Semiconductor device and method for manufacturing the same

Abstract

The TFT electric characteristic is ready to be influenced by the channel region in the neighborhood of an interface between a semiconductor and a gate insulating film. The present invention provides TFTs reduced in electric characteristic deviations and a method for manufacturing the same. The invention forms a region or layer containing an inactive element, or rear gas element, in the channel region. As shown in FIG. 1, a rear gas element is contained at least in an upper layer of the channel region.

1 . A method for manufacturing a semiconductor device comprising: 
 adding a metal element to a first semiconductor film having an amorphous structure;    crystallizing the first semiconductor film;    forming a barrier layer on a surface of the first semiconductor film after the crystallizing step;    forming a second semiconductor film on the barrier layer;    adding a rare gas element to the first semiconductor film and the second semiconductor film;    gettering the metal element to the second semiconductor film to selectively remove or reduce the metal element in the first semiconductor film; and    removing the second semiconductor film.    
     
     
         2 . A method for manufacturing a semiconductor device according to  claim 1 , wherein the gettering step is conducted by a heat treatment.  
     
     
         3 . A method for manufacturing a semiconductor device according to  claim 1 , wherein the gettering step is conducted by irradiating the first semiconductor film with a light.  
     
     
         4 . A method for manufacturing a semiconductor device according to  claim 1 , wherein the gettering step is conducted by a heat treatment and irradiating the first semiconductor film with a light after the heat treatment.  
     
     
         5 . A method for manufacturing a semiconductor device according to  claim 3 , wherein the light is at least one selected from the group consisting of a halogen lamp light, a metal halide lamp light, a xenon arc lamp light, a carbon arc lamp light, a high-pressure sodium lamp light, and a high-pressure mercury lamp light.  
     
     
         6 . A method for manufacturing a semiconductor device according to  claim 1 , wherein the metal element is one or a plurality of elements selected from the group consisting of Fe, Ni, Co, Ru, Rh, Pd, Os, Ir, Pt, Cu and Au.  
     
     
         7 . A method for manufacturing a semiconductor device according to  claim 1 , wherein the rare gas element is one or a plurality elements selected from the group consisting of He, Ne, Ar, Kr and Xe.  
     
     
         8 . A method for manufacturing a semiconductor device according to  claim 1 , wherein the semiconductor device is a liquid crystal display device.  
     
     
         9 . A method for manufacturing a semiconductor device according to  claim 1 , wherein the semiconductor device is an EL display device.  
     
     
         10 . A method for manufacturing a semiconductor device according to  claim 1 , wherein the semiconductor device is at least one selected from the group consisting of a personal computer, a video camera, a mobile computer, a goggle type display, a player using a recording medium, a digital camera, a projector, a portable telephone, and a portable book.  
     
     
         11 . A method for manufacturing a semiconductor device comprising: 
 adding a metal element to a first semiconductor film having an amorphous structure;    crystallizing the first semiconductor film;    forming a barrier layer on a surface of the first semiconductor film after the crystallizing step;    forming a second semiconductor film on the barrier layer;    adding a rare gas element to the first semiconductor film and the second semiconductor film;    gettering the metal element to the second semiconductor film to selectively remove or reduce the metal element in the first semiconductor film;    removing the second semiconductor film;    forming an insulating film over the first semiconductor film;    forming a gate electrode over the insulating film;    adding an impurity element imparting one conductivity to form a source region and a drain region; and    forming a source electrode connected to the source region and a drain electrode connected to the drain region.    
     
     
         12 . A method for manufacturing a semiconductor device according to  claim 11 , wherein the gettering step is conducted by a heat treatment.  
     
     
         13 . A method for manufacturing a semiconductor device according to  claim 11 , wherein the gettering step is conducted by irradiating the first semiconductor film with a light.  
     
     
         14 . A method for manufacturing a semiconductor device according to  claim 11 , wherein the gettering step is conducted by a heat treatment and irradiating the first semiconductor film with a light after the heat treatment.  
     
     
         15 . A method for manufacturing a semiconductor device according to  claim 13 , wherein the light is at least one selected from the group consisting of a halogen lamp light, a metal halide lamp light, a xenon arc lamp light, a carbon arc lamp light, a high-pressure sodium lamp light, and a high-pressure mercury lamp light.  
     
     
         16 . A method for manufacturing a semiconductor device according to  claim 11 , wherein the metal element is one or a plurality of elements selected from the group consisting of Fe, Ni, Co, Ru, Rh, Pd, Os, Ir, Pt, Cu and Au.  
     
     
         17 . A method for manufacturing a semiconductor device according to  claim 11 , wherein the rare gas element is one or a plurality elements selected from the group consisting of He, Ne, Ar, Kr and Xe.  
     
     
         18 . A method for manufacturing a semiconductor device according to  claim 11 , wherein the semiconductor device is a liquid crystal display device.  
     
     
         19 . A method for manufacturing a semiconductor device according to  claim 11 , wherein the semiconductor device is an EL display device.  
     
     
         20 . A method for manufacturing a semiconductor device according to  claim 11 , wherein the semiconductor device is at least one selected from the group consisting of a personal computer, a video camera, a mobile computer, a goggle type display, a player using a recording medium, a digital camera, a projector, a portable telephone, and a portable book.  
     
     
         21 . A method for manufacturing a semiconductor device comprising: 
 adding a metal element to a first semiconductor film having an amorphous structure formed over an insulating surface;    crystallizing the first semiconductor film;    forming a barrier layer on a surface of the first semiconductor film after the crystallizing step;    forming a second semiconductor film on the barrier layer;    adding a rare gas element to the first semiconductor film and the second semiconductor film;    gettering the metal element to the second semiconductor film to selectively remove or reduce the metal element in the first semiconductor film; and    removing the second semiconductor film,    wherein the first semiconductor film contains the rare gas element having a concentration gradient.    
     
     
         22 . A method for manufacturing a semiconductor device according to  claim 21 , wherein the gettering step is conducted by a heat treatment.  
     
     
         23 . A method for manufacturing a semiconductor device according to  claim 21 , wherein the gettering step is conducted by irradiating the first semiconductor film with a light.  
     
     
         24 . A method for manufacturing a semiconductor device according to  claim 21 , wherein the gettering step is conducted by a heat treatment and irradiating the first semiconductor film with a light after the heat treatment.  
     
     
         25 . A method for manufacturing a semiconductor device according to  claim 23 , wherein the light is at least one selected from the group consisting of a halogen lamp light, a metal halide lamp light, a xenon arc lamp light, a carbon arc lamp light, a high-pressure sodium lamp light, and a high-pressure mercury lamp light.  
     
     
         26 . A method for manufacturing a semiconductor device according to  claim 21 , wherein the metal element is one or a plurality of elements selected from the group consisting of Fe, Ni, Co, Ru, Rh, Pd, Os, Ir, Pt, Cu and Au.  
     
     
         27 . A method for manufacturing a semiconductor device according to  claim 21 , wherein the rare gas element is one or a plurality elements selected from the group consisting of He, Ne, Ar, Kr and Xe.  
     
     
         28 . A method for manufacturing a semiconductor device according to  claim 21 , wherein the semiconductor device is a liquid crystal display device.  
     
     
         29 . A method for manufacturing a semiconductor device according to  claim 21 , wherein the semiconductor device is an EL display device.  
     
     
         30 . A method for manufacturing a semiconductor device according to  claim 21 , wherein the semiconductor device is at least one selected from the group consisting of a personal computer, a video camera, a mobile computer, a goggle type display, a player using a recording medium, a digital camera, a projector, a portable telephone, and a portable book.  
     
     
         31 . A method for manufacturing a semiconductor device comprising: 
 adding a metal element to a first semiconductor film having an amorphous structure formed over an insulating surface;    crystallizing the first semiconductor film;    forming a barrier layer on a surface of the first semiconductor film after the crystallizing step;    forming a second semiconductor film on the barrier layer;    adding a rare gas element to the first semiconductor film and the second semiconductor film;    gettering the metal element to the second semiconductor film to selectively remove or reduce the metal element in the first semiconductor film;    removing the second semiconductor film;    forming an insulating film over the first semiconductor film;    forming a gate electrode over the insulating film;    adding an impurity element imparting one conductivity to form a source region and a drain region; and    forming a source electrode connected to the source region and a drain electrode connected to the drain region,    wherein the first semiconductor film contains the rare gas element having a concentration gradient.    
     
     
         32 . A method for manufacturing a semiconductor device according to  claim 31 , wherein the gettering step is conducted by a heat treatment.  
     
     
         33 . A method for manufacturing a semiconductor device according to  claim 31 , wherein the gettering step is conducted by irradiating the first semiconductor film with a light.  
     
     
         34 . A method for manufacturing a semiconductor device according to  claim 31 , wherein the gettering step is conducted by a heat treatment and irradiating the first semiconductor film with a light after the heat treatment.  
     
     
         35 . A method for manufacturing a semiconductor device according to  claim 33 , wherein the light is at least one selected from the group consisting of a halogen lamp light, a metal halide lamp light, a xenon arc lamp light, a carbon arc lamp light, a high-pressure sodium lamp light, and a high-pressure mercury lamp light.  
     
     
         36 . A method for manufacturing a semiconductor device according to  claim 31 , wherein the metal element is one or a plurality of elements selected from the group consisting of Fe, Ni, Co, Ru, Rh, Pd, Os, Ir, Pt, Cu and Au.  
     
     
         37 . A method for manufacturing a semiconductor device according to  claim 31 , wherein the rare gas element is one or a plurality elements selected from the group consisting of He, Ne, Ar, Kr and Xe.  
     
     
         38 . A method for manufacturing a semiconductor device according to  claim 31 , wherein the semiconductor device is a liquid crystal display device.  
     
     
         39 . A method for manufacturing a semiconductor device according to  claim 31 , wherein the semiconductor device is an EL display device.  
     
     
         40 . A method for manufacturing a semiconductor device according to  claim 31 , wherein the semiconductor device is at least one selected from the group consisting of a personal computer, a video camera, a mobile computer, a goggle type display, a player using a recording medium, a digital camera, a projector, a portable telephone, and a portable book.  
     
     
         41 . A method for manufacturing a semiconductor device comprising: 
 adding a metal element to a first semiconductor film having an amorphous structure formed over an insulating surface;    crystallizing the first semiconductor film;    forming a barrier layer on a surface of the first semiconductor film after the crystallizing step;    forming a second semiconductor film on the barrier layer;    adding a rare gas element to the first semiconductor film and the second semiconductor film;    gettering the metal element to the second semiconductor film to selectively remove or reduce the metal element in the first semiconductor film; and    removing the second semiconductor film,    wherein the first semiconductor film has at least a first portion and a second portion, the second portion being more distant from the insulating surface than the first portion, and wherein the second portion contains the rare gas element having a concentration gradient.    
     
     
         42 . A method for manufacturing a semiconductor device according to  claim 41 , wherein the gettering step is conducted by a heat treatment.  
     
     
         43 . A method for manufacturing a semiconductor device according to  claim 41 , wherein the gettering step is conducted by irradiating the first semiconductor film with a light.  
     
     
         44 . A method for manufacturing a semiconductor device according to  claim 41 , wherein the gettering step is conducted by a heat treatment and irradiating the first semiconductor film with a light after the heat treatment.  
     
     
         45 . A method for manufacturing a semiconductor device according to  claim 43 , wherein the light is at least one selected from the group consisting of a halogen lamp light, a metal halide lamp light, a xenon arc lamp light, a carbon arc lamp light, a high-pressure sodium lamp light, and a high-pressure mercury lamp light.  
     
     
         46 . A method for manufacturing a semiconductor device according to  claim 41 , wherein the metal element is one or a plurality of elements selected from the group consisting of Fe, Ni, Co, Ru, Rh, Pd, Os, Ir, Pt, Cu and Au.  
     
     
         47 . A method for manufacturing a semiconductor device according to  claim 41 , wherein the rare gas element is one or a plurality elements selected from the group consisting of He, Ne, Ar, Kr and Xe.  
     
     
         48 . A method for manufacturing a semiconductor device according to  claim 41 , wherein the semiconductor device is a liquid crystal display device.  
     
     
         49 . A method for manufacturing a semiconductor device according to  claim 41 , wherein the semiconductor device is an EL display device.  
     
     
         50 . A method for manufacturing a semiconductor device according to  claim 41 , wherein the semiconductor device is at least one selected from the group consisting of a personal computer, a video camera, a mobile computer, a goggle type display, a player using a recording medium, a digital camera, a projector, a portable telephone, and a portable book.  
     
     
         51 . A method for manufacturing a semiconductor device comprising: 
 adding a metal element to a first semiconductor film having an amorphous structure formed over an insulating surface;    crystallizing the first semiconductor film;    forming a barrier layer on a surface of the first semiconductor film after the crystallizing step;    forming a second semiconductor film on the barrier layer;    adding a rare gas element to the first semiconductor film and the second semiconductor film;    gettering the metal element to the second semiconductor film to selectively remove or reduce the metal element in the first semiconductor film;    removing the second semiconductor film;    forming an insulating film over the first semiconductor film;    forming a gate electrode over the insulating film;    adding an impurity element imparting one conductivity to form a source region and a drain region; and    forming a source electrode connected to the source region and a drain electrode connected to the drain region,    wherein the first semiconductor film has at least a first portion and a second portion, the second portion being more distant from the insulating surface than the first portion, and wherein the second portion contains the rare gas element having a concentration gradient.    
     
     
         52 . A method for manufacturing a semiconductor device according to  claim 51 , wherein the gettering step is conducted by a heat treatment.  
     
     
         53 . A method for manufacturing a semiconductor device according to  claim 51 , wherein the gettering step is conducted by irradiating the first semiconductor film with a light.  
     
     
         54 . A method for manufacturing a semiconductor device according to  claim 51 , wherein the gettering step is conducted by a heat treatment and irradiating the first semiconductor film with a light after the heat treatment.  
     
     
         55 . A method for manufacturing a semiconductor device according to  claim 53 , wherein the light is at least one selected from the group consisting of a halogen lamp light, a metal halide lamp light, a xenon arc lamp light, a carbon arc lamp light, a high-pressure sodium lamp light, and a high-pressure mercury lamp light.  
     
     
         56 . A method for manufacturing a semiconductor device according to  claim 51 , wherein the metal element is one or a plurality of elements selected from the group consisting of Fe, Ni, Co, Ru, Rh, Pd, Os, Ir, Pt, Cu and Au.  
     
     
         57 . A method for manufacturing a semiconductor device according to  claim 51 , wherein the rare gas element is one or a plurality elements selected from the group consisting of He, Ne, Ar, Kr and Xe.  
     
     
         58 . A method for manufacturing a semiconductor device according to  claim 51 , wherein the semiconductor device is a liquid crystal display device.  
     
     
         59 . A method for manufacturing a semiconductor device according to  claim 51 , wherein the semiconductor device is an EL display device.  
     
     
         60 . A method for manufacturing a semiconductor device according to  claim 51 , wherein the semiconductor device is at least one selected from the group consisting of a personal computer, a video camera, a mobile computer, a goggle type display, a player using a recording medium, a digital camera, a projector, a portable telephone, and a portable book.