DC Arc Plasma Jet CVD of Diamond Materials: A Journey from Laboratory to Industrial Applications

Abstract

Conspectus Diamond possesses a unique combination of ultrahigh hardness, exceptional thermal conductivity, broadband optical transparency, and a high critical breakdown field and is regarded as the ultimate semiconductor material. Among various chemical vapor deposition (CVD) techniques for diamond synthesis, direct current (DC) arc plasma jet CVD stands out for its ultrahigh plasma density and gas temperatures (∼10,000 K), enabling the rapid, controlled growth of high-quality (up to optical-grade), large-size diamond films. Combined with its relatively low equipment cost, this technology is well-suited to the demands of industry. Early DC arc plasma jet CVD systems are limited by intrinsic equipment constraints, confining the technique to laboratory studies. Sustained efforts by research teams at the University of Science and Technology Beijing have since overcome key technical bottlenecks. A high-power DC arc plasma torch with rotating arc-root technology and a semi-closed gas circulation system enables cost-effective growth of large-area diamond materials. Moreover, stress accumulation remains a critical challenge during diamond deposition, particularly for large-area films, often leading to cracking. To mitigate this issue, composite substrates have been developed to facilitate controlled interfacial separation after growth, yielding free-standing diamond films up to 150 mm in diameter. To further extend diamond size, a 150 kW DC arc plasma jet CVD system with a dual-level magnetic field configuration is developed, providing enhanced plasma density and uniformity. At present, leveraging this technology, we achieve an annual production capacity of up to 75 million mm3 of free-standing diamond films and have established the world’s largest production line for thermal-grade diamond wafers. Meanwhile, precise control of growth parameters further enables the synthesis of diamond across a broad range of quality grades with diameters of 30–200 mm and thicknesses of 0.3–6.5 mm, meeting diverse application requirements. This includes tool-grade diamond for precision machining, diamond heat spreaders for satellite applications, optical-grade 5-inch diamond films, diamond for field-effect transistor devices, and single-crystal diamond approaching natural type IIa quality. In this Account, we summarize the evolution of DC arc plasma jet CVD, highlighting the critical innovations in reactor design and composite substrates that have transformed this technology from a laboratory approach into an industry platform for diamond manufacturing. Furthermore, through precise regulation of the growth process, diamond materials with tailored structures and properties can be engineered to meet diverse functional requirements. We believe that the continued maturation of this technology will overcome existing cost challenges, ultimately establishing diamond as a high-performance and cost-competitive advanced material for next-generation applications.