16  15  US 9,804,493 B2  an oxygen content of the graphene derivative is equal to  or greater than about 1 wt % and equal to or less than  about 10 wt  % based on a total weight of the graphene  derivative.  2.  The composition as claimed in claim  1,  wherein the  hydrophilic group is selected from a hydroxyl group, a  carboxyl group, an amino group, an amido group, a nitro  group, a cyano group, a polyalkyleneoxide group, and a  sulfa group.  3.  The composition as claimed in claim  1,  wherein the  graphene derivative is obtained by oxidizing graphene.  4.  The composition as claimed in claim  1,  wherein a  weight average molecular weight of the graphene derivative  is about 1000 to about 20000.  5.  A composition for forming a topcoat layer, the com- position comprising:  a nonionic surfactant;  a graphene derivative including a hydrophilic group;  a solvent; and  a binder including a deep-ultraviolet absorbing group,  wherein:  the graphene derivative is present in an amount of about  0.5 to about 10 wt % based on a total weight of the  composition,  the binder is present in an amount about 0.01 to about 10  wt % based on a total weight of the composition, and  an oxygen content of the graphene derivative is equal to  or greater than about 1 wt % and equal to or less than  about 10 wt  % based on a total weight of the graphene  derivative.  6.  The composition as claimed in claim  5,  wherein an  amount of the nonionic surfactant is about 0.01 to about 0.5  wt % based on a total weight of the composition.  7.  A pattern formation method, comprising:  disposing a resist composition on a substrate, to form a  resist layer;  coating the resist layer with a topcoat composition for  forming a topcoat layer, the topcoat composition  including:  developing exposed resist layer with an alkali aqueous  solution.  subjecting the resist layer to exposure using extreme  ultraviolet light; and  heating the topcoat composition to harden the topcoat  composition;  a graphene derivative including a hydrophilic group;  and  a solvent;  8.  The pattern formation method as claimed in claim  7,  wherein the extreme ultraviolet light has a wavelength in a  range of about 5 to about 20 nm.  9.  The pattern formation method as claimed in claim  8,  wherein the topcoat composition has a thickness of about 1  to about 100 nm on the resist layer.  10.  The pattern formation method as claimed in claim  7,  wherein the heating step is carried out at a temperature of  about 25 to about 150°  C.  *  *  *  *  * 