Film-forming composition, insulating film with low dielectric constant, formation method thereof, and semiconductor device

Abstract

In the invention, a silica sol prepared by hydrolyzing and condensing a silane compound represented by the following formula: Si(OR 1 ) 4 or R 2 n Si(OR 3 ) 4-n wherein R 1 s, R 2 (s) and R 3 (s) may be the same or different when a plurality of them are contained in the molecule and each independently represents a linear or branched C 1-4 alkyl group in the presence of a hydrophilic basic catalyst and a hydrophobic basic catalyst is used for a conventional porous-film forming composition.

1 . A silica sol prepared by hydrolyzing and condensing a hydrolyzable silane compound in the presence of at least one hydrophilic basic catalyst selected from alkali metal hydroxides and quaternary ammonium hydroxides represented by the following formula (1):
   (R 1 ) 4 N + OH −   (1)   
       wherein, R 1 s may be the same or different and each independently represents a hydrocarbon group which may contain an oxygen atom and the cationic portion [(R 1 ) 4 N + ] satisfies the following relationship (2):
   (N+O)/(N+O+C)≧⅕  (2) 
 
       in which, N, O and C are the numbers of nitrogen, oxygen and carbon atoms contained in the cationic portion, respectively, and at least one hydrophobic basic catalyst selected from quaternary ammonium hydroxides which do not satisfy the above-described relationship (2). 
     
     
         2 . A composition for forming a porous film comprising the silica sol of  claim 1 . 
     
     
         3 . A porous film formed using the porous-film forming composition of  claim 2 . 
     
     
         4 . A method for forming a porous film, which comprises applying the porous-film forming composition of  claim 2  to form a thin film and sintering the thin film. 
     
     
         5 . A method for manufacturing of a semiconductor device, which comprises forming an interlayer insulating film by using the method for forming a porous film of  claim 4 . 
     
     
         6 . A semiconductor device comprising the porous film of  claim 3  as an interlayer insulating film.