Methods of forming metal-doped chalcogenide layers and devices containing such doped chalcogenide layers include using a plasma to induce diffusion of metal into a chalcogenide layer concurrently with metal deposition. The plasma contains at least one noble gas of low atomic weight, such as neon or helium. The plasma has a sputter yield sufficient to sputter a metal target and a UV component of its emitted spectrum sufficient to induce diffusion of the sputtered metal into the chalcogenide layer. Using such methods, a conductive layer can be formed on the doped chalcogenide layer in situ. In integrated circuit devices, such as non-volatile chalcogenide memory devices, doping of the chalcogenide layer concurrently with metal deposition and formation of a conductive layer in situ with the doping of the chalcogenide layer reduces contamination concerns and physical damage resulting from moving the device substrate from tool to tool, thus facilitating improved device reliability.

Integrated circuit device and fabrication using metal-doped chalcogenide materials

We present a topological model for the composition dependence of glass transition temperature and fragility. Whereas previous topological models are derived for zero temperature conditions, our approach incorporates the concept of temperature-dependent constraints that freeze in as the system is cooled from high temperature. Combining this notion of temperature-dependent constraints with the Adam-Gibbs model of viscosity, we derive an analytical expression for the scaling of glass transition temperature and fragility in the binary Ge(x)Se(1-x) system. In the range of 0<or=x<or=1/3, we reproduce the modified Gibbs-DiMarzio equation of Sreeram et al. [J. Non-Cryst. Solids 127, 287 (1991)] but without any empirical fitting parameters. The modified Gibbs-DiMarzio equation breaks down for 1/3<x<or=2/5, where the glass transition temperature decreases with increasing germanium content.

Composition dependence of glass transition temperature and fragility. I. A topological model incorporating temperature-dependent constraints.

Ge-Se chalcogenide glasses are characterized by relatively low hardness (0.39-2.35 GPa) and low fracture toughness (0.1-0.28 MPa.m 1/2 ). Actually, the hardness of chalcogen-rich glasses is low enough so that the brittleness parameter, B = H/K c , is lower than that of silicate glasses. Whereas hardness and Young's modulus increase with increasing germanium contents, fracture toughness follows a trend similar to that of the density and exhibits a maximum for the Ge 20 Se 80 composition, which corresponds to the rigidity percolation threshold. Optical microscopy and atomic force microscopy observations suggest that the indentation deformation proceeds by a localized shear deformation phenomenon. Glasses in the chalcogen-rich region behave viscoelastically at room temperature. As a consequence, an increase of the loading time results in a decrease of hardness and toughness.

Hardness, Toughness, and Scratchability of Germanium–Selenium Chalcogenide Glasses

An inverted PCRAM cell is formed by plating the bottom electrode, made of copper for example, with a conductive material, such as silver. Chalcogenide material is disposed over the plated electrode and subjected to a conversion process so that ions from the plated material diffuse into the chalcogenide material.

PCRAM memory cell and method of making same

A method and apparatus is disclosed for sensing the resistance state of a Programmable Conductor Random Access Memory (PCRAM) element using complementary PCRAM elements, one holding the resistance state being sensed and the other holding a complementary resistance state. A sense amplifier detects voltages discharging through the high and low resistance elements to determine the resistance state of an element being read.

Complementary bit PCRAM sense amplifier and method of operation

Chalcogenide glasses from the Ge–Se system behave viscoelastically at room temperature. It follows that indentation measurements are time- or rate-dependent. The study of the dependence of hardness ( H ) on the loading duration for Ge x Se 1− x glasses with x between 0 and 0.4 shows that the penetration displacement is the sum of an elastic component which reaches values as high as 60% of the total displacement, and a creep one, which is strongly non-Newtonian (shear thinning), and leads to a significant decrease of H with an increase of the loading time. The apparent viscosity and activation energy for flow were derived from the H ( t ) data on the basis of a theoretical analysis of the indentation process, and the results are in good agreement with those obtained from conventional viscosity measurements.

Ingrid Serre

Papers

Indentation creep of Ge–Se chalcogenide glasses below Tg: elastic recovery and non-Newtonian flow