Silicon nitride etching composition and method

Abstract

Compositions useful for the selective removal of silicon nitride materials relative to polysilicon, silicon oxide materials and/or silicide materials from a microelectronic device having same thereon are provided. The compositions of the invention are particularly useful in the etching of 3D NAND structures.

1 - 20 . (canceled) 
     
     
         21 . A method for removing silicon nitride from a microelectronic device, the method comprising contacting the microelectronic device with a composition, for sufficient time under sufficient conditions to at least partially remove the silicon nitride material from the microelectronic device, wherein the composition comprises:
 (a) phosphoric acid;   (b) at least one silane chosen from (i) alkylamino alkoxysilanes and (ii) alkylamino hydroxyl silanes, wherein said silane possesses at least one moiety chosen from alkoxy, hydroxyl, and fluoro;   (c) a solvent comprising water;   (d) a fluoride compound, provided that the fluoride compound is other than hexafluoro silicic acid; and   (e) an alkyl amine or phosphate salt thereof.   
     
     
         22 . The method of  claim 21 , wherein the phosphoric acid is present in a range of 50 to 95 weight percent, based on the total weight of the composition. 
     
     
         23 . The method of  claim 21 , wherein the fluoride compound is chosen from HF and monofluorophosphoric acid. 
     
     
         24 . The method of  claim 21 , wherein the fluoride compound is chosen from cesium fluoride and potassium fluoride. 
     
     
         25 . The method of  claim 21 , wherein the fluoride compound is chosen from fluoroboric acid; tetramethylammonium hexafluorophosphate; ammonium fluoride; ammonium bifluoride; quaternary ammonium tetrafluoroborates and quaternary phosphonium tetrafluoroborates having the formula NR′ 4 BF 4  and PR′ 4 BF 4 , respectively, wherein R′ may be the same as or different from one another and is selected from hydrogen, straight-chained, branched, or cyclic C 1 -C 6  alkyl, and straight-chained or branched C 6 -C 10  aryl; tetrabutylammonium tetrafluoroborate (TBA-BF 4 ); and combinations thereof. 
     
     
         26 . The method of  claim 21 , wherein the alkylamino alkoxysilane and alkylamino hydroxyl silane compounds are represented by the formula 
       
         
           
           
               
               
           
         
       
       wherein each X is independently chosen from fluorine, a C 1 -C 8  alkyl group, or a group of the formula −OR, wherein R is hydrogen or a C 1 -C 8  alkyl group, n is an integer of from 1 to 6, and each R 1  is independently chosen from hydrogen, a C 1 -C 8  alkyl group, or a group of the formula C 1 -C 8  alkoxy(CH 2 ) n —. 
     
     
         27 . The method of  claim 26 , wherein R is methyl or ethyl. 
     
     
         28 . The method of  claim 26 , wherein the alkylamino alkoxysilane and alkylamino hydroxyl silane compounds are chosen from (3-aminopropyl)triethoxy-silane; (3-aminopropyl)silane-triol; 3-aminopropyldimethylethoxysilane; 3-aminopropylmethyldiethoxysilane; and N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane; (N, N-dimethyl-3-amnopropyl)trimethoxysilane; and 3-aminopropyldimethylfluorosilane. 
     
     
         29 . The method of  claim 21 , wherein the alkyl amine or phosphate salt thereof is chosen from a primary, secondary, or tertiary C 1 -C 6  alkylamine or dihydrogen phosphate salt thereof. 
     
     
         30 . The method of  claim 21 , wherein the alkylamino alkoxysilane and alkylamino hydroxyl silane compounds are represented by the formula 
       
         
           
           
               
               
           
         
       
       wherein each X is independently chosen from fluorine, a C 1 -C 8  alkyl group, or a group of the formula —OR, wherein R is hydrogen or a C 1 -C 8  alkyl group, n is an integer of from 1 to 6, y is an integer of from 1 to 6, and wherein z is an integer of from 1 to 6. 
     
     
         31 . The method of  claim 30 , wherein R is methyl or ethyl. 
     
     
         32 . The method of  claim 30 , wherein the alkylamino alkoxysilane and alkylamino hydroxyl silane compounds are chosen from N-(3-trimethoxysilylpropyl)diethylenetriamine; N-(2-aminoethyl)-3-aminopropyltriethoxy silane; N-(2-aminoethyl)-3-aminopropyl-silane triol; (3-trimethoxysilylpropyl)dethylenetriamine; and N-(6-aminohexyl)aminopropyltrimethoxysilane. 
     
     
         33 . The method of  claim 31 , wherein the alkyl amine or phosphate salt thereof is chosen from a primary, secondary, or tertiary C 1 -C 6  alkylamine or dihydrogen phosphate salt thereof. 
     
     
         34 . The method of  claim 21  wherein the composition further comprises a surfactant, a carboxylic acid compound, or a dissolved silicate. 
     
     
         35 . The method of  claim 21 , wherein the alkylamino alkoxysilane and alkylamino hydroxyl silane compounds are represented by the formulas 
       
         
           
           
               
               
           
         
       
     
     
         36 . A method of selectively removing silicon nitride material comprising:
 contacting a substrate supporting silicon nitride with an etchant comprising:
 (a) phosphoric acid; 
 (b) at least one silane chosen from (i) alkylamino alkoxysilanes and (ii) alkylamino hydroxyl silanes, wherein said silane possesses at least one moiety chosen from alkoxy, hydroxyl, and fluoro; 
 (c) a solvent comprising water; 
 (d) a fluoride compound, provided that the fluoride compound is other than hexafluoro silicic acid; and 
 (e) an alkyl amine or phosphate salt thereof, 
   wherein the etchant has a selectivity of silicon nitride to silicon oxide of at least 30:1.   
     
     
         37 . The method of  claim 36  wherein the etchant has a temperature between 40 and 100° C. 
     
     
         38 . The method of  claim 36 , wherein contacting the substrate with the etchant occurs from about 1 to about 3 minutes. 
     
     
         39 . The method of  claim 36 , wherein the etchant has a selectivity of silicon nitride to silicon oxide of at least 1000:1. 
     
     
         40 . The method of  claim 36 , wherein etchant comprises 70 wt. % to 95 wt. % of phosphoric acid by weight of the etchant.