Performance of a Focused-Ion-Beam Implanter with Tilt-Writing Function

An FIB implanter has been developed from a previous FIB lithography system design. Pattern writing with high registration accuracy is performed by a combination of beam-vector scanning and a step-and-repeat stage movement. In order to minimize the axial and planar channeling effects, the ion optical system can be tilted manually up to 7° without venting the workpiece chamber. To correct distortion, a high-speed distortion-correction unit was added. In addition, a sublens and a dynamic-focusing unit were also included for real-time focusing correction. Writing, stitching and overlay accuracies were evaluated by measuring vernier patterns. The stitching error was 0.178 µm (2σ) in the X axis and 0.161 µm (2σ) in the Y axis direction, while the overlay error was 0.170 µm (2σ) in the X-axis and 0.183 µm (2σ) in the Y-axis direction. Ion depth distribution from the implantation of focused Si ions has been measured. The coincidence in SIMS profiles was confirmed for FIBI and conventional ion implantation, when the ion-beam channeling is controlled.