Activation of boron and recrystallization in Ge preamorphization implant structure of ultra shallow junctions by microwave annealing

In this study, high-current and low-energy (400 eV) ion implantation and low-temperature microwave annealing were employed to achieve ultra shallow junctions. To use the characteristic of microwave annealing more effectively, two-step microwave annealing was also employed. In the first step annealing, a high-power (2400 W; ∼500 °C) microwave was used to achieve solid-state epitaxial regrowth (SPER) and enhance microwave absorption. In the second step of annealing, unlike in conventional thermal annealing, which requires a higher energy to activate the dopant, a 600W (∼250 °C) microwave was used to achieve low sheet resistance. The device subjected to two-step microwave annealing at 2400W for 300 s + 600W for 600 s has the lowest Vth. It also has the lowest subthreshold swing (SS), which means that it has the highest cap ability to control sub threshold current. In these three devices, the largest I_on/I_off ratio is 2.203 × 10⁶, and the smallest I_on/I_off ratio is 2.024 × 10⁶.