1. A method comprising: forming as stacked materials on a substrate, a volume of programmable material and a signal line; conformably forming a first dielectric material on the stacked materials; forming a second dielectric material on the first material; etching an opening in the second dielectric material with an etchant that, between the first dielectric material and the second dielectric material, favors removal of the second dielectric material; and forming a contact in the opening to the stacked materials.