A method of forming a fin field effect transistor device is provided. The method includes forming a vertical fin on a substrate, and depositing a sidewall liner on exposed surfaces of the vertical fin. The method further includes removing a portion of the substrate below the sidewall liner to form a support pillar below the vertical fin. The method further includes laterally etching the support pillar to form a thinned support pillar, and forming a bottom source/drain layer on the substrate and the thinned support pillar, wherein the bottom source/drain layer has a non-uniform thickness.