Semiconductor device and method of manufacturing the same

Abstract

To provide a semiconductor device in which a semiconductor film having a leveled main surface is used as an active layer. A semiconductor film ( 5 ) having the leveled main surface with an rms of less than 10 nm and a P-V value of less than 70 nm which each indicate a surface roughness is formed by crystallizing a silicon film ( 3 ) containing germanium in a concentration of several %, preferably 0.1 to 10 atoms % and irradiating the film with a laser light. In a case of performing a crystallization by use of a metal element for accelerating the crystallization, the semiconductor film high in an orientation rate of the crystal as well as in levelness is obtained.

What is claimed is  
     
         1 . A semiconductor device comprising: 
 a thin film transistor comprising a semiconductor layer formed on an insulating film,    wherein the semiconductor layer comprising silicon as a main component and containing germanium, is used as an active layer, and    wherein the active layer has a P-V value of less than 70 nm which indicates a surface roughness of a main surface thereof.    
     
     
         2 . A device according to  claim 1 , wherein the semiconductor film contains the germanium in a concentration of 0.1 to 10 atoms % and serves as a silicon film having a crystalline structure.  
     
     
         3 . A device according to  claim 1 , wherein the semiconductor film contains a metal element in a concentration of 1×10 16 /cm 3  to 5×10 18 /cm 3  and serves as a silicon film having a crystalline structure.  
     
     
         4 . A device according to  claim 3 , wherein the metal element is a metal element for accelerating a crystallization of silicon and is at least one element selected from the group consisting of Fe, Ni, Co, Ru, Rh, Pd, Os, Ir, Pt, Cu and Au.  
     
     
         5 . A semiconductor device, wherein the semiconductor device according to  claim 1  is one selected from the group consisting of a video camera, a digital camera, a car navigation system, a personal computer, a personal digital assistant, and an electronic game equipment.  
     
     
         6 . A semiconductor device comprising: 
 a thin film transistor comprising a semiconductor layer formed on an insulating film,    wherein the semiconductor layer comprising silicon as a main component and containing germanium, is used as an active layer, and    wherein the active layer has a root mean square roughness of less than 10 nm which indicates a surface roughness of a main surface thereof.    
     
     
         7 . A device according to  claim 6 , wherein the semiconductor film contains the germanium in a concentration of 0.1 to 10 atoms % and serves as a silicon film having a crystalline structure.  
     
     
         8 . A device according to  claim 6 , wherein the semiconductor film contains a metal element in a concentration of 1×10 16 /cm 3  to 5×10 18 /cm 3  and serves as a silicon film having a crystalline structure.  
     
     
         9 . A semiconductor device according to  claim 8 , wherein the metal element is a metal element for accelerating a crystallization of silicon and is at least one element selected from the group consisting of Fe, Ni, Co, Ru, Rh, Pd, Os, Ir, Pt, Cu and Au.  
     
     
         10 . A semiconductor device, wherein the semiconductor device according to  claim 6  is one selected from the group consisting of a video camera, a digital camera, a car navigation system, a personal computer, a personal digital assistant, and an electronic game equipment.  
     
     
         11 . A semiconductor device comprising: 
 a thin film transistor comprising a semiconductor layer formed on an insulating film,    wherein the semiconductor layer comprising silicon as a main component and containing germanium, is used as an active layer, and    wherein the active layer has a root mean square roughness of less than 10 nm and a P-V value of less than 70 nm which each indicate a surface roughness of a main surface thereof.    
     
     
         12 . A device according to  claim 11 , wherein the semiconductor film contains the germanium in a concentration of 0.1 to 10 atoms % and serves as a silicon film having a crystalline structure.  
     
     
         13 . A device according to  claim 11 , wherein the semiconductor film contains a metal element in a concentration of 1×10 16 /cm 3  to 5×10 18 /cm 3  and serves as a silicon film having a crystalline structure.  
     
     
         14 . A semiconductor device according to  claim 13 , wherein the metal element is a metal element for accelerating a crystallization of silicon and is at least one element selected from the group consisting of Fe, Ni, Co, Ru, Rh, Pd, Os, Ir, Pt, Cu and Au.  
     
     
         15 . A semiconductor device, wherein the semiconductor device according to  claim 11  is one selected from the group consisting of a video camera, a digital camera, a car navigation system, a personal computer, a personal digital assistant, and an electronic game equipment.  
     
     
         16 . A method of manufacturing a semiconductor device, comprising: 
 forming on an insulating surface a semiconductor film that contains germanium in a concentration of 0.1 to 10 atoms % and has an amorphous structure;    performing heat treatment to the semiconductor film having the amorphous structure and then irradiating it with a first laser light for crystallization to form a first semiconductor film having a crystalline structure and an oxide film thereon;    removing the oxide film; and    irradiating a second laser light in an inert gas atmosphere or in a vacuum to level a surface of the semiconductor film.    
     
     
         17 . A method according to  claim 16 , wherein an energy density of the second laser light is higher than that of the first laser light.  
     
     
         18 . A method according to  claim 16 , wherein a metal element for accelerating a crystallization is added before performing the heat treatment.  
     
     
         19 . A method according to  claim 16 , wherein said semiconductor device is one selected from the group consisting of a video camera, a digital camera, a car navigation system, a personal computer, a personal digital assistant, and an electronic game equipment.  
     
     
         20 . A method of manufacturing a semiconductor device, comprising: 
 forming on an insulating surface a first semiconductor film that contains germanium in a concentration of 0.1 to 10 atoms % and has an amorphous structure;    adding a metal element for accelerating a crystallization to the first semiconductor film having the amorphous structure;    performing heat treatment to the first semiconductor film and then irradiating it with a first laser light to form a first semiconductor film having a crystalline structure and an oxide film thereon;    removing the oxide film;    irradiating a second laser light in an inert gas atmosphere or in a vacuum to level a surface of the first semiconductor film;    oxidizing the surface of the semiconductor film having the crystalline structure with a solution containing ozone;    forming a second semiconductor film including a rare gas element on the oxide film;    allowing the second semiconductor film to getter the metal element to remove or reduce the metal element in the first semiconductor film having the crystalline structure; and    removing the second semiconductor film    
     
     
         21 . A method according to  claim 20 , wherein an energy density of the laser light in the oxidizing is higher than that of the laser light in the first irradiating.  
     
     
         22 . A method according to  claim 20 , wherein said semiconductor device is one selected from the group consisting of a video camera, a digital camera, a car navigation system, a personal computer, a personal digital assistant, and an electronic game equipment.