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Product Index (Oxford Plasma) :

         n            ICP Etching - Inductively Coupled Plasma Etch

            n            RIE - Reactive Ion Etch

l           Ion Beam Deposition

Plasma Deposition Process Techniques

Oxford Instruments offers a range of process solutions for deposition of advanced materials on micro- and

nanometre scales. For further information on the key process techniques available please contact Oxford

Instruments Plasma Technology.

ICP-CVD - Inductively Coupled Plasma - Chemical Vapour Deposition

Inductively Coupled Plasma - Chemical Vapour Deposition (ICP-CVD)

Key Features

• Independent control of ion energy and ion current density

• Typical process pressure: 1- 10 mtorr

• Plasma density: ca 5 x E11 / cm2

• Plasma in contact with the substrate

• Low energy ion current during deposition

• Ion Current (Plasma Density) dependent on ICP power

• ESS (electrostatic screen) for a purely inductive plasma

Typical Applications:

• Low temperature deposition for lift off technology

• Low temperature deposition of very high quality SiO2

• Low temperature deposition of polySi

• ICP is fully automatic (2 RF automatch units)

PVD - Plasma Vapour Deposition

Physical Vapour Deposition (PVD)

• Typical process pressure: 5 - 30 mtorr

• Good step coverage

• Standard method for high quality Al (with Si/Cu/Ti), TiN, TiW

• Up to 4 x 200mm or 8 x 75mm cathodes

• Substrates on a rotating holder

• Substrate holder water cooled /heated (up to 400° C)

• PreEtch and RF Bias

• Parameter: gas flows, pressure, RF power

Typical Applications:

• High quality Al with Si/Cu/Ti

• Diffusion barriers TiN, TiW (reactive sputtering)

• Resistor films NiCr, TaN

• Noble metals: Au, Pt

PECVD - Plasma Enhanced Chemical Vapour Deposition

Plasma Enhanced Chemical Vapour Deposition (PECVD)

Key features

• Top electrode RF driven (MHz and/or kHz); no RF bias on lower (substrate) electrode

• Substrate sits directly on heated electrode

• Gas injected into process chamber via “showerhead” gas inlet in the top electrode

• 0.5-1.0 Torr operating pressure

• 0.02-0.1 Wcm-2 power density

Benefits

• Lower temperature processes compared to conventional CVD

• Film stress can be controlled by high/low frequency mixing techniques

• Dry plasma cleaning process with end-point control removes or reduces need for physical/chemical

  chamber cleaning

• Control over stoichiometry via process conditions

• Offers a wide range of material deposition, including: SiOx, SiNx and SiOxNy deposition for a wide range

  of applications including photonics structures, passivation, hard mask, etc.

• Amorphous silicon (a-Si:H)

• TEOS SiO2 with conformal step coverage, or void-free good step coverage

• SiC

• Diamond-like carbon (DLC)

Plasma Etch - Plasma Etching

Plasma etching is a form of plasma processing used to fabricate integrated circuits. It involves a high-speed

stream of glow discharge (plasma) of an appropriate gas mixture being shot (in pulses) at a sample. The

plasma source, known as etch species, can be either charged (ions) or neutral (atoms and radicals).

During the process, the plasma will generate volatile etch products at room temperature from the chemical

reactions between the elements of the material etched and the reactive species generated by the plasma.

Eventually the atoms of the shot element embed themselves at or just below the surface of the target,

thus modifying the physical properties of the target.

ICP Etching - Inductively Coupled Plasma Etch

Inductively Coupled Plasma (ICP)

Key features

• Separate RF generators for Inductively Coupled Plasma and electrode provide separate control over ion

  energy and ion density

• High conductance pumping port provides high gas throughput for fastest etch rates

• Electrostatic shield eliminates capacitive coupling, reduces electrical damage to devices, reduces chamber

  particles

• Oxford Instruments’ ICP tools include wafer clamping and helium cooling as standard, providing excellent

  temperature control with the option of a wide temperature range

ICP benefits

• High etch rates are achieved by high ion density (>1011 cm-3) and high radical density

• Control over selectivity and damage is achieved by low ion energy

• Separate control over Inductively Coupled Plasma and electrode RF provides high process flexibility

• Chemical and ion-induced etching

• Can also be run in RIE mode for certain low etch rate applications

• Can be used for deposition in ICP-CVD mode, offering:

  - very dense films at lower temperatures than PECVD

  - low damage deposition onto temperature sensitive substrates

RIE - Reactive Ion Etch

Key features

• Gas injected into process chamber via “showerhead” gas inlet in the top electrode

• Negative self-bias forms on lower electrode

• Single RF plasma source determines both ion density and energy

• Substrate is usually placed on a quartz or graphite “coverplate” to avoid sputtering/re-deposition of

  electrode material

• 5-500 mTorr operating pressure

RIE benefits

• Economical solution for general plasma etching

• Simple operation

• Multiple choices of etch processes:

  - Chemical etch – isotropic, fast rate

  - Ion induced etch – anisotropic, medium rate

  - Physical etch – anisotropic, slow rate

• Wide applications in semiconductor de-processing and failure analysis

• Wide range of materials can be etched, including:

  - Dielectric materials (SiO2, SiNx, etc.)

  - Silicon-based materials (Si, a-Si, poly-Si)

  - III-V materials (GaAs, InP, GaN, etc.)

  - Sputtered metals (Au, Pt, Ti, Ta, W, etc.)

  - Diamond-like carbon (DLC)

RIE-PE - Reactive Ion Etch - Plasma Etch

Typical applications

• Isotropic PE fotoimide etching

• Anisotropic RIE polyimide etching

• Isotropic PE SiN removal

• Anisotropic SiO2 RIE etching

Benefits

• Substrate electrode cooled

• Top or bottom electrode RF driven (13.56 MHz)

• Automatic switching

• Shower head gas inlet (in the top electrode)

• Parameter: gas flows, pressure, RF power

Atomic Layer Deposition (ALD)

Atomic layer deposition (ALD) is a true "nano" technology, allowing ultra-thin films of a few nanometres to

be deposited in a precisely controlled way. The two defining characteristics of ALD - self-limiting atomic

layer-by-layer growth and highly conformal coating offer many benefits in semiconductor engineering,

MEMS and other nanotechnology applications.

The benefits of ALD

Because the ALD process deposits precisely one atomic layer in each cycle, complete control over the

deposition process is obtained at the nanometre scale Conformal coating can be achieved even in high

aspect ratio and complex structures Pin-hole and particle free deposition is achieved

A very wide variety of materials is possible with ALD:

Oxides, including HfO2, HfSiO, Al2O3, Ta2O5, TiO2, La2O3, SiO2, ZnO

Nitrides, including TiN, TaN, AlN, SiNx, HfN

Metals, including Ru, Cu, W, Mo

The benefits of remote plasma ALD

In addition to the benefits of thermal ALD, remote plasma allows for a wider choice of precursor chemistry

with enhanced film quality:

Plasma enables low-temperature ALD processes and the remote source maintains low plasma damage

Effective metal chemistry through use of hydrogen plasma rather than complex thermal precursors

Eliminates the need for water as a precursor, reducing purge times between ALD cycles - especially for low

temperatures.

Higher quality films through improved removal of impurities, leading to lower resistivity, higher density, etc.

Ability to control stoichiometry

Plasma surface treatment

Plasma cleaning of chamber is possible for some materials

ALD Applications

Including:

High-k gate oxides

Storage capacitor dielectrics

Pinhole-free passivation layers for OLEDs and polymers

Passivation of crystal silicon solar cells

High aspect ratio diffusion barriers for Cu interconnects

Adhesion layers

Organic semiconductors

Highly conformal coatings for microfluidic and MEMS applications

Other nanotechnology and nano-electronic applications

Coating of nanoporous structures

Fuel cells, e.g. single metal coating for catalyst layers

Bio MEMS

Ion Beam Deposition

Key Features

Process type

IBD - Ion Beam Deposition: Ionfab 300 plus (SC) and (LC), Ionfab 500 plus

IBD + assist source: Ionfab 300 plus (SM) and (LC) only, assist source can also be used for sample pre-clean

Hardware

• Rotating and tiltable substrate holder (Ionfab 300 plus (SM) and (LC) only)

• Deposition Ion Source: 15 cm, 13.56 MHz driven

• PBN beam neutralisation

• Gas inlet through source, assist source and into the chamber

• Independently changeable parameters: gas flows, ion energy, ion current, accelerator voltage, beam neutralisation

• Mutiple targets with fixed shields and rotating shutters

• Second source as assist source to control stochiometry (e.g. depositing oxide from metal target) or as pre-cleaning on (Ionfab 300 plus (SC) and (LC) only)

Key Applications

• Ring laser gyroscope mirrors

• High power laser optics

• Gravity wave detector mirrors

• Astronomical instrumentation

• Anti reflecting and high reflecting coating (e.g. laser bars)

Benefits

• High surface quality

• Dense smooth films

• Very low scattering

• Very low optical losses

• Very good run to run repeatability

• Excellent uniformity

• Maximum flexibility

• Range of applications

• Process repeatability

• Low cost of ownership

Ion Beam Etch - Ion Beam Etching

Key Features:

Process type

• IBE - Inert Gas Ion Beam Etch

• RIBE - Reactive Ion Beam Etch

• CAIBE – Chemically Assisted Ion Beam Etch

Hardware

• Choice of 15cm and 35cm RF ion Sources

• High current neutraliser

• Upto 8 inch rotatable and tiltable substrate platen with heater and cooler

• Choice of single wafer load-lock and cassette to cassette multi-wafer handler

• Modular design for easy configuration into a multi-functional cluster tool

• Variable interface configuration with clean room

• Option of SIMS for end point detection

Key Applications

• GaAs Opto-electronics

• Microwave integrated circuits

• InP laser optics

• Thin film magnetic heads/MRAM

• SAW (Surface Acoustic Wave) devices

• Mask fabrication Benefits

• Excellent uniformity

• Maximum flexibility Range of applications

• Process repeatability

• Low cost of ownership 

Nanoscale Growth

Oxford Instruments offers a range of process solutions for nanostructure growth, taking in carbon

nanotubes (CNT), silicon and other material nanowires, nanometre thin film deposition and III-V/II-

VI/nitride semicondonductor epitaxial growth.

Nanostructure growth solutions - Our range of "bottom-up" nanostructure growth solutions encompasses:

• Carbon nanotubes

• Plasma-enhanced chemical vapour deposition (PECVD) growth of carbon nanotubes (CNT) in our Nanofab tools

• Nanowires

• PECVD growth of a wide range of nanowire materials in our Nanofab tools

• Nanometre thin films

• Atomic layer deposition (ALD) for ultra-thin film deposition using our FlexAL and OpAL ALD tools, with highly conformal

  (~100%), pinhole-free coverage of a wide range of oxides, nitrides, single element metals and nanolaminates materials,

  with nanometre-level control of film thickness

• Epitaxial growth of III-V, II-VI and nitride materials

Nanoscale Si etching

For "top-down" nanostructure creation, nanometre scale features can be etched in silicon using our

PlasmalabSystem100, PlasmalabSystem133 and Plasmalab80Plus plasma etch tools