NUMERICAL ANALYSIS METHOD OF PROGRAM THRESHOLD VOLTAGE OF SONOS MEMORY DEVICE

摘要

PURPOSE: A numerical analysis method of a program threshold voltage of a SONOS(silicon-oxide-nitride-oxide-silicon) memory device is provided to obtain a more precise simulation value of a program threshold voltage by using a numerical analysis method using variables of the program threshold voltage such as a trap probability, tunneling current and a Poole-Frenkel emission density. CONSTITUTION: The electric field value of a tunnel oxide layer is obtained at the present time and at the previous time. Assuming that a trap probability, tunneling current and a Poole-Frenkel emission density of a trap hole in a nitride layer are the same, a difference of an electric field value of a tunnel oxide layer between at the present time and at the previous time is calculated. An operation formula is obtained in which the electric filed of the tunnel oxide layer at the present time is the electric field of the tunnel oxide layer at the previous time from which the trap probability, a modified F/N(Fowler Nordheim) tunneling current, a trap assisted tunneling current and the Poole-Frenkel emission density are subtracted. The quantity of variation of a SONOS program threshold voltage at the present time is obtained by using the electric fields of the tunnel oxide layer at the present time and at the previous time. A final threshold voltage is obtained by using the quantity of the variation of the program threshold voltage at the present time.