Effect of Asymmetric Channel on Charging Behavior of 22-nm Quantum-Dot Floating-Gate Flash Memory Cell

The need of high density, high speed, and reliable memories is leading toward the development of new approaches such as quantum-dot floating gates (QDFGs), use of high- $k$ dielectrics as tunneling/control gate oxides, and metal-gate technology. QDFG 22-nm Flash memory cells based on these new approaches are investigated through process and device simulations using Synopsys Technology Computer-Aided Design tools. Hafnium oxide is used as both tunneling and control gate oxides along with the metal control gate. As a solution to the nonuniform charging of QDFGs in these structures, asymmetric doping of the channel region is proposed. The effect of asymmetric channel doping on the charging behavior of QDFGs is studied, and the device characteristics are compared with symmetric channel counterpart. The simulation results confirm that the asymmetric channel device is faster in terms of programming and erasing time than the symmetric channel device.