Patent ID: 7297360

Claim:
An insulation film having a thickness of from about 0.01 to 3 μm, and comprising an organosilicon polymer with a relative dielectric constant of 4 or less having a dry etching selection ratio to the compound selected from the group consisting of silicon oxide, fluorine-doped silicon oxide, organosilicate glass, carbon-doped silicon oxide, methyl silsesquioxane, hydrogen silsesquioxane, a spin-on-glass, polyorganosiloxane, and an organic polymer selected from the group consisting of polyarylene, polyarylene ether, polyimide, and fluororesin, wherein the organosilicon polymer is at least one polycarbosilane selected from the group consisting of polymers having the structural unit of the following formula (1), wherein R 1 and R 2 independently represent a hydrogen atom, an alkyl group having 1-30 carbon atoms that may have a substituent, an alkenyl group having 1-30 carbon atoms that may have a substituent, an alkynyl group having 1-30 carbon atoms that may have a substituent, or an aromatic group that may have a substituent and R 3 represents —C≡C—, —CH 2 — or fluoro-substituted —CH 2 — having a substituent linked with at least one —C≡C— group, an alkylene or fluoro-substituted alkylene group having 2-30 carbon atoms and having a substituent linked with at least one —C≡C— group, an alkenylene group having 2-30 carbon atoms and having a substituent linked with at least one —C≡C— group, an alkynylene group having 2-30 carbon atoms and having a substituent linked with at least one —C≡C— group, or a divalent aromatic group having 6-30 carbon atoms and having a substituent linked with at least one —C≡C— group.