a small dielectric constant formed on both said interlayer insulating film and said metal wires, a surface of said first dielectric film is flattened by chemical mechanical polishing;        a second dielectric film having a higher moisture absorption preventing function than said first dielectric film and formed on the entire surface of said first dielectric film, said second dielectric film having a function of suppressing moisture absorption by said first dielectric film;        an opening formed in both said first dielectric film and said second dielectric film such that a portion of at least one of said metal wires in said metal wire layer is exposed; and        a bonding pad formed in said opening so as to connect said metal wires under said opening,        wherein said bonding pad and said second dielectric film completely cover said first dielectric film within said opening so as not to expose said first dielectric film.      
     
     
       25. The semiconductor device of  claim 24 , wherein said bonding pad extends above a top surface of said second dielectric film.  
     
     
       26. The semiconductor device of  claim 25 , wherein said bonding pad has an area larger than a connecting portion with said metal wires under said opening, and extends above a top surface of said second dielectric film to reach a portion above said semiconductor elements on said semiconductor substrate.  
     
     
       27. The semiconductor device of  claim 24 , wherein said bonding pad is buried in said opening with a top surface thereof placed at a level equal to or lower than a top surface of said second dielectric film.  
     
     
       28. The semiconductor device of  claim 24 , further comprising,
   a third dielectric film for preventing moisture absorption disposed between said first dielectric film and any of said interlayer insulating film and said metal wires.      
     
     
       29. The semiconductor device of  claim 28 , wherein said third dielectric film is made from a silicon nitride film.  
     
     
       30. The semiconductor device of  claim 24 , wherein said first dielectric film is made from an oxide film or a composite film consisting at least one of a TEOS film, a silicon oxide film doped with fluorine and a porous silicon oxide film, or a composite film including an organic insulating film and at least one of a TEOS film, a silicon oxide film doped with fluorine and a porous silicon oxide film.  
     
     
       31. The semiconductor device of  claim 24 , wherein said first dielectric film has a dielectric constant of  3 . 9  or less.  
     
     
       32. The semiconductor device of  claim 24 , wherein said second dielectric film is made from a silicon nitride film.