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Title: Microwave ECR plasma electron flood for low pressure wafer charge neutralization

Abstract

Modern ion implanters typically use dc arc discharge Plasma Electron Floods (PEFs) to neutralize wafer charge. The arc discharge requires using at least some refractory metal hardware, e.g. a thermionically emitting filament, which can be undesirable in applications where no metallic contamination is critical. rf discharge PEFs have been proposed to mitigate contamination risks but the gas flows required can result in high process chamber pressures. Axcelis has developed a microwave electron cyclotron resonance (ECR) PEF to provide refractory metals contamination-free wafer neutralization with low gas flow requirement. Our PEF uses a custom, reentrant cusp magnet field providing ECR and superior electron confinement. Stable PEF operation with extraction slits sized for 300 mm wafers can be attained at Xe gas flows lower than 0.2 sccm. Electron extraction currents can be as high as 20 mA at absorbed microwave powers < 70 W. On Axcelis' new medium current implanter, plasma generation has proven robust against pressure transients caused by, for example, photoresist outgassing by high power ion beams. Charge monitor and floating potential measurements along the wafer surface corroborate adequate wafer charge neutralization for low energy, high current ion beams.

Authors:
; ;  [1]
  1. Axcelis Technologies Inc., 108 Cherry Hill Drive, Beverly, MA 01915 (United States)
Publication Date:
OSTI Identifier:
22075719
Resource Type:
Journal Article
Journal Name:
AIP Conference Proceedings
Additional Journal Information:
Journal Volume: 1496; Journal Issue: 1; Conference: 19. international conference on ion implantation technology, Valladolid (Spain), 25-29 Jun 2012; Other Information: (c) 2012 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-243X
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; BEAM EXTRACTION; BEAM MONITORING; BEAM PRODUCTION; BEAM TRANSPORT; CUSPED GEOMETRIES; DEGASSING; ELECTRIC ARCS; ELECTRON CYCLOTRON-RESONANCE; ELECTRONS; HIGH-FREQUENCY DISCHARGES; ION BEAMS; ION IMPLANTATION; MICROWAVE RADIATION; PLASMA; PLASMA DIAGNOSTICS; PLASMA PRESSURE; PLASMA PRODUCTION; REFRACTORY METALS; XENON

Citation Formats

Vanderberg, Bo, Nakatsugawa, Tomoya, and Divergilio, William. Microwave ECR plasma electron flood for low pressure wafer charge neutralization. United States: N. p., 2012. Web. doi:10.1063/1.4766562.
Vanderberg, Bo, Nakatsugawa, Tomoya, & Divergilio, William. Microwave ECR plasma electron flood for low pressure wafer charge neutralization. United States. doi:10.1063/1.4766562.
Vanderberg, Bo, Nakatsugawa, Tomoya, and Divergilio, William. Tue . "Microwave ECR plasma electron flood for low pressure wafer charge neutralization". United States. doi:10.1063/1.4766562.
@article{osti_22075719,
title = {Microwave ECR plasma electron flood for low pressure wafer charge neutralization},
author = {Vanderberg, Bo and Nakatsugawa, Tomoya and Divergilio, William},
abstractNote = {Modern ion implanters typically use dc arc discharge Plasma Electron Floods (PEFs) to neutralize wafer charge. The arc discharge requires using at least some refractory metal hardware, e.g. a thermionically emitting filament, which can be undesirable in applications where no metallic contamination is critical. rf discharge PEFs have been proposed to mitigate contamination risks but the gas flows required can result in high process chamber pressures. Axcelis has developed a microwave electron cyclotron resonance (ECR) PEF to provide refractory metals contamination-free wafer neutralization with low gas flow requirement. Our PEF uses a custom, reentrant cusp magnet field providing ECR and superior electron confinement. Stable PEF operation with extraction slits sized for 300 mm wafers can be attained at Xe gas flows lower than 0.2 sccm. Electron extraction currents can be as high as 20 mA at absorbed microwave powers < 70 W. On Axcelis' new medium current implanter, plasma generation has proven robust against pressure transients caused by, for example, photoresist outgassing by high power ion beams. Charge monitor and floating potential measurements along the wafer surface corroborate adequate wafer charge neutralization for low energy, high current ion beams.},
doi = {10.1063/1.4766562},
journal = {AIP Conference Proceedings},
issn = {0094-243X},
number = 1,
volume = 1496,
place = {United States},
year = {2012},
month = {11}
}