Overview of the Eaten 8250 medium current implanter

Eaton has developed a second generation parallel scanning medium current implanter. This implanter accomplishes hybrid scanning using a novel electrostatic scan angle correction lens to produce parallel beams. Semi-empirical modeling of the scanning and lens system has enabled design of a transport system capable of beam parallelism better than +/-0.2 degrees at the wafer. The plane of mechanical scanning is coincident with the plane of the wafer so that the distance between the wafer and all optical elements is constant for all wafer tilt and twist combinations. This implanter incorporates an extended life ion source using an indirectly heated cathode for longer source life and higher multiple charged beam currents. Beam stability is enhanced using a thermally stable ion source and extraction elements, and a field-stabilized analyzing magnet. Dosimetry is based on robust measurements of beam flux at the plane of the wafer. Other features, such as an electrostatic clamp, an improved wafer load lock, and a powerful statistical process control package are discussed. Performance to date is presented