Fundamental drift of parameters in chalcogenide phase change memory

We present the data on temporal (t) drift of parameters in chalcogenide phase change memory that significantly complement the earlier published results. The threshold voltage V-th and the amorphous state resistance R are shown to drift as Delta V-th proportional to v ln t and R proportional to t(alpha) in broad intervals spanning up to nine decades in time; the drift coefficient v depends on glass parameters and temperature, but does not depend on device thickness. We have demonstrated that drift saturates at long enough times that can be shorten with temperature increase. All available data on drift dynamics are fully consistent with the classical double-well-potential model, which gives simple analytical expressions for the observed temporal dependencies including numerical parameters. (C) 2007 American Institute of Physics.