APPLICATIONS OF TECHNOLOGY:

• Semiconductor manufacturing
• Low- and medium-energy ion implantation
• Fusion plasma systems requiring neutral beam injection for fueling and current drive

ADVANTAGES:

• Plasma neutralizer not needed in ion implantation
• Works with existing low- and medium-energy implanters
• No beam blow up on low-energy beam transport
• No gas needed for mutual neutralization

ABSTRACT:

Berkeley Lab’s beam merging system, developed by Ka-Ngo Leung and fellow researchers, represents a technical advance over the use of either positive or negative ion beams for such applications as ion implantation or neutral beam injection into a fusion device.

For semiconductor manufacturing, the technology solves one of the fundamental issues in beam implantation of wafers. During the implantation process, when positively charged ions are implanted on the silicon wafer, the wafer surface is charged and must be compensated with a negative electron beam. In this invention, a merging positive and negative beam of the same species is highlighted. This allows an implantation of both the positive and negative ions. When the currents of these beams are the same, there is no need for complicated electron neutralization. Also, when the beam is mass analyzed for mass and isotope purity, both ions can be mass analyzed in the same dipole magnet structure by placing the ion source on two sides of the beam axis. Further, the beam’s own space charge is compensated by the simultaneous transport of positive and negative charge, allowing very efficient, low energy beam transport.

In this technology, positive and negative ions are extracted from two separate ion sources and passed through an electromagnet with symmetrical trajectories so that the beams merge as they leave the electromagnet. Berkeley Lab’s beam merging system allows for a high incidence of mutual neutralization of these positive and negative ions. This overcomes some of the standard technical limitations that cause beam blow up at low-energy beam transport in ion implantation and power loss due to the large amount of unneutralized beam in high-energy neutral beam formation.

STATUS:

• U.S. Patent #6,974,950. Available for licensing or collaborative research

REFERENCE NUMBER: IB-1732