Ultra-shallow Junction Formed by Plasma Doping and Laser Annealing
We investigated ultra-shallow junction prepared by plasma doping (PLAD) and laser annealing (LA). Although PLAD is promising doping technology for the sub-45nm technology node due to the high dose rate at low energy, it has problems which is related with hydrogen or fluorine. The implanted hydrogen generally increases damage in the Si substrate. The fluorine also retards dopant activation and increases dopant deactivation during post-annealing step. Conventional one step annealing processes such as rapid thermal annealing (RTA) or excimer laser annealing (LA) are not effective method for high dopant activation. To minimize the effect of hydrogen or fluorine, we propose additional pre-annealing followed by conventional laser annealing. By employing low temperature pre-annealing, we can improve electrical characteristics such as low sheet resistance, high activation rates, shallow junction depth and reduced dopant deactivation. The improvement can be explained by reduced defect density and out-diffusion of fluorine or hydrogen which in turn enhances dopant activation during ELA
Damage in hydrogen plasma implanted silicon
The damage and defects created in silicon by hydrogen plasma immersion ion implantation (PIII) are not the same as those generated by conventional beamline ion implantation due to the difference in the ion energy distribution and lack of mass selection in PIII. Defect generation must be well controlled because damage in the implanted and surface zones can easily translate into defects in the silicon-on-insulator structures synthesized by the PIII/wafer bonding/ion-cut process. The defect formation and its change with annealing temperature were investigated experimentally employing channeling Rutherford backscattering spectrometry, secondary ion mass spectrometry, and atomic-force microscopy. We also calculated the damage energy density of the three dominant hydrogen species in the plasma (H+, H2+, and H3+) as well as displacement of silicon atoms in the silicon wafer. H2+ creates the most damage because its damage energy density is very close to the silicon threshold energy. The effects of atmospheric gas...
Thinner Silicon-on-Insulator Using Plasma Hydrogenation
We describe for the first time delamination of a single crystalline silicon film from a substrate caused by the formation of a hydrogen layer under the surface due to dc plasma hydrogenation of a trap layer. The process involves first forming a buried trap layer by implanting ions of gases in doses of 1×1015 cm-2 to 4×1016 cm-2, and then hydrogenating with a dc plasma. Following thermal annealing, delamination occurs with a depth corresponding to the maximum of vacancy-enriched defects (about Rp/2) for the lowest implantation doses and up to Rp for the high implantation doses. This process may be used as a step in the process of fabricating thin silicon-on-insulator (SOI) wafers. The authors suggest that vacancy clusters at Rp/2 serve as nuclei of hydrogen platelets that continue to grow under hydrogenation and act as infinite-capacity traps for hydrogen.