As a representative of third-generation semiconductor materials, silicon carbide (SiC) has emerged as a revolutionary substrate for high-power electronic devices, radio frequency (RF) components, extreme-environment sensors and future quantum technologies due to its outstanding properties, including a wide band gap, high thermal conductivity, high breakdown electric field, high electron saturation drift velocity, excellent chemical stability and high-temperature tolerance. The exceptional thermal conductivity of SiC is particularly critical for mitigating self-heating effects in wide-bandgap semiconductor devices such as GaN and Ga₂O₃. However, the performance enhancement and broad application of SiC-based devices face a fundamental bottleneck: conventional heteroepitaxial growth technologies, such as GaN/SiC, InP/SiC, and 3C-SiC/Si, inevitably introduce defects like high-density interface dislocations and cracks. These stem from significant lattice mismatch and differences in thermal expansion coefficients between materials, leading to substantial degradation in device performance. Moreover, high-quality crystal forms such as 4H-SiC cannot be directly epitaxially grown on mainstream substrates like silicon, which severely restricts material choices and limits the design freedom for heterogeneous integration.

In this context, wafer bonding offers breakthrough solutions and demonstrates significant research value. Direct bonding techniques, such as surface-activated bonding and plasma-activated bonding, enable precise nanoscale control of the interface. These methods effectively circumvent issues related to lattice mismatch and thermal stress, confine defects to an ultrathin interfacial region, and largely preserve the intrinsic properties of functional materials. The core significance of this approach lies in three aspects. 1) Enabling homogeneous SiC bonding to construct three-dimensional power modules with low interface resistance and high thermal stability, thereby reducing the cost of large-size wafer production. 2) Unlocking the potential for heterogeneous integration of SiC. As a high-thermal-conductivity substrate, SiC can be bonded with materials such as Ga₂O₃, diamond, Si, GaAs, and InP, substantially improving heat dissipation efficiency. Leveraging mature silicon processes also promotes the development of high-density integrated circuits, while intermediate layer technologies further optimize interfacial performance. 3) Providing large-size, low-cost integration solutions. Therefore, in-depth research on SiC wafer bonding technology is not only critical to addressing the key bottlenecks of currently limiting SiC-based device performance and unleasing its vast application potential, but also serves as a core driver advancing semiconductor heterogeneous integration technology toward higher performance, broader material compatibility and lower cost. It holds profound strategic significance for the innovation and application of next-generation semiconductor devices.

As a key process in semiconductor manufacturing, the advancement of wafer bonding technology plays a vital role in enhancing device performance. This paper provides a systematic review of the research progress and application of SiC wafer bonding technology. First, the classification system of wafer bonding technologies is summarized, with a focus on two representative methods prominent in the SiC field. One is surface activation technology tailored for SiC material characteristics, including plasma activation bonding and room-temperature surface activation bonding. These techniques significantly reduce the required temperature and pressure for bonding through pretreatment. The other is Smart Cut technology, which combines ion implantation and bonding processes. This approach is particularly suitable for producing high-quality thin-film composite substrates, such as silicon-on-silicon carbide on insulator (SiCOI) structures, offering an ideal material platform for subsequent device fabrication. Second, this review details specific technical pathways for SiC wafer bonding. This includes heterogeneous bonding between SiC and other semiconductor materials, such as Si, Ga₂O₃, and InP, which aims to integrate the superior properties of different materials to expand device functionality. Also covered is homogeneous bonding between SiC wafers, which is essential for producing large-size, high-quality SiC substrates or specific structural devices such as micro electro mechanical system (MEMS) sensors. The paper examines various bonding methods along with key process parameters and associated challenges. Third, this paper highlights application examples of SiC-based devices that demonstrate the practical value of bonding technology. These include: MEMS sensors based on SiC homogeneous bonding, which exhibit high-temperature and radiation-resistant properties; photonic devices enabled by SiCOI structures, benefiting from its superior optical confinement; RF devices fabricated by bonding piezoelectric materials such as lithium niobate (LiNbO₃) with SiC, combining efficient energy transduction with the high-frequency and high-power advantages of SiC; high-performance, low-cost SiC power devices produced by bonding high-quality single-crystal SiC layer with low-cost polycrystalline SiC or reclaimed single crystal SiC substrates via the Smart Cut process. Finally, the paper systematically summarizes the critical influence of these wafer bonding methods on the final bonding quality and the thermal performance of devices, offering valuable reference for researchers and engineers in selecting and optimizing bonding processes.

SiC wafer bonding technology effectively overcomes the thermal conduction bottlenecks and self-heating effects inherent in traditional semiconductor materials through heterogeneous integration. It enables low-damage bonding of SiC with Si, Ga₂O₃, InP and various insulating substrates, while also driving advances in homogeneous bonding toward larger wafer sizes and lower stress levels. This progress provides high-performance solutions for power devices, RF modules, MEMS sensors and photonic integration platforms. The core focus of future research lies in further uncovering the physico-chemical mechanisms at the bonding interface. There is a need to systematically elucidate the relationships among interfacial thermal resistance, contact resistance and bonding strength. Concurrent development of advanced processes, such as those enabling low lattice damage, submicron alignment, and reduced wafer warpage, is essential, with particular emphasis on defect control and energy band engineering in oxide intermediate layers. By establishing quantitative models that link the microstructural characteristics of the interface to its macroscopic electro-thermal-mechanical properties, collaborative optimization across multiple physical fields can be achieved. This will ultimately unlock the full potential of SiC wafer bonding in applications such as extreme-environment electronics, high-efficiency energy conversion, and high-speed optical communications, paving the way for a new generation of heterogeneous integrated material platforms that surpass the limitations of silicon-based technologies.