Semiconductor devices and methods for making the same includes conformally forming a first spacer on a plurality of fins. A second spacer is conformally formed on the first spacer, the second spacer being formed from a different material from the first spacer. The plurality of fins are etched below a bottom level of the first spacer to form a fin cavity. Material from the first spacer is removed to expand the fin cavity. Fin material is grown directly on the etched plurality of fins to fill the fin cavity.