Effect of Polysilicon Doping and Oxidation Conditions on Tunnel Oxide Performance For EEPROM Devices

Dielectric reliability is of critical importance in the manufacture of double polysilicon floating gate EEPROM devices.This paper reports the effect of different polysilicon oxidation and doping conditions on the properties of both the inter-poly oxide and the tunnel oxide. The paper shows that increasing the polysilicon oxidation temperature results in an improvement in inter-poly oxide breakdown field. However, it also causes a reduction of the charge to breakdown and increased charge trapping in the tunnel oxide. The paper also shows that the use of implanted polysilicon rather than POCI₃ furnace doped polysilicon, improves the intrinsic Qbd of the tunnel oxides but leads to an increase in the number of early failures.