Methods of forming semiconductor devices, memory cells, and arrays of memory cells include forming a liner on a conductive material and exposing the liner to a radical oxidation process to densify the liner. The densified liner may protect the conductive material from substantial degradation or damage during a subsequent patterning process. A semiconductor device structure, according to embodiments of the disclosure, includes features extending from a substrate and spaced by a trench exposing a portion of a substrate. A liner is disposed on sidewalls of a region of at least one conductive material in each feature. A semiconductor device, according to embodiments of the disclosure, includes memory cells, each comprising a control gate region and a capping region with substantially aligning sidewalls and a charge structure under the control gate region.