A method is provided for forming at least one TSV interconnect structure surrounded by at least one isolating trench-like structure having at least one airgap. The method comprises at least the steps of providing a substrate having a first main surface and producing simultaneous at least one a TSV hole and a trench-like structure surrounding the TSV hole and separated by remaining substrate material. The method also comprises thereafter depositing a dielectric liner in order to smoothen the sidewalls of the etched TSV hole and to pinch-off the opening of the trench-like structure at the first main surface of the substrate in order to create at least one airgap in said trench-like structure and depositing a conductive material in said TSV hole in order to create a TSV interconnect. A corresponding substrate is also provided.