Method of Beam Energy Adjustment by Using Beam Parallelism

As the market for high quality image sensors expands so has the importance of ultra-high energy ion implant. Critical implanter features include beam energy adjustment and precise beam angle control. For implant energy exceeding several MeV, only a few percent error produces several tens of keV energy difference, which means the implant depth varies several tens of nm. Sumitomo Heavy Industries Ion Technology's single wafer ultra-high energy ion implanter, the S-UHE, has an RF linear accelerator with eighteen-stage resonators to achieve beam energy up to 6.8 MeV. The S-UHE has an electro static parallelizing lens (P-lens) to generate a parallel beam from a scanned beam. The P-lens voltage can be calibrated using DC extracted beam. When an RF accelerated beam passes through the P-lens and the beam is not completely parallel using calibrated P-lens voltage, the beam energy is different from the target energy. Additionally, we can calculate exact beam energy from the measured parallelism. Given this relationship, the beam energy can be adjusted to the target energy by tuning the resonators to achieve <;1% accuracy.