Photoresist, method of manufacturing a semiconductor device and method of extreme ultraviolet lithography

A lithography method, comprising:

• spin coating a photoresist composition over a target layer to form a photoresist layer, wherein the photoresist composition comprises a tin oxide-containing compound, the tin oxide-containing compound comprises a formula (RSn)6O4(R′CO2)4(R″CO2)4Cl2, the formula comprises a structure
• each of R, R′ and R″ is an alkyl group;
• exposing the photoresist layer;
• and
• developing the photoresist layer.

A method of forming photo-active compound, comprising:

• adding RSnCl3, a first silver carboxylate salt and a second silver carboxylate salt in an organic solvent to form a mixture;
• stirring the mixture under reflux;
• and
• purifying the mixture by recrystallization to form a tin oxide-containing compound comprising a formula (RSn)6O4(R′CO2)4(R″CO2)4Cl2, the formula comprises a structure
• each of R, R′ and R″ is an alkyl group.