Test structure for determining boron diffusion coefficient in tungsten silicide

In order to study impurity diffusion in silicide, the authors patterned tungsten silicide into a line 2 mm long and 30 μm wide and selectively implanted boron into a 40-μm-long window. They modeled lateral diffusion profiles in this test structure and determined the diffusion coefficients of boron from SIMS (secondary ion mass spectrometry) line-scan profiles as 4.0×10^-10 cm² /s at 650°C, 9.5×10^-9 cm²/s at 800°C, and 2.0×10^-8 cm²/s at 900°C. This is more than 10⁶ times larger than that in silicon. The results obtained make it possible to design a thermal process for half-micron dual-gate CMOS