FOWLER-NORDHEIM TUNNELING INJECTION IN THE SI-SIO2 SYSTEM TREATED WITH ARGON PLASMA

The bulk positive charge in SiO2 layers (420-620 angstrom) generated by RF-soft Ar plasma has been studied by the high-field Fowler-Nordheim injection technique. It is proposed that the reduction in barrier height (0.4-0.5 eV) observed is a result of this plasma-created charge, which is located in the vicinity of the injecting gate electrode. Using both current-voltage and current-time characteristics, we present a new experimental method for determining the effective density of trapped charge. It has been found that after plasma treatment the trapped charge increases to a value of 5 x 10(11) cm-2 and 15 x 10(11) cm-2 for plasma exposure times of 5 and 20 min respectively. The charge centroid does not depend on the plasma exposure time or oxide thicknesses used. The plasma-generated positive charge is associated with the E' centres resulting from the plasma breaking of strained Si-O bonds.