PVD coating

8/7/2019 PVD coating

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Edwards Ltd, Crawley Business Quarter, Manor Royal, Crawley, West Sussex, RH10 9LW, UK. T:+44 (0) 1293 52 88 44

Edwards Limited 2009. All rights reserved. Registered in England and Wales No. 6124750Edwards and the Edwards logo are trade marks of Edwards Limited.

Drystar Application: Coating

Introduction and definition

Vacuum coating is the deposition of a film or a coating made under vacuum or a low-pressureplasma environment. Generally the term is applied to processes which deposit atomic (ormolecular) monolayers; such as physical vapour deposition (PVD), low-pressure chemical vapourdeposition (LP-CVD) processes or plasma-enhanced CVD (PECVD).

In PVD processes, the material being deposited comes from the vapourisation of a solid or liquidsurface. i.e. by Thermal Evaporation (resistance heated evaporation, electron beam evaporation)or Sputter Deposition (DC, RF, reactive)

In CVD processes, the material being deposited comes from a chemical vapour target speciesthat is decomposed by reduction or thermal decomposition - mostly on a hot (1000K) surface. Insome cases the material being deposited reacts with the gaseous environment or a co-depositedspecies to form a film of a compound material such as an oxide, a nitride, carbide, or acarbonitride. In CVD processing, the use of a plasma to fragment the chemical vapour target inthe vapour phase allows the decomposition or reduction processes to proceed at lowertemperatures than with thermal activation alone.(Edwards manufactures a range of pumps for CVD applications at specific temperatures and gaspurges. Please contact Edwards for more details)


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Coating examples:

Roll coating requires a good vacuum combined with well controlled deposition sourcesdepositing coatings onto equally well defined web surfaces. Barrier coatings are used onflexible polymer films and paper for food packaging to reduce the water vapour andoxygen transmission through the paper or polymer film

Glass coating of variety of metals and oxides which have a wide range of uses, fromdecorative to IR reflection or transmission

HDD drive manufacturing: hard drives store data by writing the data to a rotating harddisk known as a platter which is coated with a thin film magnetic material

Optical Filters, lenses and mirrors usually multilayer films (stacks) that affect the opticaltransmission or reflection of a surface

PVD wear and corrosion resistant coating used to increase the operational life of cuttingtools and to maintain the dimensional tolerances of components used in applicationswhere wear and corrosion can occur, such as injection moulds

Research and development and pre-production coating in areas such as optics,electronics, electrical and electron microscopy applications

Metallization of conductor lines used in hybrid microcircuit technology and in themanufacture of semiconductor devices. Often, the electrical conductors are multilayerfilms (stacks) where each layer has a function

Decorative coatings applications vary from coating polymer webs - which are thenconverted to decorative uses such as balloons and labels - to the metallization of three-dimensional articles, such as sports trophies, zinc die cast and molded polymerdecorative fixtures, and cosmetic containers

Vacuum requirements

The GV and GV/EH combinations are used for roughing and process steps in combination withsecondary turbomolecular, diffusion or cryo pumps as necessary.

Drystar InstallationTo ensure optimum performance and reliability of operation of Drystar 80 pumps the followingshould be considered when planning installation:

Purge GasN2 or CDA is required as a purge gas to ensure cleanliness to the dry swept volume and noingress of process material into the low vacuum gear box. The Drystar 80 is supplied with an in-line pressure regulator and gauge. The maximum supply pressure is 100 psi, when regulateddown to 8 psi the Drystar 80 will deliver 15 slm to the shaft seal area.In clean applications anoptional atmospheric shaft seal purge kit is available, however the continuous operating pressureof the system must be below 100 mbar to allow suitable operation.

Deleted:


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The atmospheric seal purge is not recommended for dusty, corrosive, toxic or PFPE fluidapplications. N2 purge gas only should be used when pumping flammable gases.

Inlet Isolation Valve - should be utilised in the following circumstances (1) to prevent chamberventing and/or high turbomolecular pump back pressure in the event of pump shut down, eitherplanned or unplanned (2) to prevent solids or liquids built up in the pump exhaust or silencer frombeing drawn back into the pump when shut down. (Edwards supplies a variety of valve options,please consult with our sales staff on the option best suited for your application and installation).

Exhaust Backpressure - attention on installation should be paid to the exhaust provision toensure that exhaust back pressure is not created. This relates specifically the managementand/or prevention of condensate* and solid accumulation.

*See application note on drying applications

Performance benefits for coating with Dry Pumps

Oil sealed pumps Dry PumpContamination of process/product frombackstreaming of oil

Clean vacuum, no backstreaming of oil

Speed and ultimate performance can degradewith increasing age of oil

No performance degradation for continuousand reliable performance

Water vapour builds up in oil during chamberand load-lock pumping, causing extendedpump down times

Drystar pumps have no water vapour residencyand provide faster and repeatable pump down

Oxidants give flammable/explosion risk withhydrocarbons (expensive PFPE solution) No mineral oils in vacuum space (no need forspecial fluids)Large gas flows can accelerate the degradationof the oil and oil return kits are required

No oil; large gas flows (gas, vapour andballast) supported up to 3 x that of oil pumps

Particulates from reaction by-products canresult in wear and blockage of internalpassages

No lubrication channels, good particulatehandling. Non-contacting mechanism nowearing parts

Maintenance, Environment, Safety

Oil sealed pumps Dry PumpParticulates from reaction by-products canresult in wear and blockage of internalpassages

No lubrication channels, good particulatehandling. Non-contacting mechanism nowearing parts

Corrosive gases and vapours degrade oil and

attack pump materials

No mineral oils in vacuum space. Dry

mechanism with purge/ballast maintainscorrosives in vapour phaseHot running avoids condensation

Regular oil state and level monitoring required No oil/level monitoringRegular oil changes required No oil changes; no oil to dispose ofOil filters required with requisite maintenance No filters needed no oil mist exhausted to

atmosphere


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Oil leaks can contaminate and present safetyhazard

No oil used, no backstreaming of oil to processchamber and assured vacuum cleanliness

Skilled personnel required for maintenance No onsite maintenance requiredLarge flows can accelerate the degradation ofthe oil and oil return kits required

No oil; large flows (gas, vapour and ballast)supported up to 3 x that of oil pumps

Explosion proof motors/ATEX versions information on request

PVD coating

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