Etchant composition

An etchant composition, comprising:

• an inorganic acid;
• about 0.01 parts by weight to about 0.5 parts by weight of colloidal silica;
• about 0.1 parts by weight to about 20 parts by weight of an ammonium additive;
• and
• about 20 parts by weight to about 50 parts by weight of a solvent,
• all parts by weight being based on 100 parts by weight of the inorganic acid,
• wherein the colloidal silica has a structure represented by Chemical Formula 1, the structure being formed under acidic conditions at a pH of 1 or less and a temperature of 200° C. or higher:
• wherein, in Chemical Formula 1,
• m is an integer of 2 to 8, and
• R1, R2, R3, R4, R5, R6, R7, and R8 are each independently a hydrogen atom, a hydroxyl group, or a group represented by Chemical Formula 2, at least one of R1, R2, R3, R4, R5, R6, R7, and R8 being a hydroxyl group or a group represented by Chemical Formula 2,
• wherein, in Chemical Formula 2,
• n is an integer of 0 to 5, and
• R9 and R10 are each independently a hydrogen atom, a hydroxyl group, a C1 to C20 alkyl group, a C2 to C20 alkenyl group, a C2 to C20 alkynyl group, a C1 to C20 hydroxyalkyl group, a C1 to C20 aminoalkyl group, a C1 to C20 alkoxy group, a C1 to C20 aminoalkoxy group, a nitrile group, or a carboxyl group, and
• wherein the etchant composition further comprises about 0.01% by weight (wt %) to about 1 wt % of a fluorine compound, and
• wherein the etchant composition has a pH of 1 or less and a temperature of 200° C. or higher.