Accurate dose matching measurements between different ion implanters

After a new ion implanter installation is complete, one of the first duties of the process engineer is to verify that the implant doses from selected recipes on the new system are matched to the existing systems in the same fab-or separate fab. The vast majority of end users frequently set a dose scalar (or "compensation"), simply changing the dose calculation within the control system, This effectively changes the total delivered number of dopant ions to an otherwise fired area. Some critical implanter and measurement criteria are often overlooked during this key process step. There are several major factors within the implanter, as well as factors related to post-implant process measurement, which can very readily create misleading sheet resistance and thermal wave results. This paper will present major factors which have been shown to create subtle to substantial-and in some cases, surprising dose shifts in implant situations where the actual number of ions per unit area was quite accurate. These factors include thermal wave measurement sensitivity, sheet resistance measurement sensitivity, beam current, and beam current duty cycle.