At SemiQ, we have just announced the third generation of our SiC power MOSFETs. At this stage in the technology’s lifecycle, we can achieve large improvements as we evolve from one generation to the next. Our latest devices offer significant gains in important parameters, particularly the RDS(on). Our third-generation portfolio contains packaged devices with RDS(on) from 80 mΩ to as little as 16 mΩ. We have also achieved valuable gains in switching performance that have not only increased efficiency but also make for more robust switching that’s less susceptible to noise or unwanted transients. Achieving both faster response and increased ruggedness is a win-win that makes us particularly proud.
Higher Performance, Switching Control and Design Flexibility
In moving from our 50 nm second-generation process to the new 40 nm technology, we have also introduced a new octagonal cell structure. This has helped greatly reduce the effective die size leading directly to a 25 percent improvement in RDS(on). Moreover, the smaller architecture has contributed towards achieving greater yield of devices per wafer that enables the latest devices to become more affordable.
The switching threshold voltage (VTH) has also increased between generations – by 40 percent, from 2.5 V to 3.5 V. This is particularly important for high-power applications, which demand the use of higher switching frequencies in pursuit of greater power density, with this higher VTH allowing more precise control over switching transitions and therefore greatly reducing the risk of false triggering.
As engineers have adopted SiC MOSFETs in their projects, one of the most important changes in circuit design has been in the gate-drive waveforms. The typical gate voltage (VGS) needed for full turn-on is 15-20 V (silicon devices need 10-12 V), while a negative voltage should be applied for proper turn-off. Designing the gate-drive circuit can be a challenge and care must be taken to avoid resonance that can cause ringing resulting in unwanted spurious switching. By increasing the internal gate resistance in our third-generation devices, we have been able to reduce the tendency for resonance and ringing as well as permitting a lower external resistance value thereby saving power dissipation.
Available in TO-247-4L, SOT-227 and TSPAK Packages
SemiQ currently has 1200 V devices available as bare die and discrete packaged devices. We apply 100 percent unclamped inductive switching (UIS) to screen discrete package devices at avalanche breakdown conditions, and wafer level high temperature reverse bias (HTRB) screening is available for automotive bare dies at 1200 V and 175°C. SemiQ has also already secured AEC-Q101 qualification across a number of its components, and this is set to increase with the automotive qualification program ongoing.
Parts are available in bare die and in a 4-lead TO-247 package and SOT-227, with new application opportunities for the new generation expected as a result. The enhanced affordability that comes with this smaller die size allows us to position devices for automotive systems such as e-compressors and on-board chargers (OBC) in hybrid/electric vehicles, in addition to traction inverters that typically demand bare die. These affordability and size benefits also open the advantages of SiC – including greater reliability and high-temperature capability – to industrial and appliance markets.
As we look to future development, we will begin to offer additional package options, and further broaden the appeal of these new generation devices. These will include isolated TSPAK devices, as well as topside-cooled packages.
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