Effect of interface traps for ultra-thin high-k gate dielectric based MIS devices on the capacitance-voltage characteristics

The impact of states at the Al2O3/Si interface on the capacitance-voltage C-V characteristics of a metal/insulator/semiconductor heterostructure (MIS) capacitor was studied by a numerical simulation, by solving Schrodinger-Poisson equations and taking the electron emission rate from the interface state into account. Efficient computation and accurate physics based capacitance model of MOS devices with advanced ultra-thin equivalent oxide thickness (EOT) (down to 2.5 nm clearly considered here) were introduced for the near future integrated circuit IC technology nodes. Due to the importance of the interface state density for a low dimension and very low oxide thickness, a high frequency C-V model has been developed to interpret the effect of interface state density traps which communicate with the Al2O3/Si and their influence on the C-V characteristics. We found that these states are manifested by jumping capacity in the inversion zone, for a density of interface, higher than 1 × 1011 cm− 2 eV− 1 during a p-doping of 1 × 1018 cm− 3. This behavior has been investigated with various doping, temperature, frequency and energy levels on the C-V curves, and compared with the MIS structure that contains a standard SiO2 insulator.