A process for fabricating an integrated electronic circuit comprises the formation of at least one air gap between interconnect elements above only a defined portion of a surface of a substrate, within an interconnect layer. The interconnect layer comprises a sacrificial material and extends beneath an intermediate layer of permeable material. The air gap is formed by removal, through the intermediate layer, of at least part of the sacrificial material by bringing the permeable material into contact with an agent for removing the sacrificial material, to which agent the permeable material is resistant.