Method of manufacturing a semiconductor device

Abstract

A method of performing irradiation of laser light is given as a method of crystallizing a semiconductor film. However, if laser light is irradiated to a semiconductor film, the semiconductor film is instantaneously melted and expands locally. The temperature gradient between a substrate and the semiconductor film is precipitous, distortions may develop in the semiconductor film. Thus, the film quality of the crystalline semiconductor film obtained will drop in some cases. With the present invention, distortions of the semiconductor film are reduced by heating the semiconductor film using a heat treatment process after performing crystallization of the semiconductor film using laser light. Compared to the localized heating due to the irradiation of laser light, the heat treatment process is performed over the entire substrate and semiconductor film. Therefore, it is possible to reduce distortions formed in the semiconductor film and to increase the physical properties of the semiconductor film.

1 . A method of manufacturing a semiconductor device comprising the steps of: 
 forming a crystalline semiconductor film by irradiating a laser light to an amorphous semiconductor film; and    performing a heat treatment to the crystalline semiconductor film to reduce of distortion formed in the crystalline semiconductor film wherein the distortion is caused by the irradiation of the laser light    
   
   
       2 . A method of manufacturing a semiconductor device comprising the steps of: 
 forming a semiconductor film comprising amorphous silicon on an insulating surface;    crystallizing said semiconductor film by irradiating said semiconductor film with laser light;    patterning the crystallized semiconductor film into at least one island shape semiconductor layer;    reducing distortions in the island shape semiconductor layer by performing a heat treatment at a temperature equal to or greater than 500° C. wherein said distortions are caused by the irradiation of said laser light;    after the heat treatment, forming a gate insulating film over the island shape semiconductor layer; and    forming a gate electrode over the gate insulating film.    
   
   
       3 . The method according to  claim 2  wherein the heat treatment is performed by furnace annealing.  
   
   
       4 . The method according to  claim 2  wherein the heat treatment is performed by RTA.  
   
   
       5 . The method according to  claim 2  wherein the heat treatment is performed in a nitrogen atmosphere.  
   
   
       6 . The method according to  claim 2  wherein the heat treatment is performed in an inert gas.  
   
   
       7 . A method of manufacturing a semiconductor device comprising the steps of: 
 forming a semiconductor film comprising amorphous silicon on an insulating surface;    crystallizing said semiconductor film by a first heat treatment;    irradiating the crystallized semiconductor film with laser light;    after the irradiation of the laser light, patterning the crystallized semiconductor film into at least one island shape semiconductor layer;    reducing distortions in the island shape semiconductor layer by performing a second heat treatment at a temperature equal to or greater than 500° C.;    after the second heat treatment, forming a gate insulating film over the island shape semiconductor layer; and    forming a gate electrode over the gate insulating film.    
   
   
       8 . The method according to  claim 7  wherein the second heat treatment is performed by furnace annealing.  
   
   
       9 . The method according to  claim 7  wherein the second heat treatment is performed by RTA.  
   
   
       10 . The method according to  claim 7  wherein the second heat treatment is performed in a nitrogen atmosphere.  
   
   
       11 . The method according to  claim 7  wherein the second heat treatment is performed in an inert gas.  
   
   
       12 . A method of manufacturing a semiconductor device comprising the steps of: 
 forming a semiconductor film comprising amorphous silicon on an insulating surface;    crystallizing said semiconductor film;    patterning the crystallized semiconductor film into at least one island shape semiconductor layer;    reducing distortions in the island shape semiconductor layer by performing a heat treatment at a temperature equal to or greater than 500° C.;    after the heat treatment, forming a gate insulating film over the island shape semiconductor layer; and    forming a gate electrode over the gate insulating film.    
   
   
       13 . The method according to  claim 12  wherein the heat treatment is performed by furnace annealing.  
   
   
       14 . The method according to  claim 12  wherein the heat treatment is performed by RTA.  
   
   
       15 . The method according to  claim 12  wherein the heat treatment is performed in a nitrogen atmosphere.  
   
   
       16 . The method according to  claim 12  wherein the heat treatment is performed in an inert gas.