Suppression of cobalt silicide agglomeration using nitrogen (N/sub 2//sup +/) implantation
In this paper, the effects of nitrogen coimplantation with boron into p/sup +/-poly gate in PMOSFETs on the agglomeration effects of CoSi/sub 2/ are studied. The thermal stability of CoSi/sub 2//poly-Si stacked layers can be significantly improved by using nitrogen implantation. Samples with 40-nm cobalt silicide (CoSi/sub 2/) on 210-nm poly-Si implanted by 2/spl times/10/sup 15//cm/sup 2/ N/sub 2//sup +/ are thermally stable above 950/spl deg/C for 30 s in N/sub 2/ ambient. If the dose of nitrogen is increased up to 6/spl times/10/sup 15//cm/sup 2/, the sheet resistance of CoSi/sub 2/ film is not increased at all, and TEM photographs show that the agglomeration of CoSi/sub 2/ film is completely suppressed.
Suppression of Boron Penetration in P+-Poly-Si Gate Metal-Oxide-Semiconductor Transistor Using Nitrogen Implantation
The mechanism and the optimization of nitrogen implantation for suppression the boron penetration in p+-poly-Si gate metal-oxide-semiconductor capacitor is reported. This nitrogen co-implantation process exhibits a good suppression of boron penetration and a better electrical characteristic than that of control sample. It was found that nitrogen combines with the boron to form a B-N complex, retarding the penetration of boron itself, was identified by XPS measurements. The optimum nitrogen dosage is also found in this study.
Interaction of metal layers with polycrystalline Si
Interactions of silicide films with undoped polycrystalline layers of Si grown by chemical vapor deposition at 630 °C were investigated by MeV He ion backscattering spectrometry, scanning electron microscopy, and transmission electron microscopy. For TiSi2, heat treatment in vacuum at temperatures above 850 °C results in erosion of the polycrystalline Si layer and growth of Si crystallites in the silicide film. The same phenomenon is observed for NiSi, Pd2Si, and CrSi2 at temperatures above one‐half of melting point of the corresponding silicide.