Productivity Enhancements for Shallow Junctions and DRAM Applications using Infusion Doping

Abstract

The inherent challenges for traditional ion implanters to deliver sufficiently high beam currents at sufficiently low energies required for shallow doping applications such as USJ and polysilicon doping for DRAM and has motivated the development of alternative methods for shallow doping. These include large molecule implantation, plasma doping and infusion doping with ionized gas clusters. Recent advancements in infusion doping have led to a very high flux (>100mA) of boron at low equivalent monomer implant energies (<1keV). In addition to producing uniquely high equivalent beam currents, the infusion process is physically distinct from implantation (beamline, molecular, or plasma) in the following important ways : (1) the doping depth is independent of species mass; (2) the doping depth is proportional to the one third power of the acceleration energy; (3) infusion doping is fully self‐amorphizing with no evidence of channeling or end of range (EOR) damage; (4) there is no evidence of any self‐sputtering behavior at any energy and no B build up on the surface even for very high doses (>5E16/cm2), and (5) the gas cluster beam operates at very low power requiring no wafer cooling and showing good compatibility with photo resist. In addition to discussing these differentiations, the manufacturability of the process will be discussed.