University of Warwick’s Dr Peter Gammon, associate professor in SiC power electronics explains how a probe system supplied by Inseto is key to its SiC device development


he University of Warwick has been using a SemiProbe PS4L probe system

supplied by technical distributor of equipment and materials, Inseto for developing fabrication processes for next generation silicon-carbide (SiC) power

semiconductor devices. The PS4L provides an accurate and repeatable means of mechanically interfacing fabricated prototype devices – as die or still on the wafer – with an analyser that can inject thousands of volts and measure hundreds of amps. Dr Peter Gammon, Associate Professor

(Reader) in SiC Power Electronics at the University of Warwick, said: “We’re involved in a number of projects that are pushing the boundaries of silicon carbide power device research that will hopefully lead to the volume manufacture of device types that can currently only be fabricated in silicon. The PS4L is an invaluable tool in our endeavours as not only can it handle the high power from/to the analyser, but it is semi-automated, allowing us to collect a large amount of data from highly repeatable tests.” Dr Gammon states that most

commercially available SiC power devices are unipolar structures, such as diodes and MOSFETs, which are well established and commercially available with high voltage ratings. “We’re looking beyond these though, at bipolar devices that include IGBTs and


thyristors because they will further enable highly efficient and ultra-high voltage applications, such as traction inverters and high voltage direct current in a low carbon society,” says Dr Gammon. “For example, silicon IGBTs are typically rated up to about 2,000V. As part of our work with the EPSRC Centre for Power Electronics, we are today producing silicon carbide IGBTs rated to 10,000V, with scope to go to 30,000V in the future.”

Figure 1: The University of Warwick turned to Inseto for a SemiProbe PS4L probe station to evaluate ‘next generation’ silicon carbide power semiconductors

such as diodes, in order to evaluate the repeatability of our fabrication processes.” Following the supply and commissioning

of the SemiProbe equipment, a software interface was written by Dr Gammon’s team to enable the PS4L and the high voltage parameter analyser to work together. “Both OEMs were incredibly supportive and gave us access to the source code of their respective products,” notes Dr Gammon. The equipment is in use at the University

“The equipment is in use at the University of Warwick, one of only a few

universities in the UK with SiC fabrication capabilities, and it has already enabled

Dr Gammon’s team to capture data from larger test batches

than would have otherwise been practical before”

The PS4L is enabling Dr Gammon’s team

to apply voltages of up to 10,000V and measure currents of up to 100A to confirm the performance and breakdown voltages of their devices. He says: “While we’re heading towards the production of IGBT and MOSFET switches, we’re able to do much of our work on simple structures

of Warwick, one of only a few universities in the UK with SiC fabrication capabilities, and it has already enabled Dr Gammon’s team to capture data from larger test batches than would have otherwise been practical before. Also, there is more confidence in the data collected through automated processing, as it removes the discrepancies of manually obtained data, such as probe tip to pad alignment inconsistencies and variations in contact force. Dr Gammon, concludes: “Our new

equipment represents a real game changer and the support Inseto provided has been exemplary throughout the

entire process, from them understanding our requirements through to ensuring the PS4L was fit for purpose now and in the future.”



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