Zero-change manufacturing of photonic interconnects for silicon electronics

Lead Research Organisation: University of Strathclyde
Department Name: Inst of Photonics

Abstract

The silicon electronics industry has two major challenges in the development of new products: demand for increasing levels of processing power on a single chip and the amount of energy required to run these chips. The two challenges are linked, since the more components and communications links that are integrated into the chip, the higher the associated energy usage. While the energy consumption of a single chip is relatively low, this rapidly scales to environmental levels when considering the huge volume of units produced each year is in the order of 10's of billions. Already, large scale data-centres consume around 1% of global electricity demand, so any efficiency gains in the energy consumption of integrated chips will have significant effects.

As device dimensions reach fundamental physical limits, chip designers are developing new architectures in order to continue to deliver growth in chip performance. These designs require high bandwidth communications across millimetre length scales, currently realised as simple electronic tracks. By replacing these tracks with optical interconnects, system power consumption can be reduced and communications bandwidth improved. The fundamental challenge for any alternative technology is that it must be compatible with current electronics manufacturing, where vast investments have been made over the last decades.

This project will develop an optical interconnect layer that has a link power consumption lower than equivalent electronic lines. The optical layer will be realised as a thin film chip that can be interposed between the silicon device and its packaging, meaning that this process is zero-change with respect to the manufacture of the electronic chips. Recent advances pioneered at the Universities of Strathclyde and Sheffield in ultra-high precision micro-assembly of opto-electronic membrane systems will enable a two stage process that is designed to be compatible with production at scale. Firstly, membrane optical sources, waveguides and detectors will be assembled on a glass chip that incorporates electrical vias. This interposer with integrated optical interconnects will be integrated between the electronic chip and its packaging using micro-assembly processes.

The project is supported by industrial partners Alter Technologies and Fraunhofer UK who will provide resources and expertise in opto-electronic packaging and optical systems engineering. This will ensure new process developments with industrial standards and design rules.

The proposal aligns with EPSRC's ICT and Manufacturing the Future themes and the Photonics for Future Systems priority, addressing specific portfolio areas such as Manufacturing Technologies, Optical Communications, Optical Devices & Subsystems, Optoelectronic Devices & Circuits, Components & Systems.

By the end of the project we will have demonstrated an optical transmission link with energy consumption lower than an equivalent electronic line. This link will be integrated with a commercially available silicon transceiver chip to demonstrate feasibility of developing this technology as a back-end process in the silicon electronics industry.

Planned Impact

Potentially, the impact of this project could be substantial in the field of manufacturing for silicon electronics, and opto-electronics packaging in general. Furthermore, development of an optical interconnect layer that is integrated as a back-end process to electronic chips has the potential to significantly reduce energy consumption. Although this effect is likely to be modest at the chip-scale, in the order of a few %, this would represent large energy savings at the scale of data-centre deployment. Specific activities that will be undertaken to progress the exploitation of research results towards these large scale industrial targets are detailed in the Pathways to Impact document.

In the shorter term the research will produce impact in a number of different areas:

Academic impact
The research is expected to generate results in key portfolio research areas such as Manufacturing Technologies, Optical Communications, Optical Devices & Subsystems, Optoelectronic Devices & Circuits, Components & Systems. The outcomes of the proposal will provide a new standard for integration that is directly relevant to the applications being targeted by most of these research areas. To maximise the academic impact, the outcomes of our research will appear in open-access journal papers and be accessible through the web pages of the investigators and the university libraries. Also, with the support from Alter Technologies and Fraunhofer CAP, we aim to establish a UK transfer printing capability available to academic researchers.

Industrial Impact
The vast levels of historical investment into the silicon electronics manufacturing industry and large infrastructure and running costs are prohibitive barriers to new entrants to the market. Nevertheless, next generation electronic systems will rely strongly on advanced packaging solutions and back-end processing of silicon chips. This is an area where the UK has significant expertise and infrastructure, putting it in an excellent position to lead early efforts in this area. This programme will enable the development of back-end silicon electronics manufacturing compatible with the existing industry, currently dominated by large corporations in the US and Asia. Our industrial partners Alter Technologies and Fraunhofer UK, will enable commercial access to prototyping demonstrations of technologies developed by this project, by the end of its duration. The methods and processes developed, when translated through to commercial exploitation, will enable a wide range of SMEs in the UK and around the world that require compact, low size weight and power opto-electronic systems integration. These include optical backplane technologies for small satellites and server racks, high-power electronics for switching, and optical switch network nodes.

Researcher/student Impact
The training of PhD students and PDRAs in the methods and technologies developed under this project will be a key outcome of this work. At least 3 PhD students will be trained under this programme and equipped with the required skills to become valuable resources for UK industry. The PhD students will be exposed to a rich academic and industrial research environment and will undertake advanced level training that includes skills in distributed working, collaboration, entrepreneurship and business planning skills. The project PDRAs will be encouraged to take advantage of the various opportunities, resources and support for early career researchers, such as the transferable skills training programmes that include several courses for personal, professional and career development (e.g. relating to teaching, enterprise, knowledge exchange, employability, public engagement, fellowship and proposal writing, project management). Given the close links with industrial partners, there will be significant opportunities for junior researchers to benefit from follow-on projects under the knowledge exchange agenda.
 
Description So far this project has developed the technology to integrate photonic chips from different materials together. Waveguides that guide light around the chips have been created that enable light to be emitted/received from/to the chip into the vertical direction using micro-mirror technology. In addition, micro-lasers have been developed to match these vertically coupled waveguides. This will enable more compact and energy efficient communications and computing systems in future.
Exploitation Route The latter period of this programme will convert research component advances into system demonstrations. These demonstrations will then make the technology available to end-user groups in optical communications and computing fields, both in academia and industry.
Sectors Digital/Communication/Information Technologies (including Software)

Electronics

Energy

Manufacturing

including Industrial Biotechology

 
Description This research has provided evidence of the potential of heterogeneous integration for the future of the semiconductor manufacturing industry. Results have informed contributions to policy documents and consultations.
First Year Of Impact 2023
Sector Digital/Communication/Information Technologies (including Software),Electronics,Energy,Manufacturing, including Industrial Biotechology
Impact Types Policy & public services

 
Description Contribution to policy evidence on integrated photonics
Geographic Reach National 
Policy Influence Type Implementation circular/rapid advice/letter to e.g. Ministry of Health
 
Description Contribution to policy evidence on photonics industry
Geographic Reach National 
Policy Influence Type Implementation circular/rapid advice/letter to e.g. Ministry of Health
 
Description UK Semiconductor Strategy Consultations
Geographic Reach National 
Policy Influence Type Contribution to a national consultation/review
 
Description Canada UK Commercialising Quantum Technology Programme: CR&D
Amount £515,142 (GBP)
Funding ID 10077950 
Organisation Innovate UK 
Sector Public
Country United Kingdom
Start 08/2023 
End 09/2025
 
Description Ultrafast Terahertz Polarimetry Enabled by Semiconductor Nanowire Sensors
Amount £295,821 (GBP)
Funding ID EP/W017067/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 08/2022 
End 08/2026
 
Title In-situ optical probing of integrated photonic chips in transfer print systems 
Description Optical injection of coherent and incoherent sources imaged onto photonic integrated circuit chips was enabled using custom microscopy and opto-mechanic mounts on our transfer printing system. This allowed imaging and optical probing of on-chip elements during printing stages. The major impact of this in-situ metrology was to remove the need for separate assembly and characterisation tools, making the system compatible with future volume manufacture of high precision optical components. 
Type Of Material Improvements to research infrastructure 
Year Produced 2022 
Provided To Others? Yes  
Impact Optimisation of optical component assemblies in real time. 
 
Description Collaboration with Alter Technologies 
Organisation TÜV Nord Group
Department Alter Technology TUV Nord UK Limited
Country United Kingdom 
Sector Private 
PI Contribution Collaboration on dense photonic interconnects, packaging and opto-electronic systems. Realisation of new micro-fabrication processes and devices.
Collaborator Contribution Access to state-of-the-art industrial packaging solutions. Industrial standards and design rules consultation.
Impact PhD studentship support, access to industrial tools, engineering consultations on research plans.
Start Year 2019
 
Description Collaboration with the Fraunhofer Centre for Applied Photonics 
Organisation Fraunhofer Society
Department Fraunhofer Centre for Applied Photonics (CAP)
Country United Kingdom 
Sector Academic/University 
PI Contribution A novel nanoscale alignment technique for direct transfer printing was developed by the University of Strathclyde. Through joint studentship funding with the Fraunhofer CAP, this capability was developed into an accessible computer controlled system to allow all users of the facility access to the technique.
Collaborator Contribution Fraunhofer CAP provided studentship funding, supervisory time and expertise in automated systems.
Impact The outcome of this stage of the collaboration was an accessible computer controlled system for high accuracy printing alignment.
Start Year 2017