DENSO Corporation has been continuously working towards spreading the use of electric vehicles (EVs), extending their mileage, and reducing CO2 emissions from vehicles by developing SiC (silicon carbide) power semiconductors, which incorporate DENSO’s proprietary structures and processing technologies and using them in its in-vehicle products.
SiC devices have attracted attention because they accelerate the electrification of vehicles.
Tomoo Morino / R&D.Dept.4, Power Module Eng. Div., “I was in charge of determining the specifications of the SiC power semiconductor with the power module design department and designing the device structure based on the specifications. SiC has a low resistance compared to Si and so electric current can flow more easily. Due to this property, a prototype SiC device was damaged by a sudden surge of a large electric current. We collaborated with other departments to discuss how to prevent damage to devices in the market while taking full advantage of the low-loss performance of SiC, and the issue was solved with an idea which our department could not come up with alone: high-speed cut-off of the electric current using a special driver IC.”
Tomohiro Mimura / R&D.Dept.4, Power Module Eng. Div., “I was in charge of the process design for manufacturing SiC power semiconductor devices. The hardness of SiC is second only to diamond, so it is more difficult to process than Si. I struggled to design a mass production process that can stably deal with microstructures of less than one micrometer. DENSO has been researching SiC for many years, and so there are many predecessors and senior employees. To solve this problem with SiC, I frequently talked with senior employees to learn from their experience and know-how, and also took full advantage of existing technologies. This made it possible to commercialize the product.”
Satoru Sugita / Design Dept. 2, Power Module Eng. Div., “I was in charge of the mounting design. I was responsible for determining the requirements to ensure reliability (e.g., materials, dimensions, processing conditions) required for installing SiC power semiconductors in power cards. In the design process, mounting defects occurred due to the high Young’s modulus (about triple that of Si), which is one of the characteristics of SiC materials. Such defects did not occur when Si was used. To cope with this unprecedented phenomenon, it was necessary to think laterally, beyond conventional ideas. To accurately understand the problem, I brought in an internal specialized department and external manufacturers of analysis instruments to gather different viewpoints and conducted genchi-genbutsu on-site verifications. This helped solve the problem and reflect the findings in the design requirements.”
DENSO calls these SiC technologies “REVOSIC,” conveying the idea of making “changes” in society through innovative technologies.
The company has been developing a comprehensive range of technologies from wafers to power modules and will continue R&D on REVOSIC SiC technologies and spread their use in electric vehicles to help realize a decarbonized society.