Techniques are disclosed for forming integrated circuit structures having a plurality of non-planar transistors. An insulation structure is provided between channel, source, and drain regions of neighboring fins. The insulation structure is formed during back side processing, wherein at least a first portion of the isolation material between adjacent fins is recessed to expose a sub-channel portion of the semiconductor fins. A spacer material is then deposited at least on the exposed opposing sidewalls of the exposed sub-channel portion of each fin. The isolation material is then further recessed to form an air gap between gate, source, and drain regions of neighboring fins. The air gap electrically isolates the source/drain regions of one fin from the source/drain regions of an adjacent fin, and likewise isolates the gate region of the one fin from the gate region of the adjacent fin. The air gap can be filled with a dielectric material.