Method for fabricating a semiconductor device

Abstract

A method for fabricating a semiconductor device comprises the step of depositing an insulation film 32 a with a first pressure set in a deposition chamber; the step of gradually decreasing the pressure in the deposition chamber to a second pressure which is lower than the first pressure; and the step of further depositing the insulation film 32 b with the second pressure set in the deposition chamber. The insulation film is deposited with the first pressure a little lower than a second pressure set in a deposition chamber, and the insulation film is further deposited with the second pressure lower than the first pressure set in the deposition chamber. Furthermore, the insulation film is not deposited in the state where the pressure in the deposition chamber is extremely low, and an atmosphere in the deposition chamber is unstable. Thus, a semiconductor device having the insulation film with a sufficiently flat surface can be fabricating without using reflow process.

1 . A method for fabricating a semiconductor device comprising: 
 the step of depositing an insulation film with a first pressure set in a deposition chamber;    the step of exhausting an atmosphere in the deposition chamber so as to gradually decrease the pressure in the deposition chamber while an atmosphere in the deposition chamber is being replaced by an inert atmosphere;    the pressure adjusting step of setting a second pressure lower than the first pressure in the deposition chamber; and    the step of further depositing the insulation film with the second pressure set in the deposition chamber.    
     
     
         2 . A method for fabricating a semiconductor device according to  claim 1 , wherein 
 in the step of exhausting an atmosphere in the deposition chamber, the atmosphere in the deposition chamber is exhausted so as to gradually decrease the pressure in the deposition chamber at a rate smaller than 40 Torr/sec.    
     
     
         3 . A method for fabricating a semiconductor device according to  claim 2 , wherein 
 in the step of exhausting an atmosphere in the deposition chamber, the atmosphere in the deposition chamber is exhausted so as to gradually decrease the pressure in the deposition chamber at a 5-40 Torr/sec.    
     
     
         4 . A method for fabricating a semiconductor device comprising: 
 the step of depositing an insulation film with a first pressure set in a deposition chamber;    the step of replacing the atmosphere in the deposition chamber by an inert atmosphere;    the step of exhausting the atmosphere in the deposition chamber;    the pressure adjusting step of setting a second pressure lower than the first pressure in the deposition chamber; and    the step of further depositing the insulation film with the second pressure set in the deposition chamber.    
     
     
         5 . A method for fabricating a semiconductor device comprising: 
 the step of depositing an insulation film with a first pressure set in a deposition chamber;    the step of exhausting an atmosphere in the deposition chamber while the atmosphere in the deposition chamber is being replaced by an inert atmosphere;    the pressure adjusting step of setting a second pressure lower than the first pressure in the deposition chamber; and    the step of further depositing the insulation film with the second pressure set in the deposition chamber.    
     
     
         6 . A method for fabricating a semiconductor device according to  claim 1 , wherein 
 in the pressure adjusting step, the pressure in the deposition chamber is set at the second pressure while an inert gas is being introduced into the deposition chamber.    
     
     
         7 . A method for fabricating a semiconductor device according to  claim 4 , wherein 
 in the pressure adjusting step, the pressure in the deposition chamber is set at the second pressure while an inert gas is being introduced into the deposition chamber.    
     
     
         8 . A method for fabricating a semiconductor device according to  claim 5 , wherein 
 in the pressure adjusting step, the pressure in the deposition chamber is set at the second pressure while an inert gas is being introduced into the deposition chamber.    
     
     
         9 . A method for fabricating a semiconductor device according to  claim 1 , which further comprises, 
 before the step of depositing the insulation film, the step of forming a gate electrode of a transistor on a semiconductor substrate; and    in which in the step of depositing the insulation film, the insulation film is deposited so as to cover the gate electrode.    
     
     
         10 . A method for fabricating a semiconductor device according to  claim 4 , which further comprises, 
 before the step of depositing the insulation film, the step of forming a gate electrode of a transistor on a semiconductor substrate; and    in which in the step of depositing the insulation film, the insulation film is deposited so as to cover the gate electrode.    
     
     
         11 . A method for fabricating a semiconductor device according to  claim 5 , which further comprises, 
 before the step of depositing the insulation film, the step of forming a gate electrode of a transistor on a semiconductor substrate; and    in which in the step of depositing the insulation film, the insulation film is deposited so as to cover the gate electrode.    
     
     
         12 . A method for fabricating a semiconductor device according to  claim 1 , which further comprises, 
 before the step of depositing the insulation film, the step of forming an interconnection layer above the semiconductor substrate; and    in which in the step of depositing the insulation film, the insulation film is deposited so as to cover the interconnection layer.    
     
     
         13 . A method for fabricating a semiconductor device according to  claim 4 , which further comprises, 
 before the step of depositing the insulation film, the step of forming an interconnection layer above the semiconductor substrate; and    in which in the step of depositing the insulation film, the insulation film is deposited so as to cover the interconnection layer.    
     
     
         14 . A method for fabricating a semiconductor device according to  claim 5 , which further comprises, 
 before the step of depositing the insulation film, the step of forming an interconnection layer above the semiconductor substrate; and    in which in the step of depositing the insulation film, the insulation film is deposited so as to cover the interconnection layer.    
     
     
         15 . A method for fabricating a semiconductor device according to  claim 1 , wherein 
 the first pressure is 400-600 Torr; and    the second pressure is 200-400 Torr.    
     
     
         16 . A method for fabricating a semiconductor device according to  claim 4 , wherein 
 the first pressure is 400-600 Torr; and    the second pressure is 200-400 Torr.    
     
     
         17 . A method for fabricating a semiconductor device according to  claim 5 , wherein 
 the first pressure is 400-600 Torr; and    the second pressure is 200-400 Torr.    
     
     
         18 . A method for fabricating a semiconductor device according to  claim 1 , wherein 
 in the step of depositing the insulation film, the insulation film is deposited by thermal chemical vapor deposition.    
     
     
         19 . A method for fabricating a semiconductor device according to  claim 4 , wherein 
 in the step of depositing the insulation film, the insulation film is deposited by thermal chemical vapor deposition.    
     
     
         20 . A method for fabricating a semiconductor device according to  claim 5 , wherein 
 in the step of depositing the insulation film, the insulation film is deposited by thermal chemical vapor deposition.    
     
     
         21 . A method for fabricating a semiconductor device according to  claim 1 , wherein 
 the insulation film is a BPSG film, a BSG film, a PSG film or an USG film.    
     
     
         22 . A method for fabricating a semiconductor device according to  claim 4 , wherein 
 the insulation film is a BPSG film, a BSG film, a PSG film or an USG film.    
     
     
         23 . A method for fabricating a semiconductor device according to  claim 5 , wherein 
 the insulation film is a BPSG film, a BSG film, a PSG film or an USG film.    
     
     
         24 . A method for fabricating a semiconductor device according to  claim 1 , further comprising, 
 after the step of further depositing the insulation film, the step of polishing the surface of the insulation film.    
     
     
         25 . A method for fabricating a semiconductor device according to  claim 4 , further comprising, 
 after the step of further depositing the insulation film, the step of polishing the surface of the insulation film.    
     
     
         26 . A method for fabricating a semiconductor device according to  claim 5 , further comprising, 
 after the step of further depositing the insulation film, the step of polishing the surface of the insulation film.