Ion Implantation and Synthesis of Materials - Studium

15.2 Implanters Used in CMOS Processing 221Fig. 15.4. High energy beamline featuring an RF linac with 12 resonators. The ion sourceand analyzer magnets are on the left. The final energy magnet is on the rightdouble or triple charge states in a second charge exchange cell. Typical beam sizesand overall beamline length are comparable to the linac-based beamline.15.2.2 Other SubsystemsThe effective generation and transport of ion beams is the raison d’etre of ionimplanters, but working machines in wafer factories require a variety of othertechnologies.Wafer HandlingBecause ion implanters are high-throughput, high-vacuum systems, waferhandling is rather unique and has been an area of proprietary technologydevelopment. Mechanical throughput has been on the order of 200 wafers per hour(wph) for many years, and recently throughput has increased to more than300 wph on new machines. Complex robotics are needed to automatically removewafers from cassettes or pods (in the case of 300 mm), orient them to ensurecorrect twist angle, transfer them to high vacuum (usually through a load-lockmechanism) and then to a spinning disk or electrostatic platen for implantation.Parallel operations minimize wafer-handling overhead in order to increase thefraction of time spent implanting.