Mobility And 5G Drive Adoption Of New Materials For Power Devices

Electric mobility, renewable energy, and other technology innovations like IoT, 5G, smart manufacturing, and robotics all require reliability, efficiency, and compact power systems, fueling the adoption of silicon carbide (SiC) and gallium nitride (GaN) to support lower voltages in significantly smaller devices. But chip designers must overcome the technological and economical challenges of integrating the two semiconductor materials into power systems.

SEMI spoke with Elisabeth Brandl, Business Development Manager at EV Group about trends and new developments within the power electronics industry and the devices’ application in smart mobility. Brandl shared her views ahead of her presentation at the SEMI SMART Mobility Forum, 18 February, as part of the SEMI Technology Unites Global Summit, 15-19 February 2021, online event.

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SEMI: What is driving new developments in power electronics?

Brandl: Globally there are significant changes in infrastructure requirements for communication, automotive and power conversion. We need to look no further than the rising adoption of 5G, electric and hybrid vehicles, and renewable energy as examples of drivers of these changes. The device level, particularly in the field of power electronics, figures prominently in these shifts.

The power electronics industry faces a growing number of scenarios where conventional silicon power devices are no longer suitable and are easily outperformed by new architectures mainly based on wide bandgap semiconductor materials like Silicon Carbide (SiC) and Gallium Nitride (GaN).

SEMI: What industry challenges is power electronics innovation aiming to solve?

Brandl: Power conversion efficiency is very important and needs further improvement as the related losses significantly contribute to the overall power consumption. For green power and a better environmental footprint, renewable energy is crucial, but so is overall power-consumption efficiency, yet the role of power devices is often underestimated. High-frequency and high-power applications, such as data center applications and inverters for renewable energy, where silicon power electronics are reaching their limits, are also important areas in power electronics.

SEMI: How will the transition from silicon to compound semiconductor materials help?

Brandl: The superior material properties of several compound semiconductors can tackle the need for lower losses in power conversion or better high-frequency behavior. Today, we mainly talk about GaN and SiC power devices as they are materials well-suited to address these needs. However, other materials like diamond and gallium oxide are in development for these applications. Material properties of SiC that enable thinner materials with lower power losses and better thermal behavior address power conversion efficiency as well as form factor challenges. GaN, especially in a high electron mobility transistor (HEMT), can be used for high-frequency applications.

SEMI: What enables a better and more cost-effective manufacturability of SiC and GaN power devices?

Brandl: For the end customer, a typical figure of merit regarding the cost effectiveness is $ per Ampere or Watt. While this seems simple, the reality is of course more complex. It is important to understand the main cost contributors within the manufacturing area. For SiC, this is clearly the substrate cost. In my presentation, I will show a way to reduce this cost via wafer bonding.
For GaN, epitaxy – a method for growing or depositing mono crystalline films on a substrate – is the critical parameter. And of course, yield has a very big impact on cost effectiveness too, which means that good process control including metrology is very important.

SEMI: Many semiconductor companies are already transitioning to silicon carbide and gallium nitride. Can you give us an example of a success story?

Brandl: All the big power device manufacturers have either acquired or developed their SiC and/or GaN power device technology, so they also see a bright future for these wide bandgap semiconductors in the power device market. The most prominent success story is STMicroelectronics with its SiC MOSFET power devices, which have been implemented by Tesla in its Model 3 vehicles since 2018.

SEMI: What is coming next?

Brandl: New materials for power devices are being explored, such as diamond and gallium oxide. For SiC, the trend is moving toward 8-inch substrates, which is the focus of the funded EU project REACTION under the coordination of STMicroelectronics. Cost reduction and substrate availability also play a big role. All major power device manufacturers have contracts to secure the supply chain for SiC substrates because material availability is the main uncertainty at this time. Finally, collaborations along the supply chain are crucial and generally beneficial for all parties, as development requirements are better communicated and prioritized.

Elisabeth Brandl is Business Development Manager at EV Group. She received her master in technical physics from the Johannes Kepler University Linz, Austria in Semiconductor and Solid State Physics. Since 2014, she has been responsible for Product Marketing Management for temporary bonding and compound semiconductors at EVG.