Process transferability from a spot beam to a ribbon beam implanter: CMOS device matching

The exercise of dose and energy matching is the standard way to integrate a new implanter into a manufacturing fab. Sheet resistance and secondary-ion mass spectroscopy (SIMS) measurements on bare silicon wafers have been the conventional metrologies to establish dose/energy equivalence between implanters. Invariably, matched performance on bare silicon wafers translated into matched device performance between implanters of the same kind. However, as devices scale down to 90 nm and beyond, the implanter design can become a significant factor in terms of process matching. In this paper we discuss the dynamics of transferring 120-90nm logic processes from a traditional batch, spot beam implanter to a single wafer (SW), parallel ribbon beam implanter. The results show that the traditional approach to dose matching involving the basic parameters of specie, dose and energy, although necessary, is inadequate to provide matched device performance between the two implanter types. 3-dimensional effects which cannot be represented by bare silicon wafers necessitate the use of device wafers to meet the target requirements.