Characteristics of shallow p+-n junctions formed by low-energy ion implantation and dual-step annealing processes

Preamorphization, low-energy boron-ion implantation, and dual-step annealing processes were employed for the formation of shallow p(+)-n junctions. Germanium preamorphization was performed for a group of silicon substrates. Boron, the most commonly used p-type dopant, was implanted at an energy of 2 keV and a dose of 2 x 10(15) cm(-2) into both preamorphized and non-preamorphized wafers. Dual-step annealing was used to activate implanted ions and to annihilate implantation defects. Furnace annealing (FA) was performed at 850 degreesC for 10 minutes, and rapid thermal annealing (RTA) was performed at two temperatures of 750 degreesC and 1000 degreesC for a total of 10 seconds at each temperature, The junction depth, the sheet resistance, and the leak-age current were measured to characterize the junction properties. The FA + RTA annealing sequence produced better junction properties than the RTA + FA thermal cycle.