1. A semiconductor element comprising: a cell gate structure formed on a substrate on which a plurality of interlayer insulating layers and a plurality of gate electrode layers are alternatively stacked, wherein the cell gate structure formed by selectively etching a plurality of nitride layers by a composition for the selective etching, wherein the composition for etching comprises: a first inorganic acid, a first additive represented by Chemical Formula 1, a second additive comprising a silane inorganic acid salt produced by reaction between a second inorganic acid and a silane compound; and a solvent, wherein: the second inorganic acid is at least one selected from the group consisting of a sulfuric acid, a fuming sulfuric acid, and a combination thereof; and the silane compound is a compound selected from Chemical Formulas 10, 20, and their combination, the silane inorganic acid salt is represented by Chemical Formula C230-1;

wherein (Chemical Formula 1, X is O or N, R1 to R6 are each, independently, selected from the group consisting of hydrogen, a C1-C20 alkyl group, a C1-C20 alkoxy group, a C2-C20 alkenyl group, a C3-C20 cycloalkyl group, a C1-C20 aminoalkyl group, a C6-C20 aryl group, a C1-C20 alkyl carbonyl group, a C1-C20 alkyl carbonyloxy group, and a C1-C10 cyano alkyl group, and n11 is 0 or 1;

wherein Chemical Formula 10 and Chemical Formula 20, each R1 to R10 is independently selected from a group consisting of hydrogen atom, halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, and an aryl group having 6 to 30 carbon atoms, at least one of R1 to R4 is hydrogen, or an alkoxy group having 1 to 10 carbon atoms, and n is one of integer numbers from 1 to 10;

wherein Chemical Formula C230-1, each R111 to R112 is independently selected from a group consisting of hydrogen atom, halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, and an aryl group having 6 to 30 carbon atoms, each R113 to R114 is independently hydrogen, n4 is one of integer numbers from 0 to 2, Il is one of integer numbers from 0 to 10, ml is O or 1.