| AVS 63rd International Symposium & Exhibition | |
| Thin Film | Wednesday Sessions |
| Session TF+EM+MI-WeA |
| Session: | Thin Films for Microelectronics |
| Presenter: | David Adams, Sandia National Laboratories |
| Authors: | D.P. Adams, Sandia National Laboratories K. Childs, Sandia National Laboratories T. Gurrieri, Sandia National Laboratories W. Rice, Sandia National Laboratories |
| Correspondent: | Click to Email |
Different forms of carbon-doped Ge2Sb2Te5 chalcogenide thin films have been evaluated for potential use in phase change memory and thermal sensor applications. This includes films sputter deposited from single, carbon-doped targets and refined multilayers made by sequential deposition of chalcogenideand C layers. In both forms, the crystallization temperature (Tcryt) and the resistance change through crystallization vary with carbon content. Doped chalcogenide films sputter deposited from single targets exhibit increased Tcryt as the concentration of C is made larger. For example, films having ~7 at.% C exhibit a Tcryt that is approximately one hundred and fifteen degrees above that of undoped Ge2Sb2Te5. Films with reduced C content, in the range 1-6 at.%, show intermediate crystallization temperatures. Multilayers fabricated by the sequential deposition of thin chalcogenideand C layers behave much like films grown from single targets, provided that multilayer periodicity is made small, < 3 nm. The crystallization temperature of multilayers also increases with C concentration and a prompt transition to a crystalline phase is observed when the carbon content is low. Interestingly, multilayers made with > 9 at.% C do not transition abruptly to a crystalline state. Instead, a transformation occurs over a broad range of elevated temperature. Each form of chalcogenide thin film exhibits a decreased resistivity upon crystallization. In most cases, resistivity is reduced by 5 decades upon transforming to a face centered cubic structure or a subsequent hexagonal close packed lattice at higher temperature. The changes to microstructure and thickness associated with phase change will also be described. These film properties are investigated by cross-section and plan view electron microscopy.
This work was supported by Sandia National Laboratories. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the United States Department of Energy’s National Nuclear Security Administration under Contract DE-AC04-94AL85000.