INTEGRATED CIRCUIT DEVICES INCLUDING BACKSIDE POWER RAIL AND METHODS OF FORMING THE SAME

Methods of forming an integrated circuit devices may include providing first and second active regions (12_1, 12_2), an isolation layer (11), and first and second sacrificial stack structures. The first and second sacrificial stack structures may contact the first and second active regions (12_1, 12_2), and the first and second sacrificial stack structures may each include a channel layer and a sacrificial layer. The methods may also include forming an etch stop layer (16) on the isolation layer (11), replacing portions of the first and second sacrificial stack structures with first and second source/drain regions (14_1, 14_2), forming a front contact (22) including a front contact plug (22P), forming a back-side insulator (50), and forming a back contact plug (52) in the isolation layer (11) and the back-side insulator (50). At least one of a portion of the front contact plug (22P) and a portion of the back contact plug (52) may be in the etch stop layer (16).