Temperature dependent universal mobility modeling and ECR plasma nitridation of Si for fast EEPROM

Abstract

Semi-empirical hole and electron mobility models with the temperature dependence have been proposed for the circuit simulation as well as for the process characterization. These models are based on the universal dependence of low field mobility on the effective transverse field and cover a wide range of oxide thickness as well as of temperature. The number of process-dependent parameters are minimized in our models. For holes, ours has four parameters, out of which three are technology independent. For electrons, it has five model parameters, out of which four are technology independent. Only one parameter for each model needs to be extracted depending on the process technology. The accuracy of our models is justified by comparing them with many experimental works reported in the literature as well as obtained in our laboratory. They are accurate and physical enough to be suited for the circuit simulation of modern VLSI CMOS circuit with the gate oxide thickness less then 400$\AA$ in the temperature range of 250-400 K. ECR-nitride tunneling insulator has been proposed for low-voltage alterable EEPROM. ECR nitride shows higher growth rate than the thermal nitride. The higher growth rate at relatively low temperature compared with the thermal nitridation, enables to avoid the high temperature process. And, it should be noted that it shows the linear growth rate with the nitridation time without self-limit behavior of the thermal nitridation. We have fabricated EEPROM with ECR-nitride tunneling insulator and investigated its electrical characteristics including the data retention and endurance. As expected, it shows low-voltage alterable characteristics. Particularly, the erasing voltage can be significantly diminished below 10 V. For the constant current stress, ECR nitride shows the hole trapping characteristic, which is different with the electron trapping at the thermal oxide. Surprisingly, the trapping rate is smaller than the thermal oxide for both polari...