A method for forming a semiconductor device, the method comprising: forming a fin cut mask above a semiconductor fin structure extending horizontally along a substrate, the fin structure comprising lower and upper channel layers (12, 16) separated by an intermediate layer, wherein the fin cut mask covers the fin structure in a channel region and exposes the fin structure in fin cut regions on opposite sides of the channel region, forming preliminary fin cuts in the fin structure by partially etching through the fin structure in the fin cut regions, wherein the partial etching extends through the upper layer in the fin cut regions to define an upper channel layer portion in the channel region, forming a sacrificial spacer covering end surfaces of the upper channel layer portion which are exposed in the fin cut regions on opposite sides of the channel region, subsequent to forming the sacrificial spacer, forming final fin cuts in the fin structure by further etching through the fin structure in the fin cut regions, wherein the further etching extends into the lower layer in the fin cut regions to define a lower channel layer portion in the channel region, subsequent to forming the final fin cuts, forming epitaxial lower source/drain regions on end surfaces of the lower channel layer portion which are exposed in the fin cut regions on opposite sides of the channel region, subsequent to forming the epitaxial lower source/drain regions, removing the sacrificial spacer, thereby exposing the end surfaces of the upper channel layer portion, and subsequent to removing the sacrificial spacer, forming epitaxial upper source/drain regions on the end surfaces of the upper channel layer portion. forming a fin cut mask above a semiconductor fin structure extending horizontally along a substrate, the fin structure comprising lower and upper channel layers (12, 16) separated by an intermediate layer, wherein the fin cut mask covers the fin structure in a channel region and exposes the fin structure in fin cut regions on opposite sides of the channel region, forming preliminary fin cuts in the fin structure by partially etching through the fin structure in the fin cut regions, wherein the partial etching extends through the upper layer in the fin cut regions to define an upper channel layer portion in the channel region, forming a sacrificial spacer covering end surfaces of the upper channel layer portion which are exposed in the fin cut regions on opposite sides of the channel region, subsequent to forming the sacrificial spacer, forming final fin cuts in the fin structure by further etching through the fin structure in the fin cut regions, wherein the further etching extends into the lower layer in the fin cut regions to define a lower channel layer portion in the channel region, subsequent to forming the final fin cuts, forming epitaxial lower source/drain regions on end surfaces of the lower channel layer portion which are exposed in the fin cut regions on opposite sides of the channel region, subsequent to forming the epitaxial lower source/drain regions, removing the sacrificial spacer, thereby exposing the end surfaces of the upper channel layer portion, and subsequent to removing the sacrificial spacer, forming epitaxial upper source/drain regions on the end surfaces of the upper channel layer portion.