Abstract: Diamond possesses exceptional physical and chemical properties， making it a critical material in thermal， optical， mechanical， and electrical applications. However， the scarcity of natural diamond and the limitations of high-pressure high-temperature （HPHT） methods in producing large-area films have driven the search for alternative synthesis techniques. Since the mid-20th century， chemical vapor deposition （CVD） has emerged as a leading method. Among various CVD approaches， microwave plasma chemical vapor deposition （MPCVD） is highly regarded for its high growth quality， high plasma density， absence of electrode contamination， and stable deposition parameters. This review focuses on the significant advancements and potential of lower-frequency （915 MHz） MPCVD technology for synthesizing large-area， high-quality diamond films， addressing its unique mechanisms， current technological status， and future directions. The primary objective of this work is to provide a systematic and detailed review of 915 MHz MPCVD technology， encompassing theoretical simulations， reactor design， deposition processes， and applications. It aims to elucidate the fundamental advantages of the lower frequency， analyze the design evolution and performance of various 915 MHz reactor configurations， summarize the effects of key process parameters on film characteristics， and outline prevailing challenges and future trends. The core innovation and academic value of this review lie in its comprehensive synthesis of scattered research， highlighting how the shift from 2.45 GHz to 915 MHz is not merely a scaling exercise but introduces fundamental changes in plasma physics and chemistry that are conducive to large-scale， low-defect diamond synthesis. The methodology of this review involves a critical analysis of extensive published literature and experimental reports. It examines the theoretical underpinnings， including electromagnetic field simulations and plasma modeling specific to 915 MHz systems. The review categorizes and compares mainstream reactor designs such as ellipsoidal cavities， ring-antenna coupled systems， and slit-coupled configurations—based on their microwave coupling mechanisms， electric field distributions， plasma uniformity， and operational reliability. Furthermore， it synthesizes experimental data on how key process parameters （microwave power， chamber pressure， substrate temperature， gas composition， and flow dynamics） influence the growth rate， quality， uniformity， and stress of deposited diamond films， including single-crystal （SCD）， microcrystalline （MCD）， and nanocrystalline （NCD） diamond. The results indicate that 915 MHz MPCVD offers distinct advantages over its 2.45 GHz counterpart. The longer wavelength allows for the generation of a larger and more uniform plasma volume， which is fundamental for depositing diamond films on substrates with diameters exceeding 150 mm， with reports of up to 200 mm. The plasma characteristics at 915 MHz， featuring a longer plasma sheath， a modified electron energy distribution function （EEDF）， and gentler ion bombardment energy at the substrate， contribute to reduced intrinsic film stress and lower defect density. This is particularly promising for growing semiconductor-grade single-crystal diamond. Simulations and experiments confirm that optimized reactor geometries and precise tuning can effectively focus microwave energy， suppress secondary plasmas， and enhance process stability. Institutions and companies worldwide have demonstrated the production of high-quality， crack-free， free-standing diamond wafers using 915 MHz systems with powers ranging from 20 kW to over 75 kW. In conclusion， 915 MHz MPCVD represents a pivotal technological pathway for the industrial-scale synthesis of large-area， high-performance diamond films. Its inherent advantages in plasma stability and film quality control address critical bottlenecks in traditional methods. However， key challenges remain， including the development of high-power， stable solid-state microwave sources， advanced reactor designs for improved sealing and heat management， and a deeper quantitative understanding of the plasma-chemistry-film property relationships. Future progress hinges on multi-physics coupled simulations， intelligent process control with real-time diagnostics， and breakthroughs in heteroepitaxial integration for large-area single-crystal diamond substrates. Mastering this technology from fundamental mechanisms to engineering integration will be crucial to unlocking diamond's full potential in next-generation high-power electronics， quantum information science， and extreme optical applications.

Key words: MPCVD device; diamond film; 915 MHz; microwave plasma; simulation; large area