Study of forming a p(+) poly-Si gate by inductively coupled nitrogen plasma nitridation of the stacked poly-Si layers

Formation of a p(+) poly-Si gate by using the stacked poly-Si layers that a re nitridized by using inductively coupled nitrogen plasma (ICNP) has been studied. The stacked poly-Si gate structure consists of three poly-Si layer s with thickness of 50, 50, and 100 nm, respectively. As for the control sa mples that do not receive nitrogen plasma nitridation, when they are anneal ed at 900 degrees C, the gate oxide integrity is significantly degraded and the flat-band voltage (V-fb) Shift is large, attributable to considerable boron penetration through gate oxide. If the ICNP treatment is directly don e with respect to the Sate oxide layer, the V-fb shift can be considerably reduced, but the resultant gate oxide integrity is even much worse than tha t for the control samples. However, for the specimens that sustain ICNP tre atment immediately after the deposition of the first poly-Si layer, the deg radation of Sate oxide integrity and the V-fb Shift are significantly allev iated even at 900 OC. Hence, the process scheme that employs the stacked po ly-Si gate nitridized by the ICNP treatment is highly available for forming a p(+) poly-Si gate. (C) 2000 American Vacuum Society.[S0734-211X(00)06504 -5].