POSTER Semiconductor - Air Ionizer vs X-ray

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  • 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


    Sectional Area: 1.2m2

    Volume: 1.3m3

    Carbon (2.26 g/cm2)1mm 10mm thick






    Silicon (2.33 g/cm2)0.5mm 0.75mm thick

    N2, O2, H20, Ar(.0018 g/cm2)

    0.1m 1m thick

    *1% water vapor at

    65RH, 23C






    Pb, O, Si (4.36 g/cm2)0.01mm 0.1mm thick

    SiO2, B2O2, Na2O (2.23 g/cm2)

    0.1mm 1.0mm thick

    (C5O2,H8 )n (1.18 g/cm2)

    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


    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


    ESD Volume Coverage

    Pulsed DC



    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. PhotoionizerE. Miller

    Moxtek, Inc., Orem UT, U.S.A.

    0.5 sec

    1.0 sec

    2.0 sec


    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/dx2 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

    O2 16 12.0

    CO2 22 13.7

    N2 17 15.9


    X-ray Benefits

    **Compressed Y-axis to ensure same scaling factors

    Top View

    Side View


    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,


    g g



    Pulsed DC polarity

    on HV alternating

    the ion production

    Ion wave front


    2015 International Workshop

    on the Physics of

    Semiconductor Devices