Embodiments of the present invention are directed to a method for increasing the available width of a shallow trench isolation region. In a non-limiting embodiment of the invention, a semiconductor fin is formed over a substrate. A source or drain is formed on a surface of the substrate between the semiconductor fin and the substrate. A liner is formed over a surface of the semiconductor fin and a surface of the substrate is recessed to expose a sidewall of the source or drain. A mask is formed over the semiconductor fin and the liner. The mask is patterned to expose a top surface and a sidewall of the liner. A sidewall of the source or drain is recessed and a shallow trench isolation region is formed on the recessed top surface of the substrate. The shallow trench isolation region is adjacent to the recessed sidewall of the source or drain.