LOW TEMPERATURE PLASMA STUDIES AND APPLICATIONS

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LOW TEMPERATURE PLASMA STUDIES AND APPLICATIONS

• Xiaogang Wang
• Dalian University of Technology

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OUTLINE

• Relationship with Industry
• Major Applications
• Plasma Sources
• Beams
• Pulsed Power Technology
• Atmospheric Pressure Discharge
• Plasma Etching
• Dusty Plasma Applications
• Biophysical Applications
• Discussions

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RELATIONSHIP WITH INDUSTRY

• Basic structure (USA)
• Basic researches (government support)
• Industry R Ds (Private sectors)
• Industry
• Sources Beams, Processing, Films, Electronics,
  Computer, etc.
• Current structure in China
• Basic researches (government support)
• Industry R Ds (none)
• Industry applications (???)

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Basic researches (in US)

• Pure scientific researches
• What is going to happen in 20 years?
• Such as computer beyond silicon
• Basic physical, chemical, biological processes
• Basic applied researches
• New sources, new ways, new materials
• Such as helicon in 90s, sources beams for big
  science , PSII in 80s, pulsed tech, OAPUGD
• Computer codes

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Basic researches (in China)

• Pure scientific researches
• What is going to happen in 20 years? (??)
• Basic physical (Yes), chemical (?), biological
  (?) processes
• Basic applied researches
• New sources, new ways, new materials (?)
• Computer codes (??)

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Industry R Ds (in US)

• New sources, new ways, new materials
• Overlap with basic researches, more
  profit-oriented
• Computer codes
• Overlap with basic researches, more specific
• New processes
• Very detail improvements

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Industry R Ds (in China)

• State sectors
• Government R D
• Wealthy weak, but unwilling to share resource
• State owned industry
• In bad shape itself, no enough resource
• Private sectors
• Publicly traded strongly rely on import
• Privately owned limited resource and vision

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Industry in US

• High tech leaders
• Computer chips
• New materials
• Medical and biological applications
• Government sectors
• Aero-space industry
• Environment industry
• Big sciences
• Reactors and Beams
• Sources

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Industry in China

• Not a leader
• rely on import
• Not a major manufacturer in high tech
• Japan at least need process improvement
• China small size, low-end, no such needs
• Government
• Separation of funding and human resources
• Big sciences
• Limited

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INDUSTRIAL APPLICATIONS OF PLASMAS Surface
Treatment Ion implantation, hardening,
Welding, cutting, drilling Film
deposition Volume Processing Flue gas
treatment, Metal Recovery, Waste Treatment Water
purification, Plasma spraying
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Light Sources High Intensity, Discharge Lamps,
Low Pressure Lamps, Specialty Sources, Lasers,
Field-Emitter Arrays, Plasma Displays

Switches Electric Power, Pulsed Power

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Energy Converters MHD Generators, Thermionic
Energy Converters, Beam Sources

Radiation Processing Ceramic powders,
Plant growth
Medicine Surface treatment,
Instrument Sterilization
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MAJOR APPLICATIONS

• Plasma Sources
• Beams
• Pulsed Power Technology
• Atmospheric Pressure Discharge
• Plasma Etching

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PLASMA SOURCES

• Helicons
• ECRs
• ICPs
• Magnetrons
• Gyrotrons
• Thrusters
• GEC reference reactors

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GEC Reactor

• Gaseous Electronics Conference (GEC) Reference
  Reactor (Hargis et al, 1991)
• Capacitive coupled plasmas
• RF discharge (13.56 MHz, 100 V)
• Detailed computer simulation code

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GEC Reactor Basic parameters

• Rc 5 cm
• Rr Ra 5.25 cm
• RT 10 cm
• Xc Xr 3.5 cm
• Xa 6.25 cm
• XT 10 cm
• d Xa-Xc 2.75 cm

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BEAMS

• Laser beams
• Ion beams
• Electron beams
• Energetic particle beams

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Ion beams Plasma focusing

• Offfocus of charged particle beams
• Plasma focusing

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Applications to microelectronics

• Nano microelectronics
• Quantum Ge/Si dots
• Growth by molecular beams electron beam
  evaporators for Si and Ge deposition
• Enhancement by ion implantation
• Low energy As beam (1 keV)
• Depositing current density 0.02 mA/cm2

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PULSED POWER TECH

• Pulsed voltage
• Pulsed beams

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Experiments at Materials Modification Lab, DUT

• C on Al surface
• Bombarded by pulsed electron beams
• Regular deposition thickness mms
• After a single pulse 1mm
• Multi-pulses Better results
• Anomalous diffusion effect ?

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Experiments at MMLab Pulsed electron beam
parameters

• Width mm
• Power 27.8 keV
• Energy density 3.2 J/cm2

1. Cathode, 2. Anode, 3. Target, 4. Vacuum
chamber, 5. Cathode plasma, 6.
Anode plasma, 7. Coils, 8. Sparks
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ATMOSHERIC DISCHARGES

• Arc discharges
• Circuit breakers
• Plasma guns furnaces for steel, auto and
  environment industries
• Surface physical simulation of re-entry
• Corona discharges
• Environment industry
• Glow discharges
• Filament glow discharges
• OAUGD

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Physical simulation of re-entry

• Fluid model (electrostatic MHD)
• Kink instabilities
• Two stream instabilities
• Numerical simulation codes

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DUSTY PLASMA APPLICATIONS

• Dust particles in reactors
• Removal by heart-beating waves
• Removal by bipolar diffusions
• Other applications

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Dust particles in reactors Particle creations

• Particle creation growth phases
• Cluster formation
• Nucleation and cluster growth
• Coagulation
• Particle growth

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Particle creations Major processes

• Surface processes
• Etching
• Sputtering
• PECVD processes
• Walls
• Chemical polymers

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Dust particles in reactors Impacts of particles

• Surface contamination
• Effects on sheath and electron density
• Application of dust energetics
• Particle size control and nanostrutrued thin films

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Surface contamination

• Particle emission and trapping in plasma
  processing reactors
• ICPs
• CCPs
• Helicons and ECRs

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Effects on sheath and electron density

• Energy absorption
• Electron density reduction

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Dust-free processing

• Dust cleaning (removal) techniques
• Magnetization and E X B drift
• Dust trajectory calculations
• Electrical potential configurations

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Application of dust energetics

• Dust energetics
• Heavy particle deposition
• Dust-enhanced PECVD
• Dust charging and distribution studies

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Dust size control and nanostructured thin films

• Opto-electronics applications of nano-structure
  thin films
• Nano-crystallite with dusty plasma technology

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BIOPHYSICAL APPLICATIONS

• Electroporation
• Drug delivery and gene therapy
• Seed modification (ion plasma beams) ?
• Surface sterilization
• Anti-bioterrorism application
• Medical and other industry applications
• Surface modification
• To artificial organs etc.
• High power, low duty circle pulses
• Applications to biological systems

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Electroporation Basic processes

• Applying short electrical pulses
• Charging of lipid bilayer membranes
• Fast local structure rearrangement
• Transition to pore stage
• Tremendous enhancement of ionic and molecular
  transport
• Possible candidate for seed modification?

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Electroporation Basic parameters

• Pulse width ms ms
• Pore creation period ms
• Pore relaxation time gt 1 s
• Pore radii nm
• Bilayer thickness mm
• Membrane voltage gt 1 V
• Electrical field kV/cm

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Surface sterilization Anti-bioterrorism
application

• Large scale anthrax outbreak
• Soviet Union, 1979 (Science 266, 1994)
• USA, 2001
• Plasma sterilization for large areas
• No damage to the surface
• Fast cleanup gt 10cm/s
• In-place agent destruction, no hazard waste
• Tools
• Montec steam plasma torch
• TTU arc-jet thruster

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Surface sterilization Plasma parameters

• Power 60 100 kW
• Work plasma Water steam
• Temperature gt 1500 K
• Threshold gt 3000 K
• Rate gt 10 cm/s
• Kill rate gt 80

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DISCUSSIONS

• Plasma cloaking
• Drag-reduction and EM waves absorption
• Plasma shock formation and its effect
• Plasma etching
• Plasma chemistry

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University Research Centers in US

• UW-UM Center for Plasma Aided Manufacturing
• Research Areas
• Thin Film Deposition
• Thick Film Deposition
• Plasma Etching
• Surface Modification

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Thin Film Deposition

• Plasma-mediated, surface modification of organic
  and inorganic polymeric substrates for generating
  controlled etching reactions, creating specific
  surface topographies, and implanting specific
  functionalities onto various substrate surfaces.

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• Deposition of novel and conventional
  macromolecular layers (e.g. Teflon-like thin
  layers and IR transparent films) on inorganic and
  organic surfaces by involving plasma-state and
  plasma-induced reaction mechanisms, including
  template polymerization reaction mechanisms
  initiated from surfaces with plasma-enhanced
  crystallynity.
• Investigation of the influence of plasma
  parameters (electron energy distribution, power,
  frequency, pressure, etc.) on the
  discharge-induced gas phase molecular
  fragmentation and surface-mediated
  plasma-chemistry mechanisms

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• Kinetic modeling of plasma-induced gas phase
  fragmentation and gas phase and surface-mediated
  recombination processes (e.g. Kinetic modeling of
  ammonia and hydrazine-RF plasma environments).
• Generation of intelligent substrates for
  molecular recognition and molecular machining
  processes by immobilizing and synthesizing active
  biomolecules (e.g. enzymes, oligonucleotides) on
  plasma-functionalized substrate surfaces

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• Evaluation of the influence of the amorphous and
  stereoregular nature of the polymeric substrates
  and the chemical nature and length of spacer
  molecules on the activities of the immobilized
  biomolecules.
• Development of novel plasma installations for
  specific plasma treatments, and for scaling up
  laboratory technologies to industrial
  applications

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Thick Film Deposition

• A) Plasma spraying
• Nozzle and shroud development and evaluation
  for increased plasma jet stability, and improved
  deposition efficiency and consistency of coating
  quality.
• Development of sensors and control algorithms
  for detecting and avoiding variations in plasma
  jet behavior and coating quality. 

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• B) Wire arc spraying
• Spray pattern control through different nozzle
  and shroud designs.
• Development of fundamental process correlations
  using process models and
• advanced diagnostics with a novel torch.
• Application of novel control algorithm based on
  computer analysis of arc
• voltage traces.

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• C) Thermal plasma CVD
• Texture control during high rate diamond film
  deposition through detailed understanding of the
  boundary layer chemistry based on modeling and
  diagnostics using gas chromatography.
• Arcjet deposition at high rates of hard, boron
  containing films.

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Plasma Etching

• Etch Tool Development
• Helicon plasma etching
• Magnetically enhanced inductively coupled plasmas
  (ICP)
• Large area substrates
• Modeling

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• Semiconductor Processing
• Fluorocarbon-based SiO2 etching - chemical
  characterization of gas phase using infrared
  spectroscopy, endpoint detection, etch
  selectivity/ion energy control at the wafer
  surface
• Plasma-Induced Damage - surface charging
  effects in device damage and feature profile
  evolution, discharge modulation for reduction of
  charging-induced damage, vacuum ultraviolet
  radiation damage
• Real-time Control of Plasma Etching - efforts
  includes development of sensors (e.g., wall
  deposition monitor), and control strategies

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Advanced Plasma Etch Diagnostics Diagnostics
currently under development Langmuir probe
theory in magnetized plasmas Infrared absorption
spectroscopy Electro-optical probe
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• Recent collaborations with industrial partners
• Process development for polymer etching
• Surface charging reduction during plasma etching
• Process development for etching of magnetic
  materials
• Chemical characterization of plasmas for
  fluorocarbon-based etching of SiO2

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Thank you!