Micro-nanoscale laser subsurface vertical modification of 4H-SiC semiconductor materials: mechanisms, processes, and challenges.

Wide-bandgap semiconductor materials, exemplified by silicon carbide (SiC), have emerged as pivotal materials in semiconductor devices due to their exceptional chemical stability, high electron mobility, and thermal stability. With the rapid development of microelectronic devices and integrated optical circuits, the demand for high-yield and high-quality processing of SiC wafer has intensified. Traditional SiC wafer processing technologies suffer from low efficiency and high material loss, making it difficult to meet industrial demands. Therefore, the development of efficient, low-damage processing techniques has become a pressing issue in the SiC wafer processing field. Ultrashort pulsed laser processing, with its advantages of contact free processing, no mechanical stress, and small heat-affected zones, has garnered significant attention in SiC wafer processing in recent years. By generating a modified layer within the material, laser processing plays a crucial role in wafer fabrication. However, the key challenge lies in precisely controlling the thickness of the modified layer down to the micro-nano scale to minimize material loss. This review systematically discusses the interaction mechanisms and modification processes of laser with wide-bandgap semiconductor SiC materials. It focuses on the core issue in laser modification technology, where nonlinear effects make it difficult to precisely control the modification layer depth, thereby affecting both modification quality and processing efficiency. To address this, the paper summarizes the differences in modification mechanisms with lasers of varying pulse durations and proposes a multi-strategy solution to improve modification quality and processing efficiency through pulse control and synergistic optimization of process parameters. Additionally, this review provides a comprehensive overview of advanced SiC wafer detachment processes, including cold cracking stripping, chemically assisted stripping, ultrasonic stripping, and multi-laser composite stripping, and identifies the primary challenges and future directions in the field of SiC wafer processing.