LOW-POWER mWAVE hopwood/lab/images/ICOPS03_IzaHopwood.pdf · PDF file 2007. 6....

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Transcript of LOW-POWER mWAVE hopwood/lab/images/ICOPS03_IzaHopwood.pdf · PDF file 2007. 6....

  • Northeastern University Boston, MA

    - USA -

    LLOWOW--PPOWEROWER µµWAVEWAVE PPLASMALASMA

    SSOURCEOURCE FFOROR MMICROSYSTEMSICROSYSTEMS

    Felipe Iza and Jeffrey A. HopwoodFelipe Iza and Jeffrey A. Hopwood

    ICOPS - Cheju, 2003

  • Outline

    DEVICE DESCRIPTION

    v Low-cost gap-excited microwave plasma source

    v Low-power device

    v Atmospheric pressure

    PROBE DIAGNOSTICS

    v High-density discharge

    v Low sheath voltage

    SPECTRUM ANALISYS

    v Non-equilibrium, low-temperature discharge

    CONCLUSIONS

  • Plasma Source Description

    RT/Duroid 6010.8

    Dielectric: Ceramic reinforced teflon Dielectric constant εr=10.8 Dielectric thickness: 635µm

    Conductor: Copper Conductor thickness: 9 µm

    Operation Conditions

    900 MHz 0.1 - 760 torr 0.150 - 3 W

    Ground Plane Dielectric

    Discharge gap

    Lin e

    SMA connector

    Discharge Gap

    λ/4

    ~ 2 cm

    ~ 5

    cm

    λ/2

    Matching network

    Split ring resonator

  • I V

    ? 2

    Principle of Operation

    Discharge gap

    g o h

    E 2 E g

    ≈ Ground Plane

    Dielectric

    g

    h Eo

    Eg

    Line

    Ground plane

    Line plane

    Section AA’

    Ground plane

    Line plane

    Section BB’

    A’

    A B’

    B Magnitude of the electric field |E| Simulation using HFSS from Ansoft

  • Experiment Set-up

    Glass tube

    (chamber)

    Manifold

    Plasma SourceGas outlet

    To pressure gauges

    Coaxial Probe

    Gas inlet

    Needle valve

    30dB

    900.000 -7.3

    MKS

    0.53

    0.53 - - -

  • Ignition Power & Gap engineering

    Pressure (torr)

    Ig ni

    tio n

    Po w

    er (W

    )

    0.1 1 10 100

    1

    6

    760

    3

    0.5

    500 µm gap - Argon

    50 µm gap - Argon

    500 µm gap - Air

    0.6

    0.7

    0.8 0.9

    2

    4

    5

  • Pressure Range of Operation

    Probe diagnostics: v Ion Density ~1011cm-3

    v Floating Potential

  • Probe diagnostics: Ion density

    100 mtorr 200 mtorr 300 mtorr 400 mtorr

    Power (W) 0.0 0.2 0.4 0.6 0.8 1.0 1.2

    Io n

    D en

    si ty

    n ii (c

    m -3

    )

    0.0

    2.0e+10

    4.0e+10

    6.0e+10

    8.0e+10

    1.0e+11

    1.2e+11

    1.4e+11

    [1] Iza F. and Hopwood J., Plasma Sources Science and Technology, vol. 11, no. 3, pp. 229-235, August 2002

    mICP @ 400 mtorr[1]

    mICP 400 mtorr[1]

    Ring resonator 400 mtorr

    335Q ≈

    40Q ≈

    Argon

  • Probe diagnostics: Floating Potential

    Pressure (torr)

    0.01 0.1 1 10 100 1000 10000

    Fl oa

    tin g

    Po te

    nt ia

    l ( V

    )

    -5

    0

    5

    10

    15

    20

    25

    1250 mW

    1000 mW

    750 mW

    250 mW

    500 mW

    150 mW

    Probe: Thin gold wire (d=50µm)

    Argon

  • Pressure Range of Operation

    Probe diagnostics: v Ion Density ~1011cm-3

    v Floating Potential

  • Ar: 760 torr, 1.5 W

    4000 5000 6000 7000 8000 9000 10000

    4000 4500

    Texcitation and Tvibrational @760 torr

    Ar Ground state

    E (eV)Ar+

    Ar*

    15

    10

    5

    13

    -14

    -12

    -10

    -8

    -6

    -4

    -2

    0

    2

    ln (I

    *l am

    bd a/

    A )

    7 8 9 10 11 12 14 15 -16

    Energy (eV) 16

    4000 5000 6000 7000 8000 9000

    99.9% Ar + 0.1% N2 : 760 torr, 1.5 W 1st Positive Band: 3 3 +g uB ? A→ ∑2nd Positive Band:

    3 3 u gC ? B ?→

    ∆ν = ... 0 2 3 41 -3 -1-2- 4

    ∆ν = ...

    N2 Ground state

    ν=1

    N2+

    ν=2 ν=3

    ν=1 ν=2 ν=3

    3 + uA ∑

    3 gB Π

    3 uC Π

    ... ...

    ...

    ν=1 ν=2 ν=3

    N2+

    Tvib = 0.70 eV (8124 K)

    Tvib = 0.25 eV (2901 K)

    N2:1 st positive band

    N2:2 nd positive band

    0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

    1

    Wavelength (Å)

    In te

    ns ity

    (a .u

    .)

    Ar* Ar+

    Argon

    Texc = 0.32 eV (3714 K)

    ********** *** *

    * *

    * ** **

    * *

    ***** **

    Boltzmann plot

  • 4000 5000 6000 7000 8000 90000 0.2 0.4 0.6 0.8

    1

    Wavelength (Å)

    In te

    ns ity

    -3 -1-2- 4

    1st Positive Band: 3 3 +

    g uB ? A→ ∑2nd Positive Band: 3 3

    u gC ? B ?→

    ∆ν = ... 0 2 3 41 ∆ν = ...

    Rotational Temperature Trot @760 torr

    N2 Ground state

    ν=1

    N2+

    ν=2 ν=3

    ν=1 ν=2 ν=3

    3 + uA ∑

    3 gB Π

    3 uC Π

    ... ...

    ...

    ν=1 ν=2 ν=3

    99.9% Ar + 0.1% N2 : P=760 torr, 1.5 W

    3680 3700 3720 3740 3760 3780 3800 3820 Wavelength (Å)

    2- 4

    1- 3

    0- 2

    Trot = 350 K

    Trot = 400 K

    Trot = 450 K

    gas rotT T = 400 K≈

  • Conclusions NEW DEVICE BASED ON A SPLIT-RING RESONATOR v Low cost, robust and high-Q v Low-Power

    Ø 0.5W Argon @ 760torr v Wide pressure range operation Ø 0.1-760 torr

    PROBE DIAGNOSTICS (LOW PRESSURE) v High-density discharge v Small sheath voltage at pressures > 3 torr

    SPECTRUM ANALISYS v Non-thermal plasma v 99.9% Ar +0.1%N2, 760 torr, 1.5W ØTexc= 0.32eV (3714 K) ØTvib= 0.7eV (8124 K) ØTrot= 0.03eV (400K)

    PORTABLE DEVICE

    EFFICIENT AND DURABLE

    LOW-TEMP. APPLICATIONS

  • This research has been supported by Northeastern University, the Fulbright Program, and the National Science Foundation under Grant No. DMI-0078406.

    Acknowledgment