M2A
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Development of Silicon Carbide Plasma etch processes for next generation power electronics.

Key Information

Supervisors: Prof O Guy, Dr M Jennings and J Mitchell

Expected Interview Date: March 2020

This project will develop new processes for plasma etching of Silicon Carbide (SiC) and develop new applications in Power Electronic based on SiC devices.

The market for SiC power devices is set to grow exponentially – driven by the electric vehicles market. The trend in terms of hybrid (HEV) / battery electric vehicle (BEV) powertrains is to push the DC voltage to beyond 600V, utilising high battery capacity systems. The purpose here is to reduce the demanding cabling requirements currently hampering electric vehicle performance. Beyond 600V, the only viable power semiconductor device option that can achieve the required efficiency levels is SiC. SiC power MOSFETs will be used within the main inverter powertrain, including a DC boost converter stage if required (see figure 1). Moreover, these higher voltage electric vehicle sales are set to reach 18 million by 2023 (see figure 2). When one considers that this represents 16.2% of total global vehicle sales, the market relevance becomes obviously apparent.
 

  
Figure 1: A schematic illustrating the use of SiC within an electric vehicle powertrain (Yole Development Market Report, 2018).
 
 
Figure 2: EV/HEV Market Evolution up to the year 2023 (Yole Development Market Report, 2018).
 
The EngD project will develop process technology for SiC devices, plasma dicing and new mask coatings. Robust coatings are required for etch-mask materials to pattern and etch trench structures in SiC wafers. These material coatings could be polymers, dielectrics or metals. These coatings will be deposited using SPTS tools for testing. Mask coating development will include conformal dielectric (SPTS MVD system). These coatings will also be trialled for contact pad and gate structures. Further processes will be developed to fabricate metal-oxide-semiconductor field-effect transistors (MOSFETs) in SiC. Novel SiC trench MOSFET designs will be investigated. SiC trench MOSFETs are seen as the future of SiC power devices, with the reduced device pitch enabling a greater number of devices per unit area and thus, enabling lower cost. The challenge is to minimise sidewall microtrenching and striation through efficient mask coatings and process control.

These SiC Power devices will be tested for high voltage applications such as high-efficiency inverters in DC/AC converters for solar/wind power supplies and electric/hybrid vehicles power conversion.

The project will work with the APS SPTS Technologies dielectric etch tool to develop plasma etch recipes to produce vertical side walls. Etch processes will also be investigated further to develop a deep etch process for SiC plasma dicing. Plasma dicing is a signature process for SPTS’s silicon etch tools, but dicing technology has not been fully developed for SiC. The future of power electronic devices will require SiC plasma dicing processes to decrease die size and increase fabrication flexibility.

The challenges for this project will be the development of the masking material, which needs to maintain high resolution features and survive the intense plasma etch process. Additionally, developing a high power etch process that can etch through SiC at high rates (1 µm/minute) whilst maintaining vertical (and smooth trench walls). This will be important for both the development of power devices and the plasma dicing process.

The outcomes of the proposed research are multiple and include (i) creating new masking materials for high power vacuum etch tools, (ii) developing new plasma processes for deep SiC etching for both trench and plasma dicing application (iii) characterising new power electronic devices for high voltage applications based on SiC materials.
 
The Materials and Manufacturing Academy (M2A) in the College of Engineering is a Swansea University initiative which provides postgraduate research training in partnership with industry; providing access to world-class laboratories and a wealth of academic and industry expertise.
 
The M2A is committed to providing top quality research opportunities within an inclusive environment, funded by the Welsh European Funding Office (WEFO), the Engineering and Physical Sciences Research Council (EPSRC), Swansea University and Industry partners.Interwoven through the research study are business, technical and entrep Sponsoring Company SPTS Technologies Ltd

SPTS Technologies, a KLA company, designs, manufactures, sells, and supports etch, PVD, CVD and MDS capital equipment, providing advanced wafer processing technologies and solutions for the semiconductor and microelectronics industry. SPTS are experts in semiconductor film coatings, deposition and etch technology, their revenue generation is from equipment sales and support services supplied to customers in major foundries and IDMs servicing end-market applications including micro-electromechanical systems (MEMS), advanced packaging, LED, high-speed RF device IC’s and power semiconductors. SPTS have a growing activity in technology and products related to Silcon Carbide and are keen to explore this technology with Swansea University.

Company Website Eligibility
We welcome applications from candidates with an Engineering or Physical Sciences degree (minimum level 2:1), or a combination of degree and equivalent experience to the same level.
Normally, we would expect candidates to have met the University’s English Language requirements (e.g. IELTS 6.5 overall with 5.5+ in each component) by point of application. 

Full eligibility can be found at https://www.materials-academy.co.uk/eligibility 

 

Funding
Fees at UK/EU rate and a stipend of £20000 per annum for a period of 4 years.
For full details on funding eligibility, please refer to the Materials and Manufacturing Academy (M2A) Website.
Due to funding restrictions, this scholarship is not open to ‘International’ candidates.
Closing Date 1 April 2020

Start Date October 2020


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Informal enquiries about this studentship are welcome and may be directed by email to: M2A@swansea.ac.uk