NOVELTY - Siloxane composition (I) comprises a siloxane prepolymer (II) with a siloxane backbone exhibiting a group, which is capable of being deprotonated in an aqueous base solution and further exhibiting a reactive functional group, which is capable of reacting during a thermal or radiation initiated curing step, a solvent for the siloxane prepolymer and a photo reactive compound.    USE - (I) is useful in a lithographic method, which provides an optical layer in a display device, such as an liquid crystal displays, plasma displays or organic light emitting displays, a solar cell, an light emitting diode or a semiconductor device (all claimed). (I) is useful in negative tone lithographic fabrication process, which is useful in fabrication of semiconductor devices such as integrated circuits, flat panel display devices, and in opto-electronic and photonic devices (waveguide and light-guide structures, gratings and photonic crystals).    ADVANTAGE - The film is produced by the lithographic method: has a dielectric constant of 4 or below at a frequency of 100 kHz; has an index of refraction, which is 1.2-1.9 at a wavelength of 633 nm; and exhibits a cross-linking degree of 70% or more at a UV dose of 100 mJ/cm2 or less at I-line wavelength of mercury UV source. (II) are soluble in aqueous alkaline developers, which are commonly used by industry and are environmentally safe.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for:    (1) a method of producing (I) comprising hydrolyzing at least two different silane monomers, condensing the silane monomers to form a siloxane polymer having a molecular weight of 500-20000 g/mol, and incorporating a photo reactive compound and a solvent for the siloxane polymer, in order to formulate a siloxane prepolymer liquid composition;    (2) a method of producing a siloxane prepolymer composition, comprising hydrolyzing at least two different silane monomers, condensing the silane monomers to form a siloxane polymer having a molecular weight of 500-20000 g/mol, recovering the siloxane polymer in a solvent phase, and incorporating a photo reactive compound into the solvent phase, the silane monomers including monomers containing reactive functional group, which is capable of achieving cross-linking of siloxane polymers under the induction of the photo reactive compound, where the hydrolyzing and the condensation steps are carried out such that there are at least some hydroxyl groups present in the polymer; and    (3) a method of using a siloxane prepolymer composition in a lithographic method, comprising optionally adjusting the solid contents of the prepolymer composition material to the required film thickness of the deposited film, depositing the composition on a substrate to form a layer having a film thicknesses of 10 nm-10 mu m, optionally heat treating the deposited film, subjecting the deposited material layer to lithography by using a photo mask or reticle and exposing the material to UV light, optionally heat treating the exposed material, and removing the non-exposed areas of the film, which are removed in a development step, by contacting the layer with an aqueous basic developer solution.