Ralf’s GaN & SiC News (September 14, 2023)

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Silicon Carbide News

SiC Modules Reach Price Parity with Silicon Modules

SiC power modules now are at price parity with silicon-based modules, said Victor Veliadis , executive director and CTO of PowerAmerica , in an article in Semiconductor Engineering . This in turn is prompting supply partnerships and the construction of new SiC fabs as the industry is running out of older fabs that can be refurbished for $30M. In the meantime, fabless companies are scrounging for capacity. The management of growth in SiC wafers, devices, and modules may be the toughest aspect of the SiC market so far, along with supply chain issues, filling in technology gaps, and geopolitical changes.

And there is still much to be done. SiC wafer technology needs upgrading. To fabricate these devices requires 20% new process tools and 80% modified tools. The goal is a faster turnaround for integrated and discrete power devices, which is why carmakers are moving to direct fab-to-module collaboration.

Assessment of Ceramic DC-Link Capacitor for an 800 V 550 kVA Electric Vehicle Drive Inverter

The DC-link capacitor typically represents the bulkiest component in an EV traction inverter, posing a strict limitation to the achievable converter power density and thus being subject to great pressure for improvement. In this context, novel ceramic capacitor technologies (e.g., PLZT) promise superior performance concerning well-established film-based solutions, featuring higher specific capacitance and RMS current capability.

This paper from researchers at Politecnico di Torino and the National New Energy Vehicle Technology Innovation Center (NEVC) focuses on the analysis, sizing, design, and experimental assessment of a PLZT-based ceramic DC-link capacitor for next-generation EV drive inverters, including a comparative assessment with a state-of-the-art film-based solution. In particular, given the non-linear behavior of the PLZT capacitance value concerning the DC-bias voltage and the amplitude of the excitation, a novel correlation between the effective large-signal capacitance and the peak-to-peak voltage ripple is derived experimentally, providing useful information for the DC-link capacitor sizing (i.e., not available from the capacitor manufacturer).

For verification purposes, a full-scale DC-link capacitor prototype for a SiC MOSFET 800 V, 550 kVA, 20 kHz drive inverter is realized, demonstrating superior power density (i.e., two-thirds smaller and one-third lighter than a corresponding film-based solution). Finally, the inverter prototype is also exploited to validate experimentally the proposed DC-link peak-to-peak voltage ripple estimation procedure, based on the newly obtained large-signal capacitance characterization.

Davide Cittanti , Fausto Stella , Enrico Vico, Chaohui Liu, Jinliang Shen, Guidong Xiu, Iustin Radu Bojoi , "Analysis, Design and Experimental Assessment of a High Power Density Ceramic DC-Link Capacitor for a 800 V 550 kVA Electric Vehicle Drive Inverter," in IEEE Transactions on Industry Applications, doi: 10.1109/TIA.2023.3307101.

ROHMs ‘Product Longevity Program’ Includes SiC Devices

ROHM Co., Ltd. has launched a dedicated page for a new Product Longevity Program (PLP). It provides information on the estimated supply periods of 10 to 20 years for products scheduled for long-term supply – suitable for industrial equipment and other applications with long life cycles. This program also includes SiC discretes and modules.

In recent years, semiconductors and electronic components are being increasingly installed in long-life applications, such as industrial equipment and automotive systems – requiring the disclosure of applicable products and clarification of supply periods to facilitate product selection.

The PLP sets supply periods of 10 to 20 years for products (mainly power and analog) requiring long-term supply, with relevant information such as supply status posted on ROHM’s website. This information (target products, supply periods) will be updated once a year to ensure the continuity of customer operations. ROHM Semiconductor Europe

Volvo invests in Chinese SiC-based power module maker Leadrive

沃尔沃汽车 Tech Fund, the corporate venture capital arm of Volvo Cars, has invested in Leadrive Technology of Shanghai, China, which was founded in 2017 and manufactures power electronics and control units for electric cars, specializing in designing and building power modules that use silicon carbide (SiC). The automotive OEM started this Tech Fund in 2018 to invest in companies and technology areas that transform the automotive industry, such as artificial intelligence, electrification, autonomous driving, sustainability, and digital commerce. The Tech Fund makes strategic investments to help start-ups to thrive and jointly accelerate the transformation of the global mobility industry.

This investment in Leadrive fits with Volvo’s electrification roadmap. Firmly focused on vertical integration, this roadmap also entails collaborating with relevant partners where it makes sense. To make that roadmap a reality, the automotive OEM has doubled down on critical technology investments in recent years and made key decisions on what they build versus what they buy.

“Leadrive’s technology demonstrates a lot of potential for the development of more efficient electric drivetrains,” said Alexander Petrofski , CEO of the Volvo Cars Tech Fund.

Expansion Work at SiCrystal Progressing Rapidly

After SiCrystal’s administration building A and production hall B have already been largely expanded on its company premises in the industrial park Nordostpark Nuremberg, the expansion of production hall C is also progressing rapidly. This is an important step for the subsidiary of the Japanese ROHM Group to meet the increasing demand for SiC substrates for electromobility, as well as photovoltaics, wind energy, and industrial applications. The company rapidly growing also with employers. Currently, there are well over 300 people. The goal is to reach the 400-employee mark by the end of the 2023/24 fiscal year.

“With the expansion of Hall C, we reach another milestone. But SiCrystal's growth continues, of course. We will continue to create the conditions for ever-increasing production capacity in the future so that our products can contribute to global CO2 reduction,” said Robert Eckstein, CEO of SiCrystal GmbH .

Vitesco: Innovative Transfer Molded SiC Power Modules for EV

Vitesco Technologies is developing a SiC power module that will be manufactured using transfer molding. During this process, the power electronics are sealed under a dielectric material that protects the components extremely well. The result is a very robust, cost-effective, and reliable electronic. The power module consists of three overmolded half-bridges and forms the core of an inverter system, which controls both the drive energy and the energy recovery (recuperation) in high-voltage electric vehicles. Manufactured at the Nuremberg electronics plant, the power modules will be delivered to a large global car maker from mid-2025 onwards.

“These power modules are a good example of our strategic approach of using the scalability and modularity of our power electronics to develop and manufacture submodules in addition to the complete electronics,” said Thomas Stierle , Head of Electrification Solutions at Vitesco.

Navigating Electrification: Silicon carbide technologies

With accelerating EV adoption, Silicon carbide (SiC) has paradoxically emerged as both a disruptor and an enabler of the transition. However, automakers face a complex, shifting SiC landscape — nascent technology, a dynamic value chain, diverse investments, and shifting regulations. Join us as we discuss how auto OEMs and tier-1s can sense and adapt - move quickly but stay flexible - to lead through this transition.

Join this webinar session from 麦肯锡 in which Ondrej Burkacky , Abhijit Mahindroo , Anupama Suryanarayanan , and Julia Dragon iscuss how auto OEMs and tier-1s can sense and adapt - move quickly but stay flexible - to lead through this transition.

• Date: September 19
• Time: 4 pm CET / 10 am ET

Gallium Nitride News

Shin-Etsu and OKI Promote QST Substrates for Vertical GaN

Shin-Etsu Chemical and Oki Electric Industry Co., Ltd. have jointly developed a technology to exfoliate GaN from QST substrates from Qromis, Inc. and bond it to substrates made of different materials using Crystal Film Bonding (CFB) technology. Until now, most GaN power devices have been lateral devices, but CFB technology takes advantage of the characteristics of QST substrates to realize vertical power devices that can control large currents by exfoliating a thick layer of high-quality GaN from an insulating QST substrate. To customers who manufacture GaN devices, Shin-Etsu Chemical will provide QST substrates or GaN-grown QST substrates and Oki Electric Industry will provide its CFB technology through partnering or licensing. In this way, the two companies hope to contribute to the advancement of vertical power devices.

Currently, Shin-Etsu Chemical has a line-up of 150-mm and 200-mm diameter substrates, and it is working on 300-mm diameter substrates. Especially for power devices, a continuous evaluation is underway for devices in the range of 650 V to 1800 V.

Power GaN industry: reshaping the ecosystem for enhanced solutions

Yole Intelligence has published its Power GaN 2023 report. The primary driving force behind power GaN is still consumer fast chargers and adapters. Beyond consumer, two additional growth catalysts for power GaN are anticipated: automotive and datacom. GaN adoption in the automotive powertrain is no longer a question of 'if' but rather 'when,' as several automotive Tier 1s have been closely collaborating with device suppliers for nearly a decade, focusing on OBCs and DC-DC converters. In the datacom field, GaN-based power supplies exceeding 3kW with 80Plus Titanium efficiency ratings are already accessible, offering more favorable form factors compared to silicon-based alternatives.

Is the fabless business model sustainable?

The fabless business model still dominates the Power GaN ecosystem in 2023. Most of the fabless companies work with 台积公司 . Meanwhile, other foundries, such as X-FAB and BelGaN , are attracting more attention and gaining more market share. These two foundries do not have internal epitaxy, which is an opportunity for epihouse businesses. 6-inch and 8-inch GaN-on-Si epiwafers are already commercially available from several epihouses, such as IQE , Siltronic AG , 晶湛半导体 , and SOITEC . Foundries and epihouses can also do business with IDMs when, for example, second sourcing is needed. We have already seen 意法半导体 producing its MasterGaN products with TSMC.

Looking to the future, Yole expects some fabless companies to be acquired by IDMs. Other fabless or fablite companies will continue to grow by expanding to other markets and product diversification. For example, Navitas Semiconductor entered the Power SiC business by acquiring GeneSiC Semiconductor . To keep a sustainable business, fabless companies need to invest in foundries and epihouses to secure production capacity.

EPC Blog: This is how GaN is Accelerating Vehicle Electrification

Over the past three decades, automotive electronics have undergone a remarkable evolution, transitioning from traditional internal combustion engines (ICE) to the emergence of battery electric vehicles (BEVs). This progression has not only transformed the way vehicles operate but has also driven significant changes in power distribution architectures and semiconductor components. In this blog post, Renee Yawger from EPC - Efficient Power Conversion examines the three major stages of this evolution – from ICE to mild hybrid (MHEV) to BEV – and explores the role of low-voltage power distribution in shaping the automotive landscape.

White Paper: Normally-Off D-Mode GaN Advantages Vs. Normally-Off E-Mode GaN

Transphorm Inc. has published a white paper titled The Fundamental Advantages of D-Mode GaN in Cascode Configuration. The paper provides a brief tutorial on the inherent benefits delivered by a cascode (normally-off) d-mode GaN platform. Importantly, the paper continues to explain how e-mode platforms by their very nature (physics) ultimately diminish some of those inherent performance benefits to deliver a normally-off solution.

The paper addresses what GaN naturally brings to the table physics-wise. And how a normally-off d-mode GaN solution maximizes those inherent benefits to create a superior platform with greater reliability, designability, drivability, manufacturability, and versatility.

Specifically, the paper explores the role of the 2-dimensional electron gas channel (the 2DEG), a natural phenomenon that spontaneously forms in the GaN HEMT stack. As all GaN platforms (including e-mode) are normally-on d-mode platforms at their core—the paper will go on to examine how the 2DEG’s and the overall platform’s performance is affected depending on whether a d-mode or e-mode based approach is chosen to switch the platform off.

Lastly, select myths about normally-off d-mode and e-mode device performance will be addressed.

The paper is available for free and can be downloaded here: www.transphormusa.com/document/wp-dmode-gan-advantages.

Miscellaneous News

Answer to four common questions about power module stray inductance

Stray inductance is the sum of all unwanted inductance elements from components, wires, copper planes, and traces in a current path. Especially in power modules, stray inductance has a huge impact on switching characteristics, such as switching speed, switching loss, and voltage overshoot.

Measuring the stray inductance of a power module is a complex and important task. Instead of extracting the stray inductance by measurement on a prototype, it would be beneficial to use simulation for that. This blog post from Wilfried Wessel of Siemens EDA (Siemens Digital Industries Software) takes a look at four common questions you need to answer about power module stray inductance:

1. What is the maximum stray inductance of the power module?
2. How parallel devices influence the stray inductance
3. How does the wire bond width influence stray inductance?
4. What is the maximum voltage overshoot of the power module?

WBG Semiconductors See Opportunities Emerging

A webinar was recently conducted by 弗若斯特沙利文公司 Sullivan where several industry experts came together to discuss “Growth Opportunities in Global Semiconductors,” giving due importance to the potential and the challenges of WBG semiconductors. They noted their concerns and enthusiasm toward several opportunities that have arisen for WBG semiconductors.

Stephen Oliver , VP of corporate marketing and investor relations at Navitas Semiconductor , presented the idea of “retrofitting” gallium nitride and silicon carbide. Oliver noted that these materials can be produced using old equipment, making them more accessible for production.

Jonathan Robinson , a global power and energy research leader at Frost & Sullivan, noted the surge in green hydrogen initiatives and increasing government support. “This industry, which was almost non-existent three years ago, is now rapidly deploying significant investments globally,” he said. “China, the U.S. and the European Union are leading the way, with many countries prioritizing equipment manufacturing and hydrogen production within their borders. Geopolitical events over the past 18 months to two years have further heightened the importance of green hydrogen, making it a top priority for many nations. As a result, the green hydrogen sector is on a very strong growth trajectory.”

According to Alexey Cherkasov , marketing and sales director at Leapers Semiconductor , SiC could be employed in the aerospace and hypersonic aircraft sectors. This is attributed to the recent demonstration that SiC can operate at temperatures over 800 °C, sparking interest in space exploration applications of SiC MOSFETs. “The growth prospects for WBG semiconductors in the green hydrogen and space exploration sectors are incredibly promising, and these materials are poised to revolutionize multiple industries with their efficiency and versatility,” Cherkasov said.