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...http://www.google.com/patents/US6642102?utm_source=gb-gplus-sharePatent US6642102 - Barrier material encapsulation of programmable material
