Copper alloy for wiring, semiconductor device, method for forming wiring, and method for manufacturing semiconductor device

Abstract

A wiring metal contains a polycrystal of copper (Cu) as a primary element and an additional element other than Cu, and concentration of the additional element is, at crystal grain boundaries composing the Cu polycrystal and in vicinities of the crystal grain boundaries, higher than that of the inside of the crystal grains. The additional element is preferably at least one element selected from a group consisting of Ti, Zr, Hf, Cr, Co, Al, Sn, Ni, Mg, and Ag. This Cu wiring is formed by forming a Cu polycrystalline film, forming an additional element layer on this Cu film, and diffusing this additional element from the additional element layer into the Cu film. This copper alloy for wiring is preferred as metal wiring formed for a semiconductor device.

1 . A method forming for a wiring comprising the steps of:
 forming a polycrystalline Cu film;   forming, on the polycrystalline Cu film, a layer made of an additional element to be added into the Cu film; and   diffusing the additional element from the additional element layer into the polycrystalline Cu film.   
   
   
       2 . The method for forming a wiring as set forth in  claim 1 , wherein
 a heating step of heating a substrate on which said polycrystalline Cu film has been formed, said step of forming the additional element layer, and said step of diffusing the additional element are simultaneously performed.   
   
   
       3 . The forming method for wiring as set forth in  claim 1  or  2 , wherein
 the additional element is at least one element selected from a group consisting of Ti, Zr, Hf, Cr, Co, Al, Sn, Ni, Mg, and Ag.   
   
   
       4 . A method for manufacturing a semiconductor device comprising the steps of:
 forming a polycrystalline Cu film on a substrate on which a semiconductor element is formed;   forming a layer composed of an additional element on the polycrystalline Cu film; and   diffusing the additional element from the additional element layer into the polycrystalline Cu film.   
   
   
       5 . A method for manufacturing a semiconductor device comprising the steps of:
 forming an insulating film on a substrate on which a semiconductor element has been formed;   forming concavities for wiring composed of at least either grooves or holes in the insulating film;   forming a Cu film on the insulating film so as to fill up the concavities for wiring;   removing an excessive Cu film on the insulating film excluding parts buried in the concavities for wiring by chemical mechanical polishing;   forming a layer composed of an additional element on the Cu film;   diffusing the additional element from the additional element layer into the Cu film; and   removing an excessive additional element layer.   
   
   
       6 . A method for manufacturing a semiconductor device comprising the steps of:
 forming an insulating film on a substrate on which a semiconductor element has been formed;   forming concavities for wiring composed of at least either grooves or holes in the insulating film;   forming a barrier metal film to prevent Cu from diffusing on the surface of the insulating film including inner surfaces of the concavities for wiring;   forming a Cu film on the insulating film so as to fill up the same in the concavities for wiring;   removing a Cu film and a barrier metal film on the insulating film excluding parts buried in the concavities for wiring by chemical mechanical polishing;   forming a layer composed of an additional element on the Cu film in the concavities for wiring;   diffusing the additional element from the additional element layer into the Cu film; and   removing an excessive additional element layer.   
   
   
       7 . The method for manufacturing a semiconductor device as set forth in  claim 5  or  6 , wherein
 said step of forming the additional element layer, said step of diffusing the additional element, and said step of removing the excessive additional element layer are performed before said step of removing the excessive Cu film.   
   
   
       8 . The method for manufacturing a semiconductor device as set forth in  claim 5  or  6 , wherein
 said step of forming the additional element layer, said step of diffusing the additional element, and said step of removing the excessive additional element layer are performed after said step of removing the excessive Cu film.   
   
   
       9 . The method for manufacturing a semiconductor device as set forth in any one of  claims 4 ,  5  or  6 , wherein
 a step of heating the substrate, said step of forming the additional element layer, and said step of diffusing the additional element are simultaneously performed.   
   
   
       10 . The method for manufacturing a semiconductor device as set forth in any one of  claims 4 ,  5  or  6 , wherein
 the additional element is at least one element selected from a group consisting of Ti, Zr, Hf, Cr, Co, Al, Sn, Ni, Mg, and Ag.