ON Semiconductor SiC experts comment on the debate between planar and trench, and the secrets to SiC success
Latest update time：2024-09-19
Reads：
"China is the world's largest and fastest-growing pure electric vehicle market, and Chinese OEMs are adopting ON Semiconductor's silicon carbide solutions because our chips and modules, such as the M3e we just released, have market-leading efficiency," ON Semiconductor CEO Hassane said in a conference call.
In fact, ON Semiconductor's SiC growth has been widely confirmed. In a 2023 report, Poshun Chiu, senior analyst at Yole Intelligence, pointed out that major IDMs are taking advantage of the fast-growing power SiC device market (which has doubled in size from the first quarter of 2022), but ON Semiconductor's growth rate exceeds that of its peers, including market leader STMicroelectronics.
With the market's enthusiasm for high-efficiency and green products, and the hot consumption of the new generation represented by electric vehicles, silicon carbide has become an increasingly popular selling point in the market. Throughout ON Semiconductor's recent roadshows, all analysts discussed silicon carbide as a hot topic with the company's leadership.
Recently, Dr. Das, a senior product expert from ON Semiconductor's Power Solutions Business Group, came to China and discussed with the media about the future of ON Semiconductor and silicon carbide. We also got a lot of information from the conversation. Let's explore the secret of its success.
Dr. Das, senior product expert of ON Semiconductor Power Solutions Group
Dr. Das is no stranger to China. He served as technical marketing and market director at Sanan Optoelectronics from 2020 to 2022. In 1994, Dr. Das entered Purdue University, specializing in silicon carbide, and has since worked at Cree, Wolfspeed and TI. This year marks his 30th year in the silicon carbide industry.
Vertical Integration and Fab Rignt
The geographical and market diversification strategy is the primary reason for ON Semiconductor's rapid growth in silicon carbide. Even when market growth slows, ON Semiconductor "is still expected to achieve more than 2 times the growth of the silicon carbide market in 2024."
Both Hassane and Dr. Das have repeatedly mentioned on different occasions that one of ON Semiconductor's competitive advantages is its complete vertical integration capabilities. Since the acquisition of GTAT, most of ON Semiconductor's silicon carbide substrates are manufactured internally. This IDM model also ensures that both the quality and supply of products are guaranteed.
However, Dr. Das also emphasized that ON Semiconductor has always adopted a flexible supply model. For example, for substrates, it will also retain third parties in order to flexibly meet the changing needs of the market.
ON Semiconductor's vertically integrated supply chain model
When talking about the hot topic of upgrading to 8 inches, Dr. Das also said that ON Semiconductor is currently in the process of transition, depending on market demand. "We will choose the platform that is most valuable to both us and our customers, ensuring reasonable pricing and sufficient supply." Although this is slightly conservative compared to our competitors, it is the best choice in the current market environment. Dr. Das added, "Our factories are mainly focused on brownfield expansion, so that only a small investment is required to have silicon carbide production capacity, and the utilization rate of the wafer factory can be flexibly allocated through the global layout."
Under the Fab-Right strategy, ON Semiconductor allocates specific production capacity and optimization to each wafer fab, achieving lean operations. "Compared with greenfield investment, it can reduce capital expenditure by 40%."
Flat or grooved?
The dispute between planar and groove technology is currently the two technical routes for silicon carbide, and the debate over the choice between the two has never stopped.
Dr. Das also gave a detailed explanation. First of all, for the MOSFET structure, the biggest advantage of the planar structure is the high reliability of the gate oxide layer. The gate oxide layer is the weakest link in the MOSFET. At that time, the research and development of this technology had lasted for more than 40 years, and it has been in practical application for more than 15 years to date, which has fully proved the reliability of the planar structure.
Dr. Das also pointed out the shortcomings of the currently popular trench structure. Although the trench structure can significantly reduce the chip size, the current utilization rate of the trench structure can only reach 50%. The main reason is that the gate oxide layer must be well protected, because once the gate oxide layer is exposed to the magnetic field and electric field, it will reduce the mission life and cause failure. Specifically, due to the difference in materials, the silicon carbide trench structure cannot completely replicate silicon. The electric field strength of silicon is only at the level of 200-300kV/cm, while the peak electric field of silicon carbide will reach 3000kV/cm. In the planar structure, the gate oxide is in the low electric field area, and when the gate oxide is in the trench device, it will be affected by the high electric field and it is difficult to effectively protect it.
In addition, imagine that in a trench structure, the crystal structure is in the form of silicon, carbon, silicon, and carbon. This form of oxidation is much more complicated than a planar layer.
For this reason, Dr. Das said that trench silicon carbide technology is often delayed because oxide is completely different from existing silicon-based trench technology, and all manufacturability, reliability, performance, etc. need to be re-verified.
At present, the utilization rate of the groove structure can only reach 50%.
"For ON Semiconductor, we must ensure that we have a lot of time for accumulation and verification to ensure the maturity of the technology and sufficient performance and cost-effectiveness before transitioning to the trench structure," said Dr. Das.
Dr. Das said that ON Semiconductor's latest M3e will be the last planar silicon carbide MOSFET, and ON Semiconductor has developed a detailed roadmap to switch to trench technology. "M3e is already the limit of planar MOSFET. If we want to further improve it, we can only use trench technology."
The last generation of planar architecture M3e
As the last generation and the most classic M3e, how much of the silicon's ultimate capabilities can be brought into play? Dr. Das gave a detailed explanation.
The EliteSiC M3e MOSFET significantly reduces conduction and switching losses on a reliable and field-proven planar architecture. Compared to previous generations, the platform is able to reduce conduction losses by 30% and turn-off losses by up to 50% [based on internal comparison testing with EliteSiC M3T MOSFET]. By extending the life of SiC planar MOSFETs and achieving outstanding performance with EliteSiC M3e technology, ON Semiconductor can ensure the robustness and stability of the platform, making it the technology of choice for key electrification applications.
Dr. Das specifically stated that the cell structure of M3e is optimized to reduce switch conduction loss and switching loss while reducing the size.
End customers require not only high performance, but also low cost, high reliability, and more importantly, the best performance in the system. Dr. Das emphasized that M3e has the best performance in different scenarios, whether soft switching, hard switching, high frequency or low frequency.
For example, in the traction inverter, conduction loss accounts for about 80% and switching loss is only 20%. Therefore, in this hard switching topology, conduction loss needs to be considered more. Its FOM is Qgd×Rds, where Qgd represents the switching speed from gate to drain and Rds is the on-resistance.
In the on-board charger application, the PFC power factor correction circuit is a totem pole topology. Although it is also a hard switch, the frequency is about 100Khz, which is much higher than the 10kHz of the traction inverter. Therefore, in this case, the conduction and switching losses are both 50%. In the back-end DC-DC conversion, a soft switching topology is used. There is no so-called switching loss, and only the conduction loss needs to be paid attention to. In addition, due to the high switching frequency, the loss of the gate driver is also an important consideration.
Dr. Das said that M3e has the best FOM performance in various applications. "In the development process of all new products and technologies, we track and refer to relevant factors to ensure that they are at the best level in the application so that they can be used effectively."
Understanding Optimization from a System Perspective
Dr. Das emphasized the importance of the solution in the system. In addition to achieving the best kilowatt cost and efficiency for the die itself, packaging is also very valuable, ensuring that no additional costs are added during implementation at the system level while ensuring performance optimization.
"For ON Semiconductor, we have a very strong product portfolio, not only component optimization, but also system-level optimization. Through ON Semiconductor's gate driver, controller and other product portfolios, we ensure that components work together to create best practices and cost-effective systems for customers and the industry." Dr. Das said.
Dr. Das works in the Power Solutions Business Group, while controllers and other products belong to the Analog and Mixed Signal Business Group. Through cross-departmental collaboration, we deliver out-of-the-box, optimized systems to customers, thereby accelerating their development cycles.
For example, ON Semiconductor's latest F5PB PIM module integrates 1050V FS7 IGBT and 1200V D3 EliteSiC diode, which can achieve high voltage and high current conversion while reducing power consumption and improving reliability. By optimizing the internal electrical connection, the inductance is reduced, which can help to achieve better and lower switching losses.
Final Thoughts
Dr. Das pointed out that thirty years ago, there were many unresolved issues regarding silicon carbide, which is why all the top universities established relevant laboratories. Fortunately, thirty years later, all the problems have been solved one by one, and it has truly moved from the laboratory to the market and become a mainstream technology.
"Back then, silicon carbide wafers were only the size of my fingernail, but now we have 8-inch wafers, and the cost is acceptable to the public. This is also a manifestation of the progress that technology has brought to society," said Dr. Das.
He said that silicon carbide is unique. Carbon, which is also the basic constituent element of diamond, is the material with the best quality factor among currently known power semiconductors, while silicon has the best manufacturability in the industry. The combination of the two is a perfect combination of quality and cost-effectiveness.
"I am very fortunate to have witnessed the process of silicon carbide changing the world." Dr. Das concluded. In fact, not only in the automotive field, the success of silicon carbide has extended to the industrial market. With the emergence of emerging mass market applications such as commercial heating, ventilation and air conditioning, the demand has exceeded the scope of energy infrastructure. The use of 1200-volt silicon carbide and HVAC applications can achieve more efficient, reliable and compact systems, ultimately reducing energy consumption, electromagnetic interference and operating costs. In addition, with the rise of AI, data centers are consuming more and more electricity, and silicon carbide is also entering this field to reduce the power consumption of data centers.
· END ·
What else do you want to see about automotive electronics? Please leave a message below to communicate!
You are welcome to set us as “
Star
” so that you can receive push messages as soon as possible.
Scan the QR code to follow:
Automotive Development Circle
, reply "
bus
"
Get a collection of automotive bus system design materials for free !
Scan the QR code to add the assistant and reply "join the group"
Exchange experiences with automotive developers face to face
京公网安备 11010802033920号