Larger Area of Coverage Balanced Ion Long Life No Overshoot No Particulates or Air Flow No Cleaning or Maintenance No Ozone Generation No EM Noise Not Limited to Line of Site No High E Fields Required Distance: 1.1m Diameter: 1.6m Cross Sectional Area: 1.2m 2 Volume: 1.3m 3 Carbon (2.26 g/cm 2 ) 1mm – 10mm thick Transmission (%) Silicon (2.33 g/cm 2 ) 0.5mm – 0.75mm thick http://www.engineeringtoolbox.com/water-vapor-air-d_854.html N2, O2, H20, Ar (.0018 g/cm 2 ) 0.1m – 1m thick *1% water vapor at 65RH, 23C Attenuation (%) Pb, O, Si (4.36 g/cm 2 ) 0.01mm – 0.1mm thick SiO 2 , B 2 O 2 , Na 2 O (2.23 g/cm 2 ) 0.1mm – 1.0mm thick (C 5 O 2 ,H 8 ) n (1.18 g/cm 2 ) 1.0mm – 15mm thick X-Rays pass through materials ionizing the air eliminating ESD on both sides of the wafer Sustaining near 0V ion balance throughout chamber because ionization is occurring isotopically at the same rate as recombination Front Opening Unified Pod Air ionizer is limited to “line of site” and dissipates ESD only on one side of the wafer AC pulse provides good ion balance but at the sacrifice of recombination & ion mobility ESD Volume Coverage Pulsed DC Corona Photoionization X-ray Penetration & Shielding 5keV 15keV 5keV 15keV Eliminating High Static Voltage Quickly 150mm x 150mm charge plate voltage dissipation from + 1000V to + 100V over time and distance provides a 1 dimensional map of ‘decay time’ performance. Rotating over 360 degrees by assumed axial symmetry indicates volumetric coverage. Moxtek has the highest performance and fastest decay over largest area of any photoinizer in the world due to proprietary X-ray technology. Air ionizer vs. Photoionizer E. Miller Moxtek, Inc., Orem UT, U.S.A. 0.5 sec 1.0 sec 2.0 sec f16mm MOX-10 TOC Static elimination range: 10.5kV / 0.5mA (static air: 23C, 20%RH NTP) Side by side performance capability shows X-ray have faster decay time over a larger region. X-ray are limited only by the 1/dx 2 factor rather than air flow or ion mobility, they are able to ionize the air at greater distances and more uniformly than typical corona Long Distance Performance Ionization energies (eV) AMU 1st 2nd 3rd 4th 5th N 7 14.5 29.6 47.4 77.5 97.9 O 8 13.6 35.1 54.9 77.4 113.9 Ar 18 15.8 27.6 40.7 59.8 75.0 O 2 16 12.0 CO 2 22 13.7 N 2 17 15.9 Corona X-ray Benefits **Compressed Y-axis to ensure same scaling factors Top View Side View b b X-ray spectral output of photon energies from 2,500V – 12,500V shown below allow for many Compton scatter events prior to not having sufficient energy to ionize constituent air molecules. This method of ionizing continuously throughout the entire air region mitigates much recombination factors involved with ion loss. X-ray ion balance is easily maintain because photons are continually creating an even mix of (+) ions, (-) ions and electrons across the entire volume of air. Close Distance Performance The DC pulse corona alternates the field polarity. The field will mobilize the ions in the direction of the field of opposite polarity. This causes the ions of opposite potential near each other to recombine and naturalize their charges. This creates a region of neutrality between the ion wave fronts reducing the overall effectivity of ESD on the surface. When presented with a near surface, the air tubulation will further degrade due to increased mix of ion. This was demonstrated in the DOE below. A comparative of corona and X-ray decay rates as measured on a field probe near a glass plate. Primary Photon Primary Photon The + wave form of the corona can be seen as the frequency on tope of the decay voltage signal Equipotential surface map of field gradient of a corona source Photonic path as simulated with material interaction modeling photoionization and Compton scattering, processes g g g Air Pulsed DC polarity on HV alternating the ion production Ion wave front mapping 2015 International Workshop on the Physics of Semiconductor Devices