Organic silicon oxide fine particles and preparation method thereof, porous film-forming composition, porous film and formation method thereof, and semiconductor device

Abstract

Provided are organic silicon oxide fine particles which can be formed into a porous film having a dielectric constant and mechanical strength expected as a high-performance porous insulating film and having excellent chemical stability, and a preparation method thereof. Described specifically, provided are an organic silicon oxide fine particle comprising a core containing at least an inorganic silicon oxide or an organic silicon oxide and a shell containing at least an organic silicon oxide and being formed around the core by using shell-forming hydrolyzable silane in the presence of a basic catalyst; wherein of silicon atoms constituting the core or the shell, a ratio (T/Q) of a number (T) of silicon atoms having at least one bond directly attached to a carbon atom to a number (Q) of silicon atoms having all of four bonds attached to an oxygen atom is greater in the shell than in the core; and wherein the shell-forming hydrolyzable silane comprise at least a hydrolyzable silane compound having two or more hydrolyzable-group-having silicon atoms bound to each other via a carbon chain or via a carbon chain containing one silicon atom between some carbon atoms.

1 . An organic silicon oxide fine particle comprising:
 a core containing at least an inorganic silicon oxide or an organic silicon oxide and   a shell containing at least an organic silicon oxide and being formed around the core by using shell-forming hydrolyzable silane in the presence of a basic catalyst;   wherein of silicon atoms constituting the core or the shell, a ratio (T/Q) of a number (T) of silicon atoms having at least one bond directly attached to a carbon atom to a number (Q) of silicon atoms having all of four bonds attached to an oxygen atom is greater in the shell than in the core; and   wherein the shell-forming hydrolyzable silane comprise at least a hydrolyzable silane compound having two or more hydrolyzable-group-having silicon atoms bound to each other via a carbon chain or via a carbon chain containing one silicon atom between some carbon atoms.   
   
   
       2 . The organic silicon oxide fine particle according to  claim 1 , wherein said shell-forming hydrolyzable silane comprise one or more compounds represented by the following formula (1):
   {R 1   n X 1   3-n Si—[(Y 2 )—(SiR 2   m X 2   2-m )] p } q —(Y 3 )—SiR 3   t X 3   3-t   (1)   
     wherein X 1  to X 3  each independently represents a hydrolyzable group selected from the group consisting of a hydrogen atom, halogen atoms and C 1-4  alkoxy groups; R 1  to R 3  each independently represents a C 1-20  alkyl group or a C 6-10  aryl group; Y 2  and Y 3  each independently represents a substituted or unsubstituted C 1-6  hydrocarbon group having q+1 valencies, a C 5-20  cycloalkane group which has q+1 valencies and may contain a fused ring structure, or a C 6-20  aromatic group having q+1 valencies; m each independently represents an integer from 0 to 2; n each independently represents an integer from 0 to 2; p each independently represents an integer from 0 to 4; q each independently represents an integer of 1 or greater; and t each independently represents an integer from 0 to 2. 
   
   
       3 . The organic silicon oxide fine particle according to  claim 2 , wherein said one or more compounds represented by the formula (1) are selected from the group consisting of compounds represented by the following formula (2): 
     
       
         
         
             
             
         
       
     
     and the following formula (3): 
     
       
         
         
             
             
         
       
     
     wherein X 4  to X 9  each independently represents a hydrolyzable group selected from the group consisting of a hydrogen atom, halogen atoms and C 1-4  alkoxy groups; R 4  to R 9  each independently represents a C 1-20  alkyl group or a C 6-10  aryl group; m each independently represents an integer from 0 to 2; n each independently represents an integer from 0 to 2; p each independently represents an integer from 0 to 4; r each independently represents an integer from 0 to 4; s each independently represents an integer from 0 to 4; t each independently represents an integer from 0 to 2; and u each independently represents an integer from 0 to 4. 
   
   
       4 . The organic silicon oxide fine particle according to  claim 1 , wherein the number of silicon atoms contained in the core is greater than the number of silicon atoms contained in the shell. 
   
   
       5 . The organic silicon oxide fine particle according  claim 1 , wherein the core contains a zeolite-like recurring structure. 
   
   
       6 . The organic silicon oxide fine particle according to  claim 1 , wherein said inorganic silicon oxide or said organic silicon oxide of said core is an inorganic or organic silica prepared by hydrolysis and condensation of a core-forming hydrolyzable silane in the presence of a basic catalyst. 
   
   
       7 . The organic silicon oxide fine particle according to  claim 1 , wherein said shell-forming hydrolyzable silane consists essentially of one or more hydrolyzable silane compounds having a carbon atom directly attached to a silicon atom. 
   
   
       8 . The organic silicon oxide fine particle according to  claim 1 , further comprising an intermediate layer between the core and the shell. 
   
   
       9 . A method for producing an organic silicon oxide fine particle, comprising steps of:
 adding first hydrolyzable silane to water or a mixed solution of water and alcohol to carry out hydrolysis and condensation of the resulting mixture in the presence of a basic catalyst to form a core,   wherein the first hydrolyzable silane is a silane compound or compounds, containing at least one compound represented by the following formula (4):
   Si(OR 10 ) 4   (4) 
   
     wherein R 10  may be the same or different and each independently represents a linear or branched C 1-4  alkyl group; and
 adding, to the reaction mixture for the core, second hydrolyzable silane which is a hydrolyzable silane compound or a mixture of two or more hydrolyzable silane compounds to form a shell, 
 wherein of silicon atoms constituting the first hydrolyzable silane or the second hydrolyzable silane, a ratio (T/Q) of a number (T) of silicon atoms having at least one bond directly attached to a carbon atom to a number (Q) of silicon atoms having all of four bonds attached to an oxygen atom is greater in the second hydrolysable silane than in the first hydrolysable silane; and 
 the second hydrolyzable silane contains a hydrolyzable silane compound having two or more hydrolyzable-group-having silicon atoms bound to each other via a carbon chain or via a carbon chain containing one silicon atom between some carbon atoms. 
 
   
   
       10 . The method for producing an organic silicon oxide fine particle according to  claim 9 , wherein after addition of a total amount of the first hydrolyzable silane, reaction conditions permitting progress of the hydrolysis and condensation of the added first hydrolyzable silane are maintained and then the step of adding of the second hydrolyzable silane is started. 
   
   
       11 . The method for producing an organic silicon oxide fine particle according to  claim 9 , wherein prior to completion of the addition of a total amount of the first hydrolyzable silane, the step of adding of the second hydrolyzable silane is started. 
   
   
       12 . The method for producing an organic silicon oxide fine particle according to  claim 9 , wherein the second hydrolyzable silane is represented by the following formula (1):
   {R 1   n X 1   3-n Si—[(Y 2 )—(SiR 2   m X 2   2-m )] p } q —(Y 3 )—SiR 3   t X 3   3-t   (1)   
     wherein X 1  to X 3  each independently represents a hydrolyzable group selected from the group consisting of a hydrogen atom, halogen atoms and C 1-4  alkoxy groups; R 1  to R 3  each independently represents a C 1-20  alkyl group or a C 6-10  aryl group; Y 2  and Y 3  each independently represents a substituted or unsubstituted C 1-6  hydrocarbon group having q+1 valencies, a C 5-20  cycloalkane group which has q+1 valencies and may contain a fused ring structure, or a C 6-20  aromatic group having q+1 valencies; m each independently represents an integer from 0 to 2; n each independently represents an integer from 0 to 2; p each independently represents an integer from 0 to 4; q each independently represents an integer of 1 or greater; and t each independently represents an integer from 0 to 2.