Download - POSTER Semiconductor - Air Ionizer vs X-ray

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Page 1: POSTER Semiconductor - Air Ionizer vs  X-ray

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: 1.2m2

Volume: 1.3m3

Carbon (2.26 g/cm2)

1mm – 10mm thick

Tra

nsm

issi

on

(%)

Silicon (2.33 g/cm2)

0.5mm – 0.75mm thick

http://www.engineeringtoolbox.com/water-vapor-air-d_854.html

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

0.1m – 1m thick

*1% water vapor at

65RH, 23C

Att

enu

ati

on

(%)

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

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. PhotoionizerE. 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/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

Corona

X-ray Benefits

**Compressed Y-axis to ensure same scaling factors

Top View

Side View

bb

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