Analysis and Experimentation on FIMOS (n-channel FAMOS) Devices

Non-volatile nature of FIMOS (Floating gate Ionization-injection MOS) memory is based on the storage of electrons in the floating gate. This paper analyzes the electron injection efficiency in terms of the impact ionization rate and the peak electric field in the channel. The latter is related to the device parameters such as the acceptor concentration in the channel and the oxide thicknesses. Threshold voltage shifts due to the electron injection were measured on experimental units with varied device parameters under various programming conditions. Qualitative agreements were obtained between the theoretical prediction and experimental results. Thus, the injection model should prove useful in the design of better memory devices.