EFFECT OF ANNEALING AND PLASMA PRECLEANING ON THE ELECTRICAL-PROPERTIES OF N2O SIH4 PECVD OXIDE AS GATE MATERIAL IN MOSFETS AND CCDS/

Pure SiH4 and N2O involving low total inflow of gases and very high de position rate (1400 angstrom/min) have been used to deposit PECVD oxid e films in a parallel-plate reactor system. The effect of long time (4 0 min) low temperature (450-degree-C) annealing in N2 ambient and plas ma precleaning with different gases like Ar, N2, H-2, O2, CF4/50% H-2 on the electrical properties of the deposited films have been studied. Flatband voltage, V(fb), fixed oxide charge density, D(f) interface t rap level density, D(it), dielectric breakdown strength, hysterisis an d bias stress stability are the properties studied. These properties a re relevant to the gate oxide in MOSFETs and CCDs. The deposited films involving annealing and plasma precleaning have been found to show el ectrical properties comparable to those of dry thermal oxide films gro wn at 1100-degrees-C. In particular films deposited on H-2 plasma prec leaned wafers showed no bias stress instability.