UNIVEX coating processes

UNIVEX thin film deposition processes

UNIVEX are multi-purpose coating systems for the production of functional physical vapor deposition coatings.

The properties of thin films depend on the process technology used to produce them. Different process parameters have an influence on the behaviour of a thin film. In our UNIVEX systems, various coating methods as well as a range of substrate treatments can be applied. Our Leybold coating systems are based on a modular design, which offers the possibility to realize customers' specific requirements.

Process variations of UNIVEX coating

Thermal evaporation

Thermal or resistive evaporation is the most established method of depositing thin films. This technique is used in a high vacuum chamber such as our UNIVEX system. A single thermal evaporator consists of two water-cooled current feedthroughs connected by source like boat or filament. The material will be placed into the source, due to power being applied the temperature rises till the material is evaporated.

Our standard thermal evaporation packages come in either a single, dual or dual independent configuration, suitable for single or co-deposition.

A wide range of materials can be deposited with thermal evaporation technology such as gold, silver, aluminium copper and many others.

E-beam evaporation

Electron beam evaporation is another well-established evaporation technology which is used in a high vacuum environment. The material to be evaporated is located inside a copper crucible.

An energized electron beam is generated from a tungsten filament and deflected by magnetic fields into a pocket in the crucible. The energy of this electron beam is applied to the material, which is then evaporated or sublimated.

The electron beam gun can have several configurations. Single or multi pocket crucibles with different capacities are available.

Various power supplies allow the evaporation of materials with high melting points (e.g. Mo) or even the implementation of processes with high deposition rates.

Organics evaporation

An organic evaporator is also known as Knudsen cell. It is an effusion evaporator for evaporating material with low partial pressure which requires precise temperature control, in order to deposit functional thin films.

The material is placed into a crucible which can be made from e.g. quartz or ceramic. Electrical heating is used to heat up the material until it evaporates. For temperature control, the evaporator contains an integrated thermocouple. This kind of source is very suitable for evaporating organic materials.

Sputtering

Magnetron sputtering is a highly useful and productive way to deposit difficult to evaporate or complex materials onto various substrates.

Leybold uses high-quality, stainless steel body, cylindrical or rectangular magnetrons in our sputtering deposition systems. We recommend throttling pressure control valves coupled with our high accuracy, ceramic diaphragm gauges for sputtering pressure control and reproducible processes.

DC sputtering

Direct current (DC) sputtering is often used for metallic or conductive materials e.g. Al, Ti, and ITO.

For such conductive materials, DC sputtering has a higher relative deposition rate when compared to RF sputtering and is generally preferred.

RF sputtering

Radiofrequency (RF) sputtering is particularly useful for sputtering non-conductive or ceramic materials, such as oxides or sulphides. It can be also used for conductive materials,but this has a lower deposition rate than materials sputtered with DC.

Often RF sputtering is used for shallow doping during co-sputtering with a higher rate DC based process.

Reactive sputtering

Reactive sputtering involves starting with an elemental target material and adding a gas to create a new material on the substrate.

It can be difficult to obtain oxides, nitrides and sulphides with appropriate purity for the application of interest. It is more cost effective to start with a metallic target and react it within the chamber.

Pulsed DC sputtering

Pulsed DC (PDC) sputtering is used in reactive sputtering processes where insulating films are created. Poisoning of the metallic target by the reactive gas can occur which leads to arcing and a loss of plasma stability.

Pulsed DC uses alternating voltage reversal with high frequency pulses to deliver and maintain higher relative power to the target. Cleaning of the insulating build-up on the target surface is leading to higher deposition rates and a more consistent process.

PDC power supplies typically have “active” arc suppression which can add in additional reverse pulses in case arcs are detected.

Ion source

The ion source is a device which creates energetic ions which are directed towards a substrate. The ion sources are available as griddless and gridded type of source. They are commonly used for ion-beam-assisted deposition (IBAD), precleaning, modification and activation of substrate surface.

Ion assisted deposition

In a deposition process, material arrives at the surface of the substrate with a flux, ionization potential and a specific temperature. These factors have a tremendous impact on the density, purity and crystallinity of the deposited film.

Using an ion source, extra energy can be applied to gas-phase material and the thin film via energetic ions.

This influences film properties, such as adhesion, composition, internal film stress and crystallinity.

Process gas inlet

Several deposition processes require a gas inlet, which can be argon, nitrogen, oxygen and some more. We offer suitable mass flow controllers and feedthroughs for these applications.

Film thickness measurement

Various thin film thickness measuring instruments may be installed in the UNIVEX units. The selection depends on the measurements needed and the required degree of automation. As a standard, oscillating crystal systems are used.

These may consist of one or several sensor heads with or without shutter. The sensor head is driven either by a monitor or a controller (measure/control rate and thickness).

Additional UNIVEX coating processes

Substrate treatment

To improve or change the film properties during the deposition process various methods of substrate treatment and manipulation can be applied.

Substrate rotation

Rotation is used to improve thin film uniformity across the substrate surface. We offer a wide range of possible solutions for single or multiple substrates including planetary drives.

Typical combinations with other substrate manipulation features are:

Heating, cooling
RF/DC bias
Height adjustability (source to substrate)
Tilting
Glancing angle deposition (GLAD)
Gradient shutters

Substrate heating

Substrate heating helps to prepare the substrate surface prior to deposition and supports the forming process of the deposited layers. Heating solutions up to 1000°C can be offered.

Substrate cooling

Heat-sensitive substrates or masks require cooling during deposition. We offer substrate holders that can be water-cooled, LN2 cooled or used with special cooling liquids.

Substrate bias

Deposition supported by RF or DC biasing improves the adhesive properties and stoichiometry of the thin film. For this purpose, suitable substrate holders and power supplies are available.

Planetary drives

Our planetary drives are designed for customers' specific substrates and process requirements.

The main substrate stage has a central axis of rotation. Around this axis several individual rotating planets are arranged. The certain position of a planet is always different while rotating on the central axis. This planetary arrangement improves the film uniformity.

Height adjustability (source to substrate)

The source to substrate distance is an important factor for different applications. It has an essential impact on the thin film property. Increasing the source to substrate distance influences the angle of incidence on the substrate. A right angle between the material flux and substrate surface optimizes the property of a thin film.

Depending on the application, different modular components are available.

Substrate tilting

Tilting the substrate is used for different applications. Leybold can provide substrate stages which can be tilted manually and also automatically.

Glancing angle deposition

Tilting the substrate during deposition, interesting structures/patterns (3D) can be created on the substrate. This technique is called Glancing Angle Deposition (GLAD).

Substrate rotation, tilting, heating and cooling are possible. This technique can be used, for example, with a thermal, an electron beam evaporator or a sputter source.

Gradient shutters

With our gradient shutter stage, multiple samples with different thicknesses and material properties can be created.

Cold trap

A cold trap can be placed in the process chamber to condense gases onto an appropriately cold surface. This method enables the reduction of molecules in the chamber and shortens the time until the process pressure is reached.

Load lock

A lock chamber is a very fast method for inserting substrates into high vacuum systems. Each load lock chamber has its own pump system and is connected via a gate valve to the process chamber.

Inside the load lock chamber one or multiple substrates can be stored and transported inside the process chamber. The process chamber just needs to be vented for adding material or cleaning. Transporting the substrates between the individual vacuum chambers, commonly motor driven robot arms or linear transfer drive units are used.

After completion of the process, the transfer arm returns the substrate to its place in the load lock chamber. It can be removed or even stored under a vacuum environment while a new substrate is already in a coating process.

The advantage of the load lock is the reduction of processing times while avoiding atmospheric contamination of the process module. A load lock chamber can be added to any UNIVEX system no matter what type or size.