Effects of pre- or post-bombardment by neon, argon, and silicon ions on boron-implanted resistors

MOS ion-implanted integrated circuits such as 10-MHz shift registers and 100-ns read-only memories are now being fabricated using boron as the implanted species. The sheet resistivity of boron-implanted layers, given a certain dose and energy, is determined by the anneal temperature cycle, which must be compatible with the metallization process used. Typically, at 545°C (compatible with an aluminum metallization process) about 10% of the implanted boron ions are electrically active, giving, for a dose of 10¹⁴/cm²at an energy of 80 keV, a sheet resistivity of about 2.5 kilohms/ square. However, if before or after the boron implantation one implants inert ions such as neon, one can observe drastically different sheet resistivities for the same anneal temperatures. This is probably caused by the introduction of supplementary damage by the second implant. If the neon dose is low ( /cm²), The sheet resistivity will be increased. If it is high ( /cm²), an amorphous layer is created that can lower the sheet resistivity as was previously observed by other workers. The possible applications of these effects on ion-implanted integrated-circuit technology will be discussed as well as similar observations made by pre- or post-bombardment with other inert ions such as argon or silicon.