Methods for creating uniform source/drain cavities filled with uniform levels of materials in an IC device and resulting devices are disclosed. Embodiments include forming a hard mask on an upper surface of a Si substrate, the hard mask having an opening over a STI region formed in the Si substrate and extending over adjacent portions of the Si substrate; forming low-k dielectric spacers on a lower portion of sidewalls of the opening, the spacers being formed between the sidewalls and the STI region; filling the opening with an oxide; removing the hard mask; removing an upper portion of the oxide and a portion of the low-k dielectric spacers; revealing a Si fin in the Si substrate; forming equally spaced gate electrodes, each having sidewall spacers, over the Si fin and the oxide; and forming source/drain regions in the Si fin between each pair of adjacent gate electrodes.