Semiconductor device and manufacturing method thereof

Abstract

A semiconductor device with high reliability is provided in which an insulating property of an insulating layer is high and connection failure is prevented. The semiconductor device includes: a silicon substrate; a low-temperature aluminum film formed on silicon substrate and including a polycrystal; and a high-temperature aluminum film. An opening is formed in a surface of a high-temperature aluminum film by a crystal grain boundary. A distance between side walls of the opening becomes small as closer to silicon substrate.

What is claimed is:  
     
         1 . A semiconductor device, comprising: 
 a semiconductor substrate; and    a conductive layer formed on said semiconductor substrate and including polycrystals, said conductive layer including in its surface a recess caused by a crystal grain boundary and having side walls formed such that a distance therebetween becomes small as closer to said semiconductor substrate.    
     
     
         2 . The semiconductor device according to    claim 1   , wherein said conductive layer includes: 
 a first conductive layer formed on said semiconductor substrate and including a polycrystal having a first average grain size; and    a second conductive layer formed on said first conductive layer, including a polycrystal having a second average grain size greater than said first average grain size and having said recess.    
     
     
         3 . The semiconductor device according to    claim 1   , further comprising a thin film layer formed on said conductive layer and having a material different from that of said conductive layer.  
     
     
         4 . The semiconductor device according to    claim 1   , wherein said conductive layer includes aluminum.  
     
     
         5 . The semiconductor device according to    claim 1   , further comprising an insulating layer formed on said semiconductor substrate and a barrier layer formed on said insulating layer, said conductive layer being formed on said barrier layer.  
     
     
         6 . A semiconductor device, comprising: 
 a first conductive layer formed on a semiconductor substrate and including a polycrystal having a first average grain size;    a second conductive layer formed on said first conductive layer and including a polycrystal having a second average grain size greater than said first average grain size; and    a third conductive layer formed on said second conductive layer and including a polycrystal having a third average grain size smaller than said second average grain size.    
     
     
         7 . The semiconductor device according to    claim 6   , wherein a recess is formed in a surface of said second conductive layer by a crystal grain boundary, and a distance between side walls of said recess becomes small as closer to said semiconductor substrate.  
     
     
         8 . The semiconductor device according to    claim 6   , further comprising a thin film layer formed on said third conductive layer and having a material different from that said third conductive layer.  
     
     
         9 . The semiconductor device according to    claim 6   , wherein said conductive layer includes aluminum.  
     
     
         10 . The semiconductor device according to    claim 6   , further comprising an insulating layer formed on said semiconductor substrate and a barrier layer formed on said insulating layer, said conductive layer being formed on said barrier layer.  
     
     
         11 . A method of manufacturing a semiconductor device, comprising the steps of: 
 forming a conductive layer including a polycrystal on a semiconductor substrate, said conductive layer having a recess in its surface formed by a crystal grain boundary, a distance between side walls of said recess becoming large as closer to said semiconductor substrate; and    processing said side walls of said recess such that the distance therebetween becomes small as closer to said semiconductor substrate.    
     
     
         12 . The method of manufacturing the semiconductor device according to    claim 11   , wherein said step of forming said conductive layer includes the steps of: 
 forming a first conductive layer on said semiconductor substrate at a first temperature; and    forming a second conductive layer having said recess on said first conductive layer at a second temperature higher than said first temperature.    
     
     
         13 . The method of manufacturing the semiconductor device according to    claim 11   , further comprising the step of forming a thin film layer having a material different from that of said conductive layer on said conductive layer having the processed side walls.  
     
     
         14 . The method of manufacturing the semiconductor device according to    claim 11   , further comprising the step of forming an insulating layer on said semiconductor substrate and the step of forming a barrier layer on said insulating layer, said step of forming said conductive layer including the step of forming said conductive layer on said barrier layer.  
     
     
         15 . The method of manufacturing the semiconductor device according to    claim 11   , wherein said step of processing said side walls includes the step of sputter etching said conductive layer.  
     
     
         16 . A method of manufacturing a semiconductor device, comprising the steps of: 
 forming a first conductive layer on a semiconductor substrate at a first temperature;    forming a second conductive layer on said first conductive layer at a second temperature higher than said first temperature; and    forming a third conductive layer on said second conductive layer at a third temperature lower than said second temperature.    
     
     
         17 . The method of manufacturing the semiconductor device according to    claim 16   , wherein said step of forming said second conductive layer includes the step of forming said second conductive layer with a recess formed in its surface by a crystal grain boundary and having side walls, a distance between said side walls becoming large as closer to said semiconductor substrate, said method further comprising the step of processing said side walls such that a distance therebetween becomes small as closer to said semiconductor substrate, and wherein 
 said step of forming said third conductive layer includes the step of forming said third conductive layer on said second conductive layer having said processed side walls.    
     
     
         18 . The method of manufacturing the semiconductor device according to    claim 16   , wherein said step of processing said side walls further includes the step of sputter etching said conductive layer.  
     
     
         19 . The method of manufacturing the semiconductor device according to    claim 16   , further comprising the step of forming a thin film layer having a material different from that of said third conductive layer on said third conductive layer.  
     
     
         20 . The method of manufacturing the semiconductor device according to    claim 16   , further comprising the step of forming an insulating layer on said semiconductor substrate and the step of forming a barrier layer on said insulating layer, said step of forming said conductive layer including the step of forming said conductive layer on said barrier layer.