Beamline pressure effect on ion beam transport in ion implanters

Ion implanters are one of the most flexible tools used in the manufacture of integrated circuits, with a wide range of chemistries, accelerating energies, implant angles and implant doses. Precision material engineering applications, often requiring implant doses 10-100x larger than the traditional doping steps, typically run at lower throughputs than other applications. To improve the productivity, we need to increase the beam current in ion implanters. One of the beam current loss mechanisms is the ion neutralization by collisions with the residual gas in the beamline. We have carefully measured this loss using controlled beamline pumping tests with some of the key ion species. Reducing the pressure in the beamline improves the beam transport by a different amount for different ion beam species. This learning can be used to engineer optimized vacuum systems for future tool developments and improvements.