Semiconductor device and method for producing same

Abstract

A semiconductor device having a substrate, an insulating film formed in the substrate, a conductive layer formed on the insulating film and having at least a part in contact with the insulating film made of a conductive material having a work function near a substantial center of an energy band gap of the substrate material and containing a predetermined amount of impurity, and a takeout electrode formed in the substrate and a method for producing the same.

What is claimed is:  
     
         1 . A semiconductor device comprising: 
 a substrate,    an insulating film formed in the substrate,    a conductive layer formed on the insulating film and having at least a part in contact with the insulating film made of a conductive material having a work function near a substantial center of an energy band gap of the substrate material and containing a predetermined amount of impurity, and    a takeout electrode formed in the substrate.    
     
     
         2 . A semiconductor device as set forth in  claim 1 , wherein the impurity is an impurity suppressing the grain growth of the conductive material.  
     
     
         3 . A semiconductor device as set forth in  claim 1 , wherein the impurity is oxygen, nitrogen, or boron.  
     
     
         4 . A semiconductor device as set forth in  claim 1 , wherein the conductive layer has the layer comprised of a conductive material containing impurity having different concentrations in a depth direction and having the work function near the substantial center of the energy band gap of the substrate material.  
     
     
         5 . A semiconductor device as set forth in  claim 1 , wherein the conductive layer has a refractory metal silicide layer or a refractory metal layer containing an impurity with different concentrations in a depth direction.  
     
     
         6 . A semiconductor device as set forth in  claim 1 , wherein the conductive layer has a layer comprised of a conductive material with a center region with respect to a depth direction thereof containing an impurity having a higher concentration than those of upper and lower regions thereof having the work function near the substantial center of the energy band gap of a substrate material.  
     
     
         7 . A semiconductor device as set forth in  claim 1 , wherein the conductive layer has a refractory metal silicide layer or a refractory metal layer with a center region with respect to a depth direction thereof containing an impurity having a higher concentration than those of upper and lower regions thereof.  
     
     
         8 . A semiconductor device as set forth in  claim 1 , wherein the conductive layer contains two or more types of impurities.  
     
     
         9 . A semiconductor device as set forth in  claim 8 , wherein at least one of the two or more types of impurities is oxygen, nitrogen, or boron.  
     
     
         10 . A semiconductor device as set forth in  claim 8 , wherein the conductive layer contains each of the two or more types of impurities in concentrations of 1×10 19 /cm 3  to 1×10 21 /cm 3 .  
     
     
         11 . A semiconductor device as set forth in  claim 1 , wherein the substrate material is silicon and the conductive material is a refractory metal silicide or a refractory metal.  
     
     
         12 . A semiconductor device as set forth in  claim 11 , wherein the refractory metal silicide is one, two or more types selected from a group consisting of tungsten silicide (WSi x ), molybdenum silicide (MoSi x ), tantalum silicide (TaSi x ), and titanium silicide (TiSi x ).  
     
     
         13 . A semiconductor device as set forth in  claim 11 , wherein the refractory metal is one, two or more types selected from a group consisting of tungsten (W), tantalum (Ta), and titanium (Ti).  
     
     
         14 . A semiconductor device comprising: 
 a silicon substrate,    a gate insulating film formed in the silicon substrate,    a gate electrode formed on the gate insulating film and having at least a part in contact with the gate insulating film made of a refractory metal silicide layer containing an impurity or a refractory metal layer containing an impurity, and    a takeout electrode formed in the silicon substrate.    
     
     
         15 . A semiconductor device as set forth in  claim 14 , wherein the impurity is an impurity suppressing the grain growth of the refractory metal silicide or the refractory metal.  
     
     
         16 . A semiconductor device as set forth in  claim 14 , wherein the refractory metal silicide or the refractory metal contains an impurity with different concentrations in a depth direction.  
     
     
         17 . A semiconductor device as set forth in  claim 14 , wherein the refractory metal silicide layer or the refractory metal layer contains an impurity having a higher concentration in a center region with respect to a depth direction thereof than those of upper and lower regions thereof.  
     
     
         18 . A semiconductor device as set forth in  claim 14 , wherein the impurity is oxygen, nitrogen, or boron.  
     
     
         19 . A semiconductor device as set forth in  claim 14 , wherein the refractory metal silicide layer or the refractory metal layer contains two or more types of impurities.  
     
     
         20 . A semiconductor device as set forth in  claim 19 , wherein at least one of the two or more types of impurities is oxygen, nitrogen, or boron.  
     
     
         21 . A semiconductor device as set forth in  claim 19 , wherein the refractory metal silicide layer or the refractory metal layer contains each of the two or more types of impurities in concentrations of 1×10 19 /cm 3  to 1×10 21 /cm 3 .  
     
     
         22 . A semiconductor device as set forth in  claim 14 , wherein the refractory metal silicide is one, two or more types selected from a group consisting of tungsten silicide (WSi x ), molybdenum silicide (MoSi x ), tantalum silicide (TaSi x ), and titanium silicide (TiSi x ).  
     
     
         23 . A semiconductor device as set forth in  claim 14 , wherein the refractory metal is one, two or more types selected from a group consisting of tungsten (W), tantalum (Ta), and titanium (Ti).  
     
     
         24 . A method for producing a semiconductor device comprising steps of: 
 forming an insulating film in a substrate,    forming a conductive layer made of a conductive material having a work function near a substantive center of an energy band gap of the substrate material on the insulating film,    doping an impurity into the conductive layer,    and    forming a takeout electrode in the substrate.    
     
     
         25 . A method for producing a semiconductor device as set forth in  claim 24 , wherein the step of doping the impurity into the conductive layer has a step of doping the impurity into the conductive layer by an ion implantation process.  
     
     
         26 . A method for producing a semiconductor device as set forth in  claim 24 , wherein the step of doping the impurity into the conductive layer has a step of forming a conductive film containing the impurity on the insulating film by a chemical vapor deposition process.  
     
     
         27 . A method for producing a semiconductor device as set forth in  claim 24 , wherein the step of doping the impurity into the conductive layer has a step of doping into the conductive layer a impurity suppressing a grain growth of the conductive layer.  
     
     
         28 . A method for producing a semiconductor device as set forth in  claim 24 , wherein the step of doping the impurity into the conductive layer has a step of doping into the conductive layer the impurity so that an impurity concentration varies in a depth direction.  
     
     
         29 . A method for producing a semiconductor device as set forth in  claim 24 , wherein the step of doping the impurity into the conductive layer has a step of doping the impurity so that a concentration of the impurity contained in a center region of the conductive layer with respect to a depth direction thereof becomes higher than impurity concentrations of upper and lower regions thereof.  
     
     
         30 . A method for producing a semiconductor device as set forth in  claim 24 , wherein the step of doping the impurity into the conductive layer has a step of doping oxygen, nitrogen, or boron into the conductive layer.  
     
     
         31 . A method for producing a semiconductor device as set forth in  claim 24 , wherein the step of doping the impurity into the conductive layer has a step of doping two or more types of impurities into the conductive layer.  
     
     
         32 . A method for producing a semiconductor device as set forth in  claim 31 , wherein the step of doping the impurity into the conductive layer has a step of doping at least oxygen, nitrogen, or boron into the conductive layer.  
     
     
         33 . A method for producing a semiconductor device as set forth in  claim 31 , wherein the step of doping the impurity into the conductive layer has a step of doping each of the two or more types of impurities into the conductive layer with the concentration of 1×10 19 /cm 3  to 1×10 21 /cm 3 .  
     
     
         34 . A method for producing a semiconductor device as set forth in  claim 24 , wherein a silicon substrate is used as the substrate.  
     
     
         35 . A method for producing a semiconductor device as set forth in  claim 31 , wherein the step of forming the conductive layer made of the conductive material having the work function near the substantive center of the energy band gap of the substrate material has a step of forming a refractory metal silicide layer or a refractory metal layer on the substrate.  
     
     
         36 . A method for producing a semiconductor device as set forth in  claim 35 , wherein the step of forming the refractory metal silicide layer has a step of forming a layer made of one, two or more types selected from a group consisting of tungsten silicide (WSi x ), molybdenum silicide (MoSi x ), tantalum silicide (TaSi x ), and titanium silicide (TiSi x ).  
     
     
         37 . A method for producing a semiconductor device as set forth in  claim 35 , wherein the step of forming the refractory metal layer has a step of forming a layer made of one, two or more types selected from a group consisting of tungsten (W), tantalum (Ta), and titanium (Ti).  
     
     
         38 . A method for producing a semiconductor device comprising steps of: 
 forming a gate insulating film in a silicon substrate,    forming a conductive layer made of a conductive material having a work function of a substantial center of an energy band gap of the silicon on the gate insulating film,    doping an impurity into the conductive layer,    forming a gate electrode by processing the conductive layer, and    forming a takeout electrode in the silicon substrate.    
     
     
         39 . A method for producing a semiconductor device as set forth in  claim 38 , wherein the step of doping the impurity into the conductive layer has a step of doping the impurity into the conductive layer by an ion implantation process.  
     
     
         40 . A method for producing a semiconductor device as set forth in  claim 38 , wherein the step of doping the impurity into the conductive layer has a step of forming a conductive film containing the impurity on the insulating film by a chemical vapor deposition process.  
     
     
         41 . A method for producing a semiconductor device as set forth in  claim 38 , wherein the step of doping the impurity into the conductive layer has a step of doping into the conductive layer a impurity suppressing a grain growth of the conductive layer.  
     
     
         42 . A method for producing a semiconductor device as set forth in  claim 38 , wherein the step of doping the impurity into the conductive layer has a step of doping into the conductive layer the impurity so that an impurity concentration varies in a depth direction.  
     
     
         43 . A method for producing a semiconductor device as set forth in  claim 38 , wherein the step of doping the impurity into the conductive layer has a step of doping the impurity so that a concentration of the impurity contained in a center region of the conductive layer with respect to a depth direction thereof becomes higher than impurity concentrations of upper and lower regions thereof.  
     
     
         44 . A method for producing a semiconductor device as set forth in  claim 38 , wherein the step of doping the impurity into the conductive layer has a step of doping oxygen, nitrogen, or boron into the conductive layer.  
     
     
         45 . A method for producing a semiconductor device as set forth in  claim 38 , wherein the step of doping the impurity into the conductive layer has a step of doping two or more types of impurities into the conductive layer.  
     
     
         46 . A method for producing a semiconductor device as set forth in  claim 45 , wherein the step of doping the impurity into the conductive layer has a step of doping at least oxygen, nitrogen, or boron into the conductive layer.  
     
     
         47 . A method for producing a semiconductor device as set forth in  claim 45 , wherein the step of doping the impurity into the conductive layer has a step of doping each of the two or more types of impurities into the conductive layer with the concentration of 1×10 19 /cm 3  to 1×10 21 /m 3 .  
     
     
         48 . A method for producing a semiconductor device as set forth in  claim 38 , wherein the step of forming the conductive layer made of the conductive material having the work function near the substantive center of the energy band gap of the substrate material has a step of forming a refractory metal silicide layer or a refractory metal layer on the substrate.  
     
     
         49 . A method for producing a semiconductor device as set forth in  claim 48 , wherein the step of forming the refractory metal silicide layer has a step of forming a layer made of one, two or more types selected from a group consisting of tungsten silicide (WSi x ), molybdenum silicide (MoSi x ), tantalum silicide (TaSi x ), and titanium silicide (TiSi x ).  
     
     
         50 . A method for producing a semiconductor device as set forth in  claim 48 , wherein the step of forming the refractory metal layer has a step of forming a layer made of one, two or more types selected from a group consisting of tungsten (W), tantalum (Ta), and titanium (Ti).