In-situ Interference lithography: a new manufacturing approach for the production of nanostructured arrays

Lead Research Organisation: University of Sheffield
Department Name: Electronic and Electrical Engineering


Information processing and communications enabled by advances in semiconductor technology are at the heart of the modern interconnected and application-driven world. Modern society has an enormous appetite for new platforms and services and meeting these demands places a considerable burden on device and systems development. Over the last 50 years, semiconductor manufacturing has met these demands through a scaling of device size to ever smaller dimensions. As a result, we now approach the true nanoscale regime and seek devices of size less than 10nm. The industry is however facing enormous technological and physical challenges to work at this precise scale, equivalent to only a few atomic layers. Yet with these challenges comes also enormous potential from emerging quantum device approaches which could dramatically increase in calculation capability, dramatically improve the security of data and to do this simultaneously with lower energy costs. Our well used semiconductor device production processes, based on epitaxy, patterning and etch will struggle to turn the promise of quantum technologies into manufacturable commercial devices. In contrast, we can grow naturally 'self assembled' structures with nanometer dimensions and from such materials we have extensively demonstrated quantum interactions. However self-assembly has an Achilles heel in that we cannot control the site or the dimensions because of random nucleation. As a result we cannot predict where the nanostructure is located nor its energy state. Unsurprisingly there has been very little development in terms of manufacturable devices utilising quantum technologies. What we need is an approach which combines the best aspects of patterning and self-assembly. The approach is directed (or site-controlled) self-assembly which uses lithography to define the site and then exploits self-assembly to produce the nanostructure.

Structuring with light is the manufacturing technology of the 21st century. Many products now involve cutting, milling, surface processing, sealing etc processes using laser light. Our approach seeks to exploit the capabilities of light at much smaller dimensions, specifically its capability to create regular patterns on a very small stage through the optical interference process. We will design and build a system in which laser interference interacts with semiconductor growth to create a single step in-situ manufacturing route which is free of all major limitations of conventional high cost, low throughput nanostructuring approaches. We will build and demonstrate a custom instrument in which an interference pattern from laser interference interacts with the semiconductor growth surface to nucleate self-assembled growth on a regular grid pattern. Such an arrangement is a key requirement for developing electronic and photonic circuits based on arrays of single nanostructures. The method has the further advantage of precisely controlling assembly such that the array contains identical nanostructures in terms of size, shape and electronic properties. Using this approach we will create large area state of the art quantum dot and quantum wire arrays which are essential building blocks for the semiconductor devices of the future, enabling diverse applications including electronics, photonics, sensing and biomedicine.

Planned Impact

The project seeks to have significant impact on the semiconductor industry, offering a new production method for highly ordered regular arrays of identical nanostructures. New manufacturing approaches such as this are vital to the development of new quantum device systems as well as providing significant opportunities for reduced production cost and yield gains in existing device processes. We strongly believe that present process approaches are fundamental flawed in their capability at the true nanoscale.

Each of our three objectives has the potential to generate significant academic and industrial interest, which will be realised through patents, research publications and conference/workshop, depending on the nature of the disclosure. Key developments in semiconductor nanostructuring and new device measurements enabled by these processes attract publication impact at the highest level, through leading journals such as Nature and Science and we will also seek to disseminate them at leading international conferences in the field.

Our novel approach has already generated significant interest from UK companies within the semiconductor device manufacturing sector (including IQE, Huawei and Oclaro) and Oclaro has kindly offered significant in-kind financial support. These companies have substantial operations in the UK and are world leading in optoelectronic materials and devices. They are high-value industries which underpin UK employment, generate substantial inward investment and gain high-value export revenue. Companies such as these would be in a strong position to take on further manufacturing development and to apply this process in future device schemes. An alternative route to commercial impact is through the UK semiconductor instrument manufacturing sector. In the preparation of this project we have worked closely with Mantis Deposition Ltd on the initial specification of the custom system. The company has indicated its strong interest in our developments and is willing to contribute specialist expertise and technical services to the project. There are opportunities for an SME such as Mantis to develop and sell a new class of vacuum instrument, generating jobs and export revenue.

As part of our developments we would expect to generate significant novel IP. Revolutionary process developments in the semiconductor field can attract extremely high value. We may seek to licence this IP or to develop this through a university-based spin out. Sheffield has experience and a growing track record of in-house exploitation of semiconductor developments though a licensing agreement with Fusion IP. Recent spin-outs include Seren Photonics, Phase Focus Ltd and Quantasol all of which offer suitable models for further development.


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Description We have designed and are currently building a new class of ultra high vacuum reactor within which semiconductor growth can take place whilst we can also apply laser patterning via an interference process. We have also developed an improved theoretical understanding of the interaction of pulsed laser light with semiconductor surfaces, which suggest that our novel method is a viable manufacturing process. In the 2nd year, laser interference lithography has been used to directly pattern the growing surface during Molecular Beam Epitaxy growth of self-assembled InAs quantum dots on GaAs (100) substrates. Arrays of few-monolayer high nano-islands are formed prior to InAs quantum dot growth, which we believe result from the surface diffusion promoted by transient photothermal gradients. The deposition of InAs on such a surface leads to the nucleation of quantum dots solely at the island sites. Thenumber of dots per site is determined by the island size which varies with the laser energy intensity. We are able to achieve highly ordered dense arrays of quantum dots with a single nanosecond laser pulse exposure.The InAs quantum dot arrays showed excellent photoluminescence properties. The technique offers a fast and efficient way to achieve highly-ordered nanostructures for the realization of novel photonic devices or quantum
information technologies.
Exploitation Route Ongoing discussions with industry partners such as Huawei and Oclaro.
Sectors Electronics,Manufacturing, including Industrial Biotechology

Description Developing approaches to create single photon sources for quantum applications with a local company
First Year Of Impact 2022
Sector Digital/Communication/Information Technologies (including Software),Electronics
Impact Types Economic

Description EU Horizon 2020
Amount € 4,100,000 (EUR)
Funding ID 767285 
Organisation European Commission 
Sector Public
Country European Union (EU)
Start 10/2017 
End 09/2020
Title Novel deposition system for in-situ lithographic patterning 
Description Novel MBE system for in-situ interference lithography design and delivered in early 2019 Advancements to the simulation of MBE surface growth processes under pulsed laser excitation. 
Type Of Material Improvements to research infrastructure 
Year Produced 2019 
Provided To Others? No  
Impact In-situ, resits free nano patterning of semiconductor surfaces 
Title Model of MBE surface processes under pulsed laser excitation 
Description Model for surface diffusion and quantum dot nucleation under laser light excitation 
Type Of Material Computer model/algorithm 
Year Produced 2018 
Provided To Others? No  
Impact Improved understanding of the response of semiconductor surfaces to pulsed laser excitation. Predictive modelling of the nucleation of semiconductor nano structures 
Description Research Collaboration with Aegiq 
Organisation AegiQ
Country United Kingdom 
Sector Private 
PI Contribution Collaborative development of materials for single photon sources
Collaborator Contribution Access to specialist facilities and know-how
Impact Developing quantum dot sources for new single photon source product
Start Year 2022
Description Research Collaboration with CEIT 
Organisation IK4-Cidetec
Country Spain 
Sector Private 
PI Contribution Joint research in the improvement of interference patterning techniques
Collaborator Contribution Transfer of advice and know-how. Exchange of samples and data
Impact Joint publications
Start Year 2020
Description Research collaboration SUDA 
Organisation Soochow University
Country Taiwan, Province of China 
Sector Academic/University 
PI Contribution Technical advice. Developing joint publications
Collaborator Contribution Access to research data. Technical advice.
Impact Working on joint publications based on SUDA prior work, which has strong similarities to our project
Start Year 2017