Diffusion and recrystallization of B implanted in crystalline and pre-amorphized Ge in the presence of F

Abstract

Although the diffusion control and dopant activation of Ge p-type junctions are straightforward when using B+ implantation, the use of the heavier BF2+ ions or even BF+ is still favored in terms of shallow junction formation and throughput—because implants can be done at higher energies, which can give higher beam currents and beam stability—and thus the understanding of the effect of F co-doping becomes important. In this work, we have investigated diffusion and end-of-range (EOR) defect formation for B+, BF+, and BF2+ implants in crystalline and pre-amorphized Ge, employing rapid thermal annealing at 600 °C and 800 °C for 10 s. It is demonstrated that the diffusion of B is strongly influenced by the temperature, the presence of F, and the depth of amorphous/crystalline interface. The B and F diffusion profiles suggest the formation of B–F complexes and enhanced diffusion by interaction with point defects. In addition, the strong chemical effect of F is found only for B in Ge, while such an effect is vanishingly small for samples implanted with F alone, or co-implanted with P and F, as evidenced by the high residual F concentration in the B-doped samples after annealing. After 600 °C annealing for 10 s, interstitial-induced compressive strain was still observed in the EOR region for the sample implanted with BF+, as measured by X-ray diffraction. Further analysis by cross-sectional transmission electron microscopy showed that the {311} interstitial clusters are the majority type of EOR defects. The impact of these {311} defects on the electrical performance of Ge p+/n junctions formed by BF+ implantation was evaluated.

Hot Implantations of P into Ge: Impact on the Diffusion Profile

“…3b and 3c exhibit a significant broadening, especially at the negative ω-2 angles, indicate that the presence of EOR damage gives rise to local compressive stress (negative values). 9 In fact, similar results have recently been obtained for BF and BF 2 implanted Ge both as-implanted and after RTA, 36 where the presence of interstitial {311} clusters at the EOR was confirmed by cross-sectional Transmission Electron Microscopy (TEM). From the results in Fig.…”

“…Quite often, it is found that the EOR damage, consisting of interstitial clusters dissolves at rather low temperatures, i.e., below 400 to 450 • C. Co-implantation with N or F may stabilize this damage to some extent. [32][33][34] Also at the proximity of the surface, 36 the presence of a 10 nm SiO 2 capping layer and the annealing ambient play a role in stabilizing the EOR damage. Apparently, implantation at elevated substrate temperature results in the formation of rather stable self-interstitial clusters at the EOR.…”

Progress in Contact, Doping and Mobility Engineering of MoS2: An Atomically Thin 2D Semiconductor

“…In conventional CMOS technology, substitutional doping using ion implantation is the method of choice for controllably doping selected areas of the semiconductor wafer (either Si, Ge or III-Vs) to fabricate complementary FETs and realize complex circuits with desired performances. The ion implantation technique is also used to selectively and degenerately dope the S/D regions of the FET to realize Ohmic n-and p-type contacts for NMOS (i.e., n + -p-n + ) and PMOS (i.e., p + -n-p + ) device configurations, respectively, as well as to realize various bipolar devices, such as LEDs and photodetectors, for optoelectronic applications [207,[363][364][365][366][367][368][369][370][371][372][373][374][375]. The ion implantation process is known to induce surface damage and amorphization in the as-implanted semiconductor crystals which requires further annealing to "activate" the implanted dopants and to minimize residual damage [170,[376][377][378][379][380][381].…”