A method is described for isotropic or nearly isotropic shallow doping of a non-planar surface exposed in a void. The results of ion implantation, a common doping method, are inherently planar. Some fabrication methods and devices may require doping a surface of a non-planar feature exposed in a void, such as a trench. The feature is doped by flowing a gas which will provide the dopant over the exposed surfaces, or by exposing the surfaces to a plasma including the dopant. The feature may be a patterned feature, including a top surface and a sidewall. In a preferred embodiment, a semiconductor feature having a top surface and a sidewall is exposed in a trench formed in a dielectric, and a gas providing a p-type or n-type dopant is flowed in the trench, providing a p-type or n-type dopant to the semiconductor.