Joseph Ferrara

Optima XE Single Wafer High Energy Ion Implanter

The Optima XE is the first production worthy single wafer high energy implanter. The new system combines a state‐of‐art single wafer endstation capable of throughputs in excess of 400 wafers/hour with a production‐proven RF linear accelerator technology. Axcelis has been evolving and refining RF Linac technology since the introduction of the NV1000 in 1986. The Optima XE provides production worthy beam currents up to energies of 1.2 MeV for P+, 2.9 MeV for P++, and 1.5 MeV for B+. Energies as low as 10 keV and tilt angles as high as 45 degrees are also available., allowing the implanter to be used for a wide variety of traditional medium current implants to ensure high equipment utilization. The single wafer endstation provides precise implant angle control across wafer and wafer to wafer. In addition, Optima XE’s unique dose control system allows compensation of photoresist outgassing effects without relying on traditional pressure‐based methods. We describe the specific features, angle control and dosim...

Optimization of High‐Energy Implanter Beamline Pumping

A high‐energy implanter process chamber and its pumping configuration were designed to minimize the residual gas density in the endstation. A modified Nastran™ finite‐element analysis (FEA) code was used to calculate the pressure distribution and gas flow within the process chamber. The modified FE method was readily applied to the internal geometry of the scan chamber, the corrector magnet waveguide, and the process chamber, which included the scan arm assembly, 300mm wafer, and plasma electron flood gun (PEF). Using the modified Nastran code, the gas flow and pressure distribution within the beamline geometry were calculated. The gas load consisted of H2, which is generated by photoresist (PR) outgassing from the 300mm wafer, and Xe from the plasma electron flood gun. Several pumping configurations were assessed, with each consisting of various locations and pumping capacities of vacuum pumps. The pressure distribution results for each configuration are presented, along with pumping efficiency results w...