Thin-film forming apparatus having an automatic cleaning function for cleaning the inside

Abstract

A method of cleaning the inside of a reaction chamber includes reducing the temperature of a susceptor to 470° C. or lower for cleaning; contacting the inside of the reaction chamber including the showerhead with fluorine radicals; cleaning the unwanted deposits by the fluorine radicals, wherein gaseous aluminum fluoride is inhibited from being emitted from the susceptor and solidified on the showerhead by maintaining the temperature of the susceptor at 470° C. or lower; and raising the temperature of the susceptor to 500-650° C. for film formation.

1 . A method of continuously depositing films on substrates, comprising: 
 (i) depositing a film on a substrate placed on an aluminum nitride susceptor provided in a reaction chamber by CVD using a gas introduced into the reaction chamber through a showerhead provided in the reaction chamber, said susceptor having a temperature of 500-650° C.;    (ii) repeating step (i) pre-selected times;    (iii) reducing the temperature of the susceptor to 470° C. or lower for cleaning;    (iv) contacting the inside of the reaction chamber including the showerhead with fluorine radicals at a pressure of 0.5-9 Torr, said showerhead having a temperature of 100-250° C. which is lower than the temperature of the susceptor;    (v) cleaning the unwanted deposits by the fluorine radicals, wherein gaseous aluminum fluoride is inhibited from being emitted from the susceptor and solidified on the showerhead by maintaining the temperature of the susceptor at 470° C. or lower;    (vi) upon completion of the cleaning, raising the temperature of the susceptor to 500-650° C. for film formation; and    (vii) repeating steps (i) through (vi) at least 40 times without interruption.    
   
   
       2 . The method according to  claim 1 , wherein the cleaning is conducted at a temperature of the susceptor of 450° C. or less.  
   
   
       3 . The method according to  claim 1 , wherein the fluorine radicals are produced in a plasma discharge region generated in the reaction chamber.  
   
   
       4 . The method according to  claim 1 , wherein the fluorine radicals are produced in a remote plasma discharge chamber prior to introduction of the cleaning gas into the reaction chamber, said remote plasma discharge chamber being disposed separately from the reaction chamber.  
   
   
       5 . The method according to  claim 1 , wherein the unwanted deposits include at least one of silicon nitride, silicon oxide, SiOF, SiC, SiON, or hydrocarbon.  
   
   
       6 . The method according to  claim 1 , wherein the reaction chamber is for plasma CVD or thermal CVD.  
   
   
       7 . The method according to  claim 1 , wherein steps (iii) and (vi) further comprise introducing an inert gas into the reaction chamber while reducing and raising the temperature of the susceptor.  
   
   
       8 . The method according to  claim 1 , wherein the temperature of the susceptor is changed at a rate of 20° C. or less per minute in steps (iii) and (vi).  
   
   
       9 . The method according to  claim 1 , wherein step (vii) is conducted without raising a non-uniformity of thickness of a film formed in step (a) to more than 3%.  
   
   
       10 . The method according to  claim 1 , wherein step (vii) is conducted at least 80 times without raising a non-uniformity of thickness of a film formed in step (a) to more than 3%.  
   
   
       11 . A method for preventing aluminum fluoride from depositing on a showerhead during cleaning of a reaction chamber, comprising: 
 (a) after forming by CVD a film on a substrate on an aluminum nitride susceptor having a temperature of 500-650° C., reducing the temperature of the susceptor to 470° C. or lower for cleaning;    (b) contacting the inside of the reaction chamber including the showerhead with fluorine radicals at a pressure of 0.5-9 Torr, said showerhead having a temperature of 100-250° C. which is lower than the temperature of the susceptor;    (c) cleaning unwanted deposits inside the reaction chamber by the fluorine radicals while inhibiting generation and emission of gaseous aluminum fluoride from the susceptor and solidification of the aluminum fluoride on the showerhead by maintaining the temperature of the susceptor at 470° C. or lower; and    (d) upon completion of the cleaning, raising the temperature of the susceptor to 500-650° C. for film formation.    
   
   
       12 . The method according to  claim 11 , wherein the cleaning is conducted at a temperature of the susceptor of 450° C. or less  
   
   
       13 . The method according to  claim 11 , wherein the fluorine radicals are produced in a plasma discharge region generated in the reaction chamber.  
   
   
       14 . The method according to  claim 11 , wherein the fluorine radicals are produced in a remote plasma discharge chamber prior to introduction of the cleaning gas into the reaction chamber, said remote plasma discharge chamber being disposed separately from the reaction chamber.  
   
   
       15 . The method according to  claim 11 , wherein the unwanted deposits include at least one of silicon nitride, silicon oxide, SiOF, SiC, SiON, or hydrocarbon.  
   
   
       16 . The method according to  claim 11 , wherein the reaction chamber is for plasma CVD or thermal CVD.  
   
   
       17 . The method according to  claim 11 , wherein steps (a) and (d) further comprise introducing an inert gas into the reaction chamber while reducing and raising the temperature of the susceptor.  
   
   
       18 . The method according to  claim 11 , wherein the temperature of the susceptor is changed at a rate of 20° C. or less per minute in steps (a) and (d).  
   
   
       19 . The method according to  claim 11 , wherein steps (a) though (d) are repeated without interruption at least 40 times without raising a non-uniformity of thickness of a film formed in step (a) to more than 3%.  
   
   
       20 . The method according to  claim 11 , wherein steps (a) though (d) are repeated without interruption at least 80 times without raising a non-uniformity of thickness of a film formed in step (a) to more than 3%.  
   
   
       21 . The method according to  claim 11 , wherein the susceptor temperature is 550-600° C. in steps (a) and (d).