Brian S. Freer

Germanium operation on the GSDIII/LED and ultra high current ion implanters

Germanium is typically used in ultra-shallow junction formation as an amorphization implant to reduce channeling in subsequent low energy boron dopant implants. Several equipment and process considerations can be associated with germanium operation. For example, source life may be adversely affected due to the cycling of refractory metal fluorides from materials used in the arc chamber, and cross-contamination, especially implanted As, may occur on machines that run multiple species. Tool productivity also depends on beam current and beam setup time due to the relatively high doses and low energies required. A number of design and operational improvements have been implemented on the GSDIII/LED and Ultra to address these concerns. Hardware and tuning algorithms for germanium operation are described. Data showing improved source lifetime and low species cross-contamination are presented Strategies for achieving productivity, flexibility, and cycle time improvements, including mixed species operation and germanium-boron chaining, are discussed.

Low-Energy Ion Implantation Using the Arsenic Dimer Ion: Process Characterization and Throughput Improvement

Low-energy arsenic implants used in the formation of ultrashallow junctions are characterized on a high current ion implanter. Significant advantages in beam current and process throughput are demonstrated by using the arsenic dimer ion (As + 2 ) for implant energies lower than 5 keV. Dimer implants require only half the dose and use twice the energy of equivalent As+ implants, resulting in significantly reduced implant times. Process results including Thermawave (TW), sheet resistance (R s ), secondary ion mass spectrometry (SIMS) profiles, electrical test and yield show equivalence between As + and As + 2 implants.