US Patent 11183419 Unconfined buried interconnects

Embodiments of the present invention are directed to fabrication methods and resulting semiconductor structures having a bulb-shaped buried interconnect positioned below a shallow trench isolation region. In a non-limiting embodiment of the invention, a cavity is formed below a surface of a substrate. The cavity extends under a portion of a semiconductor fin. The cavity is filled with a sacrificial material and a shallow trench isolation region is formed on the sacrificial material in the cavity. A portion of the shallow trench isolation region is removed to expose a surface of the sacrificial material in the cavity. The sacrificial material is removed from the cavity and replaced with a buried interconnect.