In the relentless pursuit of advancing semiconductor technology, researchers have long grappled with the challenge of efficiently thinning silicon carbide (SiC) wafers. These wafers, prized for their exceptional thermal conductivity and high breakdown electric field strength, are increasingly vital for power electronics in the energy sector. However, their extreme hardness—ranking 9.5 on the Mohs scale—has posed significant obstacles to conventional grinding methods. Enter Shuaipeng Chen, a researcher at the State Key Laboratory of Powder Metallurgy, Central South University in Changsha, China, who has made a groundbreaking advancement in this arena.
Chen and his team have developed a novel approach to grinding SiC wafers using intermetallic-bonded diamond grinding wheels. Their innovative method, detailed in a recent study published in ‘Jin’gangshi yu moliao moju gongcheng’ (translated to ‘Hard and Abrasive Materials Engineering’), leverages Cu3Sn and Cu6Sn5 intermetallic compounds as bonding agents. These compounds are used to create both rough and fine grinding diamond wheels, tailored specifically for thinning SiC wafers.
The research reveals that Cu3Sn, with its high bending strength of 206.6 MPa and impact toughness of 0.45 J/cm2, is ideal for preparing coarse grinding wheels. In contrast, Cu6Sn5, with a bending strength of 142.0 MPa and impact toughness of 0.31 J/cm2, is better suited for fine grinding wheels. “The key to our success lies in the unique properties of these intermetallic compounds,” Chen explains. “They provide the necessary strength and brittleness to effectively grind SiC wafers without compromising the surface quality.”
The study also highlights the critical role of porosity in the grinding process. By adjusting the amount of pore-forming agent, the researchers were able to optimize the grinding wheel’s performance. For instance, a mass fraction of 20% pore-forming agent resulted in a porosity of 35.0% and a bending strength of 42.5 MPa, which significantly improved the grinding wheel’s chip-holding and removal capabilities. “The pores act as reservoirs for chips and failed diamonds, ensuring a smooth and stable grinding process,” Chen notes.
The implications of this research are far-reaching. The energy sector, which relies heavily on efficient power electronics, stands to benefit immensely from these advancements. By improving the grinding quality of SiC wafers, Chen’s work paves the way for more efficient and reliable power devices, which are crucial for renewable energy systems and electric vehicles. Moreover, the reduced processing costs and improved surface quality of SiC chips could accelerate the adoption of SiC-based technologies in various industries.
Looking ahead, Chen and his team are already planning further improvements. They aim to enhance the brittleness of Cu6Sn5 through ceramicization, which could sharpen the grinding wheel and achieve even better surface roughness. Additionally, they are exploring the use of M0/0.5 diamond precision grinding wheels to minimize surface damage and reduce the need for subsequent chemical-mechanical polishing (CMP) processes.
As the demand for high-performance semiconductors continues to grow, innovations like Chen’s intermetallic-bonded diamond grinding wheels will be instrumental in driving the industry forward. By addressing the long-standing challenges of SiC wafer thinning, this research not only pushes the boundaries of current technology but also opens new avenues for future developments in the field.
