A silicon polymer material, which has a silicon polymer backbone with chromophore groups attached directly to at least a part of the silicon atoms, the polymer further exhibiting carbosilane bonds. The film forming composition and resulting coating properties can be tailored to suit the specific exposure wavelength and device fabrication and design requirements. By using two different chromophores the refractive index and the absorption co-efficient can be efficiently tuned. By varying the proportion of carbosilane bonds, and a desired Si-content of the anti-reflective coating composition can be obtained.