A method of forming isolation pillars for a gate structure, the method including: providing a preliminary structure including a substrate having a plurality of fins thereon, an STI formed between adjacent fins, an upper surface of the STIs extending higher than an upper surface of the fins, and a hardmask over the upper surface of the fins and between adjacent STIs; forming a first trench in a first selected STI and between adjacent fins in a gate region, and forming a second trench in a second selected STI and between adjacent fins in a TS region; and filling the first and second trenches with an isolation fill thereby forming a first isolation pillar in the gate region and a second isolation pillar in the TS region, the first and second isolation pillars extending below the upper surface of the STIs.