grows silicon dioxide on not only silicon but also silicon nitride the growth rate is about 1 for single crystal silicon and 0 6 for silicon nitride issg oxide quality is such that the oxide breakdown voltage is better than that of cvd oxide a composite layer of oxide nitride oxide ono 223 231 222 is formed with issg oxidation the bottom oxide 222 in fig2 j is grown with issg to a thickness of between about 3 0 and 5 0 nm issg reduces bird 39 s beak under the edge of the memory word gate compared to conventional thermal oxide growth regardless of doped species or concentration issg grows the oxide on the cap nitride the oxide grown with issg on nitride isolates the cap nitride and the nitride of the ono composite layer pretreatment in nh 3 ambient gt 850 u00b0 c provides a uniform nitride thickness of the composite layer the silicon nitride layer 231 in fig2 j is deposited by chemical vapor deposition with a thickness of between about 6 and 9 nm the oxide layer oxidized by issg oxidizes the nitride by between about 3 and 5 nm the remaining nitride thickness of the composite layer is reduced to between about 3 and 6 nm after issg oxidation a memory control gate 242 in fig2 k is formed as a sidewall spacer of the memory word gate the control gate of this second embodiment is easier than the.