Semiconductor device and method of manufacturing the same

Abstract

To improve reliability of a semiconductor device. There are provided the semiconductor device and a method of manufacturing the same, the semiconductor including a pad electrode that is formed over a semiconductor substrate and includes a first conductive film and a second conductive film formed over the first conductive film, and a plating film that is formed over the second conductive film and used to be coupled to an external connection terminal (TR). The first conductive film and the second conductive film contains mainly aluminum. The crystal surface on the surface of the first conductive film is different from the crystal surface on the surface of the second conductive film.

What is claimed is: 
     
         1 . A semiconductor device comprising:
 a pad electrode that is formed over a semiconductor substrate and comprises a first conductive film and a second conductive film formed over the first conductive film; and   a plating film that is formed over the second conductive film and serves to be coupled to an external connection terminal,   wherein each of the first and second conductive films comprises a film containing mainly aluminum, and   wherein a crystal surface on a surface of the second conductive film is different from the crystal surface on the surface of the first conductive film.   
     
     
         2 . The semiconductor device according to  claim 1 ,
 wherein the second conductive film is in direct contact with the plating film, and   wherein the crystal surface on the surface of the second conductive film is a (111) surface.   
     
     
         3 . The semiconductor device according to  claim 2 ,
 wherein a first insulating film comprising an oxide of a material that configures the first conductive film is formed between the first conductive film and the second conductive film.   
     
     
         4 . The semiconductor device according to  claim 2 ,
 wherein an amorphous film comprising a material different from that of the first conductive film and the second conductive film is formed between the first conductive film and the second conductive film.   
     
     
         5 . The semiconductor device according to  claim 2 ,
 wherein an element doped into the second conductive film is different from an element doped into the first conductive film.   
     
     
         6 . The semiconductor device according to  claim 2 ,
 wherein the semiconductor substrate comprises a diode formed thereon,   wherein a surface of semiconductor substrate provided with the diode is in direct contact with the first conductive film, and   wherein a crystal surface on a surface of the semiconductor substrate and a crustal surface on a surface of the first conductive film are a (001) surface.   
     
     
         7 . The semiconductor device according to  claim 2 ,
 wherein an area ratio of the (111) surface on the surface of the second conductive film is higher than that of the (111) surface on the surface of the first conductive film.   
     
     
         8 . The semiconductor device according to  claim 7 ,
 wherein the semiconductor substrate comprises a power MOSFET formed thereon, and   wherein a source electrode of the POWER MOSFET comprises the first conductive film and the second conductive film.   
     
     
         9 . A method of manufacturing a semiconductor device, comprising the steps of:
 (a) forming a first conductive film over a semiconductor substrate by sputtering;   (b) forming a second conductive film over the first conductive film by sputtering;   (c) providing a pad electrode by patterning on the first conductive film and the second conductive film; and   (d) forming a plating film for coupling to the external connection terminal over the pad electrode by electroless plating,   wherein each of the first and second conductive films comprises a film containing mainly aluminum, and   wherein a crystal surface on a surface of the second conductive film is different from the crystal surface on the surface of the first conductive film.   
     
     
         10 . The method of manufacturing a semiconductor device according to  claim 9 ,
 wherein the second conductive film is in direct contact with the plating film, and   wherein the crystal surface on the surface of the second conductive film is a (111) surface.   
     
     
         11 . The method of manufacturing a semiconductor device according to  claim 10 , further comprising the step of:
 (e) forming a first insulating film over the first conductive film between the steps of (a) and (b) by exposing a surface of the first conductive film to oxygen atmosphere.   
     
     
         12 . The method of manufacturing a semiconductor device according to  claim 11 ,
 wherein the step (e) is performed by taking out the semiconductor substrate from a sputtering device and expose the semiconductor substrate to atmospheric air.   
     
     
         13 . The method of manufacturing a semiconductor device according to  claim 11 ,
 wherein the step (e) is performed by introducing oxygen gas into the sputtering device without taking out the semiconductor substrate from the sputtering device used at the step (a), and   wherein the step (b) is performed without taking out the semiconductor substrate from the sputtering device after the step (e).   
     
     
         14 . The method of manufacturing a semiconductor device according to  claim 11 , further comprising the step of:
 (f) forming an amorphous film over the first conductive film by sputtering or CVD between the steps (a) and (b).   
     
     
         15 . The method of manufacturing a semiconductor device according to  claim 10 ,
 wherein an element doped into the second conductive film is different from an element doped into the first conductive film.   
     
     
         16 . The method of manufacturing a semiconductor device according to  claim 10 ,
 wherein the semiconductor substrate comprises a diode formed thereon,   wherein a cleaning treatment is performed on a surface of the semiconductor substrate having the diode formed thereon before the step (a),   wherein the first conductive film is formed to be in direct contact with the surface of the semiconductor substrate at the step (a), and   wherein a crystal surface on a surface of the semiconductor substrate and a crustal surface on a surface of the first conductive film are a (001) surface.   
     
     
         17 . The method of manufacturing a semiconductor device according to  claim 10 ,
 wherein temperature for forming the first conductive film is higher than temperature for forming the second conductive film, and   wherein an area ratio of the (111) surface on the surface of the second conductive film is higher than that of the (111) surface on the surface of the first conductive film.   
     
     
         18 . The method of manufacturing a semiconductor device according to  claim 17 ,
 wherein the semiconductor substrate comprises a power MOSFET formed thereon, and   wherein a source electrode of the POWER MOSFET comprises the first conductive film and the second conductive film.   
     
     
         19 . The method of manufacturing a semiconductor device according to  claim 10 ,
 wherein a zincate treatment is performed two times between the steps (c) and (d).   
     
     
         20 . The method of manufacturing a semiconductor device according to  claim 19 ,
 wherein the plating film contains mainly nickel.