Junction depth versus sheet resistivity in BF2+-implanted rapid-thermal-annealed silicon

Conditions to achieve shallow p+-junctions with low sheet resistance by using ion implantation and rapid thermal annealing (RTA), are presented. This work shows that (junction depth) × (sheet resistivity)\rho_{s}X_{j}has a smaller value with increasing implant dose and anneal temperature (boron solubility), and decreasing implant energy. However, the value is saturated for higher doses than 10¹⁶Xjcm², where Xjis junction depth in micrometers, and anneal temperature should be lower than 1100°C, because of considerable boron diffusion even in 10-s RTA.\rho_{s}X_{j} = 18Ω.µm is achieved by BF2+ implantation with 5 × 10¹⁵-cm^-2dose at 30 keV and 1000°C RTA. The possibility of further improvement in\rho_{s}X_{j}value is discussed.