Applications for Plasma Quest technology

Plasma technology for thin film applications


		PQL's Technology

		Magnetic materials High rate deposition from thick (6mm+) ferromagnetic targets. More information Optical quality dielectrics Deposition of dielectric materials for multi layer optical filters, mirrors and waveguides. More information Flexible Electronics Low temperature deposition of electronic quality materials onto plastic and other ‘delicate’ substrates. More information High Quality Alumina High rate and Very low rate deposition of near bulk property Alumina. More information Protective and wear resistant coatings very dense films deposited using PQL’s HiTUS technology have demonstrated enhanced protective and wear resistant properties. More information Alternative process from wet chemical coatings PQL’s sputter deposition technology offers an attractive alternative, with commercial benefits having already been demonstrated. More information Surface activation and cleaning The ability to direct the plasma onto the substrate enables the substrate to be cleaned of volatile materials. More information

Magnetic Materials
The HiTUS process provides substantial improvements in the sputtering of magnetic materials, both from a production and materials point of view. The confinement of magnetic field - so problematic to conventional 'magnetron' type sputter units - actually enhances the performance of the HiTUS system. When this is coupled with the usual HiTUS capability to 'tailor' plasma conditions, a powerful capability in magnetic thin film deposition can be realised.

We have demonstrated the following benefits using HiTUS:

high rate deposition of magnetic materials, including CoFe, NiFe, Co, Fe.
ability to use thick targets – 6mm normally, up to 15mm so far – with usual HiTUS high utilisation gives less process down time and reliable run to run performance.
near perfect magnetic properties – close to bulk material or theoretical ideal.
excellent adhesion, low stress films deposited onto glass, silicon, oxides, plastics.
Grain size and thereby magnetic properties control through process modification

Our standard HiTUS unit has been used in multi-target mode to deposit multi-layer GMR films – the capability to repeatedly and reliably deposit identical alternating layers without recourse to thin film monitoring and absence of cross-contamination effects from prior layers has allowed rapid progression of such work.

In addition, our current large area coating development of HiTUS has also proven equally effective in sputtering magnetic materials, opening up the potential for high rate – 500nm/min - large area deposition of magnetic thin films onto plastic or other sheet, or large batch coating of discrete substrates as required.

Optical Quality Dielectrics
PQL has demonstrated the ability of HiTUS to produce very high quality optical filters and waveguide material at very high rates, while offering significant advantages over alternative technologies.

Optical quality dielectrics The inherent independence of HiTUS system allows accurate deposition of optical multi-layer stacks

film properties are maintained at varied deposition rates
dielectrics are reactively sputtered from metallic targets in most cases, leading to the densification of the deposited films
SiO2 Ta2O5 Nb2O5 TiO2 are some of the materials we have sputtered
Deposition is controlled by target power verses time. Expensive feedback control is not necessary.
The process is very stable and is repeatable run to run

“PQL has deposited high quality waveguiding alumina layers that appeared to be unaffected by ultraviolet irradiation – a requirement for the “next generation” of upconversion lasers using thulium as the active laser ion.”

The HiTUS system in conjuction with PQL’s multiple target holder provides the capability to repeatedly and reliably deposit identical alternating layers of differing materials. Coupled with a menu driven PLC, one touch batch process control is easily achieved.

Flexible Electronics
PQL's advanced plasma processes have proven especially suited to deposition onto plastic substrates, providing a wide range of new options to support the growing field of flexible electronics.

Flexible electronics This application capitalises on specific advantages of HiTUS:

low temperature deposition: allows use of very low temperature damage threshold plastics (50 degrees C)
negligible plasma damage to substrates: or pre-coat surface modification if required e.g. for improved adhesion
zero/low stress films: controllable from slight compressive to tensile through process settings
excellent adhesion: no delamination during later processing and cutting.
high deposition rate: fast throughput, large area
near ideal physical properties: identical to those achieved on substrates of glass, silicon, etc.

We have demonstrated deposition of high quality, zero stress thin films of metals, dielectrics, ferromagnetic materials and transparent conducting oxides onto thin plastic sheet, using similar processes to those applied to more 'robust' substrates. The table shows examples of our most recent results.

Material	Power	Sep’n	Area	Rate
	(kW)	(cm)	(m2)	(nm/min)
St. steel	12	30	0.2	80
Titanium	12	26	0.2	100
Iron	6	30	0.2	45
Aluminium	11	22	0.2	100
Alumina	12	22	0.05	115

We are currently developing a new HiTUS based prototype system for roll-to-roll coating of thin plastic sheet such as PET – this is expected to provide the basis for our first commercial web coating system.

High Quality Alumina

High quality alumina The significant number of applications for this material has enabled PQL to build an impressive portfolio through continuing development. We have achieved excellent results through reactive sputtering and have also realised new applications.

High deposition rate of High quality alumina
RI very near to bulk properties
Zero breakdown
Very low stress films (controlled through process conditions)
Deposition onto plastic and delicate substrates
Also low rate deposition
Material properties as high rate
Waveguide material (link to paper)
UV stable

Protective and wear resistant coatings
The very dense films deposited using PQL’s HiTUS technology have demonstrated enhanced protective and wear resistant properties when compared to conventional techniques. Silicon dioxide reactively sputtered using HiTUS was seen to withstand extremes of temperature and aggressive environments with applications for aerospace being identified from a project jointly conducted with Surrey University.

DLC can be readily deposited that is not only mechanically hard with high conducting properties, but also has high optical transmissivity.

Alternative process from wet chemical coatings

Coating by wet processes such as electroplating is becoming increasingly less acceptable. PQL’s sputter deposition technology offers an attractive alternative, with commercial benefits having already been demonstrated.

Film densities are substantially higher than can be achieved through wet processing
Adhesion is significantly greater
The required thicknesses of the deposited films can be thinner.
The number of process operations such as post deposition annealing is reduced, leading to higher yields.

As an example, chromium and gold films sputtered onto molybdenum discs out performed electroplated devices, and were significantly better than films deposited from conventional PVD systems.

Surface activation and cleaning
The high density plasma generated from PQL’s HiTUS technology is capable of being directed onto the substrate prior to deposition; notably this redirection of the plasma is done without the need for substrate bias.

This ability to direct the plasma onto the substrate enables the substrate to be cleaned of volatile materials, whilst also activating the surface. As the substrate is not biased, the process gas ions (normally argon) diffuse into the substrate without any directionality, as there is no ion acceleration. This pre-cleaning and surface modification process is used to generate the excellent adhesion properties demonstrated by the technology.