A hardmask composition includes a solvent and an organosilicon copolymer. The organosilicon copolymer may be represented by Formula A: (SiO1.5—Y—SiO1.5)x(R3SiO1.5)y  (A) wherein x and y may satisfy the following relations: x is about 0.05 to about 0.9, y is about 0.05 to about 0.9, and x+y=1, R3 may be a C1-C12 alkyl group, and Y may be a linking group including a substituted or unsubstituted, linear or branched C1-C20 alkyl group, a C1-C20 group containing a chain that includes an aromatic ring, a heterocyclic ring, a urea group or an isocyanurate group, or a C2-C20 group containing one or more multiple bonds.