The present disclosure provides methods of semiconductor device fabrication for 3D devices. One method includes provide a substrate having a recess and forming a doping layer on the substrate and in the recess. The substrate is then annealed. The annealing drives dopants of a first type from the doping layer into the substrate. This can form a doped region that may be the source/drain extension of the 3D device. An epitaxial region is then grown in the recess. The epitaxial region can form the source/drain region of the 3D device.