The Korea Electronics Technology Institute (KETI) has developed a technology that can fully attach silicon carbide (SiC) semiconductors to devices and components. SiC semiconductors are one of the broadband gap semiconductors, and they have become a core technology for improvement of energy efficiency because they have higher thermal conductivity, lower resistance and higher withstand voltage than the existing silicon (Si) semiconductors.
The KETI research team led by Dr. Oh Chul-min and Dr. Hong Won-sik announced on Dec. 10 that they have developed a solid-state mounting technology of SiC power semiconductors using silver (Ag). Solid-state mounting means that the material and the bonded body are attached together in a solid state without melting. KETI, JMJKorea, and KAIST cooperated for development of this technology.
The new solid-state mounting technology is characterized by low temperature adhesion, which reduces the thermal deformation of the semiconductor module. Unlike normal solid-state mounting technology, pressure is not applied to the semiconductor module. This not only eliminates the need for different pressurizing devices for each product, but also reduces internal defects like voids that can increase the electrical and thermal resistance of semiconductors, leading to the development of a highly trustable product. In addition, SiC was made to stably operate at high-temperature by taking advantage of the characteristics of silver, including high melting point, high heat conductivity and high electric conductivity.
Dr. Oh Chul-min from KETI said, "Since the performance of the SiC semiconductor can be directly applied to the module through the newly developed pressure-free low-temperature process, we expect to see the technology applied to the power conversion modules that require more stringent durability, such as electric car, robot, and smart factory."
The research team developed this solid-state mounting technology because the mounting material and method are important for commercialization of SiC semiconductors.
SiC semiconductors show an energy loss that is 70% lower than conventional Si semiconductors and are also considered to be more energy efficient than other semiconductors. However, the mounting material used in conventional Si power semiconductors is likely to turn into liquid at temperatures above 300°C. To find a new technology, researchers tested soldering, transition liquid mounting, and sinter mounting. However, soldering is known to cause environmental problems by using lead, and the transition liquid mounting required a long processing time. So far, research on sinter mounting has attracted the most attention, but it also has a disadvantage that defects often occur due to high temperatures and pressures generated in the process.