Development and commercialisation of dual resist technologies for fabrication in compound semi-conductors

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Innovate UK
Innovate UK
Innovate UK
Innovate UK
Innovate UK

£1,427,845

Nov. 1, 2020

April 30, 2022

Use of III-V compound semiconductors (CS) in a range of applications including high speed/power electronics, lasers, power amplifiers for mobile phones, RF/microwave, space-tech and photonics is on rise due to their superior light receiving/emitting functionality, very high frequency signal generation capacity, at-least 100-times more power than their silicon counterparts, high-speed signal processing, low voltage operation and magnetic/heat sensitivity.

CS patterning utilises following two major lithographic tools followed by an etch step (where the written pattern is transferred into the CS substrate):

* Photolithography(PL)--widely used, working at 365, 248 and 193nm for production of Integrated circuits (ICs); shorter wavelengths are only available for largest manufacturers (e.g. Intel/Samsung/TSMC/Global Foundries) but a large industry depends on fabrication at 365nm.
* Electron Beam Lithography(EBL)--used for key steps in electronics (e.g. mask-making) and more widely in smaller foundries to produce micro/nano-structures

III-V CS hardness presents significant technical challenges to etch thin deep features at high resolution (<100nm) and to etch through multilayer structures required for high-end future applications such as micro Lasers/LEDs, nanoscale spectrometers, sensors and wireless communications.

State-of-the-art solutions include positive (ZEP520A-chloroacrylate/styrene copolymer) and negative (HSQ-hydrogensilsesquixoane) tone solutions. ZEP520A gives an etch selectivity of 5:1\. which is insufficient to write deep thin structures, or to etch through multilayers of CS. HSQ can achieve etch-sensitivity of 7:1 but has drawbacks of requiring skilled chemist/lithographer, limited shelf-life due to degradation over time and damage to CS surface through adhesion.

Building upon outputs of Innovate-UK project (\#104747) and our expertise in making Heterometallic-Ring-Complexes as building blocks, we have already developed a lab-scale manufacturing process with a throughput of 0.5litres/day of resists which can be used with silicon nanostructures (9nm wide and 330nm high).

Driven by global end-user manufacturers' (Jet Propulsion Laboratory, CST, Microsemi, NASA, Ryan Briggs, Hughes Research Labs) demand of etching thin deep features at higher resolution and to be able to etch through multilayer structures; we can produce proof-of-principle quantities of (ca. 0.3litres) high-etch resists to be used with CS.

This 18months industrial-research project aims to design and build a flexible manufacturing facility producing high-etch resists (capacity=50 litres/annum @ production cost of <£400/litre) to enable fabrication of thinner deeper structures and multilayer structures of differing CS in many fewer write-develop-etch steps.

Project success will generate a catalogue of resists, made in small batches by Sci-Tron but all ready for contract manufacture. Sci-Resists will offer competitive advantages to all adopters and help growth of UK's vital high-tech sector.