Andrew Marlow Ray

Overview of the Eaton NV-8200P high beam purity, parallel scanning implanter

Eaton has developed a medium current ion implanter to meet the requirements of emerging advanced semiconductor processes. Hybrid scanning with a novel electrostatic scan angle correction lens is used to control beam incidence. To insure repeatability of processes requiring true beam incidence control, in-situ beam profiling and two axis divergence measurement provide input to the auto-tuning system. The direction of the mechanical axis of scan is always parallel to the wafer surface so that the distance from the wafer to the various optical elements is constant for all wafer tilt and twist combinations. This feature reduces variation in beam spot size and divergence across the surface of the wafer. Specific techniques for addressing all the various forms of beam and wafer contamination are also discussed. Two beam energy filters are utilized, including one immediately before the target, to maximize energy purity when multi-charged, decelerated, or molecular beam species are implanted. The vacuum system is designed to enhance beam purity and for ease of maintenance. The system provides useful beams over the energy range of 3 to 750 keV. The control system and ion source technology are based on that used in the companys high current implantation systems.

Channeling control for large tilt angle implantation in Si 〈100〉

Abstract This investigation will present measurements of silicon 〈100〉 wafers, implanted with tilt angles in the range 7–60°, which identify combinations of tilt and azimuthal (twist) angles that avoid major channeling zones. The orientations identified in this study minimize channeling effects even for very low dose implantation. A stereographic projection demonstrates that all major variations in observed channeling behavior are explained by channeling in the six major (low Miller index) crystallographic axes and planes. The implanted wafers were characterized using modulated reflectance and SIMS measurements. We investigated the relative severity of ion channeling in major poles and planes and the effect of energy and species variations on channeling behavior. The physical basis for the observed variations is explained by employing the concepts of critical channeling angles and average distance traveled within a channel.

Optima MDxt: A high throughput 335 keV mid-dose implanter

The continuing demand for both energy purity and implant angle control along with high wafer throughput drove the development of the Axcelis Optima MDxt mid-dose ion implanter. The system utilizes electrostatic scanning, an electrostatic parallelizing lens and an electrostatic energy filter to produce energetically pure beams with high angular integrity. Based on field proven components, the Optima MDxt beamline architecture offers the high beam currents possible with singly charged species including arsenic at energies up to 335 keV as well as large currents from multiply charged species at energies extending over 1 MeV. Conversely, the excellent energy filtering capability allows high currents at low beam energies, since it is safe to utilize large deceleration ratios. This beamline is coupled with the >500 WPH capable endstation technology used on the Axcelis Optima XEx high energy ion implanter. The endstation includes in-situ angle measurements of the beam in order to maintain excellent beam-to-wafer...