A New Method for Boron Doping of Silicon by Implantation of BF2-Molecules
The annealing behavior of variable dose implants of BF2 molecules has been studied in comparison to boron implants. In the case of a 1015 cm-2 room temperature BF2 implantation the annealing data indicate that an amorphous layer was formed; the sheet resistivity after 650°C anneal is a factor of 10 lower than for an equivalent energy boron implant and the samples are nearly completely annealed. For doses of ⩽1014 cm-2 there is no marked difference in the annealing of BF2 and boron implants. These results were compared to the annealing of predamaged samples and cold implants which show lower electrical activity. Studies of range distributions and electrical profiles were performed by He-backscattering and successive layer removal techniques and show close agreement with theoretical considerations. From the electrical point of view there is no evident influence of the fluorine component of the molecule. C-V measurements were taken to determine the BF2 behavior in SiO2. It is shown that surface states are annealed out at 400°C.
KeywordsSheet Resistance Amorphous Layer Annealing Behavior Sheet Resistivity Reverse Annealing
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