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Cluster Tool

The ambient processing cluster tool is a custom-built glovebox cluster tool that integrates different vacuum as well as liquid-based deposition technologies for a wide range of functional materials into a common inert glove box atmosphere. It comprises ten glove box modules that are interconnected by a semi-automated inert atmosphere transfer system and includes tools such as thermal evaporation, sputtering, pulsed laser deposition (PLD), chemical vapour deposition (CVD) and atomic layer deposition (ALD) as well as aerosol printing, screen printing and slot-die coating. The tool also includes modules for metrology, thin film encapsulation and packaging. The tool gives access to a wide range of functional materials, including transition metal oxides for battery and other applications, organic and hybrid organic-inorganic semiconductors, two-dimensional materials, polymer composites etc.

Its unique configuration allows integration of these different classes of materials into novel hetero-architectures and but also fabrication of a wide range of devices including solar cells, batteries, mechanical or thermoelectric energy harvesters as well as integrated energy systems for energy–efficient ICT applications.

If your research interests require controlled deposition of any of the above materials or you would like to combine functional materials in novel ways and have any questions on the tool’s capabilities please contact the academic lead Professor Henning Sirringhaus ( hs220@cam.ac.uk ) or the technical lead Dr Steve Haws ( sah219@cam.ac.uk ) in the Depertment of Physics.

 

The ambient processing cluster tool is a custombuilt glovebox cluster tool that integrates different vacuum and liquid-based deposition technologies for a wide range of functional materials into a common inert glove box atmosphere. It comprises ten glove box modules that are interconnected by a semi-automated inert atmosphere transfer system. This facilitates combining different materials from both wet and vacuum processes into functional architectures.

The tool gives access to a wide range of functional materials, including transition metal oxides for battery and other applications, organic and hybrid semiconductors, two-dimensional materials, polymer composites etc. Its unique configuration allows integration of these different classes of materials into novel hetero-architectures, and enables fabrication of a wide range of devices, including solar cells, batteries, mechanical or thermoelectric energy harvesters, as well as integrated energy systems for energy–efficient ICT applications.

There are currently nine process modules that comprise the following:

A. Battery Module: PLD, evaporator, and DC/RF sputterer

This module supports deposition of sputtering of battery electrodes and solid electrolytes. With multi-source target arrays, metals and metal oxides can be deposited to form, for example, lithium ion batteries and supercapacitors. It can quickly achieve base pressure of 5 x 10-7 mbar and enables deposition of relatively thick films of transition metal oxides for cathodes and solid-state electrolytes. The module is run under an argon atmosphere.

The PLD system has single and twin beam operation, thermal ramp of substrates up to 20 °C/min to 500 °C and 10 °C/min from 500 to 1000 °C, and has six locations for 1 inch diameter, 6mm-thick targets. The system can achieve up to 4 J/cm2 laser fluence with 20 nm pulses, 28 MW power per pulse, maximum power of 700 mJ, and pulse repetition rates of up to 10 Hz. Process recipes can be programmed to allow automated running of processes. The evaporator can accommodate a wide range of materials due to a PID-controlled source temperature up to 1200 °C, and has an integral link to the sputterer to enable sequential operations without breaking vacuum. The sputterer is for deposition of metals and transition metal oxides for battery construction, with two DC and RF sputter target positions.

B. Coating 1 Module: High-resolution screen printer

This affords high resolution and high precision patterning of pin-hole free patterns to support the definition of device structures on a range of substrates, including glass and plastic film. This includes multiple-print processes, stacking, wet-dry, dry-wet and limited micro gap printing. Many different base substrates can be printed on, including ceramics, silicon wafers, foils and paper.

C. Printing Module: Aerosol printer and slot-die coater

Aerosol printing allows a wide range of materials, including silver, to be deposited in fine and complex patterns down to 10 μm resolution using a suitable ink precursor. Device structures including small contact pads can be created and aligned to previous layers. The slot-die coater allows pin-hole free films to be deposited, for example the deposition of encapsulating materials to seal solar cell devices from moisture and air.

D. Organic Module: Vacuum thermal evaporator and spin-coater

This module is designed to produce organic semiconducting devices such as organic LEDs, organic solar cells, OFETs and thermoelectrics. New device structures often require the combination of different preparation methods. The deposition of the required thin film can be realised by solution-based processes, or via physical vapour deposition under vacuum conditions. The system is split into two sections, one section is dedicated to solution processing, the second is for vacuum deposition of organic and metal layers. The evaporator allows (co-)evaporation of organic molecular compounds, inorganic compounds (e.g. MoOx, LiF) and/or metals (e.g. Au, Al, Ag). While metals and inorganic compounds can be simply evaporated using thermal sources (boat-type or effusion cells) under high vacuum conditions, organic compounds must be evaporated with special care. Precise temperature control over a wide temperature range is combined with a special source design to allow deposition of organics. The spin-coater may be programmed to modify recipes of multiple steps, and may operate over a wide parameter range (speed, acceleration, deceleration etc. may be carefully controlled). Complex devices where various solvents were used in deposition will benefit from a regenerable solvent vapour removal system integrated in the glove box purification system, to ensure a contamination-free environment.

E. Hybrid Module: Vacuum thermal evaporator, spin-coater and hotplate

The hybrid module is designed to produce combinations of organic semiconductors, polymer nanocomposites and hybrid organicinorganic semiconductors, such as metal halide perovskites. And can handle precursors such as MAI (Methylammonium iodide), PbCl2 and PbI2 for perovskite solar cells. The system is split into two sections. One section is dedicated to solution processing, the second is for vacuum deposition of layers in a special PVD system. The evaporator enables deposition of perovskite solar cells and organic/inorganic FETs. The spin-coater may produce films from a solvent based source, and the hotplate is used to drive off the solvent fraction from a coated film.

F. Coating 2 Module: Atomic Layer Deposition (ALD)

ALD affords exceptional conformal deposition of oxides in monolayer-by-monolayer precision. This allows very effective encapsulation of a device structure, and also allows fabrication of the highest quality dielectrics for capacitor and TFT structures.

G. Packaging and Encapsulation Module: Automated glue dispenser and UV curing press

This allows a range of UV-curable types of sealant beading to be precision-deposited for subsequent UV curing in the press. This module supports effective encapsulation, vital for many solar cell architectures.

H. Testing Module: Dektak profilometer

The profilometer can measure the height of features from around 50 nm to 150 μm. Surface roughness can be measured to sub-nm levels, supporting the characterisation of film morphologies. Whether measuring thicknesses to obtain critical values for device simulation or for process control, such measurements are vital for the range of deposition techniques used in battery, solar cell, TFT and OLED architectures.

I. Substrate Module: Plasma asher and vacuum oven

Plasma ashing of surfaces is an established technique for promoting adhesion of a subsequent coating, through enhancement of surface wetting characteristics by the removal of organic surface contaminants. The vacuum oven can be used with low heat to evaporate off the solvent component of a deposited layer, and may be operated without heat for temperature-sensitive systems. Such treatment can be important in the preparation of a surface for subsequent material depositions.