Modeling and Characterization of Hydrogen-Induced Charge Loss in Nitride-Trapping Memory

This paper studies hydrogen diffusion in nitride-based Flash memory. Distorted capacitance-voltage ( C-V) curves were obtained when the programmed devices were baked in an environment of hydrogen at a temperature of 400 degC. Hydrogen may invade the edge of the device. The effectively trapped electrons were eliminated by the invading hydrogen. Elimination is responsible for a nonuniform distribution of charges in capacitors and contributes to the distortion of C-V curves. The distorted C-V curve can be accurately simulated by superposing only two subcapacitors with appropriate area ratios. The hydrogen-invasion depth can also be calculated from the ratio of the subcapacitances. The hydrogen diffusion length decreased as the number of programmed electrons increased. Hydrogen invasion is modeled as a diffusion-limited process