Boron ion implantation in silicon through selectively deposited tungsten films

The effect of implanting boron into silicon through thin selective tungsten films and annealing to form silicided p
⁺
-n junctions is investigated. A rate limited thickness of 0.011-µm tungsten is shown to have the equivalent stopping power of 0.08-µm oxide and be similarly ineffective in eliminating axial boron channeling. Nonetheless, junction diodes as shallow as 0.25µm with sheet resistances of 7 Ω, exhibiting nearly ideal
I-V
characteristics from -40 to 100°C, are fabricated. Analysis of the areal and perimeter leakage currents suggests that defects at the WSi
2
-SiO
2
interface are the contributing generation-recombination sites.