Process for preparing thin layers of nanoporous dielectric materials

Process for preparing a thin layer of a nanoporous dielectric material with homogeneous porosity in which the following successive of steps are performed:

• a first thin layer of a first oxygen-free material, including Si, C, and optionally one or more other atom(s) selected from the group consisting of H, N and F, is deposited on a substrate, under conditions so that said first thin layer has a composition making it possible to generate a gas in a subsequent foaming treatment;
• on the first layer, a second thin layer of a second material including Si and at least one other atom selected from the group consisting of O, C, N, F and H is deposited under conditions so that said second thin layer has a composition that does not make it possible to generate a gas in the subsequent foaming step, and a sufficient density to limit or prevent the spread and/or diffusion of the gas generated in the first layer during the subsequent foaming treatment;
• the first layer and second layer assembly is treated under conditions so that a gas is generated in the first layer in order to enable the foaming thereof and the creation of nanopores therein, resulting in homogeneous porosity throughout the first layer;
• the second thin layer is optionally removed.