Low resistivity TiSi2 on narrow p+ polycrystalline silicon lines

We have achieved low resistivity TiSi2 on 0.25 mum wide polysilicon lines doped to 5x10(20)/cm(3) with boron by use of in situ doping of polysilicon. By controlling the Si deposition such that an amorphous undoped "cap" was deposited on p(+) polycrystalline Si (polysilicon) subsequently formed TiSi2 wires had a lower resistivity consistent with C54 phase formation, while maintaining direct contact between TiSi2 and p(+) Si. When TiSi2 was formed directly on p(+) polysilicon, it had increasing resistivity as the linewidth decreased below 0.5 mum. The mechanism for lower resistivity TiSi2 is attributed to an increased density of C49-to-C54 phase transformation sites when the silicide is formed on amorphous undoped silicon. (C) 2002 American Institute of Physics.