Method for forming an integrated circuit device (98), comprising: a. forming (901) a semiconductor device on a frontside (11) of a substrate (1) comprising: a device layer (2) on the frontside (11) of the substrate (1), the device layer (2) comprising a first active device (20), the substrate (1) comprising: shallow trench isolation structures (139, 131, 132, 133), wherein adjacent shallow trench isolation structures (139, 131, 132, 133) are separated from each other by a separating portion (1391, 1312, 1323) comprising the substrate material (100), a via (130) filled with a sacrificial plug (4) extending through the substrate material (100) in a first separating portion (1312), and wherein the sacrificial plug (4) contacts a source or drain contact (21) of the first active device (20), b. removing (902) the substrate material (100) from a backside of the substrate (1), c. depositing (903) a liner (9) covering the backside (10) of the substrate (1), d. anisotropically etching (904) the liner (9) so as to expose a first end (41) of the sacrificial plug (4), while retaining at least part of the liner (9) in the separating portions (1391, 1312, 1323), e. removing (905) the sacrificial plug (4) selectively with respect to the liner (9), and f. providing (906) an electrically conductive material (30) in the via (130), electrically coupled to a buried power rail (31, 32).